铈低压冲击相变数值模拟研究
Numerical study of shock-induced phase transformation of cerium under low pressure
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摘要: 对金属铈低压冲击γ→α相变进行了数值模拟研究.冲击加载实验的速度剖面结果表明,铈的低压相变过程中两相之间的转换较为光滑,无明显间断,其相变过程存在动态因素.通过分析金属铈低压冲击加载和卸载下的典型物理过程,对材料本构关系、Hugoniot关系和相变与逆相变过程进行了理论研究.获取了铈低压相变前后的本构关系及状态方程,并建立了非平衡相变理论模型.数值计算结果与平面冲击实验符合较好,表明该相变动态模型能够较好地描述铈的低压冲击加载和卸载过程.Abstract: The dynamic responses of cerium under low pressure, including γ→α phase transition, are numerically studied in this paper. The velocity profiles of shock experiments show that the transition process between the two phases is smooth and there is no obvious disconnection between the two plastic waves of the particle velocity profiles. Three important problems in the dynamic response, including constitutive model, Hugoniot relation and phase transition/reversal, are discussed. A multi-phase equation of state and constitutive model of Ce are presented in this paper after analyzing the typical wave configuration of cerium under the shock loading and releasing. The dynamic phase transition model is built for the non-equilibrium course in the phase γ→α transition induced by shock wave. The numerical results accord with the experimental data of the plane impact tests, indicating that the dynamic phase transition model can describe the dynamic response under low pressure of cerium more reasonably.
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