Abstract
To investigate the effects of the contact geometry, interfacial friction, and substrate recovery on the behavior of polymer scratching using a conical tip, an analytical model is proposed. The normal stress acting on the contact surface between the tip and the substrate is described as a function of the included angle θ, representing the angle between two planes across the axis of the conical tip, and the attack angle β, representing the angle between the conical surface and the substrate material surface. The effects of the rear contact geometry on the scratch friction between the tip and substrate, represented by recovery angle φ, owing to the instantaneous elastic recovery of the polymer substrate, are also introduced. Validated by the experimental and numerical results from the literature, the proposed analytical model can describe well the scratch coefficient of friction (SCOF), which is defined as the ratio of the tangential force to the normal force. Meaningful guidance is provided to understand the scratch friction behavior.
Highlights
Owing to their relatively poor mechanical properties, polymeric materials can be scratched, and the surface damage from such scratches will change/weaken the morphology, functionality, and aesthetics of the original surface
Jiang et al [15] found that the scratch performance of polypropylene (PP) improves with a decrease in interfacial friction when using the finite element (FE) method
For a large attack angle (Fig. 6(b)), the scratch coefficient of friction (SCOF) predicted by the proposed model is larger than that by the Subhash and Zhang (S&Z) model, and the difference (14%–36% for various values of and s ) cannot be ignored
Summary
Owing to their relatively poor mechanical properties, polymeric materials can be scratched, and the surface damage from such scratches will change/weaken the morphology, functionality, and aesthetics of the original surface. The contact between the rear part of the scratch tip and recovered substrate is observed, which should be considered to establish a comprehensive analytical model of the scratch behavior. Lafaye et al [37, 38] further developed this using a conical tip, a spherical tip, and a conical tip with a blunted spherical extremity They found that the effects of the instantaneous elastic recovery of the substrate on the scratch behavior cannot be neglected. An analytical model is proposed to study the scratch friction behavior of a conical tip-polymer substrate system. After validation based on experimental and numerical results from the literature [21, 25, 35, 39], the proposed analytical model is utilized to thoroughly investigate the influences of the contact geometry, interfacial friction, and substrate recovery on the scratch friction
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