Volume 11, Issue 3 (May 1983)
On the Yield Loads of Plates with Array of Holes
Scientific and technical literature is full of research papers on the investigations of stress concentrations around holes and rows of holes in plates. All these stress concentrations have been determined in specimens where the stresses and strains away from the holes are well within the elastic limit of the material. Yet literature on the load bearing capacities up to yield point of plates with holes is not available. It is of academic and practical importance to determine the yield load of a machine component with holes, as yield load may be the criterion of failure for ductile materials. In the present work, yield loads of mild steel plates with one, three, five, and nine holes in different combinations and orientations have been determined experimentally using an Instron universal testing machine. The yield loads of these specimens were very close to the yield loads of the specimens without holes. It was further observed that for up to a 30% reduction in area in the critical section (along which final fracture takes place), the yield load remains the same. Specimens with a single hole were also studied under moderately dynamic strains, up to a strain rate of 0.42/min. It was observed that yield load and yield point elongation increased with increasing strain rate. This showed that a hole in the specimen has negligible effect on these properties of the specimen.