STRESS CONCENTRATION FACTORS FOR V-NOTCHED PLATES UNDER AXISYMMETRIC PRESSURE by NATHAN

The topic of this thesis is the investigation of the local states of stress resulting from the introduction of a v-notch in a coaxial circle on the pressurized surface of a circumferentially clamped plate subject to axisymmetric loading. The understanding of the fracture behavior of a component experiencing such a condition is of particular interest to the aerospace and defense industries where circular plate components are often utilized. In such applications, it is imperative that the designer be able to predict the loading conditions facilitating dynamic fracture. As a step towards solving such problems, the quasi-static analogy is studied. Specifically, the purpose of this research is to examine and model the precise effects a stress raiser will have on the fracture behavior and strength reduction of a circular plate machined from Ultem 1000. Parametric FEM simulations were employed to determine the correlation between notch geometry and the resulting maximum stress and stress distribution in the notch root vicinity. Stress concentration factor (SCF) relationships were developed which characterize the effect individual geometric parameters have on the notch root stresses. Mathematical models were developed to provide the elastic stress concentration factor for any combination of geometric parameters within the range studied. Additionally, the stress distributions along the notch root and ahead of the notch were characterized for a variety of geometric configurations. Test coupons were employed to not only characterize the mechanical behavior of the material, but also characterize the correlation between simple and axisymmetric loading, respectively. The development of a predictive approach for designers of such circular components to be able to accurately determine the fracture behavior of these components was the motivating factor of this study.