Finite element implementation of multiaxial continuum damage mechanics for plain and fretting fatigue

The three-dimensional finite element implementation of a continuum damage mechanics formulation for multiaxial fatigue is presented, incorporating elastic modulus reduction due to fatigue damage. The implementation is validated against theoretical and published experimental results for uniaxial and notched multiaxial fatigue under different combinations of mean and alternating stresses for Ti-6Al-4V. An automatic incrementation scheme is developed for efficient computation of damage accumulation and hence stress redistribution. The method is also implemented in two-dimensional, plane strain for fretting fatigue and is shown to successfully capture the effect of contact slip on fatigue life for a round-on-flat fretting geometry. Comparisons are also made with a critical-plane multiaxial fatigue approach for fretting. The work is a first step towards a more general fatigue damage approach to unify wear and fatigue prediction for fretting.