| Abstract: | Simultaneous Dynamic and Corrosive Test, a Real World Test Method for Aircraft Structure Components Today the structures of civil and military aircrafts mostly are assembled of sheets of high strength aluminum alloys which are fastened to the internal structure. These joints cause considerable problems because they are exposed to corrosive and dynamic load. Especially this is the case when sheets and fasteners are manufactured of high strength materials. One example are sheets of the alloy AA 2024 T351 with fasteners of the titanium alloy Ti 6Al 4V. During the usual production procedure sheets are used, which were chromic acid anodized and primed with a 2-pack epoxy primer. During the assembly of the structure the countersinks were drilled, the fasteners inserted and the top coat applied. This production procedure has the cosequence that the countersinks usually are not coated. As a consequence the paint cracks around the fasteners during service, moisture, dirt and salt creep in and cause severe intergranular attack. The repair scheme applied in the military area up to now (removing the corrosion and re-application of the standard paint scheme consisting of a chromate-containing washprimer, a chromate-free 2-pack epoxy primer and a 1-pack acrylic top coat) was not very successful. For this reason a number of new coating systems for the countersink area and the fasteners were tested. In order to simulate the real world, a simultaneous dynamic and corrosive test method was chosen. |
