Mechanical performance of hybrid double- and step-lap joints in primary metallic aircraft structures: An experimental and numerical approach
Year: 2024
Type: article
Abstract: Hybrid joints, combining adhesive bonding with mechanical fasteners, address the limitations of traditional joining methods in restoring the integrity of aircraft structures. This study evaluates the static strength of double- and step-lap joint configurations, representing repairs in thin and thick metallic aircraft structures, through experimental testing and finite element analysis. Aerospace-grade 7075-T6 aluminium alloy was used for the adherends, with film adhesives and fasteners arranged in typical airframe patterns. The three-dimensional finite element (FE) models incorporated non-linear adhesive properties, fastener preload, contact interactions, and frictional forces. The FE results aligned well with experimental findings, capturing key failure modes and load distributions. Hybrid double-lap joints exhibited strength comparable to bonded joints while mitigating their brittle failures through fasteners that provided additional load-bearing capacity. In thicker step-lap joints, the hybrid configuration nearly restored the parent material’s inherent stiffness, with a moderate strength reduction due to the reduced bond area from the bolt holes, while enhancing elongation capabilities and resistance to localised stress concentrations. Stress analyses highlighted a transition from adhesive-dominated to fastener-dominated load transfer under high loads, demonstrating key interplay between adhesive and mechanical fasteners in hybrid joints. This study presents part of a systematic assessment of the mechanical performance and damage tolerance of the hybrid joining technique, compared with adhesively bonded and mechanically fastened methods, in metallic aircraft structures. • Hybrid double-lap joints restored strength, mitigating brittle adhesive failures. • Hybrid joints improved elongation and resisted localised stress concentrations. • FE models predicted overall joint behaviour, aligning with experimental findings. • Stress analysis revealed load shifts from adhesive to fasteners at high strains. • Hybrid joints acted as traditionally fastened joints after premature cohesive failure.
Source: Composites Part C Open Access
Institutions: Monash University, Defence Science and Technology Group
Language: English
Subfield: Mechanics of Materials
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,110
OpenAlex ID: W4405926359