Implementation of the Arruda-Boyce Material Model for Polymers in Abaqus
Implementation of the Arruda-Boyce Material Model for Polymers in Abaqus
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在 Abaqus 中实现聚合物的 Arruda-Boyce 材料模型
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发表时间：
2014
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通讯作者：
Vegard Tømmernes
中科院分区：
文献类型：
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作者：
Vegard Tømmernes
在本硕士论文中，聚合物的用户材料子程序在 FEA 程序 Abaqus 中实现。论文的第一部分概述了聚合物的大变形力学和阿鲁达-博伊斯本构定律。这是一个依赖于应变率的粘塑性材料模型，包括应变软化和硬化。介绍了 Abaqus 用户材料子例程背后的主要原理，并由于简单性而选择了显式方法。分析了实施过程中的一些挑战并提出了解决方案。一个特殊的问题是 Hencky 应变的计算，传统的 Pade 近似无法满足要求。本文还解释了如何在有限元分析中使用用户材料子例程，并解释弱点以及如何避免陷阱。所实施的模型经过了多种应变率和负载条件的彻底测试。模型中的材料参数也进行了检查和讨论。使用所实施的模型对聚碳酸酯中的空隙增长进行了分析。用户材料中的未知错误将分析限制为非常小的变形。然而，分析表明聚合物会经历空隙增长，但不像金属那样过度。其原因可能是聚合物链施加的应变硬化效应。结论是，用户材料子程序可以对几种类型的聚合物进行建模，但必须进一步开发它，以考虑具有大变形的复杂几何形状。本论文旨在为所有师生提供如何在 Abaqus 中开发聚合物用户材料子程序的有用技巧，从而为聚合物行为的研究做出一点贡献。
In this Masters thesis, a user material subroutine for polymers is imple- mented in the FEA-program, Abaqus. The first part of the thesis provides an overview of large deformation mechanics and the Arruda-Boyce con- stitutive law for polymers. This is a strain-rate dependent viscoplastic material model that includes strain softening and hardening. The main principles behind user material subroutines for Abaqus were presented, and an explicit approach was chosen due to simplicity. Several challenges regarding the implementation have been analyzed and solutions have been proposed. One particular problem was the calculation of Hencky strain where the traditional Pade approximation did not suffice. This thesis also explains how to use the user material subroutine in an FEA, as well as explaining weaknesses and how to avoid pitfalls. The implemented model was thoroughly tested, with several strain rates and loading conditions. The material parameters in the model were also examined and discussed. An analysis of void growth in polycarbonate was done using the implemented model. An unknown error in the user material constrained the analysis to very small deformations. However, the analysis showed that polymers experience void growth, but not as excessive as metals. The reason for this is probably the strain hardening effect imposed by the polymer chains. It was concluded that several types of polymers may be modeled by the user material subroutine, but that it has to be further developed in order to account for complex geometries with large deformations. This thesis aims to offer all NTNU students useful tips on how to develop user material subroutines for polymers in Abaqus, and thus make a small contribution to the research of polymer behavior.