Experimental Determination of Dynamic Stress Concentration Factors in Rectangular Steel Bars

Stress concentration factors obtained from impact tests indicate substantial agreement with experimentally derived static stress concentration factors. Testing was limited to one 3/8 diameter centrally located hole in a long rectangular bar 2 inches wide. The hole was located at a bar cross section where a plane wave was found to exist. Stress pulse lengths as short as 50 microseconds duration was used in the experiments. The experimental results confirm the ability of the resistance strength gage to accurately measure stress pulses. The proper amplitude response of the gage is proven by comparison with dynamic and static test results. The frequency response adequacy is inferred by correlating test results with Hertzian theory for the one-inch diameter steel ball striker. Also, gage factors derived from static calibrations were sufficiently accurate for the dynamic tests