Finite Element Simulation of Metal Cutting using LS Dyna

Abstract

The current study focuses on building a 2-Dimensional finite element model to simulate the orthogonal machining process under a dry machining environment in a commercially available FEA solver LS Dyna. One of the key objectives of this thesis is to document the use of LS Dyna to model metal cutting, allowing other researchers to more quickly build on this work. The work material used in this study is Aluminum 6061-T6 alloy. The tool material is tool steel, which is modeled as a rigid body. A Plastic Kinematic Material Hardening model is used to define the work material and the chip formation is based on the effective failure plastic strain. A constant coefficient of friction between the tool and work piece is used, the values for which are obtained from the experimental results. The simulation is carried out with a constant velocity with different rake angles and depth cuts. The cutting force and thrust force values obtained for each combination of rake angle and cut depth are validated against the experimental data obtained earlier at Auburn University. The comparison of results shows that the cutting force predicted by the model is within 20 % of the actual experimental values. The thrust force is one third of the experimental value. The trends of both the cutting force and thrust force were in good agreement with the experimental results when plotted against either rake angle or depth cut, although the magnitude is not exact. iii Including the effects of the tool in the cutting process by not modeling it as a rigid body may help in reducing the error value and by implementing the actual friction taking place should give us the exact results as that of real time experiments. This model could then be used to study the effects of forces and stresses while varying other cutting parameters, tool geometry, different tool-work material combinations and cutting environments. The model is considered valid enough to use for sensitivity analysis of the metal cutting process in aluminum alloy 6061-T6 which will be the subject of future research at Auburn University.