CONSIDERATION ON CRACK INITIATION LIFE UNDER PROGRAMME FATIGUE TEST

A programme fatigue test is a test under cyclic loading as a block which has a number of cycles of load with some types of amplitude of stress. The test is to assess the fatigue strength of products under modified conditions near to actual load. Many types of block patterns are to be considered. For the fatigue design of products, a programme fatigue test under some block patterns is examined for the restriction of time and cost and a study on the life of other patterns is carried out with the application of Miner's rule, modified Miner's or Haibach's method. The estimated lives irrespective of the above methods are widely scattered in comparison with experiments. The paper describes a proposal of the dependence of block patterns on crack initiation life for programme fatigue.