Viscoelastic-viscoplastic combined constitutive model for glassy amorphous polymers under loading/unloading/no-load states
Viscoelastic-viscoplastic combined constitutive model for glassy amorphous polymers under loading/unloading/no-load states
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DOI：
10.1108/ec-05-2019-0197
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发表时间：
2020-02
影响因子：
1.6
通讯作者：
S. Matsubara;K. Terada;Ryusei Maeda;Takaya Kobayashi;Masanobu Murata;Takuya Sumiyama;K. Furuichi;C. Nonomura
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文献类型：
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作者：
S. Matsubara;K. Terada;Ryusei Maeda;Takaya Kobayashi;Masanobu Murata;Takuya Sumiyama;K. Furuichi;C. Nonomura
本研究的目的是在有限应变下的热力学框架内提出一种新的玻璃态非晶聚合物的粘弹-粘塑性组合本构模型，该模型能够在宽的变形速率和变形量范围内捕获它们的速率依赖性非弹性力学行为。根据多机理理论建立了粘弹性和粘塑性单元串联的流变模型。然后，本构函数的基础上制定的乘法分解的变形梯度所暗示的流变模型的热力学框架内。通过对聚碳酸酯（PC）的动态力学分析（DMA）和加/卸载/空载试验，确定了材料参数，验证了模型的性能。与卸载前不同变形速率和变形量的一系列试验结果进行比较，验证了性能。结果表明，该模型能反映材料的率相关弹性、弹性滞后、应变软化、取向硬化和应变恢复等力学行为。本文提出了一种新的流变本构模型，其中粘弹性单元与粘塑性单元串联，只代表弹性行为，每个材料的响应是根据乘法分解的变形梯度制定的。特别是，屈服强度其次是各向同性硬化反映的粘弹性本构函数的松弛特性，使玻璃化转变温度可以在很宽的变形率范围内的变化。因此，该模型使我们能够正确地表示加载过程中的大变形制度，其次是卸载和空载过程。
This study aims to propose a novel viscoelastic–viscoplastic combined constitutive model for glassy amorphous polymers within the framework of thermodynamics at finite strain that is capable of capturing their rate-dependent inelastic mechanical behavior in wide ranges of deformation rate and amount.,The rheology model whose viscoelastic and viscoplastic elements are connected in series is set in accordance with the multi-mechanism theory. Then, the constitutive functions are formulated on the basis of the multiplicative decomposition of the deformation gradient implicated by the rheology model within the framework of thermodynamics. Dynamic mechanical analysis (DMA) and loading/unloading/no-load tests for polycarbonate (PC) are conducted to identify the material parameters and demonstrate the capability of the proposed model.,The performance was validated in comparison with the series of the test results with different rates and amounts of deformation before unloading together. It has been confirmed that the proposed model can accommodate various material behaviors empirically observed, such as rate-dependent elasticity, elastic hysteresis, strain softening, orientation hardening and strain recovery.,This paper presents a novel rheological constitutive model in which the viscoelastic element connected in series with the viscoplastic one exclusively represents the elastic behavior, and each material response is formulated according to the multiplicatively decomposed deformation gradients. In particular, the yield strength followed by the isotropic hardening reflects the relaxation characteristics in the viscoelastic constitutive functions so that the glass transition temperature could be variant within the wide range of deformation rate. Consequently, the model enables us to properly represent the loading process up to large deformation regime followed by unloading and no-load processes.