Impact contact behaviors of elastic coated medium with imperfect interfaces

Abstract

Imperfect interface of coating-substrate system, where displacement and stress are transmitted discontinuously, affects mechanical response of coated medium subjected to impact loading a lot. This paper proposes an impact contact model between an elastic moving ball and imperfectly bonded semi-infinite coating-substrate system with combined dislocation-like and force-like interfaces. Impact contact process obeys the second-order Newmark theory and contact theory for coated medium. Impact velocity, acceleration and reaction force of the ball are cost-effectively determined by a step by step iterative strategy, binary search method and conjugate gradient method (CGM). Analytical explicit expressions of displacement and stress fields of imperfectly bonded coating-substrate system are derived with the assistance of the Papkovich–Neuber potentials, which are further transformed to frequency domain aiming at improving calculating efficiency through employing a fast Fourier transform (FFT) algorithm. Six jumping coefficients for interfacial displacement and stress are introduced to describe different interface conditions, and their effects on impact reaction force, contact radius, contact pressure and subsurface stress of imperfectly bonded coating-substrate system under different impact velocities are studied.