注塑制品残余应力数值模拟的研究

通过预测和优化注塑成形中的残余应力，可以提高注塑制品最终形状的尺寸稳定性和力学性能。采用线性粘弹性模型，计算了无定形热塑性材料在成形过程中由温度和压力引起的残余应力。该模型可以较好地反映成形过程中的应力松弛现象和保压压力对残余应力的影响。通过采用在时间上进行差分和在厚度方向进行分层处理的方法，结合注塑成形中的特定边界条件，建立了残余应力的数值计算方法，并采用该方法模拟计算了典型注塑件的残余应力。结果表明：在脱模时刻，制品的表层有着较大的拉应力，袁层以下存在着一个应力低谷，在制品中间区域存在着抛物线形的应力分布。

Numerical Simulation of Residual Stresses in Injection Molding

The dimensional stability and mechanical performance of the final products can be improved by predicting and optimizing the residual stresses in the molding process. In this study, a detailed linear thermoviscoelastic model was used for the calculation of thermally and pressure induced residual stresses in injection molded amorphous plastic parts. In this model, effects of pressure and thermal history and stress relaxation were taken into account. The numerical calculation model was built by finite difference method in the time and layer difference in the thickness direction, combined with the specified boundary conditions. The developed simulation system was used to calculate the residual stresses in the typical injection parts, which show that the equilibrium stress variation across the thickness of a thin injection--molded strip exhibits a high surface tensile value changing to a compressive peak value close to the surface, with the core region experiencing a parabolic peak.