Stress Analysis for Surface Cracked Thin Plate

In this work, the stresses and dynamic crack growth were studied and analyzed in thin flat plate with a surface crack at the center, subjected to cycling low velocity impact loading for two types of aluminum plates (2024, 6061). Three main methods have been used in this study; first, analytical solution using classical plate theory by using Levy solution to determine stresses induced in plate due to the impact load. The impact load applied at the center of surface plate, was calculated by Hertzian contact law. The principal stresses with respect to time at the crack tip and the velocity of crack growth were calculated through elastic plastic fracture mechanics equations, because the impact loading will cause plastic zone around the crack tip and by Dugdal's model theory is found the size of this zone. Second, numerical analysis using program (ANSYS11-APDL) based on finite element method used to analyze and calculate the stresses and strains with respect to time at crack tip and then find the velocity of the crack growth under cyclic impact loading.