Analysis of Elastic/Visco-Plastic Waves of Finite Uniaxial Strain. Topical Report of the Predix Research Program

摘要

An approximate theory is presented for waves of small but not infinitesimal strains. The approximation introduced is the representation of the specific internal energy by an expansion to third order terms in elastic strains and entropy. Isotropic materials are assumed for which the coefficients in the expansion of the internal energy can be determined from ultrasonic measurements of the variation of the longitudinal and shear wave speeds with hydrostatic pressure, uniaxial stress, and temperature. Wave profiles are computed for two plastic strain-rate functions developed to model 6061-T6 aluminum. Computations are carried out using a difference method which treats the jumps at the elastic precursor explicity and is essentially a second-order accurate method in the continous wave region behind the wavefront. The computed profiles illustrate the details of the profiles near the wave front and at early times. (Author)