Impact of Stress Variations on Fatigue Crack Growth in Aluminum Alloys Under Cyclic Loading

This study provides a comprehensive analysis of the fatigue behavior of Al-6082-T6 aluminum alloy under cyclic loading conditions. Utilizing advanced finite element modeling through COMSOL Multiphysics, the research investigates stress distributions and crack propagation mechanisms associated with constant amplitude loading. A primary focus is the evaluation of pre-existing residual stresses and their influence on fatigue life and crack growth rates. The findings reveal that stress concentrations, particularly in the central regions of the specimen, significantly contribute to the initiation and progression of fatigue cracks. Numerical simulations indicate a strong correlation between these high-stress zones and crack formation, identifying them as critical failure points under cyclic loading. Furthermore, the study examines the differential impact of tensile and compressive loads on fatigue behavior. Tensile loading is observed to accelerate material degradation and fatigue damage, whereas compressive loading enhances fatigue resistance. These observations align with existing literature, suggesting that compressive stresses can mitigate fatigue damage and promote stress relaxation, thereby improving material durability. In terms of material characterization, the research emphasizes the significance of the microstructural response to cyclic loading. Analysis of stress–strain curves facilitates the identification of the transition from elastic to plastic deformation, providing insights into damage accumulation over time. Additionally, displacement distribution along the specimen’s arc length reveals localized yielding in critical regions, underscoring the necessity for refined assessments of fatigue behavior in areas of concentrated stress. The implications of this study are significant for structural design in industries where cyclic loading is a critical concern. The results underscore the importance of considering the entire stress field, including regions of moderate stress, when evaluating material performance. This advocates for a holistic approach to fatigue testing, incorporating both peak stress zones and less concentrated regions that may contribute to long-term failure.