A review of friction models in interacting joints for durability design

This paper presents a comprehensive review of friction modelling to provide an understanding of design for durability within interacting systems.Friction is a complex phenomenon and occurs at the interface of two components in relative motion.Over the last several decades,the effects of friction and its modelling techniques have been of significant interests in terms of industrial applications.There is however a need to develop a unified mathematical model for friction to inform design for durability within the context of varying operational conditions.Classical dynamic mechanisms model for the design of control systems has not incorporated friction phenomena due to non-linearity behaviour.Therefore,the tribological performance concurrently with the joint dynamics of a manipulator joint applied in hazardous environments needs to be fully analysed.Previously the dynamics and impact models used in mechanical joints with clearance have also been examined.The inclusion of reliability and durability during the design phase is very important for manipulators which are deployed in harsh environmental and operational conditions.The revolute joint is susceptible to failures such as in heavy manipulators these revolute joints can be represented by lubricated conformal sliding surfaces.The presence of pollutants such as debris and corrosive constituents has the potential to alter the contacting surfaces,would in turn affect the performance of revolute joints,and puts both reliability and durability of the systems at greater risks of failure.Key literature is identified and a review on the latest developments of the science of friction modelling is presented here.This review is based on a large volume of knowledge.Gaps in the relevant field have been identified to capitalise on for future developments.Therefore,this review will bring significant benefits to researchers,academics and industry professionals.

Wear and Friction Properties of Electrodeposited Ni-Based Coatings Subject to Nano-enhanced Lubricant and Composite Coating

This paper presents research findings on the tribological performance of electrodeposited coatings subject to nano-lubricants with the addition of nano-Al2O3 and graphene and Ni/nano-Al2O3 composite coatings. Electrodeposited coatings were produced by using a pulse electrodeposition method. Tribological experiments were conducted by using a linear reciprocating ball on fiat sliding tribometer. Experimental results confirmed that the wear and friction resistance properties were significantly enhanced by doping of nano-effects in the lubricating oil and composite coating. The addition of Al2O3 nanoparticles in the lubricating oil showed the best tribological properties, followed by Ni-Al2O3 composite coatings and nano-oil with graphene. The surface morphology and microstructure of electrodeposited coatings were examined by scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. The wear mechanisms of these coatings subjected to tribological testing were investigated by post-test surface analyses. This research provides a novel approach to design durable nano-coatings for tribological applications in various industries such as automotive, aerospace, locomotive and renewable energy technologies.