Modal damping behavior of plane and 3D curved constrained layer damping CFRP-elastomer-metal laminates

The persistent trend of investigations in lightweight design materials also leads to a high interest in suitable applications of damping concepts to those materials. Usually, lightweight materials show low damping. The resulting structures are often prone to vibrations and additional damping material has to be added to meet modern comfort and fatigue requirements. Hybrid carbon fiber reinforced plastics-elastomer-metal laminates offer adaptable damping properties by adjusting the properties of the individual constituents or their hybrid layup. The proposed hybrid laminates dissipate flexural vibrations according to the constrained layer damping mechanism. The influence of the elastomer modulus and thickness and the fiber orientation of the carbon fiber reinforced plastics constraining layers on the vibration and damping behavior is investigated. Therefore, modal analysis on cantilever beams, panel sized specimens and three dimensionally curved structures are conducted. Temperature dependent modal analysis on coupon level are performed to investigate the influence of the glass transition of the elastomer layers on the vibration damping behavior. An analytical model, which takes into account the viscoelastic behavior of the elastomer and the CFRP is used to model the damping behavior. The influence of the additional damping of the CFRP layers in off axis directions, is characterized at various temperatures. The results obtained with different specimen geometries are compared among each other and good accordance to the analytical model is observed.