Fatigue life estimation of screws under multiaxial loading using a local approach

The fatigue life estimation of screws usually applies a nominal approach on the basis of normal forces. For time-dependent, multiaxial loading of screws this method is not accurate enough; a related method has not been specified yet. In this regard, the current contribution discusses the incorporation of a local approach to predict durability. Therefore, Schneider's method is enhanced to generate an efficient procedure for calculating the fatigue-induced damage at the screws. The failure criterion is the technical relevant incipient crack length in the first load-bearing thread turn of the screw. By incorporating a submodelling technique, the presented method leads to damage values over the circumferential angle of the thread. In order to validate the method, the computed damage values are compared with experimentally determined results. In the experiments, the incipient crack length in the thread of the screws is measured by an advanced technique using a rod-type strain gauge. (C) 2017 Elsevier Ltd. All rights reserved.