薄壁曲面拉伸成形失稳起皱数值模拟

Numerical simulation of instability and wrinkling in stretch forming of thin-walled surface

起皱作为薄板成形中的常见缺陷,严重影响曲面成形质量。为研究不同加载路径下的曲面失稳起皱现象,设计了三种加载路径,并对相应成形过程进行数值模拟。结果表明,加载路径对成形曲面起皱现象具有较大影响;受到较大压应力时,处于悬空状态的板料因约束不足易产生面外失稳而出现起皱;板料与模具间的摩擦力可减小板料承受压应力,可通过调整板料与模具的接触状态,进而对起皱有效抑制;采用最小变形加载路径,板料与模具接触良好,可获取光滑、无起皱缺陷曲面。

Wrinkling is a common defect in sheet metal forming,which seriously affects the quality of surface forming.In order to study the surface instability and wrinkling under different loading paths,three loading paths were designed,and the corresponding forming processes were numerically simulated.The results showed that the loading path had a great influence on the wrinkling phenomenon of the formed surface.When subjected to large compressive stress,the sheet metal in the suspended state was prone to out-of-plane instability and wrinkling due to insufficient restraint.The friction between sheet metal and die could reduce the compressive stress of sheet metal,and the wrinkling could be effectively restrained by adjusting the contact state between sheet metal and die.In the minimum deformation loading path surface forming,the sheet metal and the die were in good contact,and a smooth and wrinkle free surface could be obtained.