A modified degradation technique for fatigue life assessment of adhesive materials subjected to cyclic shear loads

摘要

Understanding the fatigue response of adhesive joints under cyclic shear stress is important to avoid fatigue failure of the bonded structures. Recently, a cohesive zone modelling (CZM) technique was developed where the cohesive properties of the elements were degraded by a proposed empirical relation. However, based on this degradation approach, the fatigue life of the joints should be known before running the analysis. The aim of the current study is to improve the numerical method in which the fatigue life of the joints will be automatically estimated during the analysis. To achieve this, the concepts of fracture mechanics are considered by using the Paris’ law combined with the degradation model. A user material subroutine is developed to conduct the numerical calculations based on the concepts of CZM. End notched flexure (ENF) tests were carried out to evaluate the numerical data. Based on the results, it was found that the modified approach, in which the total fatigue life is obtained automatically, can be employed for fatigue life assessment of adhesive joints subjected to cyclic shear stresses.