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Results for “AXIAL COMPRESSION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1965

Dynamic buckling estimates.

Dynamic buckling of imperfection sensitive models, specifically cylindrical shells under axial compression

AXIAL COMPRESSION↗
NASA NTRS1966

Dynamic buckling estimates.

Dynamic buckling of imperfection sensitive models, specifically cylindrical shells under axial compression

AXIAL COMPRESSION↗
NASA NTRS1985

Polymer matrix and graphite fiber interface study

Hercules AS4 graphite fiber, unsized, or with EPON 828, PVA, or polysulfone sizing, was combined with three different polymer matrices. These included Hercules 3501-6 epoxy, Hercules 4001 bismaleimide, and Hexcel F155 rubber toughened epoxy. Unidirectional composites in all twelve combinations were fabricated and tested in transverse tension and axial compression. Quasi-isotropic laminates were tested in axial tension and compression, flexure, interlaminar shear, and tensile impact. All tests were conducted at both room temperature, dry and elevated temperature, and wet conditions. Single fiber pullout testing was also performed. Extensive scanning electron microphotographs of fracture surfaces are included, along with photographs of single fiber pullout failures. Analytical/experimental correlations are presented, based on the results of a finite element micromechanics analysis. Correlations between matrix type, fiber sizing, hygrothermal environment, and loading mode are presented. Results indicate that the various composite properties were only moderately influenced by the fiber sizings utilized.

Adams, D. F.↗
NASA NTRS1982

New Configuration for Compression-Test Fixture

Gravity-loades axial-compression test fixture is operated by raising lower platen and specimen against weighted upper platen. Wheel turns nut on threaded rod to move lower platen up or down. Limiting rods prevent further upward movement if sample buckles.

Shanks, G. C.↗
NASA NTRS1973

Elastic buckling analysis for composite stiffened panels and other structures subjected to biaxial inplane loads

An exact linear analysis method is presented for predicting buckling of structures with arbitrary uniform cross section. The structure is idealized as an assemblage of laminated plate-strip elements, curved and planar, and beam elements. Element edges normal to the longitudinal axes are assumed to be simply supported. Arbitrary boundary conditions may be specified on any external longitudinal edge of plate-strip elements. The structure or selected elements may be loaded in any desired combination of inplane transverse compression or tension side load and axial compression load. The analysis simultaneously considers all possible modes of instability and is applicable for the buckling of laminated composite structures. Numerical results correlate well with the results of previous analysis methods.

Viswanathan, A. V.↗
NASA NTRS2013

Structural Assessment of Advanced Composite Tow-Steered Shells

The structural performance of two advanced composite tow-steered shells, manufactured using a fiber placement system, is assessed using both experimental and analytical methods. The fiber orientation angles vary continuously around the shell circumference from 10 degrees on the shell crown and keel, to 45 degrees on the shell sides. The two shells differ in that one shell has the full 24-tow course applied during each pass of the fiber placement system, while the second shell uses the fiber placement system s tow drop/add capability to achieve a more uniform shell wall thickness. The shells are tested in axial compression, and estimates of their prebuckling axial stiffnesses and bifurcation buckling loads are predicted using linear finite element analyses. These preliminary predictions compare well with the test results, with an average agreement of approximately 10 percent.

Wu, K. Chauncey↗
NASA NTRS2002

Thermo-Mechanical Analyses of Dynamically Loaded Rubber Cylinders

Thick rubber components are employed by the Army to carry large loads. In tanks, rubber covers road wheels and track systems to protect roadways. It is difficult for design engineers to simulate the details of the hysteretic heating for large strain viscoelastic deformations. In this study, an approximation to the viscoelastic energy dissipated per unit time is investigated for use in estimating mechanically induced viscoelastic heating. Coupled thermo-mechanical simulations of large cyclic deformations of rubber cylinders are presented. The cylinders are first compressed axially and then cyclically loaded about the compressed state. Details of the algorithm and some computational issues are discussed. The coupled analyses are conducted for tall and short rubber cylinders both with and without imbedded metal disks.

Johnson, Arthur R.↗
NASA NTRS1977

Experimental studies of graphite-epoxy and boron-epoxy angle ply laminates in compression

A test program aimed at studying the nonlinear/inelastic response under axial compression across a wide range of angle ply was graphite-epoxy and boron-epoxy laminates was presented and described. The strength allowables corresponding to the various laminate configurations were defined and the failure mechanisms which dictate their mode of failure were detected. The program involved two types of specimens for each laminate configuration: compression sandwich coupons and compression tubes. The test results indicate that the coupons perform better than the tubes displaying considerably high stress-strain allowables and mechanical properties relative to the tubes. Also, it is observed that depending on their dimensions the coupons are susceptible to very pronounced edge effects. This sensitivity results in assigning to the laminate conservative mechanical properties rather than the actual ones.

Weller, T.↗
NASA NTRS2000

Coupled Thermo-Mechanical Analyses of Dynamically Loaded Rubber Cylinders

A procedure that models coupled thermo-mechanical deformations of viscoelastic rubber cylinders by employing the ABAQUS finite element code is described. Computational simulations of hysteretic heating are presented for several tall and short rubber cylinders both with and without a steel disk at their centers. The cylinders are compressed axially and are then cyclically loaded about the compressed state. The non-uniform hysteretic heating of the rubber cylinders containing a steel disk is presented. The analyses performed suggest that the coupling procedure should be considered for further development as a design tool for rubber degradation studies.

Johnson, Arthur R.↗
NASA NTRS1974

Plastic buckling

The present article is concerned mainly with the post-bifurcation and imperfection-sensitivity aspects of plastic buckling. A simple two-degree-of-freedom model is used to introduce post-bifurcation behavior and a second model illustrates features of the behavior of continuous solids and structures. Hill's bifurcation criterion for a class of three-dimensional solids is applied to the Donnell-Mushtari-Vlasov (DMV) theory of plates and shells. A general treatment of the initial post-bifurcation behavior of plates and shells is given within the context of the DMV theory. This is illustrated by problems involving columns and circular plates under radial compression. Numerical results are given for a column under axial compression, a circular plate under radial compression, and spherical and cylindrical shells.

Hutchinson, J. W.↗
NASA NTRS2003

Mode Jumping of an Isogrid Panel Under Quasi-Static Compression

A wide column test of a composite isogrid panel subjected to quasi-static, axial compression is modeled with a hybrid-static dynamic computational method. The data from the test panel exhibited discontinuous responses in the compressive load for slowly increased end-shortening. The computational model was developed to corroborate these discontinuities with the phenomenon of mode jumping. Mode jumping refers to the transient response of the panel from an unstable bifurcation point on a postbuckled equilibrium path to a second stable equilibrium state on a new equilibrium path. On the new equilibrium path, both the analysis and test show that the panel can resist increased endshortening beyond that of the unstable critical point. Fair agreement is achieved between the analysis and test.

Muheim, Danniella M.↗
NASA NTRS1973

Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 3: Major component development

Analytical and experimental investigations, performed to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites, are reported. Aluminum-boron-epoxy and titanium-boron-epoxy were used in the design and manufacture of three major structural components. The components were representative of subsonic aircraft fuselage and window belt panels and supersonic aircraft compression panels. Both unidirectional and multidirectional reinforcement concepts were employed. Blade penetration, axial compression, and inplane shear tests were conducted. Composite reinforced structural components designed to realistic airframe structural criteria demonstrated the potential for significant weight savings while maintaining strength, stability, and damage containment properties of all metal components designed to meet the same criteria.

Bryson, L. L.↗