Uniaxial and biaxial multi-path cyclic loading experiments were carried out using the plate dumbbell-shaped specimens and the cruciform-shaped specimens prepared by silane-modified polyurethane adhesive, respectively. The uniaxial testing results showed that the stress–strain curve of the material was nonlinear, and its mechanical properties were viscoelastic. The adhesive exhibited cyclic softening and cyclic strain increase (cyclic creep and cyclic strain accumulation) under the tensile cyclic loading. The biaxial multi-path testing results showed that the non-proportional loading path caused additional ratcheting strain, which was related to different loading paths. According to the experimental observation, a uniaxial cyclic constitutive model was proposed. Furthermore, a biaxial cyclic constitutive model of the material was developed by introducing the loading path coefficient. By comparing the model prediction results with the experimental data, it was shown that the evolution of ratcheting strain and cyclic softening of the material under uniaxial cyclic loading was accurately described using the proposed model. Also, the biaxial cyclic constitutive model can well predict the mechanical behaviors of silane-modified polyurethane adhesive under biaxial multi-path cyclic loading.

中文翻译：

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单轴和双轴循环载荷作用下粘弹性软胶的棘轮应变和循环软化研究


分别使用硅烷改性聚氨酯胶粘剂制备的板哑铃形试件和十字形试件进行了单轴和双轴多径循环加载实验。单轴试验结果表明，该材料的应力-应变曲线为非线性，其力学性能为粘弹性。胶粘剂在拉伸循环载荷下表现出循环软化和循环应变增加 （循环蠕变和循环应变积累）。双轴多径试验结果表明，非比例加载路径引起额外的棘轮应变，这与加载路径不同有关。根据实验观察，提出了单轴循环本构模型。此外，通过引入加载路径系数，建立了该材料的双轴循环本构模型。通过将模型预测结果与实验数据进行比较，表明所提出的模型准确描述了材料在单轴循环载荷作用下棘轮应变和循环软化的演变。此外，双轴循环本构模型可以很好地预测硅烷改性聚氨酯胶粘剂在双轴多径循环载荷下的力学行为。