Application of continuum damage mechanics model in terms of fatigue life assessment for low cycle and quasi static loadings

Abstract

The aim of this study is to test the classical Lemaitre model based on continuum damage mechanics (CDM) approach in the range of low cycle and quasi-static fatigue life. Study is carried out with the use of results of experimental tests for C45 steel (according to AISI: 1045 steel) carried out under variable-amplitude loading. Loading programs are of two-step character and include blocks of cycles of different lengths and R = -1 coefficients. Fatigue lives are calculated according to Lemaitre model from experimentally obtained stress and strain histories recorded during fatigue tests. The results are compared with experimental tests results and with fatigue lives calculated with the use of by traditional fatigue approach based on Palmgren-Miner damage summation hypothesis. Experimental test of fatigue life calculation results for C45 steel reveals that continuum damage method, using the recorded stresses and strains, predicts fatigue life better as compared to the remaining methods. The study also contains many detailed analyses of experimental results.