面外约束对韧性材料的断裂韧度的影响  

EFFECT OF OUT-OF-PLANE CONSTRAINT ON DUCTILE FRACTURE TOUGHNESS

作　　者：王兆希[1] 施惠基[1] 

机构地区：[1]清华大学工程力学系,北京100084

出　　处：《工程力学》2007年第11期19-24,共6页Engineering Mechanics

基　　金：国家自然科学基金资助项目(10472049);清华-砝马通联合基金(N10);国家重点基础研究发展计划项目(2006CB605003)资助

摘　　要：与脆性断裂的断裂韧度随厚度的增加而逐渐趋近于一个常数的变化趋势不同,韧性较好材料的弹塑性断裂韧度的特征为:在一定范围内随着厚度的增加,弹塑性断裂韧度逐渐增加。主要研究在保持试件的面内约束(a/w)保持不变的条件下,面外约束(厚度的变化)对同种材料的试件的断裂韧度的影响。首先采用韧性较好的材料进行断裂韧性实验,通过实验得到结果:试件的弹塑性断裂韧度J积分及临界裂纹尖端张开位移CTOD随着试件厚度的增加而线性增加。然后从能量平衡的角度出发,考虑在裂纹扩展过程中的所有的宏观能量耗散机制,根据通过实验验证的假设,化简后,得到最终的结果:一定程度上表征能量耗散的断裂韧度随着厚度的增加而增加,与实验结果吻合得较好。Instead of the reducing tendency of the brittle fracture toughness with the increment of the thickness of the specimens, the elastic-plastic fracture toughness of the ductile material increases with the thickness of the specimens. In this paper, the effect of out-of-plane constraint to the fracture toughness of specimens is studied, which is defined as the different thickness of the specimens w varying with crack length a, while keeping the a/w as a constant. Experiments of ductile material fracture tests are carded out with the results： the elastic-plastic fracture toughness, J integral increases linearly with the thickness of the specimens. Theoretically, the energy release system is discussed according to the energy balance equations. With the energy release system, final results show that the fracture toughness J integral increases linearly with the thickness of the specimens, which are quite consistent with the experimental results.

关 键 词：断裂韧性 面外约束 厚度效应 积分 弹塑性断裂 能量耗散 

分 类 号：O346.12[理学—固体力学]