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  • 1
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    Design for cyclic loading endurance of composites (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The present paper describes the application of the computer code IPACS (Integrated Probabilistic Assessment of Composite Structures) to air craft wing type structures. The code performs a complete probabilistic structural analysis for composites taking into account the uncertainties in geometry, boundary conditions, material properties, laminate lay-ups and loads. Results of the analysis are presented in terms of cumulative distribution functions (CDF) and probability density function (PDF) of life of a wing type composite structure under different hygrothermal environments subjected to random pressure. The sensitivity of fatigue life to a number of critical structural/material variables is also computed from the analysis.
    Keywords: STRUCTURAL MECHANICS
    Type: In: International SAMPE Technical Conference, 24th and International SAMPE Metals and Metals Processing Conference, 3rd, Toronto, Canada, Oct. 20-22, 1992, Proceedings. Vol. 24 (A93-53376 23-23); p. T241-T255.
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  • 2
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    HITCAN: High temperature composite analyzer (1990)
    In:  CASI
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    Publication Date: 2004-12-04
    Description: A computer code, HITCAN (High Temperature Composite Analyzer) was developed to analyze/design metal matrix composite structures. HITCAN is based on composite mechanics theories and computer codes developed at NASA LeRC over the last two decades. HITCAN is a general purpose code for predicting the global structural and local stress-strain response of multilayered (arbitrarily oriented) metal matrix structures both at the constituent (fiber, matrix, and interphase) and the structure level and including the fabrication process effects. The thermomechanical properties of the constituents are considered to be nonlinearly dependent on several parameters including temperature, stress, and stress rate. The computational procedure employs an incremental iterative nonlinear approach utilizing a multifactor-interaction material behavior model. HITCAN features and analysis capabilities (static, load stepping, modal, and buckling) are demonstrated through typical example problems.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA. Langley Research Center, The Third Air Force(NASA Symposium on Recent Advances in Multidisciplinary Analysis and Optimization; p 476-481
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  • 3
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    Computational simulation of high-temperature metal matrix composites cyclic behavior (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A procedure was developed and is described that can be used to computationally simulate the cyclic behavior of high-temperature metal matrix composites (HTMMC) and its degradation effects on the structural response. This procedure consists of HTMMC mechanics coupled with a multifactor-interaction constituent material relationship and with an incremental iterative nonlinear analysis. The procedure is implemented in a computer code that can be used to computationally simulate the thermomechanical behavior of HTMMC starting from the fabrication process and proceeding through thermomechanical cycling, accounting for the interface/interphase region. Results show that combined thermal/mechanical cycling, the interphase, and in situ matrix properties have significant effects on the structural integrity of HTMMC.
    Keywords: COMPOSITE MATERIALS
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  • 4
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    Composite interlaminar fracture toughness - Three-dimensional finite-element modeling for mixed mode I, II, and fracture (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A computational method/procedure is described which can be used to simulate individual and mixed mode interlaminar fracture progression in fiber composite laminates. Different combinations of Modes 1, 2, and 3 fracture are simulated by varying the crack location through the specimen thickness and by selecting appropriate unsymmetric laminate configurations. The contribution of each fracture mode to strain energy release rate is determined by the local crack closure methods while the mixed mode is determined by global variables. The strain energy release rates are plotted versus extending crack length, where slow crack growth, stable crack growth, and rapid crack growth regions are easily identified. Graphical results are presented to illustrate the effectiveness and versatility of the computational simulation for: (1) evaluating mixed-mode interlaminar fracture, (2) for identifying respective dominant parameters, and (3) for selecting possible simple test methods.
    Keywords: STRUCTURAL MECHANICS
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  • 5
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    Fiber Composite Sandwich Thermostructural Behavior - Computational Simulation (1988)
    In:  Other Sources
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    Publication Date: 2013-12-09
    Description: Four computational simulation methods with different levels of sophistication were used to simulate thermal behavior and structural changes of composite sandwich panels with a honeycomb core subjected to a variety of environmental effects. The models on thich these methods are based include three-dimensional finite-element modeling, three-dimensional finite-element modeling assuming a homogeneous core, laminate theory, and simple equations for predicting the equivalent properties of the honeycomb core. A procedure was developed and embedded in a composite mechanics computer code, which made it possile to conduct parametric studies to determine 'optimum' composite sandwich configurations for specific applications. The procedure was applied for the evaluation of composite sandwich behavior at the global, local, laminate, ply, and micromechanics levels when the composite sandwich is subjected to hygral, thermal, and mechanical loading environments.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Composites Technology and Research (ISSN 0885-6804); 10; 93-99
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  • 6
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    Computational simulation methods for composite fracture mechanics (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Structural integrity, durability, and damage tolerance of advanced composites are assessed by studying damage initiation at various scales (micro, macro, and global) and accumulation and growth leading to global failure, quantitatively and qualitatively. In addition, various fracture toughness parameters associated with a typical damage and its growth must be determined. Computational structural analysis codes to aid the composite design engineer in performing these tasks were developed. CODSTRAN (COmposite Durability STRuctural ANalysis) is used to qualitatively and quantitatively assess the progressive damage occurring in composite structures due to mechanical and environmental loads. Next, methods are covered that are currently being developed and used at Lewis to predict interlaminar fracture toughness and related parameters of fiber composites given a prescribed damage. The general purpose finite element code MSC/NASTRAN was used to simulate the interlaminar fracture and the associated individual as well as mixed-mode strain energy release rates in fiber composites.
    Keywords: COMPOSITE MATERIALS
    Type: NASA. Lewis Research Center, Lewis Structures Technology, 1988. Volume 2: Structural Mechanics; p 157-169
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  • 7
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    Design procedures for fiber composite box beams (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Step-by-step procedures are described which can be used for the preliminary design of fiber composite box beams subjected to combined loadings. These procedures include a collection of approximate closed-form equations so that all the required calculations can be performed using pocket calculators. Included is an illustrative example of a tapered cantilever box beam subjected to combined loads. The box beam is designed to satisfy strength, displacement, buckling, and frequency requirements.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Reinforced Plastics and Composites (ISSN 0731-6844); 8; 370-397
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  • 8
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    Free-edge delamination - Laminate width and loading conditions effects (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The width and loading conditions effects on free-edge stress fields in composite laminates are investigated using a three-dimensional finite element analysis. This analysis includes a special free-edge region refinement or superelement with progressive substructuring (mesh refinement) and finite thickness interply layers. The different loading conditions include in-plane and out-of-plane bending, combined axial tension and in-plane shear, twisting, uniform temperature and uniform moisture. Results obtained indicate that: axial tension causes the smallest magnitude of interlaminar free edge stress compared to other loading conditions; free-edge delamination data obtained from laboratory specimens cannot be scaled to structural components; and composite structural components are not likely to delaminate.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Composites Technology and Research (ISSN 0885-6804); 11; 15-22
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  • 9
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    ICAN/PART: Particulate composite analyzer, user's manual and verification studies (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A methodology for predicting the equivalent properties and constituent microstresses for particulate matrix composites, based on the micromechanics approach, is developed. These equations are integrated into a computer code developed to predict the equivalent properties and microstresses of fiber reinforced polymer matrix composites to form a new computer code, ICAN/PART. Details of the flowchart, input and output for ICAN/PART are described, along with examples of the input and output. Only the differences between ICAN/PART and the original ICAN code are described in detail, and the user is assumed to be familiar with the structure and usage of the original ICAN code. Detailed verification studies, utilizing dim dimensional finite element and boundary element analyses, are conducted in order to verify that the micromechanics methodology accurately models the mechanics of particulate matrix composites. ne equivalent properties computed by ICAN/PART fall within bounds established by the finite element and boundary element results. Furthermore, constituent microstresses computed by ICAN/PART agree in average sense with results computed using the finite element method. The verification studies indicate that the micromechanics programmed into ICAN/PART do indeed accurately model the mechanics of particulate matrix composites.
    Keywords: Composite Materials
    Type: NASA-TM-107297 , NAS 1.15:107297 , E-10375
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  • 10
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    Micromechanics for particulate reinforced composites (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A set of micromechanics equations for the analysis of particulate reinforced composites is developed using the mechanics of materials approach. Simplified equations are used to compute homogenized or equivalent thermal and mechanical properties of particulate reinforced composites in terms of the properties of the constituent materials. The microstress equations are also presented here to decompose the applied stresses on the overall composite to the microstresses in the constituent materials. The properties of a 'generic' particulate composite as well as those of a particle reinforced metal matrix composite are predicted and compared with other theories as well as some experimental data. The micromechanics predictions are in excellent agreement with the measured values.
    Keywords: Composite Materials
    Type: NASA-TM-107276 , NAS 1.15:107276 , E-10344
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