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arXiv 2012.09011cond-mat.mtrl-sci
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粘弹性材料与弹性材料界面处的裂纹扩展

Crack propagation at the interface between viscoelastic and elastic materials

M. Ciavarella, R. McMeeking

摘要:

自20世纪70年代以来,许多作者使用Barenblatt内聚模型来理解粘弹性材料中的裂纹扩展。在聚合物和金属蠕变中,通常假设松弛模量为零,因此我们通常具有取决于应力强度因子的某个幂的裂纹速度。一般来说,当有一个有限的松弛模量,它已被证明,韧性增加之间的值在非常低的速度在阈值韧性G0,一个非常快的断裂值在Ginf,并在无限系统(其中经典奇异断裂力学场占主导地位)的增强因子简单地对应于瞬时松弛弹性模量的比率。在这里,我们适用于弹性和粘弹性材料之间的双材料界面的情况下,假设裂纹仍然在界面处的凝聚力模型,并忽略双材料奇异性的细节。对于麦克斯韦材料在低速下的情况,裂纹以仅取决于粘度和应力强度因子的四次方的速度传播,而不取决于任一材料的弹性模量。对于无松弛模量的Schapery型幂律材料,有更一般的结果。对于任意粘弹性材料与非零松弛模量,我们表明,最大韧性增强将减少相对于一个经典的粘弹性裂纹在均匀材料。

英文摘要:

Crack propagation in viscoelastic materials has been understood with the use of Barenblatt cohesive models by many authors since the 1970's. In polymers and metal creep, it is customary to assume that the relaxed modulus is zero, so that we have typically a crack speed which depends on some power of the stress intensity factor. Generally, when there is a finite relaxed modulus, it has been shown that the toughness increases between a value at very low speeds at a threshold toughness G0, to a very fast fracture value at Ginf, and that the enhancement factor in infinite systems (where the classical singular fracture mechanics field dominates) simply corresponds to the ratio of instantaneous to relaxed elastic moduli. Here, we apply a cohesive model for the case of a bimaterial interface between an elastic and a viscoelastic material, assuming the crack remains at the interface, and neglect the details of bimaterial singularity. For the case of a Maxwell material at low speeds the crack propagates with a speed which depends only on viscosity, and the fourth power of the stress intensity factor, and not on the elastic moduli of either material. For the Schapery type of power law material with no relaxation modulus, there are more general results. For arbitrary viscoelastic materials with nonzero relaxed modulus, we show that the maximum toughness enhancement will be reduced with respect to that of a classical viscoelastic crack in homogeneous material.

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