Different Properties In Tension Research Articles

Creep of materials with different properties in tension and compression

Creep of materials with different properties in tension and compression

Models for Fibrous Composites With Different Properties in Tension and Compression

It has been observed that certain filamentary composite materials exhibit a different Poisson compliance when loaded transversely to the fibers than when loaded longitudinally (parallel to the fibers). In such cases the following widely used reciprocal relation is not satisfied: νLT/EL=νLT/ET where EL and ET are the L (longitudinal) and T (transverse) Young’s moduli and νLT and νTL are the Poisson’s ratios obtained from uniaxial loading in the L and T directions. Here two entirely different approaches are used to develop mathematical models of an elastic composite material behaving as described above. One method permits the compliance matrix to be unsymmetric but vary smoothly with the angular orientation. The other method, which is believed to be more valid, incorporates one set of symmetric compliances when the fibers are loaded in tension and a different set of symmetric compliances when the fibers are loaded in compression. The two different models are applied to some data for rubber reinforced by aramid (Kevlar) cord. For this composite, the above reciprocal relation is least satisfied, since νTL/ET is approximately 147 times νLT/EL.

Creep of hardening materials with different properties in tension and compression

Creep of hardening materials with different properties in tension and compression

Incremental versus total-strain theories for proportionate and nonproportionate loading of torsion-tension members

Incremental and total-strain theories have been presented in the literature for hollow and solid circular torsion-tension members. The differential equations obtained for the incremental theory have been solved only for the conditions that the torsion-tension member is made of a nonstrain-hardening material and is subjected to restricted deformation histories. Computer programs were written to obtain numerical incremental solutions for hollow and solid circular torsion-tension members made of strain-hardening materials and subjected to any deformation or loading path. Test data were obtained for three different materials: (a) a nonstrain-hardening steel, annealed SAE 1035 steel, with identical properties in tension and compression; (b) a strain-hardening steel, annealed rail steel, with identical properties in tension and compression; (c) a strainhardening alumimum alloy, 2024-T4, with different properties in tension and compression. In all cases, the average of the tension and compression stress-strain diagram was approximated by two straight lines to obtain material properties.