Numerical simulation of the heating stage of thermoplastics in thermoforming requires a good knowledge of the behavior of the materials used. To this end, a study is being conducted on the characterization of the viscoelastic behavior of a circular membrane, made of high‐density polyethylene (HDPE), under the combined effect of temperature and the force of gravity. The experimental tests were carried out in a convection oven for five temperatures (100, 110, 120, 130 and 140°C). For the numerical characterization of the viscoelastic behavior, two viscoelastic models were considered: the classic Kelvin‐Voigt model and the new three‐parameter modified Burger's model (Jeffrey model) that we propose. The mechanical parameters of both models were identified using the Levenberg‐Marquardt algorithm. The thermal‐dependency of the viscosity was characterized by two thermal models: the Arrhenius law and the William‐Landel‐Ferry (WLF) equation.

中文翻译：

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温度和重力共同作用下高密度聚乙烯膜的粘弹性表征，用于热成型应用

热成型中热塑性塑料加热阶段的数值模拟需要对所用材料的性能有充分的了解。为此，在温度和重力的共同作用下，正在研究由高密度聚乙烯（HDPE）制成的圆形膜的粘弹性行为。在对流烤箱中对五个温度（100、110、120、130和140°C）进行实验测试。为了对粘弹性行为进行数值表征，我们考虑了两个粘弹性模型：我们提出的经典的Kelvin-Voigt模型和新的三参数改进的Burger's模型（Jeffrey模型）。使用Levenberg-Marquardt算法识别了两个模型的机械参数。