预应力作用下微尺度激光弯曲成形的数值模拟

Numerical Study on the Laser Bending of Stainless Steel Foilwith Pre-Stresses

应用一种新的激光弯曲成形工艺,通过施加位移约束,使厚度为0.1 mm的304不锈钢箔加热区产生预期的预应力分布.针对激光弯曲成形的特点,建立三维热力耦合模型,基于塑性皱曲机制(BM),对三种不同预约束应力状态下微尺度激光弯曲成形过程进行数值模拟.通过对比三种不同模型的模拟结果,分析了预约束应力作用下,微尺度激光弯曲成形的成形机制.研究发现,预应力作用下激光弯曲成形是热应力与预应力综合作用的结果,在预应力作用下激光弯曲成形效果显著增加.在塑性皱曲机制下,通过控制预约束作用的方向和大小以及选择合适的激光工艺参数可以得到任意方向的弯曲成形角.弯曲角度随预应力的增大而增大,两者之间呈近似线性关系.

Through using a new laser bending process, the distribution of expected pre-stress was obtained on the heated zone of AISI 304 steel foil with thickness of 0.1 mm by applying initial displacement to the sample＇s free end. Considering the characteristics of laser bending, three-dimensional （3D） thermomechanical finite element method （FEM） models of laser bending process with various pre-stresses were developed based on the buckling mechanism （BM）. Through comparing the simulation results of different models, the mechanism of laser bending with pre-stresses was explained. The simulation results show that the deformation of the stainless steel foil under buckling mechanism depends on the integration of the thermal stress and the pre-stress when the laser beam irradiates the foil. The forming performance can be improved significantly under pre-stress, and the deformation direction can also be controlled easily by changing the direction and value of the pre-loading. The bending angles of the steel foils increase remarkably with the increase of the pre-loading, and both are almost in linear relationship.