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Abstract The increasing reliance of the aerospace industry on lightweight yet robust materials, notably carbon fiber‐reinforced polymers (CFRPs), has emphasized the need for efficient joining methods for composite structures. This study investigates the influence of various bonding techniques on the strength of two distinct joint configurations: CFRP/CFRP and CFRP/301 steel interfaces. The CFRP/CFRP joints were configured as single lap joints, where two CFRP laminates and/or prepregs were overlapped and bonded using co‐curing, secondary bonding, or co‐bonding. The configuration ensured adhesion between the cured or uncured CFRP layers, depending on the bonding technique applied. For CFRP/301 steel, CFRP laminates and/or prepregs were similarly bonded to 301 steel substrates in an overlapping region. Both configurations were subjected to single lap shear tests following ASTM D3165 standards to assess the mechanical performance of each bonding method. The post‐test interface damage and fracture mechanisms were analyzed using optical microscopy, providing insights into the failure modes for each joint type. This study offers comprehensive experimental data on various joining techniques that can be useful during the initial design phase of aerospace systems, ultimately resulting in cost savings. The findings of this study, when analyzed from an industrial standpoint, indicate that co‐curing offers a promising solution due to its affordability and simplicity, making it especially advantageous for CFRP/301 steel overlap joining when combined with adhesive films. Highlights Co‐curing, co‐bonding, and secondary bonding techniques were applied to CFRP/steel joints in real aircraft components. The CFRP/CFRP joints obtained via co‐curing exhibited improved thermal stability and strength. Peel ply surface preparation enhanced adhesion the strength of the CFRP/CFRP bonded samples. Cohesion failure was observed in adhesive joints, with no failure at the bond lines.
Akalın et al. (Wed,) studied this question.