Numerical analysis of elastic coated solids in line contact

WANG Ting-jian(王廷剑), WANG Li-qin(王黎钦), GU Le(古乐), ZHAO Xiao-li(赵小力)

(School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China)

Abstract:A line contact model of elastic coated solids is presented based on the influence coefficients (ICs) of surface displacement and stresses of coating-substrate system and the traditional contact model. The ICs of displacement and stresses are obtained from their corresponding frequency response functions (FRF) by using a conversion method based on fast Fourier transformation (FFT). The contact pressure and the stress field in the subsurface are obtained by employing conjugate gradient method (CGM) and discrete convolution fast Fourier transformation (DC-FFT). Comparison of the contact pressure and subsurface stresses obtained by the numerical method with the exact analytical solutions for Hertz contact is conducted, and the results show that the numerical solution has a very high accuracy and verify the validity of the contact model. The effect of the stiffness and thickness of coatings is further numerically studied. The result shows that the effects on contact pressure and contact width are opposite for hard and soft coatings and are intensified with the increase of coating thickness; the locations of crack initiation and propagation are different for soft and hard coatings; the risk of cracks and delaminations of coatings can be brought down by improving the lubrication condition or optimizing the non-dimensional parameter h/b_h. This research offers a tool to numerically analyze the problem of elastic coated solids in line contact and make the blindness and randomness of trial-type coating design less.

Key words:coating-substrate system; contact pressure; stress field; frequency response function; influence coefficient