Prediction of interlaminar fatigue damages in adhesively bonded joints using mixed-mode strain based cohesive zone modeling

Abstract

A new mixed mode strain based cohesive zone model (CZM) has been developed for progressive damage analyses of adhesively bonded joints under fatigue loading. Independency of this method from experimental characterization of mixed-mode conditions is the contribution of this approach. The developed method become effective for repetitive simulations such as optimization in composite laminates design. In the developed method, a bi-linear softening constitutive law governs the evolution of damage and material degradation. The peak value of each load cycle is considered for the analysis, because damage evolution does not occur in unloading. In order to decrease the computational efforts, the envelope load damage model was used. Damage evolution is performed for the certain set of increments and the deleterious effect of this damage was extrapolated within the cycle intervals. Progressive mixed-mode interlaminar damage analyses are performed for adhesively bonded laminates under static and fatigue loading using the developed procedure and user material subroutine in ABAQUS software. Virtual crack closure technique (VCCT) is also used for interlaminar fatigue damage growth of the specimens. It is shown that the obtained results from both methods are in good agreement. It shows the capability of the new developed CZM for prediction of interlaminar fatigue damage in adhesively bonded joints. Another feature of the presented model is significant reduction of computational costs.