Лако-красочные материалы — производство

The bonding of aluminium alloy components for structural engineer­ing applications has been the subject of extensive research by the Dutch TNO Institute for Building Materials and Structures! 19, 20). Apart from the evaluation and testing of a number of adhesive systems, experimental research was carried out on several structural details. Aluminium alloy surface pretreatment was by degreasing only, to represent a ‘practical’ procedure.

Three-point bend tests on beams of hollow rectangular section, fabricated from angle sections and flat plates bonded together, demonstrated the importance of adhesive ductility and toughness; beams fabricated with a relatively brittle epoxide split apart at the onset of buckling, whereas those bonded with tougher adhesives behaved in a more ductile manner.

Aluminium pretreatment: degreased only

General test arrangement

Fig. 8.15. Bonded aluminium cruciform joints (Ref. 19).

A number of cruciform joints of rectangular hollow section were fabricated with adhesive gusset plates (Fig. 8.15). Hollow sections of two different sizes were used, and some of the specimens were subjected to accelerated ageing prior to testing in tension. The structural behaviour of these joints was also predicted by non-linear, three-dimensional, finite-element analysis. Very good agreement was obtained between the experimental and predicted load-displacement behaviour.

The performance of curtain walling wall panels fabricated with bonded and with bolted channel section stiffeners was compared. Under simulated wind pressure, the bonded stiffeners accommodated gross panel deformations representing several times the design requirements.

Some beam specimens were fabricated whose flanges and webs were spliced at mid-span in a similar way to Fig. 8.13. The performance in four-point bending was encouraging, although yield in the aluminium alloy was rarely experienced.

Several semi-structural elements with polyurethane bonded cover plates were also tested, demonstrating ample performance character­istics.

In general, two-part cold-cured modified epoxides and modified acrylics were found to meet the strength and deformation require­ments for structural bonding. However, the strength levels attained with joints made with the acrylics were somewhat lower. Longer — term performance and durability remain subjects for further evaluation.