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Automobile body and truck cab structures are composed primarily of stampings formed from monolithic and constant gage blanks. Cost and weight penalties can arise when strength or other requirements in one small area of the part leads to the use of a material or gage that is overmatched to the needs of the rest of the stamping. Tailor Welded Blanks (TWBs) are hybrid sheet products composed of either different materials or different thickness sheets that are joined together, then subjected to a stamping operation to create a formed assembly. The strategy is employed generally to save weight and material costs in the formed assembly by placing higher strength or thicker sections only where needed. The forming or stamping process requires the joint to be severely deformed along with the parent sheets. Aluminum TWBs for automotive applications are particularly problematic because of the low formability of aluminum weld metal.

Exhaust systems are a necessary solution to reduce combustion engine noise originating from flow fluctuations released at each firing cycle. However, exhaust systems also generate a back pressure detrimental for the engine efficiency. This back pressure must be controlled to guarantee optimal operating conditions for the engine. To satisfy both optimal operating conditions and optimal noise levels, the internal design of exhaust systems has become complex, often leading to the emergence of undesired noise generated by turbulent flow circulating inside a muffler. Associated details needed for the manufacturing process, such as brackets for the connection between parts, can interact with the flow, generating additional flow noise or whistles. To minimize the risks of undesirable noise, multiple exhaust designs must be assessed early to prevent the late detection of issues, when design and manufacturing process are frozen. However, designing via an experimental approach is challenging.

This paper presents the coupon performance data of friction stir welded tailor welded blanks (TWBs) joined to a monolithic aluminum sheet by self-piercing rivets (SPRs). Uniaxial tensile tests were performed to characterize the joint strength and the total energy absorption capability of the TWB/monolithic sheet joint assemblies. Cyclic fatigue tests were also conducted to characterize the fatigue behavior and failure mechanisms of the jointed assemblies. This study provides data for the automotive designer to determine whether friction stir welded aluminum TWB/monolithic sheet joints are within the target joint strengths for a particular application if it should be pierced during the assembly process.

Air flow in the underhood area is the primary source of engine cooling. A quick look at the vehicle underhood reveals exceptionally complex geometry. In addition to the engine, there are fans, radiator, condenser, other heat exchangers and components. The air flow needs to have adequate access to all relevant parts that require cooling. Due to complex geometry, the task to ensure sufficient air cooling is not a simple one. The air flow entering from the front grille is affected by many components on its path through the underhood. Even small geometry details affect the flow direction and can easily cause recirculation regions which reduce the cooling efficiency. Therefore, air cooling flow analysis requires detailed treatment of the underhood geometry and at the same time accurate air flow modeling. Recent advances in the lattice-Boltzmann equation (LBE) modeling are allowing both.

The accuracy of the Lattice-Boltzmann based simulation method for prediction of aerodynamic drag on a heavy truck was evaluated by comparing results to twenty percent scale model wind tunnel measurements from the University of Washington Aeronautical Laboratory (UWAL). A detailed preproduction Kenworth T2000 tractor trailer was used as the scale model. The results include a comparison of normalized drag between simulation and wind tunnel as well as percentage drag change with the addition of a radius to the rear edge of the trailer. Significant effort was involved to model all of the wind tunnel details affecting the tractor-trailer drag. These are discussed along with the results of additional simulations which were performed to study the impact of the UWAL tunnel geometry relative to a tunnel with the same blockage and constant cross-sectional area, and a case with negligible blockage.