We were asked to perform a failure analysis on a pump used in fracking operations. The pump is driven through a transmission by a 2700 HP engine which varies in RPM. The transmission is connected to the pump by a universal joint to a flange and shaft assembly.
The assembly was made up of a flanged input hub, key, and pump input shaft. The flanged hub and input shaft had an interference fit reducing the overall load on the key. The original design incorporated a 4 inch diameter shaft, which, during testing, had failed. We not only determined the fatigue life of the 4 inch shaft, but also designed a 5 inch shaft to increase the expected design life of the new pumps.