Estimation of Modal Damping Ratio from Specific Shear Modulus for Monolithic Materials and Hybrid Cored Multilayer Composites

Damping properties are of significant importance in determining the dynamic response of structures, and accurate prediction of them at the design stage, especially in the case of light-weight structures is very desirable. Unfortunately, damping parameters cannot be deduced deterministically from other structural properties and recourse is generally made to data from experiments conducted on completed structures of similar characteristics. Such data is scarce but valuable, both for direct use in design and for furthering research into the phenomenon and modelling of damping. Till date, no work has been reported on the estimation of the damping ratio of the material purely from its elastic and physical constants. In this work, an effort has been made to obtain modal damping ratio for the fundamental mode of the structure from both analytical and experimental technique. The damping properties of PURE materials such as Aluminium, Polyurethane foam, Cork material, and of laminated composites (GFRP materials), are determined by classical modal analysis and also from their respective shear modulus and density constants. These theoretical developments in line with classical modal analysis, give impetus towards understanding damping mechanisms in Hybrid composite systems.