Effect of sliding velocity on the nanoscale friction behaviour of articular cartilage contact interface: insights from all-atom molecular dynamics investigation

Abstract

ABSTRACT This study employs molecular dynamics simulations to explore nanoscale friction behaviour as a function of varying loading and sliding speeds on a developed top-layer articular cartilage contact interface atomistic model. To investigate nanotribological behaviour, sliding speed variations on the normal force, friction force, non-bonded interaction energy and interface temperature is obtained at the inter-cartilage interface. Analysis conducted at high velocity in a simplified tissue-like hydrated environment revealed ice-like dynamic smooth sliding behaviour of protein chains when cartilage interfaces are even 3.8 Å apart. With an increase in velocity, the coefficient of friction (COF) increases significantly in a hydrated environment. Additionally, at lower loads, the effect of sliding velocity is more pronounced than at higher loads. However, results show that articular cartilage adapts to higher load and speed sliding conditions exhibiting lower friction (COF-0.03–1.17) by means of interfacial water rearrangements and protein side-chain non-bonded interactions reducing heavy shear deformation. This is attributed to an alteration in the load-bearing and friction mechanism owing to water rearrangement and adsorption at nanoconfined biointerfaces. This study provides mechanistic insights into friction mechanisms at the cartilage interface which could lead to wear-like conditions under physiological sliding contact conditions, thereby facilitating the design of better implants.