Predicting fatigue damage in adhesively bonded joints using a cohesive zone model

A reliable numerical damage model has been developed for adhesively bonded joints under fatigue loading that is only dependant on the adhesive system and not on joint configuration. A bi-linear traction–separation description of a cohesive zone model was employed to simulate progressive damage in the adhesively bonded joints. Furthermore, a strain-based fatigue damage model was integrated with the cohesive zone model to simulate the deleterious influence of the fatigue loading on the bonded joints. To obtain the damage model parameters and validate the methodology, carefully planned experimental tests on coupons cut from a bonded panel and separately manufactured single lap joints were undertaken. Various experimental techniques have been used to assess joint damage including the back-face strain technique and in situ video microscopy. It was found that the fatigue damage model was able to successfully predict the fatigue life and the evolving back-face strain and hence the evolving damage.