热动力学框架内的RPC材料弹塑性各向异性损伤本构建模研究

考虑材料刚度的退化,不可恢复应变,非弹性体胀及单边效应,建立了RPC材料的弹塑性各向异性损伤本构关系.采用有效应力张量的正负分解,拉压不同的塑性硬化法则和拉压不同的损伤演化法则对RPC材料的单边效应进行了建模.采用张量型的损伤变量来描述损伤的各向异性,通过四阶损伤效应张量和应变等效假设建立有效构形和损伤构形中的物理量之间的关系.在热动力学框架内,建立了RPC材料的状态势和耗散势,由状态律给出了与状态变量共轭的热动力学广义力与状态变量之间的关系,由动力律给出了状态变量的演化关系,由塑性加载条件,损伤准则和一致性条件给出了塑性乘子和损伤乘子的大小,最终推导出弹塑性损伤切线刚度张量,为数值方法的实施典定基础,讨论了材料参数确定的方法和模型的局限性,为进一步的工作指明了方向.

Research on Coupled Elastic-plastic Anisotropic Damage Constitutive Model for RPC within Thermodynamic Framework

The degradation of material stiffness,irrecoverable strain,inelastic volumetric expansion and unilateral effects were considered,a coupled elastic-plastic anisotropic damage constitutive model for RPC was presented in this paper.Positive and negative decomposition of effective stress tensor,different tensile and compressive plastic hardening law and different tensile and compressive damage evolution law were adopted,simulated effectively for the unilateral effects.Used to tensor damage variables,anisotropic evolution of damage were described,and the relationship of physical quantities,which were used in both effective configuration and damaged configuration,were established through the fourth order damage effect tensor and the strain equivalence hypothesis.Within the thermodynamics framework,state potential energy function and dissipation potential function had been established,and the relationship between state variables and the generalized force,which conjugated with state thermodynamic variables,were founded through the state law,the evolutions of state variables were set up simultaneously by the power law,meanwhile,the plastic multiplier and damage multipliers were derived through three conditions(the plastic loading conditions,damage criteria and consistency conditions).Based on previous work,the elastic-plastic damaged tangent stiffness tensor has been eventually established,which was foundation of implementation of numerical methods.Finally,summarized the key formula for the constitutive model,and discussed the identification of material parameters and the limitations of the methods for further work.