形状记忆合金管接头固紧力跌落数值仿真分析

Numerical Simulation Analysis on the Drop of Fastening Force of Shape Memory Alloy Pipe Connection

摘要: 形状记忆合金(Shape memory alloy, SMA)管接头固紧力跌落，会导致连接管件在后续使用过程中发生脱落，进而影响整个系统的安全可靠性。为系统研究SMA管接头的固紧力跌落规律，本文借助于非线性有限元软件ABAQUS二次开发用户自定义材料(UMAT)子程序，对不同管接头壁厚连接系统的装配过程进行数值模拟分析。研究结果表明：固紧力跌落发生在SMA管接头接触中间部位；相同管接头壁厚下，固紧力跌落现象在装配完成冷却前比冷却后更加明显；随着管接头壁厚增大，管接头内壁与被接管外壁之间接触压应力以及管接头内壁马氏体体积分数增大；管接头内壁的马氏体体积分数在管接头内壁中间部位发生不同程度的增大现象。本文工作可为SMA管接头的优化设计提供力学基础和技术参考。

Abstract: The drop of the fastening force of the shape memory alloy (SMA) pipe connection will lead to the fall off of the connecting fittings in the process of subsequent use, which will affect the safety and reliability of the whole system. In order to systematically study the drop law of the SMA pipe con-nection fastening force, the nonlinear finite element ABAQUS user-defined material subroutine (UMAT) program is employed to simulate the assembly process of the pipe connection system with different pipe connection wall thickness. The results show that the drop of the fastening force occurs in the middle part of the SMA pipe connection, and with the same wall thickness of SMA pipe connection, the drop of the fastening force is more obvious before cooling down during the assembly process. The contact pressure between the inner wall of the SMA pipe connection and the outer wall of the connected pipe, and the martensite volume fraction of the inner wall of the pipe connection gradually increase with the increase of the wall thickness of the SMA pipe connection; and in the middle part of the inner wall of the SMA pipe connection, the martensite volume fraction of the inner wall of the pipe connection increases to different degrees. The work in this paper can provide the mechanical foundation and technical reference for the optimization design of SMA pipe connection.