Coupling of Dafalias-Popov’s Two-Surface Plasticity with Notch Stress-Strain Estimation Methods in Plane Stress Problems under Monotonic Uniaxial Loading

In most mechanical parts, geometrical discontinuities or notches exist. Usually the material response in these discontinuities is elastoplastic. Because of complexity and time consuming of plastic analysis, researchers have proposed estimation methods based on the linear elastic behavior. In this paper, a new estimation method, based on Dafalias-Popov’s two surface plasticity model, is proposed which is coupled with incremental Neuber’s rule and incremental equivalent strain energy density methods. Although the method has simple equations, but Dafalias-Popov’s plasticity model has complexities and challenges, like bounding line effect on the model prediction and shape parameter determination. To verify the model and evaluating the challenges, a plate with elliptical and traction free hole under remote monotonic uniaxial load is considered. Plane stress condition is assumed and elastoplastic behavior is of Ramberg-Osgood type. Results show that the bounding line effect can be neglected, in most engineering problem which strain range is less that 20 percent. It is shown that the shape parameter has optimum value in certain range. Results show that accuracy of the model in stress-strain prediction is in acceptable range