SPH Modelling of Cutting Forces while Face Turning Of Ti6Al4V Alloy

A growing interest in modelling and simulation of machining processes has been witnessed in the past few decades. Smoothed particles hydrodynamics (SPH), one of the latest and developing methods used for that purpose, is a powerful technique that can be efficient in handling problems in which large deformation occurs. This technique is able to overcome the shortcomings of the traditional finite element methods. One of these shortcomings is the need to adopting a damage model that artificially initiates the crack, and therefore, the accuracy will be affected. On the other hand, the SPH method does not require any damage model to be adopted for the simulation. The previous research studies in which SPH is employed to represent the workpiece in machining modelling were limited to 2D orthogonal cutting simulation. Furthermore, most of them validated the force in the cutting direction only. Therefore, it is necessary to extend the use of SPH method in 3D cutting simulations in order to evaluate the ability of SPH method to predict all components of forces. The current work aims to present and evaluate the use of SPH in 3D advanced models. A coupled thermo-mechanical analysis of the 3D model is performed using LS-DYNA to predict the cutting forces during face turning of Ti6Al4V alloy, at different cutting speeds. The workpiece was represented by a traditional finite element in the region of low deformation, and SPH particles in the region of high deformation. The Johnson-Cook material constitutive model is used since it is well suited to simulate materials subjected to large strain, high strain rates, and high temperature. In order to optimize the model, the both linear polynomial and Gruneisen equations of state are adopted in order to accurately simulate the material behavior and investigate their effects on the results. Different friction coefficient values were used in order to accurately predict the cutting forces. The simulation results are validated using a previously published experimental work.