Prototyping Adhesively Bonded Metal-Composite Hybrid Structures for Aircraft Interior Applications

Abstract

This research explores the application of adhesively bonded CFRP-aluminium hybrid structure for aircraft interior application. A concept of using an adhesively bonded hybrid structure to replace the original full aluminium structure (fastener joining method) was established. The current structure will be built by 6061 T6 aluminium alloy and the T700 carbon fibre reinforced polymer. The new joining method uses epoxy adhesive to bond them together since the CFRP cannot be welded, and drilling holes will decrease the strength of the parts.

This is the support structure of the air attendant seat used in commercial aircraft. This project requires building a prototype test demonstrator to conduct tensile tests, and the test demonstrator is to simulate the aircraft's air attendant seat’s support structure. The experiment aims to investigate the hybrid structure's performance and further provide development suggestions through the experiments. A total of three test demonstrators were built for conducting the tensile test. Since the build of the test demonstrator was not related to any standard, three demonstrators can enhance the result accuracy. Strain gauges were used to monitor the strain change during the experiments.

The experiment result indicates that the concept is reliable for further research since the aluminium and the CFRP can withstand high loads. The adhesive layer cracked before reaching the minimum design load, but none of the CFRP tubes loosened from the joints after the experiments. The adhesive thickness of the joints was 0.2 mm, and the experiment results showed that the thickness could be further reduced as long as the parts can be bonded in a stable connection. The structure's performance has mainly relied on the parts, not the adhesive. The failure mode of the joints was mainly an adhesive failure that occurs on the aluminium surface, which indicates the surface treatment method of the aluminium needs to improve. The SolidWorks FEA has been applied to the study, and the results suggested the structure deformation pattern and the CFRP tube strain pattern can be used as references. The aluminium strain simulation failed since the simplified structure cannot simulate the actual setup in the experiments.

This project suggests that future research can be focused on the aluminium parts surface treatment, adhesive layer thickness, and the joint depth for CFRP tubes. The NDT exam method and the suitable parts replacement and maintenance methods should also be researched.