This study presents a numerical model for the thermal-elastohydrodynamic lubrication of heterogeneous materials in impact motion,in which a rigid ball bounces on a starved non-Newtonian oil-covered plane surface of an...This study presents a numerical model for the thermal-elastohydrodynamic lubrication of heterogeneous materials in impact motion,in which a rigid ball bounces on a starved non-Newtonian oil-covered plane surface of an elastic semi-infinite heterogeneous solid with inhomogeneous inclusions.The impact–rebound process and the microscopic response of the subsurface inhomogeneous inclusions are investigated.The inclusions are homogenized according to Eshelby’s equivalent inclusion method.The Elrod algorithm is adopted to determine the lubrication starvation based on the solutions of pressure and film thickness,while the lubricant velocity and shear rate of the non-Newtonian lubricant are derived by using the separation flow method.The dynamic response of the cases subjected to constant impact mass,momentum,and energy is discussed to reveal the influence of the initial drop height on the impact–rebound process.The results imply that the inclusion disturbs the subsurface stress field and affects the dynamic response of the contact system when the surface pressure is high.The impact energy is the decisive factor for the stress peak,maximum hydrodynamic force,and restitution coefficient,while the dynamic response during the early approaching process is controlled by the drop height.展开更多
This paper presented a numerical approach to solving the problem of a flat-ended punch in contact with a half-space matrix embedded with multiple three dimensional arbitrary-shaped inhomogeneities.Based on the semi-an...This paper presented a numerical approach to solving the problem of a flat-ended punch in contact with a half-space matrix embedded with multiple three dimensional arbitrary-shaped inhomogeneities.Based on the semi-analytical method(SAM)and the equivalent inclusion method,numerical procedures were developed and the effects of inclusion shape and distribution were analyzed.Fast Fourier transform technique was implemented to accelerate the calculation of surface deformation and subsurface stress.Interactions of inter-inclusions and inclusion-matrix were taken into account.Numerical results showed the presence of inhomogeneities(i.e.,microstructures in solids)indeed had a great effect on local contact pressure and a strong disturbance to the subsurface stress field in the vicinity of inclusions.The effects were dependent on the shape and distribution of inclusions and inter-inclusion interactions.The physical significance of this study is to provide an insight into the relation between the material microstructure and its response to the external load,and the solution approach and procedures may find useful applications,for example,the analysis of fatigue and crack propagation for composite materials,prediction of stress field in solids containing material defects,and study of the mechanism of chemical-mechanical polish(CMP)for inhomogeneous materials,etc.展开更多
基金the National Research Foundation(NRF),Singapore,SMRT,Singapore and Nanyang Technological University,Singapore.Q.B.also acknowledges the support from National Natural Science Foundation of China,China(Grant No.51905051).
文摘This study presents a numerical model for the thermal-elastohydrodynamic lubrication of heterogeneous materials in impact motion,in which a rigid ball bounces on a starved non-Newtonian oil-covered plane surface of an elastic semi-infinite heterogeneous solid with inhomogeneous inclusions.The impact–rebound process and the microscopic response of the subsurface inhomogeneous inclusions are investigated.The inclusions are homogenized according to Eshelby’s equivalent inclusion method.The Elrod algorithm is adopted to determine the lubrication starvation based on the solutions of pressure and film thickness,while the lubricant velocity and shear rate of the non-Newtonian lubricant are derived by using the separation flow method.The dynamic response of the cases subjected to constant impact mass,momentum,and energy is discussed to reveal the influence of the initial drop height on the impact–rebound process.The results imply that the inclusion disturbs the subsurface stress field and affects the dynamic response of the contact system when the surface pressure is high.The impact energy is the decisive factor for the stress peak,maximum hydrodynamic force,and restitution coefficient,while the dynamic response during the early approaching process is controlled by the drop height.
基金supported by the National Basic Research Program of China(Grant Nos.2009CB724200,2011CB013404 and 2011CB706602)
文摘This paper presented a numerical approach to solving the problem of a flat-ended punch in contact with a half-space matrix embedded with multiple three dimensional arbitrary-shaped inhomogeneities.Based on the semi-analytical method(SAM)and the equivalent inclusion method,numerical procedures were developed and the effects of inclusion shape and distribution were analyzed.Fast Fourier transform technique was implemented to accelerate the calculation of surface deformation and subsurface stress.Interactions of inter-inclusions and inclusion-matrix were taken into account.Numerical results showed the presence of inhomogeneities(i.e.,microstructures in solids)indeed had a great effect on local contact pressure and a strong disturbance to the subsurface stress field in the vicinity of inclusions.The effects were dependent on the shape and distribution of inclusions and inter-inclusion interactions.The physical significance of this study is to provide an insight into the relation between the material microstructure and its response to the external load,and the solution approach and procedures may find useful applications,for example,the analysis of fatigue and crack propagation for composite materials,prediction of stress field in solids containing material defects,and study of the mechanism of chemical-mechanical polish(CMP)for inhomogeneous materials,etc.
