Influence of Boundary Anomaly on Vibration Fatigue of Aluminum Beams Under Harmonic and Random Excitations

Mechanical components often exhibit boundary anomalies such as loose fasteners, variable friction, misalignment, and asymmetric clamping, which induce nonlinear dynamics and degrade fatigue life predictability. This study examines their influence on vibration fatigue of beam‐type aluminum alloy specimens using experimental testing and fracture mechanics modeling. Specimens with symmetric and asymmetric clamping under deterministic and stochastic excitations were analyzed. Asymmetric clamping reduced vibration amplitudes by up to 35% and fatigue crack growth (FCG) rates by 42% relative to symmetric clamping. Damping ratios increased with crack growth in both cases, with asymmetric clamping providing 39% higher damping for transient cracks and 54% for stationary cracks. Divergence rate analysis revealed persistent nonlinear dynamics, with complex vibrations occurring over approximately 40% of fatigue life in symmetric clamping and 80% in asymmetric clamping under periodic loading. Numerical life predictions captured experimental trends but exhibited reduced accuracy under random loading as nonlinear effects intensified.