中文摘要：

基于刚粘塑性有限元法,在模拟过程中采用分步模拟的方法,对有限元网格进行分步重划分和步长的分步设置,并提出了解决体积损失问题的补偿方法,在Deform-3D有限元软件上实现了薄壁复杂截面铝型材的分流组合模挤压成形过程的三维数值模拟。分析了铝合金口琴管挤压过程中的金属的流动和变形行为,获得了速度场、温度场、应力场和应变场的分布图,数值模拟结果与理论分析结果吻合较好。结果表明：采用有限元分步模拟可以在保证模拟精度的前提下大幅缩短模拟运算时间,是模拟薄壁复杂截面铝合金空心型材挤压成形过程的有效方法。

英文摘要：

A new simulation system was developed by multi-stage mesh generation and step size dynamic adjustment based on rigid-viscoplastic finite element method The methods of element volume compensation were proposed. The porthole die extrusion of complex thin-walled aluminum Harmonica-shaped tube was successfully simulated in the new simulation system on the platform of Deform-3D. The deformation behavior of metals in harmonica-shaped tube extrusion process was analyzed. The distribution of velocity field, stress field, effective strain field and temperature field during the extrusion process were discussed. The results of numerical simulation are in good match with the theoretical analysis. The results indicate that simulation time could be shortened greatly with new simulation system on the premise of guaranteeing result precision. The multi-stage FEM is an effective numerical simulation method for complex thin-walled aluminum extrusion process.