形状记忆合金超弹性缆索力学行为的有限单元法

Finite Element Method for Mechanical Behavior of Shape Memory Alloy Superelastic Cables

由于涉及材料和接触双重非线性问题,很难建立描述形状记忆合金(Shape memory alloy,SMA)超弹性缆索力学行为的理论模型,为了克服试验成本高和易受环境因素影响的缺点,基于形状记忆因子概念和SMA本构模型,推导了适于有限单元法的增量型SMA本构模型。利用ABAQUS二次开发功能,考虑相变过程中SMA弹性模量的变化,编写了SMA用户材料子程序,实现了SMA超弹性缆索力学行为的有限元单元法。利用建立的有限单元法对SMA超弹性缆索的相变和力学行为进行数值模拟,并将数值结果与文献中试验结果进行了对比验证,在此基础上,分析了SMA超弹性缆索外线股螺距对缆索整体力学行为的影响。计算结果及其与试验结果的对比表明,提出的有限单元法能有效描述和预测SMA超弹性缆索在拉伸过程中的相变和力学行为,SMA超弹性缆索外线股轴线螺距对缆索整体相变和力学行为有明显影响,研究工作可为SMA超弹性缆索设计及工程应用提供计算方法与技术指导。

It is difficult to establish a theoretical model to describe the mechanical behavior of the shape memory alloy(SMA)superelastic cable because of the nonlinear material and contact problems.In order to overcome the disadvantages of high cost and susceptibility to environmental factors of experiment,an incremental SMA constitutive model suitable for finite element method is derived based on the concept of shape memory factor and SMA constitutive model.The ABAQUS user material subroutine is written to realize the finite element method for the mechanical behavior of the SMA superelastic cable with considering the change of elastic modulus during the transformation process by employing the secondary development function of ABAQUS software.The phase transition and mechanical behavior of the SMA superelastic cable is carried out numerically by using the established finite element method,and the numerical results are compared with the experimental results.Then the influence of the pitch of the outside strands on the mechanical behavior of the SMA superelastic cable is analyzed.The numerical result and its comparison with the experimental results show that the proposed finite element method can effectively describe and predict the phase transition and mechanical behavior of SMA superelastic cables during the tension process.The pitch of the outside strands has obvious influence on the phase transition and mechanical behavior of the SMA superelastic cable.The research work can provide calculation methods and technical guidance for the design and engineering application of SMA superelastic cables.