材料期刊网

脆性材料的破坏通常是瞬态快速断裂,亚临界慢裂纹扩展特别是宏观慢扩展,很难在实验中观察.它一定程度上制约了玻璃陶瓷等材料的失效过程分析和阻力特性研究.本研究利用MFPA2D(Material Failure Process Analysis)软件成功地模拟了玻璃类脆性材料在平面应力状态下承受单向、双向应力时的亚临界裂纹扩展全过程,着重研究了脆性材料的慢裂纹扩展和扩展速度所受双向应力的影响,并讨论这种影响的机理和作用.通过声发射特性的数值模拟得到脆性材料在单向及双向应力状态下的亚临界裂纹扩展长度-荷载步曲线.结果表明,平行于裂纹面的拉应力对裂纹扩展有一定程度的阻碍作用,而平行于裂纹的压应力对裂纹有驱动效果.该数值实验结果与相关的实验结果取得了较好的一致,表明数值实验的可靠性,从而为脆性材料的可靠性和寿命评价提供理论基础和手段.

The failure of brittle materials such as glass is always unstable. Therefore, it is usually difficult to observe in situ the subcritical crack growth in experiment with a brittle sample. This restricts the analysis of failure process and the study of crack resistance of brittle materials. Whether biaxial stress influences the crack growth of brittle materials is always a controversial issue. The aim of this study is to demonstrate the influence of the stress parallel to the crack plane on subcritical crack growth in brittle materials by numerical code MFPA2D. The mechanism of this influence is also discussed. The curves of subcritical crack extension vs. strain of brittle materials under biaxial and uniaxial stress were numerically obtained through numerical simulation test with acoustic emission characteristics. The results showed that the tensile stress parallel to the crack plane had the effect on crack arrest, while the compressive stress parallel to the crack plane contributed to crack opening for brittle materials in plane stress state. The numerical simulation results were consistent with correlative experimental result, which showed the reliability of the numerical simulation.