Fatigue Crack Propagation Analysis of an Aluminium River Boat: State of Sustainable Infrastructure

It is estimated that 50% to 90% of ship accidents caused by mechanical failure are caused by fatigue. A calculation of the fatigue life of the structure must be carried out to determine the time required for the crack to propagate from the initial crack until the crack can be said to be dangerous or will fail. Fatigue crack growth occurs due to three basic factors, i.e. maximum tensile stress, large variations or fluctuations in stress, and large stress cycles. In this study, the fatigue life prediction was carried out on the aluminum ship, especially on the bottom structure using a fracture mechanics approach. The loading carried out was based on the ship's hydrodynamic load on the hogging and sagging conditions. A global stress analysis was carried out by modeling the intact condition to obtain the maximum tensile stress. Furthermore, a local stress analysis and crack propagation were carried out on the bottom structure which was reviewed using an initial crack of 5 mm. The fracture mechanics method was used to analyze the strength of the ship's base structure and estimate the fatigue life of the structure. The value of the stress intensity factor in the local model was 168.51 MPa√mm. The fatigue life using 5083 aluminum alloy material was obtained for 271.18 days.