倾斜疲劳裂纹在混合型应力下张开及滑移特性  

Opening and sliding displacement behavior of a slant angle fatigue crack under mixed-mode conditions

作　　者：马有理[1] 黎庆 林晶[1] 

机构地区：[1]哈尔滨商业大学轻工学院,黑龙江哈尔滨150028 [2]黑龙江石油化学研究院化工中心,黑龙江哈尔滨150040

出　　处：《哈尔滨工程大学学报》2009年第3期271-275,共5页Journal of Harbin Engineering University

基　　金：黑龙江省教育厅海外学人科研资助项目.(1153h20)

摘　　要：对于存在裂纹的机械零件或者构件,它很有可能会受到来自不同方向的作用力,因此有必要研究裂纹在混合型应力条件下的传播特性.该文使用具有不同倾斜角度的裂纹——这些裂纹是在应力比R=0的Ⅰ型循环应力下制作的,通过测量裂纹的开口方向和滑移方向的位移量,计算了裂纹端部Ⅰ型应力强度因子(KⅠ)mes和Ⅱ型应力强度因子(KⅡ)mes.裂纹的倾斜角度是指载荷方向与裂纹间的夹角.结果表明,对于存在压缩残余应力的疲劳裂纹,当倾斜角度较大,即β=60°时,应力强度因子的实验值(KⅠ)mes小于理论计算值(KⅠ),但此时实验值(KⅡ)mes与理论值(KⅡ)基本一致.另一方面,对于倾斜角度较小β=45°的疲劳裂纹,其(KⅠ)mes减少的同时,由于裂纹上下表面相互接触,从而导致(KⅡ)mes同时下降.It is necessary to study crack propagation behavior under mixed-mode conditions because an actual crack in a structure maybe subject to strain from various directions. In particular, crack surfaces tend to be forced into contact as load is applied because of the residual compressive stress around the crack and the zigzag crack surface morphology. In this study, therefore, using cracks with different slant angles （defined as the angle between load and crack direction in a rectangular plate） , cracks were made with cyclic stress of mode I with a stress ratio of R =0. Mode I and mode Ⅱ stress intensity factors （KⅠ）mes and （KⅡ） were calculated according to the crack＇s opening and sliding displacements. As a result, the stress intensity factor （KⅠ）rues for the fatigue crack with a slant angle β= 60° was smaller than the theoretically determined KⅠ. But （KⅡ）mes is about the same as KⅡ for the same crack. On the other hand, for fatigue cracks with a smaller slant angle β= 45°, （ KⅡ ） mes declined because of crack-surface contact while （KⅠ） mes was reducing.

关 键 词：疲劳裂纹 回火裂纹 压缩残余应力 不连续位移量 应力强度因子 

分 类 号：TU51[建筑科学—建筑技术科学]