脆性材料复合型裂纹的断裂准则

实际工程中,脆性材料中的裂纹多处于复合型受力状态,因此,确定脆性材料中的复合型裂纹起裂角和临界荷载有着重要的理论意义和实用价值。以复合型裂纹为研究对象,将裂纹尖端的最小无量纲塑性区尺度ρmin和广义合成偏应力强度理论相结合,建立脆性材料复合型裂纹的断裂准则,预测裂纹起裂角及临界荷载,将其结果与最大周向应力准则和应变能密度因子准则相比较发现,基于该文方法得到的临界荷载曲线大于最大周向应力准则得到的临界荷载曲线,与应变能密度因子准则得到的临界荷载曲线比较接近。因而,表明了用该文的方法来预测脆性材料复合型裂纹起裂角和临界荷载是行之有效的。

THE FRACTURE CRITERION OF THE MIXED MODE CRACK IN BRITTLE MATERIAL'S

Cracks are mostly in mixed mode in practical engineering. For mixed mode crack, it is key to determine its initiation angle and critical load. Combining the minimum normalized plastic zone size ρ minand the strength theory of generalized composed deviator stress, this paper proposes a fracture criterion of the mixed mode crack in brittle material to predict the initiation angle and critical load. Comparing the results by the proposed criterion with those of the maximum stress criterion and strain energy density factor criterion, it is found that the critical load curve by the proposed criterion is greater than that of maximum stress criterion and it is close to that of strain energy density factor criterion. Therefore, the proposed criterion is effective for predicting the initiation angle and critical load.