Constitutive Modeling for Strain-Rate Dependency of Natural and High Damping Rubbers

研究了天然橡胶(NR)和高阻尼胶(HDR)的微观结构和力学行为。在这项研究中，大部分的注意力都集中在压缩机制上。力学试验表明，所有试件均存在Mullins效应、应变率依赖性、滞回效应和残余应变效应。在天然橡胶中，这些影响的程度被发现与微结构空洞的存在有内在的关系。所有这些影响的存在在人类发展报告中也被发现是显著的。此外，在低压缩拉伸水平下，应变速率相关的高初始刚度特征也从实验中变得明显。然而，目前研究的显微结构观察不能解释HDR的这些特征。这就需要考虑现象学的方法来得到一个通用的本构模型。引入了一个基于现象学激励的本构模型来模拟应变率依赖关系。A…提出了更多改进的超弹性模型来描述包含高初始刚度特性的与速率无关的弹性响应。对所提出的超弹性模型进行了对比评价，结果表明该模型的性能优于传统模型。在有限变形率相关模型结构中引入了超弹性关系。提出了一种从实验数据中识别平衡响应和瞬时响应参数的参数识别方案。克服了在这种高粘性材料上直接施加无限快或无限慢的加载速度来获得这些响应，从而识别非线性弹性参数的困难。对实验结果进行了外推，并使用了所提出的超弹性模型。将所提出的方案应用于三种类型的试件。对不同变形模式下的试验结果进行了数值模拟，并进行了灵敏度分析，验证了所提出的模型和参数识别方案的充分性和鲁棒性。较少

The microstructure and the mechanical behavior of natural rubber (NR) and high damping rubber (HDR) were investigated. In this study, most of the attention was paid to the compression regime. The mechanical tests revealed the existence of Mullins' effect, strainrate dependency, hystersis and residual strain effects in all the specimens. In NR, the extent of these effects were found to have a inherent relation with the presence of microstructural voids. The presence of all these effects was also found to be significant in HDR. In addition, the strain-rate dependent high initial stiffness feature at low compressive stretch levels also became evident from the experiments. However, the microstructural observation of the current study could not explain these features of HDR. This prompted for the need of considering a phenomenological approach to reach a general constitutive model.A constitutive model based on phenomenological motivation was introduced to model the strain-rate dependency. A … More n improved hyperelasticity model was proposed to represent the rate-independent elastic responses including high initial stiffness characteristics. A comparative evaluation was carried out to display the better performance of the proposed hyperelasticity model over the conventional ones. The hyperelasticity relation was incorporated in a finite deformation rate-dependent model structure. A parameter identification scheme was proposed to identify the parameters for the equilibrium and the instantaneous responses from the experimental data. The difficulties of direct application of infinitely fast or slow loading rate on such highly viscous material to obtain these responses and thereby to identify the nonlinear elastic parameters were overcome. Experimental results were extrapolated and the proposed hyperelasticity model was used. The proposed scheme was applied on three types of specimens. Numerical simulation of the test results at different deformation modes followed by sensitivity studies verified the adequacy and the robustness of the proposed model and the parameter identification scheme. Less