Development of the Damage Tolerance Criteria for an Aging Fleet

Abstract : In order to enhance the strategy for resolve the problem of the ageing fleet, it is necessary to plan this strategy using the tools of fracture mechanics and fatigue crack propagation. In this work, the measure of the fatigue life of four different aeronautic pieces is proposed. As well, a static numerical model is applied in order to analyze the points of maximum stress and maximum strain, in each sample. From this, samples will be cracked in a fatigue testing machine, measuring the crack growth rate. A composite based repair will be proposed in order to decrease the crack growth rate, computing the increase in the fatigue life due to repair. This repair will be applied by means of a structural adhesive using the appropriate conditions to cure the system constituted by the resin and the hardener. Standard methods to fabricate the repairs will be used, in accordance with ASTM and other codes. A numerical model will be applied in order to predict the fatigue life in the case of repaired samples, calibrating the model if it is necessary. Commercial software will be used for static and dynamic modelling. The results of this work will be published in international congress of fracture mechanics or fatigue and will be published in ISI publications.