Stress Concentration Factors From Overlapping Stress Fields in Uniaxial Tension

Standard transmission photoelastic techniques were used to determine the resultant stress concentration factors produced by multiple stress raisers in flat, rectangular bars under uniaxial tension. Observations were made on the overlapping stress fields due to various combinations and orientations of holes and semicircular grooves. Two cases of directly superposed discontinuities were also investigated. The results of this investigation indicate that the sizes and relative positions of the discontinuities had a substantial effect on the resultant stress concentration factor. In some cases the stress concentration factor would be decreased while in other cases it would be increased. In the case of superposed stress raisers considered in this investigation, the resultant stress concentration factor can be taken as the product of the individual stress concentration factors; this is in agreement with the results of other investigators. However, for other cases, much judgment and experience will be required to decide when this can be done. And even then this product should be considered only as the probable upper limit of the actual stress concentration factor.