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arXiv 1808.06245cond-mat.softcond-mat.mtrl-sci
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实际断裂准则对裂纹形态的影响

Implications of Realistic Fracture Criteria on Crack Morphology

Bjørn Skjetne, Alex Hansen

摘要:

我们研究了实际断裂准则对随机离散元方法数值模拟得到的裂纹形态的影响。结果得到两个标准,这是一致的弹性理论,并与以前的结果相比,使用原始标准,选择时的方法首次出版,传统的选择一直考虑的组合加载之间的相互作用弯曲和拉伸力,完全忽略了剪切力。此外,旧准则中所用的弯曲和拉伸的组合仅适用于塑性形变。我们的研究结果表明,剪切力的列入裂纹形态有深远的影响。我们考虑两种类型的外载荷,扭转施加到一个圆柱和拉伸施加到一个立方体。在拉伸的情况下,指数的特点与系统尺寸的裂纹粗糙度的缩放被发现是非常接近的实验值zeta = 0:5时,使用现实的断裂准则。在目前的计算中,我们得到zeta = 0.52,一个对所有疾病保持不变的值。有人提出,小规模的指数zeta = 0.8出现作为一个后果的晶面之间的解理,因此需要一个不同的断裂准则比,这是在较大的规模上使用。

英文摘要:

We study the effects realistic fracture criteria have on crack morphology obtained in numerical simulations with a stochastic discrete element method. Results are obtained with two criteria which are consistent with the theory of elasticity and compared with previous results using the original criterion, chosen when the method was first published, The conventional choice has been to consider the combined loading as an interaction between bending and tensile forces only, leaving out shear forces altogether. Moreover the combination of bending and tension used in the old criterion is correct only for plastic deformations. Our results show that the inclusion of shear forces have a profound effect on crack morphology. We consider two types of external loading, torsion applied to a circular cylinder and tension applied to a cube. In the tensile case, the exponent which characterises scaling of crack roughness with system size is found to be very close to the experimental value zeta = 0:5 when realistic fracture criteria are used. In the present calculations we obtain zeta = 0.52, a value which remains constant for all disorders. It is proposed that the small-scale exponent zeta = 0.8 appears as a consequence of cleavage between crystal planes and consequently requires a different fracture criterion than that which is used on larger scales.

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