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Previous fatigue tests on mechanically fastened aerospace joints showed fatigue cracks often initiated in the countersink of the fastener hole where the fastener head was in contact with and caused fretting on, the hole bore. The work presented here evaluated the potential of a number of possible fastener coatings to reduce fretting and increase the fatigue life of the joint. The coatings were tested in a fretting fatigue test and in a ‘zero load’ fatigue test. The results showed that the best fretting resistance and fatigue life was obtained when aluminum pigmented coating (in accordance with NAS 4006) was used. The results also suggest that both test methods provide a similar ranking of performance. This means that the simpler fretting fatigue test may be useful as an initial screening method. However, more testing is needed to confirm this relationship.

In aerospace fastener industry, all materials used or being considered for fastener applications must meet specified minimum shear strength values. It is widely known that shear strength is dependant on the type of shear test. However despite the suspected test dependencies, no detailed open research literature on the fastener shear test, especially shear strength variation via single and double shear approaches, and factors including surface coatings that affect tested shear values, has been conducted. Thus, the objective of this program is to systematically evaluate the effect of coating tribology on the threaded fasteners shear property tested via single shear and double shear testing methods. Five most common fastener finishes were selected, including uncoated, Aluminum CVD, Hi-KOTE, MoS2 coated, and Anodized.

Societal demands for greater automotive fuel economy, lower environmental impact and improved performance have produced a trend towards lightweighting in automobiles. In this context, the effect of car mass and size on occupant safety is receiving considerable attention in the literature. Concerns have been raised about the safety of occupants of smaller, lighter cars involved in accidents with larger, heavier vehicles. The evidence supporting these concerns comes from crash data of existing steel-bodied cars. In this paper, the possibility of using an aluminum body structure to reduce automobile mass is explored. The use of lightweight aluminum provides the opportunity for a larger low mass structure than could be achieved by traditional steel body construction. This paper provides technical data related to the energy-absorbing characteristics of aluminum components.

Increasing use of aluminum in automotive components has led to lower fuel consumption and enhanced performance of automotive designs. From a manufacturing standpoint, aluminum provides the additional advantage of utilizing same processes as steel. Performance and durability of painted aluminum cars, however, is dependent on proper optimization of process conditions. As part of an extensive study of factors influencing corrosion resistance of painted aluminum, the present study deals with the influence of pretreatment and coating variables and the interaction of alloy composition with zinc phosphate and electrocoat. Interfacial analysis of corrosion products indicates the relative influence of alloying elements on stability of the metal/phosphate/electrocoat interface. As a result, guidelines and recommendations on aluminum processing in an automotive manufacturing floor have been developed.

Aluminum autobody sheets produce appreciable amounts of slivers during trimming operations when trimmed with dies conventionally designed for steel sheets. The slivers can be carried through downstream processes and cause damage to the surface of formed parts which results in significantly increased repair-rates. A systematic experimental investigation was conducted on trimming 6111-T4 and 6022-T4 aluminum autobody sheets using straight cutting blades/pads under unlubricated conditions. It is shown that slivers can be reduced or eliminated by modifying the current trimming tools designed for steel sheets. With appropriate tool design, trimming of 6111-T4 and 6022-T4 sheets actually can be more robust than that of steel sheets, the clearances can be less restrictive and tools may require much less sharpening.