Fatigue Life Study of Medium Boat Made of 5052H34 Aluminium Alloy

This study presents a fatigue analysis of a medium-sized motorboat commonly used in the Amazon region, built from 5052H34 aluminium alloy. The research was motivated by the appearance of cracks in some vessels of the same model. The analysis focused on welded joints, with stresses estimated numerically using the finite element method. Pressure fields derived from regional wave data, accounting for dynamic slamming effects, were applied to a representative hull model. Fatigue life was assessed using Δ σ -N Δ σ - N (stress range-number of cycles) curves obtained experimentally from welded and unwelded specimens of equivalent plate thickness, covering the low-cycle to high-cycle fatigue transition, up to the conventional boundary of the very-high-cycle fatigue (VHCF) regime ( ~ 10⁷ ∼ 10 7 cycles). Results for the most critical operating scenarios indicate a predicted fatigue crack initiation life of less than two years, suggesting that cracking may occur within this period. These findings indicate that fatigue is a key factor in the structural design of aluminium boats subjected to repetitive slamming loads.