Adhesion Properties of Bonded Composite-to-Aluminium Joints Using Peel Tests

Abstract

In this research, the adhesion properties of bonded compositeto-aluminium joints are evaluated using floating roller peel tests. Tests were performed using two different adhesives and different adherend lay-ups: composite-to-aluminium, composite-to-composite and aluminium-to-aluminium. The results show that floating roller peel tests, widely used in metal bonding, can also be used to assess adhesion properties of composite bonding and compositeto-aluminium bonding. However, attention should be paid on which results are important to take from the peel tests. In adhesion tests, the failure mode is more important than the failure load. The peel load can only be compared when using exactly the same type of flexible adherend. Even when the adhesion properties are good (cohesive failure), the peel load value can decrease up to a factor of 10 when peeling off a composite flexible adherend instead of an aluminium flexible adherend.

Test method to assess interface adhesion in composite bonding

“…This results in higher peel strengths at high temperatures than at RT. It has been shown by previous studies published by the authors that cohesive failure results in higher strengths than ILFC [12].…”

“…As it has been addressed in previous studies of the authors, peel loads can differ significantly when peeling off different adherend materials, and it does not mean a poor interface adhesion [12]. Peel loads can only be compared if using exactly the same type of flexible adherend (peeling off member).…”

“…A lay up of two plies [0°/90°] was used to produce the flexible composite adherend with approximately 0.37 mm thickness. The stacking sequence was optimized in a pre-study and it is further explained in a previous paper of the authors [12]. The plies were autoclave cured at 180°C for 120 min, under 6 bars pressure.…”

“…The test method is fast, robust and has a potential for multi-purpose: static adhesion, bond durability, surface and adhesives screening and, ultimately, it can be used as in-process test coupon for manufacturing control of composite bonded parts. This study is the follow up of a the previous study performed by the authors in which different combination of adherend composite vs. Aluminium was investigated [12].…”

Failure analysis of adhesively-bonded skin-to-stiffener joints: Metal–metal vs. composite–metal

“…[5,6]. Since adhesion is one of the key components for guarantying the integrity of bonded joints, new peel tests have been developed in order to assess the adhesion quality of composite-to-metal bonded joints [7].…”