温度对冲击相变波传播的影响

冲击加载下，相界面的传播是一热力耦合过程。相变波阵面不仅是力学和物质间断面，也是温度界面。为考虑温度对相变波传播的影响，本文首先建立了相界面上的热传导方程和热力耦合的相变本构方程，然后采用一维特征线理论和有限差分数值计算相结合的方法，分析了温度界面和相变波的基本相互作用规律，进而给出了连续温度梯度下和绝热冲击下相变波传播规律。结果表明，温度对相变波传播的作用主要体现在两个方面，一方面是作为温度界面将与各类间断面相互作用，另一方面冲击相变波阵面后区域热力学状态变化影响卸载波结构。其原因在于相变方式（可逆、不可逆）和相变阈值应力具有强烈的温度相关性。

Effect of temperature on the phase transition shock wave propagation

First-order martensitic transformations usually undergo temperature variations because of release/absorption of latent heat. Such temperature variations, in turn, affect the process of phase transition and the propagation of phase boundary, especially for shock loading. In fact, the phase transition wave front is not only a discontinuity of mechanics and matter, but also a moving temperature interface. This temperature interface is bound to influence the phase transition wave profiles and make the space-time pattern of its propagation more complex. However, it may bring some new wave propagation phenomena, which will have important theoretical value for the extension of stress wave theory. In this paper, the effect of temperature on the propagation of phase transition wave was studied theoretically and numerically. First, we treated the temperature interface as a fixed one to study the basic interaction between the temperature interface and phase transition wave by using the method of one-dimensional characteristic line theory and finite difference numerical calculation. The results showed that such an interaction was related to the temperature gradient of the interface and the applied stress pulse amplitude. Second, the propagation of phase transition wave was given under the conditions of continuous temperature gradient and adiabatic impact, respectively. The results showed that for loading from the austenitic phase to the mixed phase or martensite phase, a shock wave would be generated due to the mixed phase hardening effect; while for unloading, a shock wave was predicated due to a change in the unloading path, which has barely been studied. Through analysis of the thermo-mechanical coupling constitutive equations with phase transition, it was found that the nonlinear hardening characteristics and the change of unloading path are both rooted in the interaction between the self-heating (latent heat and dissipated energy) and the temperature dependence of phase transition stress, reflecting the intrinsic characteristics of materials with strong thermo-mechanical coupling properties. The results are helpful for the design and control of impact resistance for phase transition materials and structures.