Development of a Push-Pull Fatigue Testing Machine under High Pressure, and the Results of Preliminary Fatigue Tests

Abstract

A push-pull fatigue testing machine under high pressure up to 6000kg/cm² was developed. Using this machine, the preliminary fatigue tests in the low-cycle fatigue range were conducted under the load-cycling conditions with OFHC copper, 5005 Al alloy and S35C carbon steel under hydrostatic pressures up to 4000kg/cm². The unnotched fatigue strength showed a slight but definite increase with increasing ambient pressure. No discernible difference was observed in the notched fatigue strength of OFHC copper between 0 and 3000kg/cm² ambient pressure. The scanning electron fractograph of unnotched OFHC copper specimens revealed no apparent difference in the striated regions of fatigue-fractured specimens under 3000kg/cm² and zero ambient pressure.