Data from: Effect of Relaxation-Dependent Adhesion on Pre-Sliding Response of Cartilage

Possible links between adhesive properties and pre-sliding (static) friction response of cartilage are not fully understood in the literature. The aims of this study are to investigate the relation between adhesion and relaxation time in articular cartilage, and to investigate the effect of relaxation-dependent adhesion on pre-sliding response of cartilage. Adhesion tests were performed to evaluate the work of adhesion of cartilage at different relaxation times. Friction tests were conducted to identify the pre-sliding friction response of cartilage at relaxation times corresponding to adhesion tests. The pre-sliding friction response of cartilage was systematically linked to the work of adhesion and contact conditions by a slip-based failure model. It was found that the work of adhesion increases with relaxation time. Also, the work of adhesion is linearly correlated to the resistance to slip-based failure. In addition, as the work of adhesion increases, the critical adhered area at the moment of failure increases, and the propagation rate of the annular slip (crack) area toward its center increases. These findings offer the mechanistic explanation of the pre-sliding friction behavior and stick-slip response of soft hydrated interfaces such as articular cartilage and hydrogels. Besides, the linear correlation between adhesion and threshold to slip-based failure enables estimation of adhesive strength of such interfaces directly from pre-sliding friction response (e.g., shear wave elastography).

目前学界尚未完全阐明软骨黏附特性（adhesive properties）与滑移前（静）摩擦（pre-sliding (static) friction）响应之间的潜在关联。本研究旨在探究关节软骨（articular cartilage）的黏附功（work of adhesion）与松弛时间之间的关联，并分析依赖松弛过程的黏附特性对软骨滑移前摩擦响应的影响。研究通过黏附测试评估了不同松弛时间下软骨的黏附功；同时开展摩擦测试，以确定与黏附测试对应松弛时间下的软骨滑移前摩擦响应。借助基于滑移的失效模型（slip-based failure model），研究将软骨的滑移前摩擦响应与黏附功及接触条件进行了系统关联。结果显示，黏附功随松弛时间延长而升高；且黏附功与基于滑移的失效抗力呈线性相关。此外，随着黏附功提升，失效瞬间的临界黏附面积随之增大，环形滑移（裂纹）区域向中心扩展的速率也相应提高。上述发现为关节软骨及水凝胶（hydrogels）这类软性水合界面（hydrated interfaces）的滑移前摩擦行为与黏滑响应（stick-slip response）提供了机理性解释。此外，黏附特性与滑移失效阈值之间的线性相关性，使得可直接通过滑移前摩擦响应（例如剪切波弹性成像（shear wave elastography））估算这类界面的黏附强度。