| Machining introduces a large amount of plastic deformation in the workpiece and affects surface integrity. This plastic strain is nonuniform, and therefore residual stresses are often an undesirable but unavoidable by-product of machining.; Reviewing previous work on the mechanics of metal cutting and residual stresses in machining reveal that the following questions are still not answered clearly or at all: First, there are no empirical data on distributions of residual stress and plastic strain on the same specimen. Second, it is evident that there is no analytical model to predict the depth of plastic deformation in the machined surface.; A mathematical model to predict the depth of plastic deformation in a machined surface was developed using the true stress-strain characteristics of the workpiece, the shear stress and shear strain on the shear plane, and the distribution of plastic strain below the machined surface. An experimental machining approach with a QSD, a workpiece material characterization protocol by XRD, and experimental true stress-strain diagrams was developed to verify the mathematical model. The average difference between the measured and computed depths of plastic deformation was 1.57 percent. |
