CYCLIC STRESS-STRAIN RESPONSE OF POROUS ALUMINUM

A model of endochronic constitutive theory is applied to the analysis of stress-strain behavior of sintered high purity aluminum powder-based material (P/M) under uniaxial strain-controlled cyclic test conditions. Different strain amplitudes were used on specimens which during fabrication were subjected to cold isostatic pressure of 25 ksi. It was found that mean strain does not significantly affect the fatigue life. It was also discovered that Poisson's ratio at the peak tensile strain decreases gradually with the number of loading cycles, while it reaches a constant value at the peak compressive strain as the number of cycles increases. Results provide a comparison between theory and experiment for both hydrostatic and deviatoric stress-strain behavior for several cases of peak strains in the strain-controlled test. Reasonable agreement has been achieved. The changing trends of the peak volumetric strain, deviatoric stress, hydrostatic stress and Poisson's ratio versus loading cycles are also reported for each case. © 1990.