Lightweighting Semi Truck Structural Rails via the MELD Process

Additive manufacturing (AM) enables manufacturers the ability to “print” complex geometries in a wide array of materials and composites including metals. The Additive Friction Stir (AFS) process is a novel AM technology that creates fully-dense products with near wrought properties, reduced distortion, and high deposition rates. The process principle is similar to Friction Stir Welding (FSW) with the exception of the use of filler material. This technology is well suited for creating large complex geometries in near-net shape.

Lightweighting is a prominent objective of manufacturers within the transportation industry, among others, which involves reducing the weight of a vehicle in order to improve fuel efficiency. In an effort to reduce the weight of the support rails of semi-trucks manufacturers are investigating the use of light-weight aluminum alloys in lieu of heavier and more conventional steel alloys. During initial design reviews it was discovered that certain areas along the rail required additional material support and that conventional fasteners were creating stress risers that lead to premature failure during fatigue testing. Like FSW, the AFS process is well suited for depositing aluminum alloys and was selected as a potential method for adding the needed reinforcement to the aluminum rails.

In this work two means of influencing the geometry of aluminum structural rail via the AFS process are presented. The first study is on the deposition of bracket geometries on the aluminum rail as means for attaching cross member supports and eliminating the use of fasteners. The second study is on the deposition of rib stiffeners through the aluminum rail as a method of improving strength by selectively adding material where needed. Each of these applications resulted in a lighter and stronger aluminum rail.