Investigation of the strain rate and stretch level dependent behavior of elastomeric nanocomposites in complex uniaxial tests under finite strains

IF 3.4 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials Pub Date : 2024-10-09 DOI:10.1016/j.mechmat.2024.105177

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Abstract

The mechanical behavior of elastomeric nanocomposites in experiments with nested stress-strain cycles and in cyclic tests with increasing strain amplitude was considered. In the proposed testing procedures, long time stops at each stage of the change in loading direction were of great importance. This revealed two significant features of the behavior of elastomeric nanocomposites that have received little attention. It was shown that material softening (the Mullins effect) should be considered not only in the elastic part of the Cauchy stress tensor, but also in its dissipative part. The second peculiarity was the difference between the characteristic relaxation time at loading and the characteristic relaxation time at unloading observed in the experiments.

This paper focuses on the behavior of highly-filled elastomeric materials based on different matrices (styrene-butadiene rubber (SBR) and nitrile-butadiene rubber (NBR)) and with different concentrations of carbon black (CB) or a combination of two fillers (CB and purified multi-walled carbon nanotubes (MWCNTs)).

A mathematical model of the viscoelastic behavior of elastomeric nanocomposites under finite strains is proposed. It takes into account the peculiarities of the behavior of highly filled elastomers observed in the experiments. The specificity of the model consists in a new variant of the form of the free energy potential. It is shown that the new model satisfies the thermodynamic inequality, which is a consequence of the first law of thermodynamics and the second law in the form of the Clausius-Duhem inequality. A good agreement between theoretical calculations and experimental data was obtained.

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有限应变下复杂单轴试验中弹性纳米复合材料的应变率和拉伸水平相关行为研究

在嵌套应力-应变循环试验和应变振幅不断增大的循环试验中，考虑了弹性纳米复合材料的机械行为。在拟议的测试程序中，加载方向变化的每个阶段都需要长时间停止，这一点非常重要。这揭示了弹性纳米复合材料行为的两个重要特征，而这两个特征很少受到关注。研究表明，材料软化（穆林斯效应）不仅应在考奇应力张量的弹性部分中考虑，还应在其耗散部分中考虑。第二个特点是在实验中观察到加载时的特征松弛时间与卸载时的特征松弛时间之间存在差异。本文重点研究了基于不同基质（丁苯橡胶（SBR）和丁腈橡胶（NBR））、不同浓度的炭黑（CB）或两种填料组合（CB 和纯化多壁碳纳米管（MWCNTs））的高填充弹性材料的行为。该模型考虑到了实验中观察到的高填充弹性体行为的特殊性。该模型的特殊性在于自由能势形式的新变体。研究表明，新模型满足热力学不等式，这是热力学第一定律和克劳修斯-杜恒不等式形式的第二定律的结果。理论计算与实验数据之间取得了良好的一致性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Mechanics of Materials 工程技术-材料科学：综合

CiteScore

7.60

自引率

5.10%

发文量

243

审稿时长

46 days

期刊介绍： Mechanics of Materials is a forum for original scientific research on the flow, fracture, and general constitutive behavior of geophysical, geotechnical and technological materials, with balanced coverage of advanced technological and natural materials, with balanced coverage of theoretical, experimental, and field investigations. Of special concern are macroscopic predictions based on microscopic models, identification of microscopic structures from limited overall macroscopic data, experimental and field results that lead to fundamental understanding of the behavior of materials, and coordinated experimental and analytical investigations that culminate in theories with predictive quality.