Abstract: The rectangular beams were widely used in architectural engineering, cracks would be appeared with the increase of service life and some human factors, and any cracks in it might cause hidden risks. The SIF was a physical quantity that reflected the elastic stress field of the crack tip, which was related to the size of the crack, the geometrical characteristic of the component and the load. Meanwhile, it was very important to find a simple method to solve the SIF for not only the fracture theory but also engineering application, as it was a key content of fracture mechanics. In previous studies, the shape of initial crack must be known to get SIF, but it was very difficult to be seen under the condition of test. This paper took the bending beam as an example, a new method to formulize the SIF for three kinds of cracks in rectangular beam under bending load was proposed by the basis of the conservation J integral.

Key words: Stress intensity factor, J integral, Cracks, Energyrelease rate, Rectangular beams

摘要： 建筑工程中的梁大多数都是矩形梁,随着使用年限的增加以及受一些人为因素的影响,梁会产生裂纹,而所产生的任何裂纹都会使梁结构存在安全隐患。应力强度因子是反映裂纹尖端弹性应力场强弱的物理量,与裂纹的尺寸或构件的几何特征及载荷有关。同时,断裂力学中的一个重要内容就是计算应力强度因子,无论是对断裂理论还是工程应用,寻求一个简单的求解应力强度因子的方法极其重要。在以往的研究中,要想求得裂纹的应力强度因子需要测得初始裂纹的形状,但是测初始裂纹的形状常常会受到测试条件的约束,可见这是相当困难的。以弯曲梁为例,基于守恒积分法求解裂纹非自发扩展的能量释放率,建立了一个求解弯曲载荷作用下矩形梁的三种裂纹开裂情况下的应力强度因子新方法。

关键词: 应力强度因子, J 积分, 裂纹, 能量释放率, 矩形梁