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  • General Chemistry  (809)
  • Inorganic Chemistry  (723)
  • Cell & Developmental Biology
  • STRUCTURAL MECHANICS
  • 1975-1979  (1,990)
  • 1970-1974
  • 1960-1964
  • 1975  (1,990)
Collection
Keywords
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  • 1975-1979  (1,990)
  • 1970-1974
  • 1960-1964
Year
  • 1
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    Fracture testing with surface crack specimens (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: This paper is a report of ASTM Task Group E24.01.05 on Part-Through Crack Testing. It includes recommendations for the design, preparation, and static fracture testing of surface crack specimens based on the current state of the art. The recommendations are preceded by background information including discussions of stress intensity factors, crack opening displacements, and fracture toughness values associated with surface crack specimens. Cyclic-load and sustained-load tests are discussed briefly. Recommendations for further research are included.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Testing and Evaluation; 3; Sept
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  • 2
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    Structural reanalysis via a mixed method (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A study is made of the approximate structural reanalysis technique based on the use of Taylor series expansion of response variables in terms of design variables in conjunction with the mixed method. In addition, comparisons are made with two reanalysis techniques based on the displacement method. These techniques are the Taylor series expansion and the modified reduced basis. It is shown that the use of the reciprocals of the sizing variables as design variables (which is the natural choice in the mixed method) can result in a substantial improvement in the accuracy of the reanalysis technique. Numerical results are presented for a space truss structure.
    Keywords: STRUCTURAL MECHANICS
    Type: Computers and Structures; 5; Apr. 197
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  • 3
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    Three-dimensional elastic stress and displacement analysis of finite geometry solids containing cracks (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement distributions in various bodies containing cracks. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. When decoupling the equations and their boundary conditions is not possible, the use of a successive approximation procedure permits the analytical solution of the resulting ordinary differential equations. The results obtained show a considerable potential for using this method in the three-dimensional analysis of finite geometry solids and suggest a possible extension of this technique to nonlinear material behavior.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 11; June 197
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  • 4
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    Structural design and analysis. Part 1 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Topics in anisotropic elasticity are discussed along with the analysis of truss, beam, frame, and membrane components. Attention is given to failure criteria and failure analysis of composite structural components. Other subjects considered are related to the analysis of plates, the analysis of shells, and questions of wave propagation and impact in composite materials. Individual items are announced in this issue.
    Keywords: STRUCTURAL MECHANICS
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  • 5
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    Analysis of truss, beam, frame, and membrane components (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Truss components are considered, taking into account composite truss structures, truss analysis, column members, and truss joints. Beam components are discussed, giving attention to composite beams, laminated beams, and sandwich beams. Composite frame components and composite membrane components are examined. A description is given of examples of flat membrane components and examples of curved membrane elements. It is pointed out that composite structural design and analysis is a highly interactive, iterative procedure which does not lend itself readily to characterization by design or analysis function only.-
    Keywords: STRUCTURAL MECHANICS
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  • 6
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    Panel flutter optimization by gradient projection (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A gradient projection optimal control algorithm incorporating conjugate gradient directions of search is described and applied to several minimum weight panel design problems subject to a flutter speed constraint. New numerical solutions are obtained for both simply-supported and clamped homogeneous panels of infinite span for various levels of inplane loading and minimum thickness. The minimum thickness inequality constraint is enforced by a simple transformation of variables.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal for Numerical Methods in Engineering; 9; 2, 19; 1975
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  • 7
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    Application of boundary integral method to elastoplastic analysis of V-notched beams (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The boundary integral equation method was applied in the solution of the plane elastoplastic problems. The use of this method was illustrated by obtaining stress and strain distributions for a number of specimens with a single edge notch and subjected to pure bending. The boundary integral equation method reduced the nonhomogeneous biharmonic equation to two coupled Fredholm-type integral equations. These integral equations were replaced by a system of simultaneous algebraic equations and solved numerically in conjunction with the method of successive elastic solutions.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 11; Apr. 197
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  • 8
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    Surface energy and surface tension at holes and cracks (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The concept of surface tension and surface energy of solids was used by Griffith to obtain a criterion for the extension of cracks in brittle materials. Griffith, however, neglected the stresses due to the normal traction at the crack implied by the surface tension. A complete solution to the problem of an elliptic hole in an infinite plate with surface tension loading at the hole is given. Complex potentials are given in closed form in terms of elliptic integrals of the first, second, and third kinds. Stress distributions are studied. For a flat crack, the nature of the singularity at the tip is shown to be radically different from that usually encountered in fracture mechanics. The implications of our analysis for theories of fracture in brittle materials are discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 11; Feb. 197
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  • 9
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    The computer in shell stability analysis (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Some examples in which the high-speed computer has been used to improve the static stability analysis capability for general shells are examined. The fundamental concepts of static stability are reviewed with emphasis on the differences between linear bifurcation buckling and nonlinear collapse. The analysis is limited to the stability of conservative systems. Three examples are considered. The problem of cylinders subjected to bending loads is used as an example to illustrate that a simple structure can have a sufficiently complicated nonlinear behavior to require a computer analysis for accurate results. An analysis of the problems involved in the modeling of stiffening elements in plate and shell structures illustrates the necessity that the analyst recognizes all important deformation modes. The stability analysis of the Skylab structure indicates the size of problems that can be solved with current state-of-the-art capability.
    Keywords: STRUCTURAL MECHANICS
    Type: American Society of Civil Engineers; Journal
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  • 10
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    Boundary-layer effect in panel flutter (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The present note shows that if the supersonic Mach number is not too large, an analytical expression can be obtained for the generalized aerodynamic force relating the pressure fluctuation at the surface of a flexible plate to the plate displacement in the presence of an adjacent boundary layer. The low supersonic Mach numbers are the ones of maximum interest since it is in this Mach number region that the boundary layer has the most influence. In this respect, Dowell (1971) has already shown that the presence of a boundary layer causes about a 300% increase in flutter dynamic pressure at a Mach number of about 1.2, while it causes only about a 20% increase at a Mach number of 2.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 13; Sept
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  • 11
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    Fracture angle and strain-energy-density-factor of a crack at hole at an arbitrary angle (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: For both the maximum stress criterion and strain-energy-density-factor (S) theory, fracture angle (the initial angle of crack growth) is predicted by using opening and sliding mode stress intensity factors. These theoretical predictions are consistent with experimental fracture angles. For the S theory, the crack spreads in the direction of the negative fracture angle in a plane for which S is a minimum. This quantity was obtained analytically. The experimental data of the critical S on plexiglass fracture specimens remains essentially constant.
    Keywords: STRUCTURAL MECHANICS
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  • 12
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    Design of composite structural components (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Aspects related to the evolution of design are examined. A schematic of the evolution of the design objective and a schematic of designing a structural component from fiber composites are presented. A description of conventional design procedures is given, taking into account design handbooks, design guides, various sources of design information, and typical design data. Optimization methods are discussed, giving attention to parametric studies, the structural index method, aspects of structural synthesis, and questions of simultaneous material and structural design optimization.
    Keywords: STRUCTURAL MECHANICS
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  • 13
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    Experimental characterization of composites (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The experimental characterization for composite materials is generally more complicated than for ordinary homogeneous, isotropic materials because composites behave in a much more complex fashion, due to macroscopic anisotropic effects and lamination effects. Problems concerning the static uniaxial tension test for composite materials are considered along with approaches for conducting static uniaxial compression tests and static uniaxial bending tests. Studies of static shear properties are discussed, taking into account in-plane shear, twisting shear, and thickness shear. Attention is given to static multiaxial loading, systematized experimental programs for the complete characterization of static properties, and dynamic properties.
    Keywords: STRUCTURAL MECHANICS
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  • 14
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    The automated multi-stage substructuring system for NASTRAN (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The substructuring capability developed for eventual installation in Level 16 is now operational in a test version of NASTRAN. Its features are summarized. These include the user-oriented, Case Control type control language, the automated multi-stage matrix processing, the independent direct access data storage facilities, and the static and normal modes solution capabilities. A complete problem analysis sequence is presented with card-by-card description of the user input.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 571-591
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  • 15
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    Analysis of nonlinear structures via mode synthesis (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An effective procedure for NASTRAN was developed that permits any number of substructures of any size to be synthesized for the purpose of developing normal modes of vibration of the complete structural system. The technique is extended to permit modal transient analysis of the subdivided system. This latter procedure permits the use of NASTRAN's ability to include nonlinear forces in the problem. The five-phase process is accomplished using standard NASTRAN rigid formats with problem-independent alter packages and DMAP sequences.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 341-360
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  • 16
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    On eigenvectors of multiple eigenvalues obtained in NASTRAN (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: In the case of nonmultiple eigenvalues, each of the three real eigenvalue extraction methods available in NASTRAN will, for a given type of normalization, give essentially the same eigenvectors, but this is not so in the case of multiple eigenvalues. This discrepancy is explained and illustrated by considering the example of a NASTRAN demonstration problem that has both multiple and nonmultiple eigenvalues.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 285-300
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  • 17
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    NASTRAN solutions of problems described by simultaneous parabolic differential equations (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: NASTRAN solution techniques are shown for a numerical analysis of a class of coupled vector flow processes described by simultaneous parabolic differential equations. To define one physical problem type where equations of this form arise, the differential equations describing the coupled transfers of heat and mass in mechanical equilibrium with negligible mass average velocity are presented and discussed. Also shown are the equations describing seepage when both electrokinetic and hydrodynamic forces occur. Based on a variational statement of the general problem type, the concepts of scalar transfer elements and parallel element systems are introduced. It is shown that adoptation of these concepts allows the direct use of NASTRAN's existing Laplace type elements for uncoupled flow (the heat transfer elements) for treating multicomponent coupled transfer. Sample problems are included which demonstrate the application of these techniques for both steady-state and transient problems.
    Keywords: STRUCTURAL MECHANICS
    Type: NASTRAN: Users' Experiences; p 65-90
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  • 18
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    NASTRAN maintenance and enhancement experiences (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The current capability is described which includes isoparametric elements, optimization of grid point sequencing, and eigenvalue routine. Overlay and coding errors were corrected for cyclic symmetry, transient response, and differential stiffness rigid formats. Error corrections and program enhancements are discussed along with developments scheduled for the current year and a brief description of analyses being performed using the program.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences (SEE N75-31485 22-39)
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  • 19
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    Understanding the NASTRAN structural plotter (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Functions of the plotting hardware and the operations performed by the NASTRAN structural plotter are summarized to provide the user an insight into how the program works. The processing performed in response to each plot command is described and the interrelationships of the various parameters are explained. To assist in the effective and efficient utilization of the system, examples are provided which also illustrate several not yet documented capabilities of the Level 16 structural plotter.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 475-492
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  • 20
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    The impact of fourth generation computers on NASTRAN (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The impact of 'fourth generation' computers (STAR 100 or ILLIAC 4) on NASTRAN is considered. The desired characteristics of large programs designed for execution on 4G machines are described.
    Keywords: STRUCTURAL MECHANICS
    Type: NASTRAN: Users' Experiences; p 431-447
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  • 21
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    NASTRAN thermal analyzer status, experience, and new developments (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The unique finite element based NASTRAN Thermal Analyzer originally developed as a general purpose heat transfer analysis incorporated into the NASTRAN system is described. The current status, experiences from field applications, and new developments are included.
    Keywords: STRUCTURAL MECHANICS
    Type: NASTRAN: User's Experiences; p 523-528
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  • 22
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    Recent improvements to BANDIT (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The NASTRAN preprocessor BANDIT, which improves NASTRAN's computer efficiency by resequencing grid point labels for reduced matrix bandwidth is described. The addition of (1) the Gibbs-Poole-Stockmeyer (GPS) algorithm, and (2) the user option to reduce matrix profile rather than matrix bandwidth is also described. It is shown that, compared to the Cuthill-McKee algorithm on which BANDIT was originally based, GPS is faster and achieves similar results. Current capabilities and options of BANDIT are summarized.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 511-521
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  • 23
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    Transient analysis of bodies with moving boundaries using NASTRAN (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A scheme is presented which allows the modeling of a moving boundary with NASTRAN NOLIN cards. Various aspects and limitations of the approach are explained. Recommendations are given as to the procedure to be used in implementing the method.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 377-388
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  • 24
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    Nonlinear seismic analysis of a reactor structure impact between core components (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The seismic analysis of the FFTF-PIOTA (Fast Flux Test Facility-Postirradiation Open Test Assembly), subjected to a horizontal DBE (Design Base Earthquake) is presented. The PIOTA is the first in a set of open test assemblies to be designed for the FFTF. Employing the direct method of transient analysis, the governing differential equations describing the motion of the system are set up directly and are implicitly integrated numerically in time. A simple lumped-nass beam model of the FFTF which includes small clearances between core components is used as a "driver" for a fine mesh model of the PIOTA. The nonlinear forces due to the impact of the core components and their effect on the PIOTA are computed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 397-418
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  • 25
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    Application of NASTRAN in nonlinear analysis of a cartridge case neck separation malfunction (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The problem of case neck separation malfunction in the field of ammunition structural analysis is investigated. The axi-symmetric solid of revolution RING element was utilized in the manual piecewise linear analysis to obtain the expansion of the wall of the cartridge case and barrel chamber by the pressure of propellant gases and the stresses in the structure. The analysis included the varying material properties along the wall of the case and the chamber. Additional instructions were provided to change the element material ID's without recomputing the entire stiffness matrix.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 389-395
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  • 26
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    The effects of localized damping on structural response (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The effect of localized structural damping on the excitability of higher order normal modes of the large space telescope was investigated. A preprocessor computer program was developed to incorporate Voigt structural joint damping models in a NASTRAN finite-element dynamic model. A postprocessor computer program was developed to select critical modes for low-frequency attitude control problems and for higher frequency fine-stabilization problems. The mode selection is accomplished by ranking the flexible modes based on coefficients for rate gyro, position gyro, and optical sensors, and on image-plane motions due to sinusoidal or random power spectral density force and torque inputs.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 301-320
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  • 27
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    Shuttle wing panel stability analysis (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The use of the NASTRAN program in the shuttle wing stability analysis is described, and details of the actual structure, the finite element idealization, and the NASTRAN results are given. A comparison of the NASTRAN results with those obtained with another computer program and with hand generated results indicates good agreement. An alternate approach for solving eigenvalue problems is illustrated and shows a considerable savings in computer time. Some emphasis is placed on the relationship of the NASTRAN analysis in the design process bringing out more clearly the contribution of the results and showing the importance of the mode plots. A deficiency in the NASTRAN plate elements when used to model structures made up of intersecting plates is discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 137-169
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  • 28
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    Modeling damaged wings: Element selection and constraint specification (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The NASTRAN analytical program was used for structural design, and no problems were anticipated in applying this program to a damaged structure as long as the deformations were small and the strains remained within the elastic range. In this context, NASTRAN was used to test three-dimensional analytical models of a damaged aircraft wing under static loads. A comparison was made of calculated and experimentally measured strains on primary structural components of an RF-84F wing. This comparison brought out two sensitive areas in modeling semimonocoque structures. The calculated strains were strongly affected by the type of elements used adjacent to the damaged region and by the choice of multipoint constraints sets on the damaged boundary.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 105-119
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  • 29
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    A survey of NASTRAN improvements since level 15.5 (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Several improvements and capabilities were developed and installed in intermediate levels and are being analyzed and evaluated. A survey of current improvements to the program is presented which includes static analysis with differential stiffness rigid format, normal modes with differential stiffness rigid format, the TRIAAX and TRAPAX elements, the CNGRNT feature, fully stressed design, element strain energy and grid point force balance, and complex modal displacement plots.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 11-22
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  • 30
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    NASTRAN pre and postprocessors using low-cost interactive graphics (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A design for a NASTRAN preprocessor is given to illustrate a typical preprocessor. Several displays of NASTRAN models illustrate the preprocessor's capabilities. A design of a NASTRAN postprocessor is presented along with an example of displays generated by that NASTRAN processor.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 449-460
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  • 31
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    Application Experiences of NASTRAN Thermal Analysis in Engineering (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The application of the thermal analysis phase of NASTRAN in engineering is described. Some illustrative samples are presented to demonstrate the applicability and limitation of NASTRAN thermal analysis capability. The results of the evaluation of the relative efficiency, applicability and accuracy among NASTRAN, other finite element programs, and finite difference programs are also presented.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: User's Experiences; p 529-531
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  • 32
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    The NASTRAN Error Correction Information System (ECIS) (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A data management procedure, called Error Correction Information System (ECIS), is described. The purpose of this system is to implement the rapid transmittal of error information between the NASTRAN Systems Management Office (NSMO) and the NASTRAN user community. The features of ECIS and its operational status are summarized. The mode of operation for ECIS is compared to the previous error correction procedures. It is shown how the user community can have access to error information much more rapidly when using ECIS. Flow charts and time tables characterize the convenience and time saving features of ECIS.
    Keywords: STRUCTURAL MECHANICS
    Type: NASTRAN: Users' Experiences; p 493-509
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  • 33
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    The dynamic analysis of submerged structures (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Methods are described by which the dynamic interaction of structures with surrounding fluids can be computed by using finite element techniques. In all cases, the fluid is assumed to behave as an acoustic medium and is initially stationary. Such problems are solved either by explicitly modeling the fluid (using pressure or displacement as the basic fluid unknown) or by using decoupling approximations which take account of the fluid effects without actually modeling the fluid.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 419-429
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  • 34
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    Application of NASTRAN to propeller-induced ship vibration (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An application of the NASTRAN program to the analysis of propeller-induced ship vibration is presented. The essentials of the model, the computational procedure, and experience are described. Desirable program enhancements are suggested.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 361-375
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    Dynamic substructure analysis of the International Ultraviolet Explorer (IUE) spacecraft (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The results are presented of a steady state vibration analysis of the IUE spacecraft simulating its sinusoidal vibration test. The model of the spacecraft, including solar arrays and the scientific instrument, consisted of three separate substructure models one of which was used to represent the two identical solar arrays. Substructuring techniques were used since the large overall size of the problem precluded solving it utilizing a single model. The models used for each substructure are discussed, including reduction to an acceptable size for the combined dynamic analysis. The DMAP alters needed for performing the modal analysis and the subsequent modal frequency response and substructure data recovery are included. Comparison of the results with data obtained during vibration tests of the spacecraft are also included.
    Keywords: STRUCTURAL MECHANICS
    Type: NASTRAN: Users' Experiences; p 221-248
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  • 36
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    Application of NASTRAN to a fluid solids unit in the petroleum industry (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The application of NASTRAN to the design of a fluid solids unit plenum/cyclone/dipleg assembly is described. The major loads considered are thermal, pressure, and gravity. Such applications are of interest in the petroleum industry since the equipment described is historically critical.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 121-136
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  • 37
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    NASTRAN nonlinear vibration analysis of beam and frame structures (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A capability for the nonlinear vibration analysis of beam and frame structures suitable for use with NASTRAN level 15.5 is described. The nonlinearity considered is due to the presence of axial loads induced by longitudinal end restraints and lateral displacements that are large compared to the beam height. A brief discussion is included of the mathematical analysis and the geometrical stiffness matrix for a prismatic beam (BAR) element. Also included are a brief discussion of the equivalent linearization iterative process used to determine the nonlinear frequency, the required modifications to subroutines DBAR and XMPLBD of the NASTRAN code, and the appropriate vibration capability, four example problems are presented. Comparisons with existing experimental and analytical results show that excellent accuracy is achieved with NASTRAN in all cases.
    Keywords: STRUCTURAL MECHANICS
    Type: NASTRAN: Users' Experiences; p 259-284
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  • 38
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    Pressure deformation of tires using differential stiffness for triangular solid-of-revolution elements (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The derivation is presented of the differential stiffness for triangular solid of revolution elements. The derivation takes into account the element rigid body rotation only, the rotation being about the circumferential axis. Internal pressurization of a pneumatic tire is used to illustrate the application of this feature.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 171-179
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  • 39
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    NASTRAN applications to aircraft propulsion systems (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The use of NASTRAN in propulsion system structural integration analysis is described. Computer support programs for modeling, substructuring, and plotting analysis results are discussed. Requirements on interface information and data exchange by participants in a NASTRAN substructure analysis are given. Static and normal modes vibration analysis results are given with comparison to test and other analytical results.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 91-104
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  • 40
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    NASTRAN status and plans (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Current status and future NASA plans for the NASTRAN program are presented and discussed. Information is also presented to indicate the extent of NASTRAN use throughout the world.
    Keywords: STRUCTURAL MECHANICS
    Type: NASTRAN: Users' Experiences; p 1-10
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  • 41
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    Loadcell supports for a dynamic force plate (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An apparatus was developed to accurately measure components of force along three mutually perpendicular axes, torque, and the center of pressure imposed by the foot of a subject walking over its surface. The data obtained were used to supplement high-speed motion picture and electromyographic (EMG) data for in-depth studies of normal or abnormal human gait. Significant features of the design (in particular, the mechanisms used to support the loadcell transducers) are described. Results of the development program and typical data obtained with the device are presented and discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Kennedy Space Center 9th Aerospace Mech. Symp.; p 265-280
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  • 42
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    An improved DMAP capability (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A set of improvements designed and implemented into a test version of the NASTRAN DMAP (Direct Matrix Abstraction Program) compiler is presented. These modifications simplify the use of the DMAP control language while enhancing its power and versatility. The implemented changes are described and examples are presented to illustrate their use.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 595-602
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  • 43
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    Scanning NASTRAN output data for maximum and minimum values (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A computer program called NASCAN (NASTRAN scan) is described. NASCAN enables users to scan lengthy NASTRAN output files for maximum and minimum values in easy user oriented categories. Areas of high stress or deflections in any of the NASTRAN rigid formats are quickly detected and listed out for project documentations. The NASTRAN model is then revised if necessary by updating an input file tape which is processed through the NASTRAN program.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 461-474
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  • 44
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    A review of research on aeronautical fatigue in the United States, 1973 - 1975 (1975)
    In:  Other Sources
    Details
    Publication Date: 2016-03-09
    Keywords: STRUCTURAL MECHANICS
    Type: Eidenoessisches Flugzeugwerk Minutes of the 14th Conf. of the Intern. Comm. on Aeron. Fatigue (ICAF); 101 p
    Format: text
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  • 45
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    Rigid format alter packets for the analysis of electromagnetic field problems (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The computer program NASTRAN is used to solve electromagnetic field problems. The diffusion equation and the boundary conditions valid for problems of these kinds together with a replacing potential energy function are given. The extent to which an analogy with finite element displacement and temperature approaches holds is indicated. The outputting of complex quantities is made possible after adjustment of standard rigid format 1 input data blocks to module SDR2. The applications made involve the study of the proximity effect in a system of three parallel conductors and the analysis of the magnetic field in the vicinity of the points of contact in circuit breakers.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 557-570
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  • 46
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    Analytical and experimental study of two concentric cylinders coupled by a fluid gap (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: From a structural point of view a liquid coolant type nuclear reactor consists of a heavy steel vessel containing the core and related mechanical components and filled with a hot fluid. This vessel is protected from the severe environment of the core by a shielding structure, the thermal liner, which is usually a relatively thin steel cylinder concentric with the reactor vessel and separated from it by a gap filled with the coolant fluid. This arrangement leads to a potential vibration problem if the fundamental frequency, or one of the higher natural vibration frequencies, of this liner system is close to the frequency of some vibration source present in the reactor vessel. The shell rigidly clamped at its base and free at the top was investigated since it is a better description of the conditions encountered in typical reactor designs.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 249-257
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  • 47
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    A failsafe analysis using NASTRAN's piecewise linear analysis and a nine node linear crack element (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A two-dimensional crack element was implemented into NASTRAN as a user dummy element and used to study failsafe characteristics of the C5A fuselage. The element is formulated from Reitsner's functional requiring that it satisfy compatability with the linear boundary displacement elements in NASTRAN. Its accuracy is demonstrated by analyzing for the stress intensity factors of two simple crack configurations for which there are classic solutions.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 181-200
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  • 48
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    NASTRAN modeling and analysis of rigid and flexible walled acoustic cavities (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The acoustic slot elements, CSLOTi, are applied to analyze two-dimensional enclosures with fixed or moving boundaries. The capability utilized to compute (a) the acoustic natural modes and frequencies of a rigid walled enclosure and (b) the sound pressure at any point inside an enclosure when the surrounding walls are forced to vibrate. Applications to an automobile passenger compartment illustrate the technique. The axisymmetric fluid elements, CFLUIDi, are used in conjunction with a suitable choice of symmetry planes and a model of the surrounding structure to approximate a two-dimensional enclosure with flexible walls. The enclosure walls are modeled using finite elements or structural modes. Illustrative examples include a comparison of rectangular cavity modes with those calculated using the acoustic slot element and the free vibration modes of two enclosures coupled through a flexible rectangular panel.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: User's Experiences; p 615-631
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  • 49
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    On fracture toughness evaluation for semi-brittle fracture (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The existing methods of assessing the fracture toughness of materials exhibiting semi-brittle fracture are critically reviewed. The methods concern the Crack Growth Resistance (R-curve), the Crack Opening Displacement (COD), and the J-integral. An analysis of the shortcomings of the methods described makes it possible to formulate a new definition of fracture toughness appropriate to semi-brittle fracture. An improved simple experimental method for measuring fracture toughness for semi-brittle fracture is proposed which takes into account both crack growth and plastic nonlinear effects at crack front. The proposed method is shown to be free of the theoretical and experimental discrepancies encountered in the R-curve, COD, and J-integral methods.
    Keywords: STRUCTURAL MECHANICS
    Type: Engineering Fracture Mechanics; 7; Mar. 197
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  • 50
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    Measurement of the spectrum of the submillimeter cosmic background (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The spectrum of the night sky has been measured in the wave number range from 3 to 40 per cm using a fully calibrated liquid-helium-cooled balloon-borne spectrophotometer at an elevation of 39 km. A model based on the known molecular parameters was used to subtract the atmospheric emission. In the range from 4 to 17 per cm, the spectrum of the background radiation is that of a blackbody with a temperature of about 2.99 K.
    Keywords: STRUCTURAL MECHANICS
    Type: Physical Review Letters; 34; Apr. 21
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  • 51
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    Users manual: MSFC crack growth analysis computer program (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The input and output formats and options are described along with the technical approaches used within the computer program. Included are example data and problems.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-143923
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  • 52
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    Design and fabrication of composite wing panels containing a production splice (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Bolted specimens representative of both upper and lower wing surface splices of a transport aircraft were designed and manufactured for static and random load tension and compression fatigue testing including ground-air-ground load reversals. The specimens were fabricated with graphite-epoxy composite material. Multiple tests were conducted at various load levels and the results were used as input to a statistical wearout model. The statically designed specimens performed very well under highly magnified fatigue loadings. Two large panels, one tension and compression, were fabricated for testing by NASA-LRC.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-2549
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  • 53
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    Vibration of skewed cantilever plates and helicoidal shells (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Theoretical vibration frequencies and mode shapes are obtained for skewed plates and helicoidal shells with a cantilever boundary. Using Hamilton's law of varying action, a power series solution is developed to obtain converged numerical results for the five lowest frequencies. Effects of geometrical variables such as aspect ratio, sweep angle and shell radius to thickness ratio are investigated. Accuracy of the solution method is substantiated by comparison with existing skewed plate spherical cap, and conical shell results.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-2588
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  • 54
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    Delta wing flutter based on doublet lattice method in NASTRAN (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The subsonic doublet-lattice method (DLM) aeroelastic analysis in NASTRAN was successfully applied to produce subsonic flutter boundary data in parameter space for a large delta wing configuration. Computed flow velocity and flutter frequency values as functions of air density ratio, flow Mach number, and reduced frequency are tabulated. The relevance and the meaning of the calculated results are discussed. Several input-deck problems encountered and overcome are cited with the hope that they may be helpful to NASTRAN Rigid Format 45 users.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 603-613
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  • 55
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    Application of NASTRAN for stress analysis of left ventricle of the heart (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Knowing the stress and strain distributions in the left ventricular wall of the heart is a prerequisite for the determination of the muscle elasticity and contractility in the process of assessing the functional status of the heart. NASTRAN was applied for the calculation of these stresses and strains and to help in verifying the results obtained by the computer program FEAMPS which was specifically designed for the plane-strain finite-element analysis of the left ventricular cross sections. Adopted for the analysis are the true shape and dimensions of the cross sections reconstructed from multiplanar X-ray views of a left ventricle which was surgically isolated from a dog's heart but metabolically supported to sustain its beating. A preprocessor was prepared to accommodate both FEAMPS and NASTRAN, and it has also facilitated the application of both the triangular element and isoparameteric quadrilateral element versions of NASTRAN. The stresses in several crucial regions of the left ventricular wall calculated by these two independently developed computer programs are found to be in good agreement. Such confirmation of the results is essential in the development of a method which assesses the heart performance.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center NASTRAN: Users' Experiences; p 201-219
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  • 56
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    Modal coupling procedures adapted to NASTRAN analysis of the 1/8-scale shuttle structural dynamics model. Volume 2: Supporting data (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Appendices are presented to a dynamic substructuring analysis of the 1/8 scale space shuttle orbiter finite element model. For Volume 1, see .
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-132667
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  • 57
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    A finite-difference program for stresses in anisotropic, layered plates in bending (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The interlaminar stresses induced in a layered laminate that is bent into a cylindrical surface are studied. The laminate is modeled as a continuum, and the resulting elasticity equations are solved using the finite difference method. The report sets forth the mathematical framework, presents some preliminary results, and provides a listing and explanation of the computer program. Significant among the results are apparent symmetry relationships that will reduce the numerical size of certain problems and an interlaminar stress behavior having a sharp rise at the free edges.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-8059
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  • 58
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    Buckling tests of three 4.6 meter diameter aluminum honeycomb sandwich conical shells loaded under external pressure (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Three aluminum honeycomb sandwich conical shells with a 120 apex angle and a 4.6-m (15.0-ft) base diameter were loaded to failure by a uniform external pressure. The cones differed from one another only in the thickness of their respective face sheets. Test specimen details, test procedure, and test results are discussed. Both buckling and prebuckling data are compared with appropriate theoretical predictions, and good agreement was obtained between test and theory. Extensive imperfection measurements were made and reported on the three cones in the as fabricated condition.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-7935 , L-9936
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  • 59
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    Analytical and experimental investigation of fatigue in a sheet specimen with an interference-fit bolt (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A fatigue analysis, based on finite-element calculations and fatigue tests, was conducted for an aluminum-alloy sheet specimen with a steel interference-fit bolt. The stress analysis of the region near the bolt hole showed that the beneficial effect of an interference-fit bolt can be interpreted as the combined result of two effects: (1) load transfer through the bolt and (2) the compressive interference stresses in the sheet. Results of the fatigue tests show that progressively higher interference levels produced longer fatigue lives. The tests also show that a high level of interference prevents fretting at the bolt-sheet interface and that interferences larger than this level produced little additional improvement in fatigue life.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-7926 , L-10067
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  • 60
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    Analytical modeling requirements for tilting proprotor aircraft dynamics (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Proprotor and cantilever wing aeroelastic behavior is applied to a gimballed rotor and a hingeless rotor to develop an analytical model for prediction of tilting proprotor aircraft dynamics. Particular attention is given to: the influence of coupled flap/lag bending modes; the influence of rotor blade torsion degrees of freedom on proprotor dynamics; and, to a constant coefficient approximation representing the dynamics in nonaxial flow through the rotor. The following are also examined: the number of blade bending and torsion modes required; the influence of the rotor aerodynamic model; the influence of the blade trim bending deflection; the importance of the rotor rotational speed degree of freedom; and the effect of the wing aerodynamic forces. The origin of the significant influence of the blade pitch motion on the proprotor dynamics is discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-8013 , A-5698
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  • 61
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    The influence of crack closure and elasto-plastic flow on the bending of a cracked plate (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The influence of crack closure and elastoplastic flow on the bending behavior of thin cracked plates is investigated using an incremental elastoplastic plate bending finite element computer program. The finite element program was developed using assumptions consistent with Kirchhoff fourth-order plate theory while the material property treatment permits general isotropic work hardening with local elastic unloading. This technique is applied to the problem of a large centrally through cracked plate subject to remote circular bending. Comparison is drawn between two cases of the bending problem. The first neglects the possibility of crack face interference with bending, and the second includes a kinematic prohibition against the crack face from passing through the symmetry plane. Results are reported which isolate the effects of elastoplastic flow and crack closure.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 11; Dec. 197
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  • 62
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    Buckling of laminated composite cylinders - A review (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A brief review of the available static buckling theory for both geometrically 'perfect' and 'imperfect' anisotropic composite circular cylinders is presented for various loading configurations. For comparison purposes, relevant experimental data are discussed, including recent combined loading test results and recommendations are made concerning the design of composite cylinders.
    Keywords: STRUCTURAL MECHANICS
    Type: Composites; 6; Jan. 197
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  • 63
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    Analysis and trade-off studies of large lightweight mirror structures (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A candidate mirror, hexagonally lightweighted, is analyzed under various loadings using as complete a procedure as possible. Successive simplifications are introduced and compared to an original analysis. A model which is a reasonable compromise between accuracy and cost is found and is used for making trade-off studies of the various structural parameters of the lightweighted mirror.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-143881 , R-873
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  • 64
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    Vibration Responses of Test Structure No. 2 During the Edward Air Force Base Phase of the National Sonic Boom Program (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: In order to evaluate reaction of people to sonic booms of varying overpressures and time durations, a series of closely controlled and systematic flight tests/studies were conducted from June 3 to June 23, 1966. The dynamic responses of several building structures were measured, with emphasis on a two-story residence structure. Sample acceleration and strain recordings from F-104, B-58, and XB-70 sonic boom exposures are included, along with tabulations of the maximum acceleration and strain values measured for each one of about 140 flight tests. These data are compared with similar measurements for engine noise exposures of the building during simulated landing approaches and takeoffs of KC-135 aircraft.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-X-72704
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  • 65
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    Coordinate transformation and truncation for rotating spacecraft with flexible appendages (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The analytical structures of alternative coordinate transformations for the variables that characterize the deformations of finite element models of flexible appendages on rotating spacecraft are examined. Particular emphasis is given to the truncation operations that are essential for efficient numerical simulations of flexible spacecraft, due to the necessarily large number of coordinates employed in a finite element description. A theorem is developed which establishes necessary conditions for the commutativity of the required truncation and inversion operations. The recommended alternative for the rotating elastic appendage is a complex transformation with previously published orthogonality properties, which permit the derivation in this paper of a relatively simple explicit set of transformed and truncated equations of modal vibration in real variables.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 13; Dec. 197
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  • 66
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    Crack opening stretch in a plate of finite width (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The problem of a uniaxially stressed plate of finite width containing a centrally located damage zone is considered. It is assumed that the flaw may be represented by a part-through crack perpendicular to the plate surface, the net ligaments in the plane of the crack and through-the-thickness narrow strips ahead of the crack ends are fully yielded, and in the yielded sections the material may carry only a constant normal traction with magnitude equal to the yield strength. The problem is solved by neglecting the bending effects and the crack opening stretches at the center and the ends of the crack are obtained. Some applications of the results are indicated by using the concepts of critical crack opening stretch and constant slope plastic instability.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 11; Dec. 197
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    Properties of axial or torsional free-vibration frequency of rods (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The investigation reported shows that for a clamped rod with an odd number of degrees of freedom, the middle frequency is independent of any nonuniformity in the area distribution. The frequencies in the lower half of the spectrum of a rod are found to be conjugate to the frequencies in the upper half. In the case of a design modification which leaves a certain frequency in the lower half spectrum unchanged, the conjugate frequency in the upper half will also remain unchanged.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 13; Aug. 197
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  • 68
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    Stress concentration factors for circular, reinforced penetrations in pressurized cylindrical shells (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effect on stresses in a cylindrical shell with a circular penetration subject to internal pressure was investigated in thin, shallow linearly, elastic cylindrical shells. Results provide numerical predictions of peak stress concentration factors around nonreinforced and reinforced penetrations in pressurized cylindrical shells. Analytical results were correlated with published formulas, as well as theoretical and experimental results. An accuracy study was made of the finite element program for each of the configurations considered important in pressure vessel technology. A formula is developed to predict the peak stress concentration factor for analysis and/or design in conjunction with the ASME Boiler and Pressure Vessel Code.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-X-68733
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    NASTRAN user's guide: Level 15 (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The NASTRAN structural analysis system is presented. This user's guide is an essential addition to the original four NASTRAN manuals. Clear, brief descriptions of capabilities with example input are included, with references to the location of more complete information.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-2504
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  • 70
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    Experimental evaluation of the tensor polynomial failure criterion for the design of composite structures (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The experimental measures and techniques are described which are used to obtain the strength tensor components, including cubic terms. Based on a considerable number of biaxial pressure tests together with specimens subjected to a constant torque and internal pressure, a modified form of the plane stress tensor polynomial failure equation was obtained that was capable of predicting ultimate strength results well. Preliminary data were obtained to determine the effect of varying post cure times and ambient temperatures (-80 F to 250 F) on the change in two tensor strength terms, F sub 2 and F sub 22. Other laminate configurations yield corresponding variations for the remaining strength parameters.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-142701
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  • 71
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    The motion of interconnected flexible bodies (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The equations of motion for an arbitrarily interconnected collection of substructures are derived. The substructures are elastic bodies which may be idealized as finite element assemblies and are subject to small deformations relative to a nominal state. Interconnections between the elastic substructures permit large relative translations and rotations between substructures, governed by Pfaffian constraints describing the connections. Screw connections (permitting rotation about and translation along a single axis) eliminate constraint forces and incorporate modal coupling. The problem of flexible spacecraft simulation is discussed. Hurty's component mode approach is extended by permitting interconnected elastic substructures large motions relative to each other and relative to inertial space. The hybrid coordinate methods are generalized by permitting all substructures to be flexible (rather than only the terminal members of a topological tree of substructures). The basic relationships of continuum mechanics are developed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-120740 , UCLA-ENG-7513-VOL-3
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  • 72
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    Analysis of bonded joints (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A refined elastic analysis of bonded joints which accounts for transverse shear deformation and transverse normal stress was developed to obtain the stresses and displacements in the adherends and in the bond. The displacements were expanded in terms of polynomials in the thicknesswise coordinate; the coefficients of these polynomials were functions of the axial coordinate. The stress distribution was obtained in terms of these coefficients by using strain-displacement and stress-strain relations. The governing differential equations were obtained by integrating the equations of equilibrium, and were solved. The boundary conditions (interface or support) were satisfied to complete the analysis. Single-lap, flush, and double-lap joints were analyzed, along with the effects of adhesive properties, plate thicknesses, material properties, and plate taper on maximum peel and shear stresses in the bond. The results obtained by using the thin-beam analysis available in the literature were compared with the results obtained by using the refined analysis. In general, thin-beam analysis yielded reasonably accurate results, but in certain cases the errors were high. Numerical investigations showed that the maximum peel and shear stresses in the bond can be reduced by (1) using a combination of flexible and stiff bonds, (2) using stiffer lap plates, and (3) tapering the plates.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-7855 , L-9563
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  • 73
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    Optimization of structures undergoing harmonic or stochastic excitation (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The optimal design was investigated of simple structures subjected to dynamic loads, with constraints on the structures' responses. Optimal designs were examined for one dimensional structures excited by harmonically oscillating loads, similar structures excited by white noise, and a wing in the presence of continuous atmospheric turbulence. The first has constraints on the maximum allowable stress while the last two place bounds on the probability of failure of the structure. Approximations were made to replace the time parameter with a frequency parameter. For the first problem, this involved the steady state response, and in the remaining cases, power spectral techniques were employed to find the root mean square values of the responses. Optimal solutions were found by using computer algorithms which combined finite elements methods with optimization techniques based on mathematical programming. It was found that the inertial loads for these dynamic problems result in optimal structures that are radically different from those obtained for structures loaded statically by forces of comparable magnitude.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-142936
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  • 74
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    The NASTRAN SRB slapdown water impact analysis (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A computer analysis was made of the hydroelastic interaction between a shell structure representing the space shuttle solid rocket motor case and an incompressible fluid during the slapdown phase of water impact. The large motions and hydroelastic response of the system were obtained by numerical integration of the combined hydrodynamics and structural equations of motion and are analyzed for a selected interval after the initial nozzle impact. The computerization of the slapdown hydroelastic capability was incorporated into the general purpose NASTRAN computer code. The development of the theoretical basis, a guide to the program's usage, results of correlation and parameter studies, and a detailed description of the computer code are also included.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-143862
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  • 75
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    Computer analysis of multicircuit shells of revolution by the field method (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The field method, presented previously for the solution of even-order linear boundary value problems defined on one-dimensional open branch domains, is extended to boundary value problems defined on one-dimensional domains containing circuits. This method converts the boundary value problem into two successive numerically stable initial value problems, which may be solved by standard forward integration techniques. In addition, a new method for the treatment of singular boundary conditions is presented. This method, which amounts to a partial interchange of the roles of force and displacement variables, is problem independent with respect to both accuracy and speed of execution. This method was implemented in a computer program to calculate the static response of ring stiffened orthotropic multicircuit shells of revolution to asymmetric loads. Solutions are presented for sample problems which illustrate the accuracy and efficiency of the method.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-2535
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  • 76
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    Thermal loading in the laser holography nondestructive testing of a composite structure (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A laser holographic interferometry method that has variable sensitivity to surface deformation was applied to the investigation of composite test samples under thermal loading. A successful attempt was made to detect debonds in a fiberglass-epoxy-ceramic plate. Experimental results are presented along with the mathematical analysis of the physical model of the thermal loading and current conduction in the composite material.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TR-R-439 , M-133
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  • 77
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    Design and fabrication of Rene 41 advanced structural panels (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The efficiency was investigated of curved elements in the design of lightweight structural panels under combined loads of axial compression, inplane shear, and bending. The application is described of technology generated in the initial aluminum program to the design and fabrication of Rene 41 panels for subsequent performance tests at elevated temperature. Optimum designs for two panel configurations are presented. The designs are applicable to hypersonic airplane wing structure, and are designed specifically for testing at elevated temperature in the hypersonic wing test structure located at the NASA Flight Research Center. Fabrication methods developed to produce the Rene panels are described, and test results of smaller structural element specimens are presented to verify the design and fabrication methods used. Predicted strengths of the panels under several proposed elevated temperature test load conditions are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-132646
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  • 78
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    Bifurcation and collapse analysis of stringer and ring-stringer stiffened cylindrical shells with cutouts (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Results for cylindrical configurations using the STAGS computer program were presented. Discontinuities were imposed upon the shell's skin by incorporating symmetrical cutout openings. In addition, the surface is stiffened with both stringer and ring-stringer arrangements. The cutout problem has been shown to be highly nonlinear for smooth surface shells, but it was found that bifurcation and collapse loads are close when one is considering stiffened skin configurations. In order to arrive at this conclusion, it was necessary to evaluate the following: (1) comparison between smeared and discrete stiffener theory for linear solutions, (2) numerical finite difference convergence as directed toward buckling determination, (3) collapse load results with the various skin stiffeners. A linear bifurcation study relating to stiffening effects around cutout areas present within stringer and ring-stringer shell surfaces was included. Comparisons were made between a variety of geometric positions considering cutout frame and thickened skin additions.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-146777
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  • 79
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    Shear-flexible finite-element models of laminated composite plates and shells (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Several finite-element models are applied to the linear static, stability, and vibration analysis of laminated composite plates and shells. The study is based on linear shallow-shell theory, with the effects of shear deformation, anisotropic material behavior, and bending-extensional coupling included. Both stiffness (displacement) and mixed finite-element models are considered. Discussion is focused on the effects of shear deformation and anisotropic material behavior on the accuracy and convergence of different finite-element models. Numerical studies are presented which show the effects of increasing the order of the approximating polynomials, adding internal degrees of freedom, and using derivatives of generalized displacements as nodal parameters.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-8044 , L-10414
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  • 80
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    Effect of axial load on mode shapes and frequencies of beams (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: An investigation of the effect of axial load on the natural frequencies and mode shapes of uniform beams and of a cantilevered beam with a concentrated mass at the tip is presented. Characteristic equations which yield the frequencies and mode shape functions for the various cases are given. The solutions to these equations are presented by a series of graphs so that frequency as a function of axial load can readily be determined. The effect of axial load on the mode shapes are also depicted by another series of graphs.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-8109 , E-8433
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  • 81
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    PLANS: A finite element program for nonlinear analysis of structures. Volume 1: Theoretical manual (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The PLANS system is described which is a finite element program for nonlinear analysis. The system represents a collection of special purpose computer programs each associated with a distinct physical problem class. Modules of PLANS specifically referenced and described in detail include: (1) REVBY, for the plastic analysis of bodies of revolution; (2) OUT-OF-PLANE, for the plastic analysis of 3-D built-up structures where membrane effects are predominant; (3) BEND, for the plastic analysis of built-up structures where bending and membrane effects are significant; (4) HEX, for the 3-D elastic-plastic analysis of general solids; and (5) OUT-OF-PLANE-MG, for material and geometrically nonlinear analysis of built-up structures. The SATELLITE program for data debugging and plotting of input geometries is also described. The theoretical foundations upon which the analysis is based are presented. Discussed are the form of the governing equations, the methods of solution, plasticity theories available, a general system description and flow of the programs, and the elements available for use.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-2568 , RE-501-VOL-1
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  • 82
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    A numerical method for determining the natural vibration characteristics of rotating nonuniform cantilever blades (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A method is presented for determining the free vibration characteristics of a rotating blade having nonuniform spanwise properties and cantilever boundary conditions. The equations which govern the coupled flapwise, chordwise, and torsional motion of such a blade are solved using an integrating matrix method. By expressing the equations of motion and matrix notation, utilizing the integrating matrix as an operator, and applying the boundary conditions, the equations are formulated into an eigenvalue problem whose solutions may be determined by conventional methods. Computer results are compared with experimental data.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-X-72751
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  • 83
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    Finite element techniques applied to cracks interacting with selected singularities (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The finite-element method for computing the extensional stress-intensity factor for cracks approaching selected singularities of varied geometry is described. Stress-intensity factors are generated using both displacement and J-integral techniques, and numerical results are compared to those obtained experimentally in a photoelastic investigation. The selected singularities considered are a colinear crack, a circular penetration, and a notched circular penetration. Results indicate that singularities greatly influence the crack-tip stress-intensity factor as the crack approaches the singularity. In addition, the degree of influence can be regulated by varying the overall geometry of the singularity. Local changes in singularity geometry have little effect on the stress-intensity factor for the cases investigated.
    Keywords: STRUCTURAL MECHANICS
    Type: American Ceramic Society; vol. 58
    Format: text
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  • 84
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    Stress corrosion susceptibility of stress-coined fastener holes in aircraft structures (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The cold working process of stress coining is used to provide fatigue improvement of fastener holes in aircraft structures. The cold working produces a radial flow of the metal. The residual stresses resulting from stress coining provide protection against fatigue damage by opposing the applied tensile stresses in service at the edge of the fastener hole. However, it is shown in this paper that in addition to the compressive stresses surrounding the stress coined hole, there are tensile stresses that result from the coining operation and that these residual tensile stresses can have a deleterious effect on the stress corrosion susceptibility of the postcoined structure.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 13; July 197
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  • 85
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    The design, development, fabrication and testing of two (2) Non-Spin Platforms, (NSP) (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The non spin platform is a means for achieving the very low acceleration requirements for cost effective space processing experiments on research rocket flights. These platforms have a low initial cost, are re-usable and have extremely low refurbishment cost. In order to attain this goal, commercially available components were used and only the necessary quality control standards were imposed. A detailed system description, the very few design problems encountered, the operational procedures (both pre-flight and post-flight), and the maintenance requirements are described.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-144178 , D180-19335-1-REV-A
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  • 86
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    Analytical and experimental vibration studies of a 1/8-scale shuttle orbiter (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Natural frequencies and mode shapes for four symmetric vibration modes and four antisymmetric modes are compared with predictions based on NASTRAN finite-element analyses. Initial predictions gave poor agreement with test data; an extensive investigation revealed that the major factors influencing agreement were out-of-plane imperfections in fuselage panels and a soft fin-fuselage connection. Computations with a more refined analysis indicated satisfactory frequency predictions for all modes studied, within 11 percent of experimental values.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-7964 , L-9806
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  • 87
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    Analytical stability and simulation response study for a coupled two-body system (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: An analytical stability study and a digital simulation response study of two connected rigid bodies are documented. Relative rotation of the bodies at the connection is allowed, thereby providing a model suitable for studying system stability and response during a soft-dock regime. Provisions are made of a docking port axes alignment torque and a despin torque capability for encountering spinning payloads. Although the stability analysis is based on linearized equations, the digital simulation is based on nonlinear models.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-144002 , TR-250-1400
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  • 88
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    Nonlinear vibration of cylindrical shells (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The large amplitude vibration of a thin-walled cylindrical shell is analyzed. A perturbation method is used to solve the steady-state forced vibration problem. The simply-supported boundary conditions and the circumferential periodicity condition are satisfied. The resulting solution indicates that in addition to the fundamental mode, the response contains asymmetric modes as well as axisymmetric modes with the frequency twice that of the fundamental mode. Vibrations involving a single driven mode response are investigated. The results indicate that the nonlinearity is either softening or hardening depending on the mode. The vibrations involving both a driven mode and a companion mode are also investigated. An experimental investigation is conducted, and the results are in qualitative agreement with the theory. 'Nonstationary' response is detected at some frequencies for large amplitude response in which the amplitude drifts from one value to another. Various nonlinear phenomena are observed and comparisons with the theoretical results are made.
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 13; July 197
    Format: text
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  • 89
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    Mixed isoparametric elements for Saint-Venant torsion (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Mixed isoparametric elements are presented for the Saint-Venant torsion problem of laminated and anisotropic bars. Both triangular and quadrilateral elements are considered. The 'generalized' element stiffness matrix is obtained by using a modified form of the Hellinger-Reissner mixed variational principle. Group-theoretic techniques are used in conjunction with computerized symbolic integration to obtain analytic expressions for the stiffness coefficients. The accuracy of the mixed isoparametric elements developed is demonstrated by means of numerical examples, and their advantages over commonly used stress and displacement elements are discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: Computer Methods in Applied Mechanics and Engineering; 6; Sept
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  • 90
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    Parametric constraints with application to optimization for flutter using a continuous flutter constraint (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA Journal; 13; Apr. 197
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  • 91
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    Fatigue performance of metal-lined graphite/epoxy pressure vessels (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Using an ultrahigh-strength graphite fiber, a program was started to develop a thin metal-lined fiber/epoxy pressure vessel that would have a fatigue life of over 1000 cycles. First, the performance factor of the fiber/epoxy composite was found to be 351 kN m/kg from the average of 18 rubber-lined pressure vessels. Then, both aluminum- and titanium-lined vessels were filament wound with the graphite fiber in an epoxy matrix. Several of these metal-lined vessels were subjected to hydraulic fatigue testing to about 50% of their expected burst pressures. The average fatigue life of the aluminum-lined vessels was 462 cycles; the average for the titanium-lined vessels was 2190 cycles.
    Keywords: STRUCTURAL MECHANICS
    Type: Composites; 6; Nov. 197
    Format: text
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  • 92
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    Prevention of thermal bending of multilayered beams and plates (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: By adding an extra layer to multilayer beams or plates of different isotropic materials, it is possible to prevent the thermal bending of these materials. With the proper selection of thermoelastic properties the curvature produced prior to this addition would be eliminated. Several numerical examples are presented for various temperature distributions. A simple experiment was conducted, involving the addition of a brass strip to a bimetallic strip made of aluminum and steel at room temperature. The trimetal strip was placed in a furnace and remained straight for varying temperatures.
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  • 93
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    The Application of Strain Range Partitioning Method to Torsional Creep-Fatigue Interaction (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The method of strain range partitioning was applied to a series of torsional fatigue tests conducted on tubular 304 stainless steel specimens at 1200 F. Creep strain was superimposed on cycling strain, and the resulting strain range was partitioned into four components; completely reversed plastic shear strain, plastic shear strain followed by creep strain, creep strain followed by plastic strain and completely reversed creep strain. Each strain component was related to the cyclic life of the material. The damaging effects of the individual strain components were expressed by a linear life fraction rule. The plastic shear strain component showed the least detrimental factor when compared to creep strain reversed by plastic strain. In the latter case, a reduction of torsional fatigue life in the order of magnitude of 1.5 was observed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-134817
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  • 94
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    Experimental transient and permanent deformation studies of steel-sphere-impacted or impulsively-loaded aluminum beams with clamped ends (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The sheet explosive loading technique (SELT) was employed to obtain elastic-plastic, large-deflection transient and/or permanent strain data on simple well-defined structural specimens and materials: initially-flat 6061-T651 aluminum beams with both ends ideally clamped via integral construction. The SELT loading technique was chosen since it is both convenient and provides forcing function information of small uncertainty. These data will be useful for evaluating pertinent structural response prediction methods. A second objective was to obtain high-quality transient-strain data for a well-defined structural/material model subjected to impact by a rigid body of known mass, impact velocity, and geometry; large-deflection, elastic-plastic transient response conditions are of primary interest. The beam with both ends clamped and a steel sphere as the impacting body were chosen. The steel sphere was launched vertically by explosive propulsion to achieve various desired impact velocities. The sphere/beam impact tests resulted in producing a wide range of structural responses and permanent deformations, including rupture of the beam from excessive structural response in two cases. The transient and permanent strain data as well as the permanent deflection data obtained are of high quality and should be useful for checking and evaluating methods for predicting the responses of simple 2-d structures to fragment (sphere) impact. Transient strain data very close to the point of impact were not obtained over as long a time as desirable because the gage(s) in that region became detached during the transient response.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-134922 , ASRL-TR-154-11
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  • 95
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    Buckling of continuously supported hinged beams (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The effect on the buckling load of a hinge at the center of an infinite beam supported by a semiinfinite elastic continuum is analyzed using the complex Fourier transforms. An expression is obtained for the relationship between the surface deflection of the elastic continuum and the pressure distribution acting on the surface, and solutions are obtained for the assumed form of the pressure distribution below the beam. The analysis is applied to cases of uniform pressure over the width of the beam and a pressure distribution that occurs below a rigid stamp. The results show that the buckling loads for an infinite beam with a hinge at the center and supported by a semiinfinite elastic continuum are approximately one half of those for a beam without a hinge, and that this ratio is exactly one half for an infinite beam resting on a Winkler foundation.
    Keywords: STRUCTURAL MECHANICS
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  • 96
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    Elastic-plastic analysis of an infinite sheet having a circular hole under pressure (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: An exact elastic-plastic solution for the stresses in an infinite sheet having a circular hole subject to pressure is obtained on the basis of J2 deformation theory together with a modified Ramberg-Osgood law. The sheet is orthotropic but isotropic in its plane. The results are assessed on the basis of Budiansky's criterion for the acceptability of J2 deformation theory. By using exact elastic-plastic stresses, the function connecting the pressure at the hole with the radial enlargement is obtained. Upon release of the pressure, residual stresses around the hole are produced.
    Keywords: STRUCTURAL MECHANICS
    Type: ASME PAPER 75-APM-15
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  • 97
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    Stored energy function and compressibility of compressible rubberlike materials under large strain (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: By using new invariants in the theory of finite elasticity an expression is obtained for the stored energy function of slightly compressible materials in which the effects of the distortional change (change of shape) and of the volume change are clearly separated. The volume-related terms are expressed as a function of the third invariant, the classical compressibility, and an induced anisotropy of the effective compressibility which is due to the large deformations. After evaluating the terms, using data on pressure, volume, uniaxial strain, and fractional volume change vs strain data on natural rubber from the literature, it is shown that the volume change contribution to the total stress observed in a simple tensile experiment can be clearly separated from the distortional contribution, even at finite strains.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Applied Physics; 46; June 197
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    ALARM: A highly efficient eigenvalue extraction routine for very large matrixes (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A highly efficient computer program, called ALARM, for the determination of eigenvalues and eigenvectors of large symmetric matrices (over 10,000 degrees of freedom), was described. As such, it is highly useful for analyzing complex finite element and finite difference idealizations encountered in structural dynamics and acoustic probelms. The program is based upon a scheme which reduces a large matrix to an equivalent tridiagonal one of much smaller size. The main strength of the algorithm lies in its ability to retain all the information required to obtain the eigenvalues at either end of the original matrix spectrum.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Bull., Vol. 7, No. 12, Dec. 1975; p 3-9
    Format: text
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    Experimental parametric studies of transonic T-tail flutter (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Wind-tunnel tests of the T-tail of a wide-body jet airplane were made at Mach numbers up to 1.02. The model consisted of a 1/13-size scaled version of the T-tail, fuselage, and inboard wing of the airplane. Two interchangeable T-tails were tested, one with design stiffness for flutter-clearance studies and one with reduced stiffness for flutter-trend studies. Transonic antisymmetric-flutter boundaries were determined for the models with variations in: (1) fin-spar stiffness, (2) stabilizer dihedral angle (-5 deg and 0 deg), (3) wing and forward-fuselage shape, and (4) nose shape of the fin-stabilizer juncture. A transonic symmetric-flutter boundary and flutter trends were established for variations in stabilizer pitch stiffness. Photographs of the test configurations are shown.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-8066 , L-10367
    Format: application/pdf
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    Development and demonstration of a flutter-suppression system using active controls (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The application of active control technology to suppress flutter was demonstrated successfully in the transonic dynamics tunnel with a delta-wing model. The model was a simplified version of a proposed supersonic transport wing design. An active flutter suppression method based on an aerodynamic energy criterion was verified by using three different control laws. The first two control laws utilized both leading-edge and trailing-edge active control surfaces, whereas the third control law required only a single trailing-edge active control surface. At a Mach number of 0.9 the experimental results demonstrated increases in the flutter dynamic pressure from 12.5 percent to 30 percent with active controls. Analytical methods were developed to predict both open-loop and closed-loop stability, and the results agreed reasonably well with the experimental results.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TR-R-450 , L-10446
    Format: application/pdf
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