Influence of adhesive bond line thickness on joint strength of composite aircraft structures

Abstract

Abstract Methods for assessing the effect of the thickness of the adhesive layer in the adhesive joint of thin-walled composite structural elements on the strength of the entire joint are considered; a critical analysis of existing theoretical methods for predicting the strength of adhesive joints is given. The contradiction between the theoretical estimates of the effect of the adhesive thickness on the strength and the results of experiments and practical experience in the use of adhesive joints of composite panels is established. It is revealed that the most effective methods for predicting the load-bearing capacity of adhesive joints are energy models of fracture mechanics based on the intensity of the release of fracture energy and the formation of a pre-fracture zone in the adhesive layer. Assuming the determining role of changes in the size and shape of the initial fracture zone depending on the thickness of the adhesive layer, the results of the prediction of the strength of the adhesive joint are compared with experimental data.