Cycle Counting Methods and the Development of Block Load Fatigue Programmes

The basis of block load fatigue testing is the cycle counting method used to produce the test programme. The poor correlation with random loading often found may be due to the traditional counting methods. The paper discusses the new and more physically realistic “rain flow” counting method and presents test results which show that it can be used to give a more accurate simulation of random load fatigue damage than three traditional counting methods.

The techniques advocated are particularly applicable to industrial fatigue testing where simple digital computing facilities are available.