耦合孪生晶体塑性模型硬化参数的灵敏度分析

基于经典晶体塑性理论,建立了耦合孪生的晶体塑性本构模型并进行了全隐式积分的数值实现.该本构模型采用饱和硬化法则,并采用孪生阻力与滑移硬化之间的正比关系来描述孪生对滑移硬化影响及孪生硬化行为.针对该本构模型的13个参数,结合各参数物理意义提出了参数的分类确定方法.以孪生诱导塑性（TWIP）钢Fe-22Mn-0.6C为例,着重对硬化参数的局部灵敏度进行了分析,研究了各硬化参数对宏观力学响应、孪生激活和演化的影响,根据变形机制的不同宏观变形过程可区分为孪生硬化阶段和孪生硬化失效阶段,进而给出了硬化参数确定的步骤及其建议取值范围.结果表明:初始滑移阻力与屈服极限线性相关,取值范围在80~160 MPa之间;孪生硬化指数增大使得孪生硬化阶段减弱,其取值范围应在0~3之间;孪生阻力与滑移阻力比值增大,则孪生增长率降低,硬化率拐点后移,直至拐点消失,其取值范围在1~1.3之间. 

Sensitivity analysis of hardening parameters in the crystal plasticity model exhibiting deformation twinning

A crystal plasticity model exhibiting deformation twinning is introduced based on the classical crystal plasticity theory,and its numerical implementation is conducted in which a fully implicit integration procedure is employed. In this constitutive model,the saturation-type hardening law is adopted and the direct proportion relationship between twin resistance and slip hardening is used to describe the effect of twinning on slip hardening and twin hardening. By considering the physical meaning of all the 13 parameters in this model,the classification methodology is presented for these parameters. Taking Fe-22Mn-0.6C twinning induced plasticity(TWIP) steel as an example,a local sensitivity analysis of hardening parameters is investigated emphatically. The effects of hardening parameters on the macro-mechanical response,the activation and evolution of twinning and the strategy for determining the hardening parameters are discussed. According to the difference of deformation mechanisms,the macroscopic deformation are divided into a twin hardening stage and a twin hardening failure stage. And then the determination method and the suggestive ranges for the hardening parameters are given. It is found that the initial slip resistance is linearly associated with the yield limit,and the value of initial resistance stress ranges from 80 MPa to 160 MPa. The twin hardening stage weakens when the twin hardening index increases,the range of values allowed for the twin hardening index is 0 to 3. When the ratio between twinning resistance and slip resistance increases,thegrowth rate of twinning decreases and the turning point of the hardening stage moves backward until it is disappeared. The range of values for the ratio between twinning resistance and slip resistance will be 1 to 1.3.