Aerospace Technic and Technology

Adhesive lap joints are widely used in many ways of modern technology, particularly in aircraft and aerospace, because to the fact that adhesive joints don't break the integrity of the composite structure. Moreover, adhesive joints ensure the transfer of the loads from the surface of the structure and have low weight, excellent tightness, etc. Mathematical models of the stress-strain state in the adhesive joints are based on the certain hypotheses of the distribution of stresses and displacements in the adhesive layer and in the bearing layers. As a rule, hypotheses about the uniform distribution of shear and normal stresses in the adhesive layer are currently used in articles. The stress state of the joint in the regular area, that is, the area distant from the edge of the adhesive layer, is well described by mathematical models based on these hypotheses. However, in a neighborhood of the edge of the joint, the adhesive layer is in a complex stress state and various factors affect the stress state, including the boundary conditions at the outer edge of the adhesive layer. The research on stresses in a neighborhood of the joint area is carried out in the article. The influence of the stress in the adhesive layer of such designed solutions, such as chamfers on the edges of the bearing layers and glue callus, is shown. The designing solutions, such as the creation of a chamfer on the edge of the bearing layer and the callus of excess glue, can reduce stress at the edge of the joint is also shown in the article. The chamfer in the bearing layer on the side facing the adhesive layer on the one hand allows to reduce the rigidity of the bearing layer, on the other hand to increase the compliance of the adhesive layer. However, the entire space between the outer layers must be filled with adhesive. Thus, the presence of a chamfer and callus of glue significantly reduces the maximum stresses in the adhesive layer, and thereby increases the strength of the structure.

adhesive joints; analytical model; the finite element method

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