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Train: Panel Deformation

Optimizing Quality Through Simulation


Door and window panel CAD geometry, deformation contours for door and window panels, and window panel seal deformation detail.

To maximize fuel efficiency and performance, vehicles are designed with minimum weight. Savings in part weight can reduce the cost of parts and directly reduces the engine power required for vehicle acceleration. However, reduction of material from structural parts and body panels leads to reduced stiffness and increases the susceptibility of the parts to vibration, which might transmit noise to the vehicle interior or affect driver perception of vehicle quality. These vibrations can occur due to dynamic loads produced by the vehicle aerodynamics. Reduced stiffness can also cause panels to deform under static loading conditions and might lead to air leakage through door and window seals, which creates significant noise transmission to the vehicle interior. Static load conditions can occur due to aerodynamic load distributions under normal driving conditions or under strong crosswind.

TECHNICAL CHALLENGES

Vehicle engineering to meet structural requirements while avoiding vibration and panel deformation is challenging because of the unique coupling of structural performance with aerodynamic loading.  Typically, testing for this occurs very late in the design process using fully detailed prototypes. Wind tunnel tests can show static loading conditions, but cannot replicate the transient onset conditions found on the road. Only road tests can detect some panel vibration failures.

Early in the design process, structural requirements are usually met by overdesigning parts, retaining more part weight and leading to greater parts cost. Door mounts and seals are designed to retain seal contact with the frame. The cost of missing some vibration or door seal problems can be high, because correcting for structural stiffness problems late in the design process greatly increases retooling and parts costs.


Animation above demonstrates the sudden onset crosswind flow and its effect on the overall aerodynamics of the vehicle.; below shows the primary vibration mode of the hood panel, which is excited by the transient aerodynamic load.


EXA SOLUTION


PowerFLOW is inherently transient, easily and accurately predicting surface pressure fluctuations causing vibrations and the static loads, thus providing a predictive capability to address panel deformation problems. Static and transient loads are coupled with your choice of structural solver to compute vibration, static deformation, and seal performance.

EXA SOFTWARE USED FOR THIS APPLICATION

Simulation Preparation: 
Simulation: 
Results Analysis: