Estimation of Plastic Stress Concentration Factor around Elliptical Cut Outs

Design of structures needs to cater to key requirements of safety and weight. To achieve these requirements, smooth flow of stresses and optimum factor of safety at all points in the structure are necessary. However, presence of cut outs becomes a necessary feature in the structures which obstruct the flow of stresses and there will be local concentration of stresses near the cut outs which needs to be estimated so that a safe and weight efficient design may be worked out. In this work, stress concentration factors (both elastic and plastic) near the elliptical cut outs of various standard geometries and for different material are computed using FEA and a comparison is made with analytical and semi-empirical methods available which demonstrates the behaviour of the structures with cut outs in the plastic regime. The ratio of nominal stress at failure to the ultimate strength of the material is calculated for the different plastic stress concentration factors for all the elliptical cut out configurations and a comparison is made between the theoretical and FEM results.