Analysis of Towbar Weld Heat Affected Zones

Document Type

Student Presentation

Presentation Date


Faculty Sponsor

Darryl Butt


AERO Specialties designs, manufactures, and delivers ground support equipment for aircraft. One of their products, aluminum towbars, are used to transport private aircraft along the tarmac. The high loads and cyclic nature of transporting aircraft can result in premature failure of the towbars while in operation. Failures have been observed to occur in the welded joint between the towbar body and the towbar head, which is attached to the aircraft landing gear. Following the materials science tetrahedron, it is hypothesized that the processing of these aluminum towbars impact the microstructure, which in turn impacts mechanical properties. Particularly, the heat affected zone (HAZ) adjacent to the weld is suspected of compromising towbar strength. Microstructural analysis was performed, as well as microhardness testing, which gives an indirect measurement of yield strength. A 60% decrease in yield strength was observed in a component that required above average energy input to ensure a successful weld, whereas a 20-40% decrease in yield strength within the HAZ was observed for components welded under nominal processing conditions. Based on this work, a series of processing recommendations that have the potential to minimize the weakening of the HAZ have been developed for AERO Specialties.

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