Knife Crumbs Friction Simulation Analysis On The Effects Of Residual Stress Distribution

Residual stresses are those that are remained inside body but balanced themselves after all the external loads are removed. When a component is under manufacturing process, it's easy to bring residual stresses. The quality of a mechanical component such as its geometrical stability and fatigue life are significantly affected by the residual stresses.Metal cutting generally involves a large amount of plastic deformation and is coupled thermomechanical process. It always comes with several hundred MPa of residual stresses on the machined surface. From the literature review on the study of residual stresses induced by machining process, it is clear that the residual stresses vary largely with cutting conditions and workpiece material. Recently, with the improvement that production practices require, it's necessary to predict the residual stresses remained inside the part. Currently, the determination of residual stress heavily depends on experimentation. However, experimental approach has many limitations such as time consuming, high costs etc.In the past, a large number of expert and scholar have used the finite element method to simulate the whole machine process, and has predicted the distribution of the residual stresses under the surface. It is proved that the simulation results are consistent well with the experimentation. Still, residual stresses are found to depend strongly on the tool-chip friction.Taking into account that the complexity of the contact between tool and chip, it's some more difficult to express accurately the friction. In most common simulation, researchers used to take the Coulomb friction to gain the relationship of shear stress and normal stress at the tool-chip interface. In this thesis, we'll find that the coefficient of friction has significant influence on the distribution of residual stresses.Taking the average coefficient of friction in conventional approach obviously simplified the complex contact between tool rake face and chip. Then, we suggest a polynomial model of friction. By comparing the results with those from the conventional approach, the analysis of the influence of different friction model upon the residual stresses is performed.