摘要
The maximum Mode Ⅰ and Mode Ⅱ stress intensity factors(SIFs), KI,kmax(θ) and KII,kmax(θ)(0°<θ<360°), of inclined parallel multi-crack varying with relative positions(including horizontal and vertical spacings) are calculated by the complex function and integration method to analyze their interacting mechanism and determine the strengthening and weakening zone of SIFs. The multi-crack initiation criterion is established based on the ratio of maximum tension-shear SIF to predict crack initiation angle, load, and mechanism. The results show that multi-crack always initiates in Mode Ⅰ and the vertical spacing is better not to be times of half crack-length for crack-arrest, which is in good agreement with test results of the red-sandstone cube specimens with three parallel cracks under uniaxial compression. This can prove the validity of the multi-crack initiation criterion.
采用复变函数和积分方法,计算多条平行斜裂纹的最大Ⅰ型和Ⅱ型应力强度因子KI,kmax(θ)和KII,kmax(θ)(0°<θ<360°)随裂纹相对位置(包括垂直间距和水平间距)的变化值,分析多裂纹相互作用机理,并得到应力强度因子的强化区和弱化区。基于最大拉-剪应力强度因子比,建立多裂纹起裂判据,并预测裂纹起裂角、起裂荷载和起裂机理。预测结果表明:多裂纹起裂机理为I型;为便于止裂,多裂纹之间的垂直间距不宜等于裂纹半长的倍数。预测结果与单轴压缩下三平行裂纹的红砂岩立方体试件试验结果吻合较好,验证多裂纹起裂准则的有效性。
基金
The authors are grateful for the financial supports from the National Natural Science Foundation of China(51874351,51474251)
Hunan Provincial Innovation Foundation For Postgraduate,China(CX2018B047)
the Open Sharing Fund for the Large-scale Instruments and Equipments of Central South University,China(CSUZC201923).
