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  • 1
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    The structural optimization of a spreader bar for twin lift helicopter operations (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: An optimization study was performed to develop a minimum weight spreader bar to allow two helicopters to lift the same payload. With this arrangement, the maximum payload that can be lifted is almost doubled without the expense of designing and building a new helicopter. The concept has had some limited use by civil helicopter operators using small helicopters and has been demonstrated in large scale by two CH-54's which successfully lifted a total load of 20 ton. To this point, rather heavy available beams or tower structures have been used for the spreader bar. Since the weight of the bar not only detracts from payload but also adds to the logistics problem, there are more than the usual incentives to minimize weight. Since the design requirement is for classic beam column with uniform side loads resulting from bar weight and aerodynamic drag, the design problem is particularly amenable to optimization. A study has been performed at Sikorsky to establish the minimum weight for a spreader bar sized to carry a load equal to the capacity of two Army BLACK HAWK helicopters. Toward this end, a computer program was written to analyze the spreader bar deflections and stresses and coupled to the NASA developed CONMIN optimization routines.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 12 p
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Design, Fabrication and Test of Composite Curved Frames for Helicopter Fuselage Structure (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Aspects of curved beam effects and their importance in designing composite frame structures are discussed. The curved beam effect induces radial flange loadings which in turn causes flange curling. This curling increases the axial flange stresses and induces transverse bending. These effects are more important in composite structures due to their general inability to redistribute stresses by general yielding, such as in metal structures. A detailed finite element analysis was conducted and used in the design of composite curved frame specimens. Five specimens were statically tested and compared with predicted and test strains. The curved frame effects must be accurately accounted for to avoid premature fracture; finite element methods can accurately predict most of the stresses and no elastic relief from curved beam effects occurred in the composite frames tested. Finite element studies are presented for comparative curved beam effects on composite and metal frames.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-172438 , NAS 1.26:172438 , SER-510145
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Optimization guide for programs compiled under IBM FORTRAN H (OPT=2) (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Guidelines are given to provide the programmer with various techniques for optimizing programs when the FORTRAN IV H compiler is used with OPT=2. Subroutines and programs are described in the appendices along with a timing summary of all the examples given in the manual.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-TM-X-71307 , X-530-77-72
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
    Electronic Resource
    Electronic Resource
    A study of the structural integrity of graphite composite structure subjected to low velocity impactPresented at the 35th Annual Technical Conference, 1980 Reinforced Plastics/Composites Institute, the Society of the Plastics Industry, Inc. (1981)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 493-498 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An analysis for the transient deflections, bending strains, and interlaminar shear stresses in a simply supported laminated composite plate subject to low velocity impact has been obtained using a series solution of the plate governing equations. Results are presented showing the effect of plate geometry and impact location on damage mode. Computed stresses and strain are compared with impact test data to verify, the analysis.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760210809
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    Paper (German National Licenses)
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