Practical fatigue analysis of hydraulic cylinders – Part II, damage mechanics approach

The paper is continuation and extension of the previous article (Marczewska et al., 2006) published in Journal of Fatigue in 2006. Our previous model of analysis (Marczewska et al., 2006) was based on classical S–N curves and equivalent amplitude stress concept. Now more physically justified damage mechanics approach to fatigue analysis is applied. The analysis used in both our papers is based on particular application of the constitutive model described in Oller et al. . Hydraulic cylinders investigated under E.C. project “PROHIPP” are analyzed. Modeling of fatigue crack propagation is performed. The new elements, in comparison with previous paper (Marczewska et al., 2006) are: application of the thermodynamic basics of damage mechanics approach to fatigue analysis with taking into account plastic deformations, introduction of damage evolution surface in fatigue analysis, modification of analytical form of S–N curve proposed in Oller et al. and fatigue crack propagation modeling using damage mechanics approach. As it was mentioned in Marczewska et al. the “marriage” of stress analysis and fatigue data is still one of deficiencies in the current European Norm EN 13445, chapter 18: detailed assessment of fatigue life . Our paper is an attempt to further reduce this deficiency.