脆性材料在双向应力下阻力特性数值模拟

Numerical simulation to resistance characteristic of brittle materials under biaxials stress

应用一个材料失效分析模拟软件MFPA2D模拟了玻璃在平面双向应力下不同破坏失稳过程,重点研究了平行于裂纹面的应力对脆性材料临界断裂参数的影响,运用数值模拟和试验及理论分析相结合的方法,阐明脆性材料在双向和单向应力下断裂参数的区别等问题.研究结果证明,双向应力对断裂韧性有明显影响,平行于裂纹面的拉应力对裂纹扩展有抑制作用,压应力对裂纹扩展有促进作用.因此,线弹性材料在双向荷载作用下,传统的应力强度因子准则不适用,裂纹扩展由裂纹尖端应变决定,即双向应力下裂纹扩展具有应变依赖性.

The fracture behavior of brittle materials under biaxial plane stress, especially the influence of the stress parallel to the crack plane on critical fracture parameters, was investigated by means of MFPA2D (Material Failure Process Analysis) computer simulation method. The purposes of this study are to clarify the difference of fracture dependence of brittle materials under biaxial and uniaxial stress state based on numerical simulation, experimental and analytical approaches. The results indicate that the biaxial stresses affect the fracture toughness of glass. It is confirmed that the tensile stress parallel to the crack plane has the action of crack arrest, while the compressive stress parallel to the crack plane contributes to crack opening for glass in plane stress state. Thus, the fracture criterion by the stress intensity factor is questioned for the biaxial plane stress issues. The crack growth was determined by the crack tip strain. Strain dependence of crack growth is discussed to explain the influence of biaxial stress.