The commercial vehicle development process needs to consider the vehicle aerodynamics not only in ideal flow conditions, but also in the turbulent real world environment. The turbulent real world environment includes not only atmospheric turbulence, but also the vehicle to vehicle interactions that happen when driving around other vehicles or into and out of the wake of in/on coming vehicles.
A vehicle driving into the wake of an oncoming vehicle not only experiences an increase in the total aerodynamic forces, it also experiences unsteady transient loads over the vehicle components such as windshield, mirror, sunvisor, door and side fairing. To properly design specific components, designers need to understand the magnitude of unsteady forces on various vehicle components, otherwise these components may fail which imposes warranty and safety risks.
In this paper, we attempt to understand the various forces acting on the primary vehicle during a passing maneuver. The main purpose is to understand the incremental unsteady forces acting on the major components such as windshield, side door, sunvisor and mirror.
Result from this study shows, very large swings in side-force magnitude, which could lead to vehicle stability issues for empty trailers that are subjected to large forces acting on little inertial mass. Local forces on isolated components show very high frequency unsteady load that could lead to component fatigue and failure if these loading conditions are not incorporated as part of the vehicle component design.
