圆形等通道转角挤压过程三维数值模拟

基于网格重划分技术,采用有限元软件Marc对等通道转角挤压(Equal Channel Angular Pressing,ECAP)进行数值模拟,得到了模具转角φ=90°、ψ=0°以及不同摩擦条件下圆形试样ECAP变形过程的网格、载荷变化以及等效应变分布规律。结果表明:由于剪切变形和外摩擦作用,底部网格产生畸变,出口端部形成半球形;圆形ECAP过程经历开始变形、稳定变形和终了三个阶段,在开始变形阶段载荷急剧增加,进入稳定阶段后变化平稳,但由于摩擦和加工硬化作用载荷继续增加;与无摩擦情况相比,摩擦的存在增加了试样与模具接触的接触面积、载荷值以及变形的不均匀性。此外,试样中心较表面变形更均匀,而中间截面相比头尾变形较为均匀。

3D numerical simulation of circular equal-channel angular pressing process

Based on re-meshing technology,by use of FE model Marc,the numerical simulation of equal-channel angular pressing has been executed.As a result,the mesh,change of load and distribution of equivalent strain have been gained under φ=90°、ψ=0° and different friction conditions.It shows that the mesh has been distorted at the bottom with semi-sphere exit because of shearing deformation and external friction.Three stages including initial deformation,steady deformation and finial deformation in the circular ECAP have been occurred.The load increases greatly at the initial deformation stage while the load continuously increases slowly in the steady stage from friction and work hardening.Furthermore,the friction increases the contact area between sample and die,load and in-homogeneity of deformation.In addition,the deformation is more uniform at the center and middle section comparing with those of surface and head and tail of sample.