多孔铁电陶瓷冲击压缩响应与损伤演化的离散元数值模拟

Discrete element simulation on dynamic response and damage evolution in porous ferroelectric ceramics under shock compression

采用flat-joint粘结模型,建立多孔铁电陶瓷在一维应变冲击压缩下的PFC (particle flow code)颗粒流离散元模型,通过数值模拟再现了平板撞击实验中实测的自由面速度剖面历史,并揭示了多孔铁电陶瓷在冲击压缩下的响应过程与损伤演化机制。多孔铁电陶瓷在冲击压缩下的响应过程可分4个阶段:弹性变形、失效蔓延、冲击压溃变形、冲击Hugoniot平衡状态;其中,失效蔓延的内在机制是由剪切裂纹的成核与增长,而冲击压溃变形的主要机制是孔洞的塌缩以及层状剪切裂纹的形成与扩展;冲击速度与孔隙率对铁电陶瓷的响应有显著的影响,Hugoniot弹性极限强烈依赖于孔隙率,但与冲击速度的大小无关,宏观损伤累积随着冲击速度和孔隙率的增加而增加。

Based on the flat-joint bonding model, the PFC(particle flow code) particle flow discrete model of porous ferroelectric ceramics under one-dimensional strain shock compression was established. The free-surface velocity profiles measured in plate impact experiments have been well reproduced by the discrete element simulation,and the response process and damage evolution mechanism of porous ferroelectric ceramics under shock compression were revealed. The response process of porous ferroelectric ceramics under shock compression can be divided into four stages: elastic deformation, failure spread, shock crushing deformation and shock Hugoniot equilibrium state. The mechanism of failure spread is the nucleation and growth of shear cracks. The main mechanism of shock crushing deformation is the formation and propagation of layered shear cracks and the collapse of voids. The impact velocity and porosity have significant effects on the dynamic response and damage evolution of porous ferroelectric ceramics. The Hugoniot elastic limit strongly depends on porosity and is not affected by impact velocity. The damage accumulation increases with the increase of impact velocity and porosity.