Co-authors​ :

 Alexander JACKSTADT (GERMANY), Luise KÄRGER (GERMANY) 

The numerous benefits of fiber metal laminates (FMLs), such as superior fatigue behavior and high impact resistance, have been thoroughly studied and valued in numerous structural applications, for example in the form of glass-fiber-reinforced aluminium (GLARE). However, these laminates can exhibit an undesirable dynamic behavior when subjected to vibrations due to their high stiffness and low weight. This might not only be a comfort issue, but can also lead to premature failure of components during use. Further hybridization by the inclusion of viscoelastic interlayers, such as elastomers, can provide a viable measure to passively damp these structures due to a mechanism called constrained-layer damping (CLD) [1]. Hybrid laminates containing an elastomeric damping layer, such as hybrid carbon fiber reinforced polymer (CFRP) elastomer metal laminates (HyCEMLs) have been developed and found to significantly improve the dynamic behavior of such FMLs under impact and vibration [2, 3]. Following the viscoelastic material characterization of three different KRAIBON® damping materials in the frequency domain, this study applies a previously published analytical model [4] based on a unified plate formulation to predict the vibration characteristics of lightweight CLD laminates. Different laminate lay-ups and commercially available elastomer damping materials are considered. In particular, the free and forced vibration of simply-supported plates is investigated under consideration of the frequency-dependent material properties. The results include optimal laminate lay-ups for a maximized modal damping behavior while maintaining a high static bending stiffness. By using the analytical model, relevant design parameters are identified, and their influence is quantified. In particular, the choice of the elastomer damping material is found to have the predominant influence on the vibration and damping characteristics of HyCEML. Size effects, the role of anisotropy within the laminate and mode-dependency are also addressed. To conclude, general design guidelines for efficient lightweight CLD structures are presented, which include optimal stiffness and thickness ratios of the constrained and constraining layers, simplifying the materials selection process.