Abstract
Optimum design of elliptical Defense Hole System (DHS) under biaxial loading in a finite plate with a row of circular holes is presented. Maximum stress reduction is made possible by introducing elliptical auxiliary holes close to the mainmain holes in the areas of low stresses along the principal stress direction. A systematic study is undertaken by using the finite element analysis (FEA) to determine the optimum shape, location and size of the auxiliary defense hole system. These parameters are examined in relation to plate dimensions for a number of plates with different mainmain-hole-diameter to plate-width ratios and different pitch to main-hole-diameter ratios. Maximum stress reductions from 6–18% were achieved. With such reduction in the maximum stress level the improvement in fatigue life of a structural part can be very significant. The FEA results are validated experimentally by applying an enhanced RGB-photoelasticity technique. The photoelasticity experimental results and the FEA results show good agreement.