Modeling the role of microplasticity on material response under fatigue loading using a microelement plastic strain accumulation model

Fatigue failure is greatly impacted by the progressive accumulation of microplastic deformation when subjected to cyclic loading below the macroscopic yielding. This paper presents microplastic deformation and its influence on fatigue response both in low and high cycle fatigue regimes using a recently developed Microelement Plastic Strain Accumulation (MPSA) approach. The MPSA approach is based on the Jenkin–Masing model, which treats materials as a large number of linear elastic–perfectly plastic parallel microelements. This microelement model provides insights into material behavior below the macroscopic yield limit under different loading conditions, which is essential for modeling high cycle fatigue failure of materials. We evaluate the evolution of the microplastic strain, ratcheting strain, stress–strain hysteresis loops, and material degradation during cyclic loading using this model. The evolution of microplastic strain allows the model to predict high cycle fatigue. Finally, we study the strength and stiffness degradation in terms of the fraction in fatigue life.