An evaluation of strength wearout models for the lifetime prediction of adhesive joints subjected to variable amplitude fatigue

Fracture mechanics and damage mechanics based fatigue lifetime prediction of adhesively bonded joints subjected to variable amplitude fatigue

“…This is in agreement with previous work, which has indicated load interaction effects in the variable amplitude fatigue testing of bonded joints, with both mean load changes and overloads resulting in damage acceleration [10][11][12][13][14]. These effects need to be accommodated in any lifetime prediction procedure if the variable amplitude fatigue behaviour of adhesively bonded joints is to be accurately predicted.…”

“…Most of this work has involved constant amplitude sinusoidal fatigue. However, recent work has indicated that fatigue induced degradation of bonded joints is accelerated when overloads and mean load changes are incorporated into the fatigue spectrum [11][12][13][14], thus, predictive methods based on constant amplitude fatigue (CAF) data for bonded joints will tend to be non-conservative. As most bonded joints in structural applications are subjected to variable amplitude fatigue (VAF), this effect requires further investigation and the development of life-prediction methods that take into account any VAF induced damage acceleration effects.…”

Fatigue damage modelling of adhesively bonded joints under variable amplitude loading using a cohesive zone model

“…Some of the methods employed for fatigue prediction of bonded joints under VA loading include total life, strength wearout, fracture mechanics based and damage mechanics based methods [6][7][8][9]. The total life method expresses the fatigue life as a function of a loading variable such as the maximum or the amplitude of the stress, strain or load cycle.…”

“…The strength wearout approach [7] has been used to predict the VA fatigue life. In this approach, the reduction in initial strength is measured by conducting partial fatigue tests on the adhesively bonded joints to induce partial failure followed by a quasi-static test up to complete failure.…”

“…Some methods have been developed to predict the fatigue life of bonded joints under VA fatigue loading [6][7][8][9]. However, they are either empirical (providing limited understanding of the underlying mechanisms) or are unable to take important VA fatigue characteristics (such as load shifts) into account.…”