A New Mechanical Random Fatigue Testing Machine and Some Test Results

抄録

A new mechanical random fatigue testing machine was devised and manufactures which could give the random load to the specimen by using various sizes of steel balls mixed at an arbitrary ratio. The testing machine proved to be practical from a statistical point of view. Some kinds of random fatigue tests were carried out with this testing machine, and each random load-time history was analyzed by three different load count methods, namely the peak count method, the range count method and the full wave count method. Fatigue lives were estimated from these analytical results by applying Miner's law, and they were compared with the actual lives obtained empirically in order to discuss the propriety of the load count method for service loads. The evaluated lives by the full wave count method coincided to a considerable extent with the actual fatigue lives irrespective of the extent of the irregularity of the random load, which means that the full wave count method is most desirable for the random load counting.