An experimental study of 3-D crack growth from initial cracks of different shapes and inclinations in biaxial compression with different biaxial load ratios ( $$ \sigma_{x} /\sigma_{y} $$ σ x / σ y ) is presented. Unlike 3-D crack growth in uniaxial compression, which is characterised by the presence of intrinsic limits on 3-D growth of wing cracks associated with wing wrapping, in biaxial compression the wing crack can grow extensively and is parallel to the free surfaces of the specimen as long as the $$ \sigma_{x} /\sigma_{y} $$ σ x / σ y ratio exceeds a threshold. Surprisingly, the threshold is extremely low: around 0.05 for all cases considered; below this threshold, the wing crack growth is restricted. It is found that the shape and inclination of the initial crack have minor effect on this transition process.

中文翻译：

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双轴压缩中的 3D 裂纹扩展：初始裂纹的形状和倾斜度的影响

提出了在不同双轴载荷比 ($$\sigma_{x} /\sigma_{y} $$ σ x / σ y ) 的双轴压缩中不同形状和倾斜度的初始裂纹的 3-D 裂纹扩展的实验研究。与单轴压缩中的 3-D 裂纹扩展不同，单轴压缩中的 3-D 裂纹扩展的特点是存在与机翼包裹相关的机翼裂纹 3-D 扩展的固有限制，而在双轴压缩中，机翼裂纹可以广泛扩展并平行于机翼的自由表面。只要 $$ \sigma_{x} /\sigma_{y} $$ σ x / σ y 比率超过阈值，样本就可以。令人惊讶的是，阈值非常低：对于所有考虑的情况，大约为 0.05；低于此阈值，机翼裂纹扩展受到限制。发现初始裂纹的形状和倾角对该过渡过程的影响较小。