SHORT TIME EVALUATION OF METALLIC MATERIALS' FATIGUE POTENTIAL COMBINING DESTRUCTIVE AND NON-DESTRUCTIVE TESTING METHODS

摘要

Fatigue of engineering structures is an issue from an engineering design point. The lifetime of materials being subject to repeated mechanical loads is limited. Different examples of failures and fateful air accidents have caused significant cost and claims to the operators as well as manufacturers in excess of fatalities. Criticality of failure increases with increasing age and the uncertainty of operational loads applied. In such a case a reassessment of a structural materials' condition is in big need should damage tolerance criteria still be met, being the essential ground rule for aeronautical structural design. It is therefore the challenging aim to use a metallic material's microstructure characterizing non-destructive testing (NDT) parameter or a combination of those as a parameter to be scanned over a defined surface of the component considered to more realistically characterize the damage condition and to use this information twofold: a) to more precisely assess the structural component's residual life and b) to feed the information recorded back into a specific database belonging to an approach named PHYBAL. The physically based fatigue life evaluation method (PHYBAL) is a short-time procedure for the evaluation of fatigue data based on a small number of fatigue tests performed on un-notched specimens only. This method significantly reduces the effort for experimentation in terms of time and cost by around 90% and inhibits remarkable scientific as well as economic advantages. The paper highlights the high capability of PHYBAL as well as the suitability for assessing the residual life of aeronautical components also with respect to the application of this approach in the light of structural health monitoring issues.