Fatigue reliability evaluation of riveted lap joints using a new rivet element and DFR

Fatigue reliability evaluation of a lap shear riveted joint has been faced using a Detail Fatigue Rating (DFR) method combined with FE simulations performed with a new rivet element. The Rivet Element, based on a closed-form solution of a theoretical model of the rivet joint, is able to accurately evaluate, in FE analysis, both local and overall stiffness of riveted joints with a very low contribution of dofs. The classic DFR approach needs global FE analysis of the complete structure in order to detect loads acting on the joint and the stress concentration factors, sacrificing necessarily the computation time or the accuracy of the results. In the paper is proposed the combination of a FE model of the complete structure with Rivet Elements and the introduction of suitable analytical formulations to evaluate stress concentration factors, starting from the values of loads on rivets. The elaboration of these results with this new DFR-Rivet Element approach allows assessing fatigue reliability of actual structures with a reduction of at least 95% of the total computation time, compared to classic DFR approach, which is already one of the fastest methods for the evaluation of the fatigue reliability of riveted structures.