The Experimental Study And Finite Element Simulation On Precision Grinding Residual Stress Of Nanostructured WC/Co Coatings

Nanostructured ceramic coatings is a novel class of engineering material in recent years, its fine properties make it have very extensive application perspective in industry. This thesis deals with the precision grinding residual stresses for nanostructured ceramic coatings (n-WC/12Co). Through experimential investigation and finite element simulation, precision grinding residual stresses for nanoatructured ceramic coatings(n-WC/12Co) are discussed. The results add a great value to the nanoatructured ceramic coatings in terms of industrial application.In present thesis, the precision grinding residual stresses of thermally sprayed nanostructured ceramic coatings (n-WC/12Co) with diamond wheel is studied in detail. The effect of grinding parameters such as grinding depth of grinding wheel, feedrate, bond type as well as wheel grit size on grinding residual stresses are analyzed. Some important conclusions are obtained in this study. The current study is helpful in understanding the residual stress state in coatings and in selecting the grinding parameters to control residual stresses to a desired state.On the other hand,This thesis presents thermal elastoplastic Finite Element Analysis(FEA) for calculating surface residual stress when machining nanostructured WC/12Co coatings.Ignoring phase transformation, APDL of ANSYS software was applied to complete the whole process which was composed of establishing model, defining material properties,meshing the model, loading and solution.The experiments were perfonned and the results show the validity of the FEA model.In the present thesis, a movable uniform thermal flux and grinding force distribution were taken into account in the analysis. The workpiece is separated into some sections according to the contact length of the grinding wheel with the surface. According to the speed of the grinding wheel and the grinding time and section,the calculation process is divided into several steps. The load is moved along the surface of workpiece.Each step of movement is equal to the contact length. All the cutting force F_t , the extruding force Fn and the force Fz from axis direction are acting on every surface element together. At the same time every element has its corresponding temperature numerical value in the instantaneous temperature field. After calculating the stresses on all elements the load is moved directionally. Each step of movement is equal to contact length and it is bound to follow up-load, unload and temperature field change. After going through a whole grinding path the...