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首页> 外文期刊>Engineering Fracture Mechanics >An efficient mixed-mode rate-dependent cohesive fracture model using sigmoidal functions
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An efficient mixed-mode rate-dependent cohesive fracture model using sigmoidal functions

机译：使用乙型函数的高效混合率依赖性粘性裂缝模型

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摘要

Rate-dependent fracture processes can be investigated by means of cohesive zone models (CZMs). For instance, one approach enhances existing CZMs with phenomenological expressions used to represent the fracture energy, cohesive strength, and/or maximum crack opening as a function of the crack opening rate. Another approach assumes a vis-coelastic CZM in front of the crack tip. Although computationally less expensive, the former approach misses most of the physics driving the rate-dependent fracture process. The latter approach better represents the physics driving the rate-dependent fracture process, yet it is computationally more expensive. This work presents a methodology for studying mixed-mode rate-dependent fracture that is both efficient and approximates the viscoelastic material behavior in front of the crack tip. In this mixed-mode approach, we approximate the viscoelastic behavior in front of the crack tip using two rate-dependent springs. One spring acts in the normal direction to the crack plane, while the other acts in the tangential direction. In order to mimic a viscoelastic CZM, we assume that the stiffness of each spring is a function of the crack opening rate and enforce that their tractions are continuous with respect to changes in the crack opening rates. To account for damage, we scale the tractions from the rate-dependent springs using two damage parameters extracted from the Park-Paulino-Roesler (PPR) cohesive fracture model. The rate-dependent model is implemented as a user defined element (UEL) subroutine in Abaqus. While attaining a high level of accuracy, the present approach allows for significant savings in computational cost when compared with a CZM based on fractional viscoelastic theory. (C) 2017 Elsevier Ltd. All rights reserved.
机译：可以通过粘性区域模型（CZMS）来研究依赖依赖性裂缝方法。例如，一种方法增强了现有的CZMS，其具有用于表示裂缝能量，内聚强度和/或最大裂缝开口的现有的CZMS作为裂缝开口速率的函数。另一种方法在裂纹尖端前面采用VIS型CZM。虽然计算不那么昂贵，但前一种方法遗漏了大多数物理学，驾驶速率依赖性骨折过程。后一种方法更好地代表了驱动速率依赖性骨折过程的物理学，但它是计算更昂贵的。该工作提出了一种用于研究混合模式率依赖性骨折的方法，其既有效，近似于裂纹尖端前面的粘弹性材料行为。在这种混合模式方法中，我们使用两个速率依赖的弹簧近似裂纹尖端前面的粘弹性行为。一个弹簧在正常方向上行使到裂缝平面，而另一个弹簧作用在切向方向上。为了模仿粘弹性CZM，假设每个弹簧的刚度是裂缝开口速率的函数，并且实施其牵引对于裂缝开度速率的变化是连续的。为了造成损坏，我们使用从公园 - Pailino-Roesler（PPR）内聚裂缝模型中提取的两个损伤参数来扩展级级弹簧的诉讼。速率依赖模型是在ABAQU中的用户定义的元素（UEL）子例程。在获得高精度水平的同时，与基于分数粘弹性理论的CZM相比，本方法允许在计算成本上显着节省。 （c）2017 Elsevier Ltd.保留所有权利。

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