轴对称正挤压的刚塑性有限元模拟

SIMULATION FOR AXI SYMMETRIC FORWARD EXTRUSION BY RIGID-PLASTIC FINITE ELEMENT METHOD

采用刚塑性有限元法,模拟具有锥底凹模和平底凹模的轴对称正挤压过程。利用自编程序对正挤压时的挤压力,应力场和应变场分布以及挤压件前端部的“双峰”现象等进行了研究。此外,还对轴对称正挤压时可能出现的中心缩孔和表面裂纹缺陷进行了模拟研究,得到了预测上述缺陷的曲线或数据。 在计算过程中,对刚塑性有限元计算技巧也作了一些改进,例如提出了处理八节点四边形单元奇异点和质点跟踪技术的新方法等。 试验结果表明,理论计算结果与试验结果相当一致。

In this paper, the rigid-plastic finite element method is applied to simulate the axi-symmetric forward extrusion processes with cone and flat dies.Extrusion forces,distributions of the stress and strain fields during extrusion, and the phenomenon of the two-peaks on the front end of the product, etc.are studied with the computing program.Moreover, the program is also used to simulate and analyse the cavity and the surf ace crack during extrusion.Some curves and data for prediction of the above-mentioned defects have been worked out.Some improvements have been made in the calculation of the rigid-plastic finite element.For example, new techniques for handling the singularity in the eight-nodes quadrilateral mesh and for tracking the movement of a certain particle are proposed.Experiments show that the computed results agree rather well with the experimental data.