基于3D-ILC球体45°三维双内裂纹复合断裂研究

Fracture characteristics of sphere with 45° double embedded cracks based on 3D-ILC

断裂力学是各领域基础科学,材料内裂纹相互作用是断裂力学的重要研究领域,但目前球体内裂纹相互作用研究成果较少。基于三维激光疲劳内裂纹(3D-ILC)技术,在对球体试样表面无任何损伤的情况下,制作三维平行纯内裂纹,开展45°倾角平行双内裂纹单轴压缩试验,对双内裂纹的裂纹扩展过程、应力双折射规律、断口特征、破坏形态、相互作用等多方面开展研究,进行含双内裂纹Ⅰ-Ⅱ-Ⅲ型圆球断裂数值模拟,分析KⅠ、KⅡ、KⅢ分布规律,与试验相符。结果表明:(1)球体双内裂纹在单轴压缩下之间发生屏蔽作用,主裂纹面穿过两预制内裂纹;(2)翼型裂纹光滑区呈现Ⅰ-Ⅱ型裂纹断口特征,翼型裂纹侧面撕裂区呈现"矛状"Ⅲ型裂纹特征;(3)基于M积分计算的KⅠ、KⅡ、KⅢ分析与基于断裂特征的Ⅰ、Ⅱ、Ⅲ型裂纹类型分析一致。3D-ILC技术可用于球体内裂纹相互作用断裂试验研究,球体内裂纹试验与理论分析为脆性材料内裂纹扩展及相互作用研究提供试验与理论参考。

Crack interaction in materials is an important research area of fracture mechanics that plays a fundamental role in various fields, but few studies have been conducted on the interaction between internal cracks of brittle spherical material. Based on the 3D-internal laser-engraved crack(3D-ILC) technology, two 45° embedded cracks were generated internally in the spherical glass, and uniaxial compression test was performed. The crack propagation, failure morphology and interaction of the cracks were analysed in this experimental research. The distributions of KⅠ, KⅡ, KⅢ were also analysed based on the M-integral, and the results were consistent with experiments. The results show that: 1) The interaction between two cracks occurs in the test. Due to the shielding effect between the double embedded cracks, the crack growth presents obvious anti-symmetric characteristics. 2) The wing crack growth surface presents both smooth area and tear area, corresponding to the Ⅰ-Ⅱ crack and Ⅲ crack respectively. 3) The simulation result is consistent with the experimental observation. The 3D-ILC technology introduced by the paper can provide experimental and theoretical basis for the study of fracture theory of brittle spheres with parallel internal cracks.