Probabilistic optimization of welded joints maintenance versus fatigue and fracture

This paper presents a probabilistic maintenance optimization procedure for welded joints damaged by fatigue. The linear elastic fracture mechanics stands as a basis for fatigue crack growth while the crack depth at failure is determined according to brittle or ductile fracture. The first order reliability method being applied, the assessment is then based on reliability indices. At an inspection instant, different events can occur: no crack detection, crack detection, and repair. All these events are uncertain and are expressed in terms of probabilities. As they are cost-dependent, the total expected cost of maintenance could be obtained. The inspection instant is therefore searched by minimizing that total expected cost. Such an approach appears as a good compromise between reliability and costs. The paper provides some sensitivity studies and an application on a real case.