接触模型对搅拌摩擦焊接数值模拟的影响

在完全热力耦合搅拌摩擦焊接数值模型中采用两种接触模型--经典的Coulomb接触模型和修正的Coulomb接触模型,模拟了搅拌摩擦焊接过程,以分析不同接触模型对搅拌摩擦焊接过程数值模拟的影响.结果表明,对于低转速的搅拌摩擦焊接,两种模型的预测结果区别不大;但是对于高转速,由于界面摩擦剪切应力没有上限,采用经典的Coulomb接触模型无法模拟,需采用修正的Coulomb接触模型.搅拌头转速的增加不会改变搅拌摩擦焊接技术固态连接的本质.当采用高转速时,焊接构件上、下表面的变形趋于均匀.有利于得到均匀的显微结构.

EFFECT OF CONTACT MODEL ON NUMERICAL SIMULATION OF FRICTION STIR WELDING

Two contact models, the classical Coulomb contact model and the modified Coulomb contact model, are used in a fully coupled thermo-mechanical numerical model of friction stir welding, and the suitabilities of the two models to simulate the welding process are analyzed. Results indicated that there are little differences between the numerical results of the two contact models for friction stir welding in low rotating speed. In high rotating speed, the classical Coulomb contact model fails due to no limit of shear stress at the interface, but the modified Coulomb contact model may be used. The increase of the rotating speed does not change the nature of solid joining in friction stir welding. When higher rotating speed is adopted, the deformations on the top and bottom surfaces of the weldment become more similar, which led to more uniform microstructures.