AN ANALYSIS OF LOW CYCLE FATIGUE BASED ON HYSTERESIS ENERGY

Abstract— Cyclic deformation behaviour of medium carbon steel, armco iron and copper has been investigated. A model based on the energy absorbed for the fracture process at the crack tip, given in the form (Δw*_p)^y where Δw*_p is the hysteresis energy at the crack front and the exponent y decides the energy spent for the fracture process, is proposed for the crack growth in low cycle fatigue. The value of the exponent y has been found to be around 0·26 to 0·28 for medium carbon steel and armco iron and around 0·52 for copper. These values of y give good prediction of the relations between the total fracture energy and the stress amplitude and the total fracture energy versus the fatigue life. The energy based approach has been extended to predict the cumulative damage in a single step stress variation. Good correlation has been obtained between the experimental data and the theoretical prediction.