考虑材料强化的塑性安定性分析

Plastic Shakedown Analysis for Structures Subjected to Cyclic Thermal Loading

采用较真实的材料本构模型,在Ponter和Karadeniz提出的扩展的安定性理论以及彭得到的考虑混合强化的安定性定理的基础上,发展了计及应变强化和循环强化的结构塑性安定区的分析方法。通过将循环强化和应变强化分别引入子区域V_F和V_S,利用材料安定性假设,得到了较为合理的塑性安定边界,克服了以前的工作中对处于V_F和V_S区中的材料分别采用完全各向同性强化(或假设热应力史是弹性应力史)和完全塑性的理想材料模型所带来的不合理性和误差。对受机械载荷和变化的热应力场作用的二杆结构和Bree板进行了安定分析,结果表明热应力史是弹性应力史的假设可能导致过于保守的安定边界,也可能过高地估计塑性循环过程中的屈服应力而导致偏于危险的结果。

Making use of a more realistic constitutive model, the method for the determination of plastic shakedown bound is developed on the basis of the extended shakedown theory proposed originally by Ponter and Karadeniz. The plastic strain hardening is introduced into shakedown region V_s and the cyclic hardening into fatigue region V_F·The assumption that the thermal stress history is the linear elastic stress history is ignored because it differs markedly from the realistic constitutive response and brings about great error in shakedown analysis. A two-bar structure and a Bree plate subjected to fixed mechanical load and cyclic thermal load are analyzed respectively, which produces more reasonable plastic shakedown bounds than those given in [l] by using fully isotropic hardening rule in V_F and perfact plasticity in V_s·