Abstract It is important to investigate the constitutive behavior of high density polyethylene (HDPE) under cyclic loading since it is widely used for industrial applications. However, there are only a few preliminary investigations on the constitutive behavior of HDPE under cyclic loading. This work aims at investigating the deformation mechanism, developing the constitutive model especially for the cyclic-loading behavior, and proposing an efficient approach for model calibration. Firstly, the deformation mechanism was successfully explored by conducting a special designed relaxation-unloading test by which the time-independent elastic-plastic behavior was decoupled from the time-dependent overall deformation behavior. Then, a nonlinear elastic-viscoplastic constitutive model was developed based on the parallel rheological framework (PRF) composed of an elastic-plastic network in parallel with multiple nonlinear viscoelastic networks. Finally, an approach was proposed to calibrate the constitutive model by means of relaxation-unloading tests and material parameter optimizations. The agreement between the prediction and the test data successfully demonstrated that the model could be used to precisely simulate the constitutive behavior of HDPE under static, quasi-static and dynamic cyclic loading. The developed constitutive model is beneficial to the long-term durability evaluation of HDPE. The methodology for exploring the deformation mechanism and calibrating the constitutive model may also be applicable to other polymers.

中文翻译：

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循环载荷下高密度聚乙烯弹粘塑性行为的本构建模

摘要 由于高密度聚乙烯 (HDPE) 广泛用于工业应用，因此研究循环载荷下高密度聚乙烯 (HDPE) 的本构行为非常重要。然而，关于 HDPE 在循环载荷下的本构行为的初步研究很少。这项工作旨在研究变形机制，开发本构模型，特别是循环加载行为，并提出一种有效的模型校准方法。首先，通过进行特殊设计的松弛-卸载试验，成功地探索了变形机制，通过该试验将与时间无关的弹塑性行为与与时间相关的整体变形行为解耦。然后，基于平行流变框架 (PRF) 开发了一种非线性弹-粘塑性本构模型，该框架由一个弹-塑性网络与多个非线性粘弹性网络并行组成。最后，提出了一种通过松弛卸载试验和材料参数优化来校准本构模型的方法。预测与试验数据的一致性成功表明，该模型可用于精确模拟 HDPE 在静态、准静态和动态循环载荷下的本构行为。开发的本构模型有利于 HDPE 的长期耐久性评估。探索变形机制和校准本构模型的方法也可能适用于其他聚合物。