Abstract With regard to the application of shape memory polymers (SMPs) in smart structures, it is difficult to accurately predict their shape memory effects (SMEs) triggered by various external environments. Therefore, developing constitutive models for SMPs in multi-field environments is crucial. In this paper, a hygro-thermo-mechanical finite deformation constitutive model incorporated with structural relaxation and moisture diffusion is proposed for hygrothermally activated amorphous SMPs. One of the main novelties is that for the first time an internal state variable modeling approach is used in the model to describe the structural relaxation of hygrothermally activated SMPs in the vicinity of the glass transition. The other novelty is that the theory of moisture diffusion is applied to split the absorbed moisture into the mobile (free) and bound phases, and their respective effects on the hygro-thermo-mechanical behavior are also considered in the model. Comparisons between the model results and the test data for both, thermally activated and moisture-activated SMEs, present a good agreement.

中文翻译：

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有限变形下湿热活化形状记忆聚合物的湿热机械本构模型

摘要 关于形状记忆聚合物（SMPs）在智能结构中的应用，很难准确预测其由各种外部环境触发的形状记忆效应（SMEs）。因此，在多场环境中为 SMP 开发本构模型至关重要。在本文中，提出了一种结合结构松弛和水分扩散的湿热机械有限变形本构模型，用于湿热活化的无定形 SMP。主要的创新之处之一是首次在模型中使用内部状态变量建模方法来描述玻璃化转变附近湿热活化的 SMP 的结构松弛。另一个新颖之处是应用水分扩散理论将吸收的水分分为流动相（自由相）和束缚相，模型中还考虑了它们各自对湿热机械行为的影响。模型结果与热激活和湿激活 SME 的测试数据之间的比较显示出良好的一致性。