Influence of the Nail Hole Adhesive Layer on Mechanical Properties of Bonded-Bolted Hybrid Joint

Abstract

AbstractThe bonded-bolted hybrid joint with the nail hole glue layer is widely used in the overall fuel tank structure of the UAV wing due to its both bearing and sealing capabilities. During the service of the aircraft, the bonded-bolted hybrid joint is prone to breakage and debonding of the adhesive layer, which causes problems such as load-bearing and leakage. Based on the design of the thickness of the nail hole adhesive layer, this paper analyzes the variation law of the tensile load of the ordinary bolt and the high-lock bolt hybrid joint with the thickness of the adhesive layer, and uses the scanning electron microscope to observe the failure mode of the nail hole adhesive layer. The results show that for ordinary bolts, the tensile load is optimal when the thickness of the nail hole adhesive layer is 0.03 mm, while for high-lock bolts, the tensile load increases with the increase of the adhesive layer thickness in the range of 0–0.05 mm adhesive layer thickness. During the tensile failure of the joint, the cohesive failure of the nail hole adhesive layer and the debonding failure of the composite material-adhesive layer interface are the main factors, and the bonding performance of the titanium alloy and the adhesive layer interface is better.KeywordsNail hole adhesive layerBonded-bolted hybrid connectionTensile loadAdhesive layer failure