Tensile cracks can shatter classical speed limits
Tensile cracks can shatter classical speed limits
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拉伸裂纹可以打破经典的速度限制
作者：
Mei Wang;Songlin Shi;J. Fineberg
脆性材料因快速破裂而损坏。经典断裂力学描述了拉伸裂纹的运动，其在其尖端的点状区域内耗散释放的弹性能量。在这个框架内，一个“经典”的拉伸裂纹不能超过瑞利波速度，cR。使用脆性新胡克材料，我们实验证明存在的“超剪切”拉伸裂纹，超过剪切波速度，CR。超剪切裂纹平稳地加速超过cR，达到接近膨胀波速度的速度。超剪切动力学是由不同的原则比那些指导“经典”裂纹;这种断裂模式是激发在临界（材料相关）施加应变。这种非经典的拉伸断裂模式代表了我们对断裂过程理解的根本转变。描述编辑小结在拉伸状态下，材料中靠近裂纹尖端的体积中的应力被放大，当势能超过材料的断裂能时，裂纹将向断裂方向扩展。一般认为，运动裂纹的最大速度不能超过瑞利波速度。Wang等人使用脆性水凝胶作为模型材料，其中裂纹尖端前面的结构中的薄弱层在原本完美的水凝胶板中形成一种颈部（参见Marder的Perspective）。作者观察到裂纹的传播速度超过剪切波的速度，并发现超剪切动力学行为不同于经典的开裂理论。在脆性水凝胶的断裂过程中观察到超剪切开裂。
Brittle materials fail by means of rapid cracks. Classical fracture mechanics describes the motion of tensile cracks that dissipate released elastic energy within a point-like zone at their tips. Within this framework, a “classical” tensile crack cannot exceed the Rayleigh wave speed, cR. Using brittle neo-hookean materials, we experimentally demonstrate the existence of “supershear” tensile cracks that exceed shear wave speeds, cR. Supershear cracks smoothly accelerate beyond cR, to speeds that could approach dilatation wave speeds. Supershear dynamics are governed by different principles than those guiding “classical” cracks; this fracture mode is excited at critical (material dependent) applied strains. This nonclassical mode of tensile fracture represents a fundamental shift in our understanding of the fracture process. Description Editor’s summary Under tension, stresses are amplified in a material in the volume close to a crack tip, and the crack will propagate toward fracture when the potential energy exceeds the material’s fracture energy. It is generally thought that the maximum velocity of a moving crack cannot exceed the Rayleigh wave speed. Wang et al. use brittle hydrogels as a model material in which a weak layer in the structure in front of the crack tip forms a sort of neck in an otherwise perfect hydrogel plate (see the Perspective by Marder). The authors observed cracks traveling faster than the shear wave speed and found that the supershear dynamics behaved differently from the theories of classical cracking. —MSL Supershear cracking is observed during the fracture of brittle hydrogels.
影响因子：
16.6
作者：
Gori M;Rubino V;Rosakis AJ;Lapusta N
通讯作者：
Lapusta N
影响因子：
56.9
作者：
Kim, Junsoo;Zhang, Guogao;Suo, Zhigang
通讯作者：
Suo, Zhigang
影响因子：
5.3
作者：
Wang, Yecheng;Nian, Guodong;Kim, Junsoo;Suo, Zhigang
通讯作者：
Suo, Zhigang