This is a fractographic case study of a mechanically loaded glass plate that formed a remarkable spiral crack when the plate fractured. Common radial and circumferential cracking in disks and plates in general are first reviewed. The exceptional spiral crack is then analyzed. The origin of failure was an unusual flaw on the nominal compression side of the plate. The complex spiral fracture pattern has been observed in other large plate glass fractures that break under blunt impact conditions. Spiral cracks can form and propagate from flaws on the front side of a flexed plate that is rigidly supported at its rim or, alternatively, is supported from underneath and has a large overhang.

中文翻译：

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在破裂的玻璃板上出现径向，周向和螺旋形裂纹

这是对机械加载的玻璃板进行分形的案例研究，该玻璃板在断裂时会形成明显的螺旋形裂纹。首先，首先回顾一下磁盘和板中常见的径向和周向裂纹。然后分析异常的螺旋裂纹。失败的根源是板的名义压缩侧的异常缺陷。在其他大型平板玻璃破裂中也观察到了复杂的螺旋破裂模式，这些破裂在钝的冲击条件下破裂。螺旋形裂纹可能会从挠性板正面的裂纹处形成并传播，该挠性板的边缘被牢固地支撑，或者从下方支撑，并且具有较大的悬垂度。