engleski

Laboratory tests of adhesively bonded aluminium angle cleat connections

The classical methods of joining aluminium structures have progressed in recent years, but the fundamental problems of degradation of mechanical properties are still present if welding is used as a joining technique. A different, more suitable, but not yet fully investigated, method for joining aluminium members is adhesive bonding. In this study, the application of adhesives in joining aluminium and steel components is investigated. The experimental study was carried out with the aim of characterising a bonded aluminium angle cleats connection in tension using four different types of adhesives. The laboratory tests included a tensile (Mode I) test of the pair of aluminium angle cleats adhesively bonded to a steel plate. A total of 12 pairs of angle cleats were tested, three specimens for each of the four different adhesive types. All specimens consist of two extruded aluminium angles L 100x100x10 mm (EN AW 6060-T66), 140 mm in length, with one leg bonded to a 30 mm thick steel plate. The other angle legs are bolted (6xM12, quality 8.8) to a steel plate mounted on the static testing machine with a capacity of 600 kN. The preparation of the surfaces and application of the adhesives was carried out by Sika Croatia staff, who provided all four types of adhesives. Two ductile (SikaFast 555 L10 – label A and SikaPower 4720 – label B) and two brittle (Sikadur 330 – label C and Sikadur 31 CF Normal – label D) adhesives were applied. In addition to conventional measurement techniques such as the LVDT sensors, the entire displacement field was measured using the non-contact stereophotogrammetric 3D measurement system. Due to the relatively small displacements, the non-contact measurement system proved to be very beneficial in capturing the realistic behaviour of these sensitive connections. All specimens failed over adhesives in different percentages of failure through the adhesive layer. The fracture surfaces varied for each specimen. The most consistent results were obtained for the specimens labelled B. The load-bearing capacity of the mentioned specimens was roughly 60 kN. The results of the specimens labelled C and D were quite scattered, mainly due to the different thickness of the adhesive layer, but also to the insufficient mechanical preparation of the cleat’s surface. The specimens labelled A showed the highest ductility, while the specimens labelled C were the most brittle.

aluminium connections, adhesive bonding, digital image correlation, laboratory testing

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