注射成型残余应力的数值模拟

Numerical simulation of residual stresses in injection molding

对注射成型过程中的残余应力进行了研究.针对注射成型的特点,采用线性粘弹性模型计算了注射成型过程中温度和压力引起的残余应力,充分考虑了保压压力和应力松弛对残余应力的影响,数值实现中采用了在时间上有限差分的计算方法.通过模拟计算平板形状制品残余应力在壁厚方向和流动方向上的分布及其在成型中的变化过程,深入讨论了注射成型过程中残余应力的形成机理和演变情况.实验证明了所提出的残余应力模型和计算方法的正确性与合理性.通过预测和优化注射成型中的残余应力,可以提高制品最终形状的尺寸稳定性和力学性能,对实际生产有一定的指导意义.

Residual stresses in the injection molding process were investigated. Based on the characteristics of injection molding, a linear thermoviscoelastic model is adopted to calculate thermally and pressure induced residual stresses, which takes the effect of stresses relaxation and pressure into account. A finite difference method in the time is presented. Distribution and history of residual stresses in plaque-like geometries are numerically simulated, which helps to understand the mechanics and evo- lution of the residual stresses in the injection molding process. Results show that the mathematical model and its algorithm used in the simulation program are correct and reasonable. The dimension stability and mechanical performance of final products can be improved by predicting and optimizing the residual stresses in the molding process, which is helpful in production.