Optimized Design for Vehicle Underbody System

Underbody systems are defined as parts, which are added below the body of a car, with aerodynamic functions and with the aim of improving its protection and acoustic performances. Underbody parts are subject to a variety of loads during vehicle operation, which degrade their original performances. Thus, an accurate design of the underbody shape is needed, in order to preserve its correct functioning and optimize its performances. In particular, it would be desirable to reduce the deflection of the underbody part under operating loads, while preserving the same bill of material (cost) or even reducing it.

In this work, we study the best possible part profiles by making use of CAE optimization. Our study aims at defining design guidelines, which can be used by the product engineers in order to design parts with an optimal solution since the beginning of the development.

Simulations have been carried out by using Altair optimization software “Optistruct”, with the objective of increasing the stiffness of the panels, while reducing the compliance under aerodynamic load and increasing the resonance frequencies. For this purpose, a topography optimization has been performed for some shape patterns. More precisely, the different areas of the panels are constrained to a different level of maximum dislocation, depending on the packaging space available. In this way, some “special” shapes have been found, which are applicable in a large variety of configuration panels.

Finally, the optimization results allow us to propose different modification solutions (some of them have been prototyped), with the objective to increase the flexural stiffness of our panels. A 20% weight reduction of the parts is achievable by these modifications, thus fulfilling the functional requirements with a minimal material part layout.


The Author

Emanuele Santini
Products and Systems Simulation Specialist
Autoneum Management AG