整体壁板增量压弯过程应力应变模拟

Finite element simulation of stress and strain on the incremental bend forming technology of the integral wing-skin panel

整体壁板结构特点为蒙皮和纵横交错的加强筋为一整体,将机械加工后的平面外形的壁板毛坯成形为具有复杂曲面外形的壁板零件具有很大的难度。本文采用MARC有限元软件分析了整体壁板成形过程中应力应变变化情况。研究表明:整体壁板成形过程中,筋条处的应力状态最为恶劣,筋条与蒙皮过渡区处于三向拉应力状态,同时有剪切塑性应变发生,容易导致该处开裂,对于高筋条来说,还容易导致失稳现象发生;筋条的塑性变形既有凸模下压导致的塑性变形,又有蒙皮回弹导致的塑性变形;塑性变形区主要集中于筋部,蒙皮几乎不发生塑性变形;成形后的壁板将保留较大的残余应力,该应力主要是由蒙皮弹性回复所引起。

The characteristic of this integral wing-skin panel is that the skin and the grid-type ribs is a whole body, it is very difficult to form the machined panel into required shape. In this paper, the change of stress and strain in panel process is simulated by MARC. The research indicates that the stress state on ribs is severe in panel bend forming and keep draw stress between ribs and skin, shear plastic strain happens which may cause craze. The plastic deformation on ribs caused by punch push down and skin springback. Most plastic deformation focues on grid-type ribs and little plastic deformation focues on skin. The panel production will preserve large remained stress which caused by the springback.