TOWARDS ASSEMBLING A MATRIX HYBRID COMPOSITE AIRCRAFT SIDE SHELL USING INTERDIFFUSION JOINING

Kurzfassung

Hybrid airframe structures that combine thermoset (TSC) and thermoplastic (TPC) carbon-fiber composites promise lightweight, high-performance components amenable to high-rate production. However, the combination of TSC and TPC poses some challenges for component assembly when conventional joining technologies, such as bolting or adhesive bonding, are to be replaced by material-compatible, high-rate alternatives. This study investigates Assembly Inter-Diffusion Joining (AIDJ), an out-of-autoclave, low-temperature interdiffusion process, for the frame-to-skin joint of the HERFUSE lateral fuselage panel. Three laminate configurations were fabricated: (i) HexPly 8552 / Ultem 1000B (TSC/PEI), (ii) Cetex TC1225 / Ultem 1000B (TPC/PEI), and (iii) a full matrix-hybrid stack replicating the actual joint. Specimens were consolidated under industry-relevant pressure-temperature cycles, inspected with water-coupled ultrasonic testing, and evaluated by slotted single-lap shear and apparent interlaminar shear strength tests. Reflected-light microscopy confirmed a continuous, undisturbed polymer interphase. The results demonstrate that low-temperature interdiffusion joining provides reliable bonds for matrix-hybrid aerospace structures, enabling scalable production and supporting economic objectives.