Simulation of the gas-assisted injection moulding process using a viscoelastic extension to the Cross-WLF viscosity model
Simulation of the gas-assisted injection moulding process using a viscoelastic extension to the Cross-WLF viscosity model
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DOI：
10.1177/0954408911409134
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发表时间：
2011-08
期刊：
影响因子：
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通讯作者：
P. Olley;L. Mulvaney-Johnson;Philip D. Coates
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文献类型：
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作者：
P. Olley;L. Mulvaney-Johnson;Philip D. Coates
近似的粘弹性麦克斯韦模型的开发和组合的跨WLF剪切和温度依赖的模型作为一种手段，引入粘弹性方面的跨WLF模型在一个低的计算成本。该模型的主要目标是模拟气体辅助注射成型（GAIM）过程中的材料的应变历史方面。结果表明，该模型给出了一个瞬态和稳态响应的Doi-Edwards粘弹性模型在恒定速率剪切和单轴变形，并遵循WLF温度依赖性。该模型是在一个三维有限元代码中使用的“伪浓度”的方法来模拟聚合物和气相。与实验结果相比，普通的Cross-WLF模型对剩余壁厚（RWT）测量值的预测一致偏低。结果表明，粘弹性扩展到跨WLF模型给出了一个显着增加RWT，并表现出应力松弛和历史依赖方面。该模型针对其他过程控制参数的变化进行了测试。结果表明，模拟给出了正确的定性响应的所有控制参数的评估，定量预测在一个因素为2。
An approximation to the viscoelastic Maxwell model is developed and combined with a Cross-WLF shear- and temperature-dependent model as a means of introducing aspects of viscoelasticity into the Cross-WLF model at a low computational cost. The main objective of the model is to simulate the gas-assisted injection moulding (GAIM) process with the aspect of a material's strain history included. It is shown that the model gives a transient and steady response comparable to the Doi–Edwards viscoelastic model in constant rate shear and uniaxial deformations, and follows WLF temperature dependence. The model is implemented in a three-dimensional finite element code using the ‘pseudo-concentration’ method to model the polymer and gas phases. The ordinary Cross-WLF model had demonstrated a consistent under-prediction of residual wall thickness (RWT) measurements in comparison to experimental results. It is shown that the viscoelastic extension to the Cross-WLF model gives a marked increase in RWT and exhibits aspects of stress relaxation and history dependence. The model is tested against variations of other process control parameters. It is shown that the simulation gives the correct qualitative response for all control parameters assessed, with quantitative prediction within a factor of 2.