关键词: 对流扩散方程, 混合有限元法, 时间间断时空有限元法, 收敛性, combined stress, phase transition wave, thin-walled tube, shape memory alloy (SMA)

Abstract: The incremental constitutive relation and governing equations with combined stresses for phase transition wave propagation in a thin-walled tube are established based on the phase transition criterion considering both the hydrostatic pressure and the deviatoric stress. It is found that the centers of the initial and subsequent phase transition ellipses are shifted along the σ-axis in the στ-plane due to the tension-compression asymmetry induced by the hydrostatic pressure. The wave solution offers the “fast” and “slow” phase transition waves under combined longitudinal and torsional stresses in the phase transition region. The results show some new stress paths and wave structures in a thin-walled tube with phase transition, differing from those of conventional elastic-plastic materials.

Key words: convergence, convection diffusion equations, mixed finite element method, time discontinuous space-time finite element method, combined stress, phase transition wave, thin-walled tube, shape memory alloy (SMA)