Ⅰ-Ⅱ混合型裂纹相变增韧分析

摘要

By use of the pressure sensitive stress criterion and the methodof weight function, the fracture toughness enhancement induced by mixed mode Ⅰ-Ⅱ cracks in phasetr ans formation toughened ceramics is predicted theoretically. The theoretical express ions for the toughening effects of both the stationary and the steady-state growing cracks are given respectively. Results show that there is a negative effect from the stationary cracks and it increases with the increase of KⅠ/KⅡ, and that the toughening effect of the steady-state growing cracks I s not only associated with the modulus of elasticity, the width of transformation area and the transformation volume fraction, but also decreases with the increase of KⅠ/KⅡ.%采用压力敏感准则和权函数法对相变增韧陶瓷Ⅰ-Ⅱ混合型裂纹的增韧效应进行了理论预测，分别给出了静止裂纹和定常扩展裂纹相变塑性屏蔽的理论表达式。结果表明：相变对静止裂纹有负屏蔽效应，并随KⅡ/KⅠ的比值增大而增大；对定常扩展裂纹的增韧结果除与材料弹性模量、相变尾区高度和相变体积分数有关外，还随KⅡ/KⅠ的比值增大而减小。