注射成形残余应力与翘曲变形的数值模拟

The Numerical Simulation of Residual Stresses and Warpage in Injection Molding

根据注射成形的特点,建立了制品残余应力和翘曲变形的综合数值模拟方法.残余应力的模拟采用线性粘弹性模型.数值实现中,根据成形不同阶段的特点提出复合边界条件和假设,采用在时间上有限差分和在厚度方向分层处理的计算方法.翘曲变形的模拟中,采用平面膜元和弯曲板元组成的平板型壳元模型,并提出了基于制品表面网格的改进模型,避免了使用传统板壳模型的缺陷.通过与实际生产的制品的对比分析,证明了所提出数值模拟方法的可行性,表明所开发应力翘曲分析模块对提高制品质量和生产效率具有一定的应用价值.

Numerical simulations of residual stresses and warpage were undertaken upon the characteristics of injection molding. A linear thermoviscoelastic model was adopted to simulate residual stresses. The numerical calculation was carried out by finite difference method in the time and layer discretization in the thickness direction, combined with multiple boundary conditions during different molding stages. A finite element model formed by combining the membrane element and bending element was employed in the warpage simulation. A modified flat model was proposed based on surface mesh, which avoided the deficiencies of traditional flat models. Simulation results were compared with experimental data for validation of the developed program. It was found that the numerical simulations and corresponding software are effective in enhancing the quality of products and productivity.