Investigation of the Effect of Using Different Material Models on Finiste Element Simulations of Machining | NIST

Choosing the appropriate constitutive model is important for finite element analyses (FEA) of different metal forming processes. Due to the presence of high values of strain, strain rate and temperature in machining, it is extremely important to evaluate the performance of the different material models. Typically these were developed at much lower strains, strain rates and temperature. To model orthogonal machining, we use coupled thermo-mechanical analysis of machining using a commercial finite element analysis system. The workpiece material, AISI 1045, is both well characterized in the form of different constitutive models and widely used in industry. We use three different constitutive models for AISI 1045 deforming under high strain rate and temperature, the Oxley model, Johnson-Cook model, and Maekawa history dependent model. To normalize the comparison of the performance of these models, the friction coefficient for each simulation is set to a value that results in the closest match between the predicted cutting force and measured cutting force. A detailed comparison of the other process outputs of interest, namely, thrust force, chip thickness, shape of the primary and secondary shear zones and temperature distributions, is carried out to compare the performance of different material models to each other and experimental results.