Axisymmetric Compression Tests Research Articles

Barreling of Solid Cylinders Under Axial Compression

Axisymmetric compression tests of solid aluminum cylinders, over a wide range of “aspect ratios” (length/diameter) and both under dry as well as lubricated conditions, suggest that the resulting curvature of the “barrel” formed fits closely a circular arc and its radius follows a power law with the true axial compressive stress. The true compressive stress-strain curve, extrapolated from the experimental data in each test, shows that within the variety of lubricants used the Specific Forming Energy is minimum with teflon sheets as dry lubricant, and increases successively with silicon spray, motor oil, and dry friction.

On Strain Rate Enhanced Shear Localization In Light And Heavy Metals

Localized quasi-adiabatic shear bands (QASB) which are marked and accentuated under high strain rates actually dominate deformation/failure behavior in metallic and non-metallic systems. Particularly in rapid deformation rates, nucleation and growth of non-crystallographic, transgranular and non-isothermal localized bands are enhanced with direct implications on various processes. These include, machining, forming, erosion, fragmentation and armor/ penetrator performances. The current phenomenological study adopt a material approach while emphasizing the fine-scale features. Beside some illustrations even in non-metallic materials, two polycrystalline metallic systems were further elaborated. Here, the 2090-T81, Al-Li alloys, with high symmetry crystal structure and the relatively low symmetry orthorhombic U-Ti alloy were selected. Experimentally, the development from homogeneous to inhomogenous up to localized shear band onset was imposed by axisymmetric compression tests conducted at temperature range of 77-296K under intermediate strain rates between 10 to 10 2 sec -1 Even in the sense of macroscopic observations, the study intends to explore microscopic origins for macro-band formation. This by realizing that analysis which is based solely on continuum argumentation might provide only a partial view or general deformation and fracture behavior trends.