Load Ratio Effect on the Fatigue Behaviour of Adhesively Bonded Joints: An Enhanced Damage Model

ISSN： 0021-8464

Source： Journal of Adhesion, Vol.86, Iss.3, 2010-02, pp. : 257-272

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Abstract

Structural adhesives are used widely in aerospace and automotive applications. However, fatigue damage in these adhesives is an important factor to be considered in the design of adhesively bonded structural members that are subjected to cyclic loading conditions during their service life. Fatigue life of adhesively bonded joints depends mainly on the fatigue load and the load ratio. A fatigue damage model is presented in this paper to include the effect of fatigue mean stresses on the failure behaviour of adhesively bonded joints. The fatigue damage model is developed using an effective strain-based approach. The model is implemented on a tapered single lap joint configuration and is validated by experimental test results. The adhesive layer in the tapered single lap joint is modelled by using a cohesive zone with a bi-linear traction-separation response. The adverse effect of increasing fatigue mean stresses on the failure behaviour of adhesively bonded joints is successfully predicted.