Comparison Between Finite Elements Model and Experimental Results for Static Stiffness and Normal Vibration Modes on a Unibody Vehicle

It is a well-know fact that cost and time-to-market constraints have gained an ever-increasing importance in the recent years in the global automotive industry. Either due to economic problems in emerging markets or to the presence of strong competition is US and Europe, automakers strive, using different strategies, to find ways of satisfying these constraints. One of the most promising tools to assist in reducing both development cost and time is CAE (Computer Aided Engineering) or Virtual Prototyping which, by using numerical models of components, systems and/or vehicles, is capable of assessing their behavior in areas such as noise, vibration and harshness (NVH), durability, impact safety and vehicle dynamics. A very important question that is frequently faced by CAE development teams is related to how well the numerical results match those that will be obtained when the vehicle is actually built. This work shows a study carried out for the new Ford Fiesta, focused on NVH behavior. Results from both numerical models and actual physical testing for static stiffness (bending and torsion) and normal vibration modes are compared, allowing development engineers to have a clear picture of what is the degree of accuracy they can expect to current CAE techniques in the body NVH area.