非常规态型近场动力学热黏塑性模型及其应用

NON-ORDINARY STATE-BASED PERIDYNAMIC THERMAL-VISCOPLASTIC MODEL AND ITS APPLICATION

在非常规态型近场动力学(non-ordinary state-based peridynamics,NOSB-PD)理论框架下构建了考虑应变率效应、塑性硬化、热软化效应和材料断裂特征的非局部三维热黏塑性固体本构模型以及相应的非局部空间积分型数值算法,并应用于金属类材料和构件在冲击载荷作用等工况下的高应变率热黏塑性变形与破坏分析.通过对经典含初始裂纹Kalthoff-Winkler板冲击试验进行三维近场动力学模拟,可得到裂纹的起裂角度、扩展路径、扩展速度以及裂纹扩展过程中靶板等效应力和温度分布,所得结果与已有试验结果和其他数值方法结果吻合较好.在此基础上,应用该模型分析了不同冲击速度作用下金属靶板的变形与裂纹扩展过程,结果表明:该模型能较好地模拟不同冲击速度(应变率)情况下靶板的变形与破坏全过程.随着冲击速度变化,初始裂纹的起裂时间、扩展方向和扩展速度呈一定规律变化.冲击速度越低,起裂时间越晚(直至冲击速度低于某值时初始裂纹不扩展),裂纹扩展速度峰值越低,冲击过程中靶板温度峰值越低,完全扩展所需时间越长.

A three-dimensional non-local thermo-visco-plastic solid model considering the strain rate effect, plastic hardening, thermal softening and fracture characteristics of materials, together with corresponding non-local spatial integral-type numerical method,have been proposed under the configuration of the recently developed non-ordinary state-based peridynamic（NOSB-PD） theory, and the model and numerical method have been employed to analyze the high-rate thermal-viscoplastic deformation and failure behavior of metallic materials and components under impact loads. The validity of the proposed model and algorithms was established through simulating the three-dimensional classical Kalthoff-Winkler impact experiment and comparing the numerical results including the cracking initiation time and orientation, crack propagation path and propagation speed, and the distribution of temperature and equivalent stresses in the target with experimental observations and available numerical results in literature. The proposed model and method were further applied to simulate the deformation and failure mechanism of double-notched metallic plates subjected to impact loads with different impacting velocities. Numerical results show that the present model inherits the advantages of both peridynamics and classical thermo-visco-plastic models, and is able to describe the whole elastic and plastic deformation and crack propagation processes qualitatively as well as quantitatively. Moreover, the effect of impact velocity on crack initiation time, crack propagation path and crack propagation speed were investigated. When subjected to impact load with lower impacting velocity, the crack initiation time of the target plate will be later（until no crack propagation appears when impacting velocity is lower than some value）, and both the crack propagation speed and the peak temperature in the target plate will decrease.