In this study, we investigated two aspects of a multi-layer, lightweight damping treatment. The first aspect studied was an equivalent material property estimate for a simplified finite element (FE) model. The simplified model is needed for computational efficiency, i.e. so that Tier 1 and OEM users can represent this complex, multi-layer treatment as a single, isotropic solid layer plus an aluminum constraining layer. Therefore, the use of this simplified FE model allows the multilayer treatment to be included in large body-in-white structural models. An equivalent material property was identified by first representing three unique layers (two adhesive layers plus a connecting standoff layer) by a single row of isotropic solid elements, then an optimization tool was used to determine the “best fit” for two properties including Young’s modulus and material loss factor. Equivalent properties were validated for various substrate thickness and coverage areas heights by comparison to center-driven long bar test results.
Secondly, the effect of damping treatment size was studied using the previously identified equivalent material properties. This was a damper placement study to determine if a smaller, higher performing damping patch can perform as well as a larger, lower performing patch. The multi-layer damping material produces high system loss factors and it was therefore expected to perform similarly to a larger, lower performing treatment. The study showed that there is a geometry dependency for performance and also showed that performance does not strictly scale with material loss factor and treatment area. It is possible that two different treatments will produce similar damping - one with high material loss factor, small treatment area and the other with lower material loss factor and a larger area. However, achieving good results with a smaller treatment area requires knowledge of the structural modes and proper placement of the treatment.