Using the SPH Method to Easier Predict Wear in Machining

Abstract

Usage of FE-models to predict wear is a tricky business. There is the question of material behaviour that gives the loading on the tool. There is the question of wear models and parameters that determine the amount of wear that can be expected for each combination of loadings. And there is the question of FE-specific features like re-mesh or failure modelling in the chip separation zone.The main objective with this paper is to better characterise the wear in numerical simulations by using the SPH modelling technique and determine wear model with wear parameters suitable for such simulations. The SPH(Smoothed Particle Hydrodynamics) modelling technique is used because of its capability to capture large deformations in a consistent way. Wear studies are used as a base for the choice of appropriate simulation based wear model. Two materials with seemingly similar elastic-plastic material behaviour but with distinct different wear behaviour will be compared.Wear can be assumed to derive from the loading on the tool in combination with the surface to surface slip. It is known that a change of failure model and parameter together with friction values used in a simulation yields a change the shape of the chip. And the shape of the chip determines the loading on the tool. Moreover, the wear model that is used in the analysis will capture the the effect of the loading and the combination of the tool-work piece material. The tool-work piece contact is characterised by shear zone where no slip is present followed by an unloading sequence where slip is present with subsequent visible wear. loading patterns from the simulations were consistent with the observed wear and consequently the SPH method was determined as suitable for the task.