Abstract This paper presents a computational study on the role of poroelasticity in gel friction. Motivated by recent experimental studies in the literature, we develop a plane strain finite element model to elucidate the contact mechanics between a circular indenter and a thick poroelastic substrate under both normal and shear loadings. Two cases are considered: i) steady state sliding under fixed normal displacements, and ii) relaxation under fixed normal and shear displacements. In steady state sliding, we find that a net friction force can arise even if no intrinsic adhesive or frictional interaction is implemented at the indenter/substrate interface. Such friction force exhibits a non-monotonic dependence on the sliding velocity and peaks at an intermediate velocity. Our model reveals that this friction force is induced by poroelastic diffusion in the gel substrate which can lead to considerable asymmetry in both the contact profile and contact pressure. In terms of relaxation, if the indenter/substrate interface is set to be frictionless, we find that the friction force induced by poroelasticity relaxes to zero with a characteristic time much faster than that of the normal force. When a finite friction coefficient is introduced at the interface, the normalized relaxation curve for the friction force approaches that for the normal force as the friction coefficient increases. These modeling results suggest that poroelasticity can be an important contributing mechanism for gel friction.

中文翻译：

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平面应变圆形压头与厚多孔弹性基材之间的摩擦

摘要 本文对多孔弹性在凝胶摩擦中的作用进行了计算研究。受最近文献中的实验研究的启发，我们开发了一个平面应变有限元模型，以阐明在法向和剪切载荷下圆形压头和厚多孔弹性基材之间的接触力学。考虑两种情况：i) 固定法向位移下的稳态滑动，和 ii) 固定法向和剪切位移下的松弛。在稳态滑动中，我们发现即使在压头/基板界面处没有实现固有的粘附或摩擦相互作用，也会产生净摩擦力。这种摩擦力表现出对滑动速度的非单调依赖性，并在中间速度处达到峰值。我们的模型表明，这种摩擦力是由凝胶基质中的多孔弹性扩散引起的，这会导致接触轮廓和接触压力的相当大的不对称。在松弛方面，如果将压头/基板界面设置为无摩擦，我们发现多孔弹性引起的摩擦力松弛为零，其特征时间比法向力快得多。当在界面处引入有限摩擦系数时，随着摩擦系数的增加，摩擦力的归一化松弛曲线接近法向力的松弛曲线。这些建模结果表明多孔弹性可能是凝胶摩擦的重要促成机制。在松弛方面，如果将压头/基板界面设置为无摩擦，我们发现多孔弹性引起的摩擦力松弛为零，其特征时间比法向力快得多。当在界面处引入有限摩擦系数时，随着摩擦系数的增加，摩擦力的归一化松弛曲线接近法向力的松弛曲线。这些建模结果表明多孔弹性可能是凝胶摩擦的重要促成机制。在松弛方面，如果将压头/基板界面设置为无摩擦，我们发现多孔弹性引起的摩擦力松弛为零，特征时间比法向力快得多。当在界面处引入有限摩擦系数时，随着摩擦系数的增加，摩擦力的归一化松弛曲线接近法向力的松弛曲线。这些建模结果表明多孔弹性可能是凝胶摩擦的重要促成机制。随着摩擦系数的增加，摩擦力的归一化松弛曲线接近法向力的松弛曲线。这些建模结果表明多孔弹性可能是凝胶摩擦的重要促成机制。随着摩擦系数的增加，摩擦力的归一化松弛曲线接近法向力的松弛曲线。这些建模结果表明多孔弹性可能是凝胶摩擦的重要促成机制。