Finite element analysis of fretting fatigue fracture in lug joints made of high strength steel

Many structural applications are aiming for weight reduction by using high strength steel. In a lug joint the load is transmitted by a pin, which leads to a pressure distribution on the hole in the lug. When a lug joint is subjected to axial cyclic loading conditions, the stress distribution becomes multiaxial, i.e. a combination of normal and tangential stresses. In such loading case, a fretting crack initiates at the contact interface between the pin/lug connection which is followed by a fatigue crack propagation up to the final rupture of the lug. In this study, the fretting fatigue crack initiation and propagation in a pin/lug joint are simulated using multiaxial fatigue criterion and fracture mechanics, respectively. To do so, first a 2D finite element model is developed for obtaining stresses and strains at the contact interface in a pin/lug joint. Using the extracted data, fretting fatigue failure parameters are analysed. Next, the obtained stresses and strains are used to estimate the crack initiation lifetime using a fatigue multiaxial critical plane model. A 3D model is set-up to simulate the crack propagation using eXtended Finite Element Method (XFEM). Eventually, the predicted total fatigue lifetimes are compared against experimental observations taken from literature.

Publication year:2018

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