Amplitude-Dependent Damping: Experimental Determination and Functional Interpretation for Metal–Plastic Composites

Composite materials offer a high freedom of design with regard to stiffness, strength and damping. In contrast to efficient anisotropic but linear material models, these composites often tend to react nonlinearly. Commonly, such nonlinear material damping models imply frequency and temperature dependency. In addition, some materials show a substantial amplitude sensitivity of the damping. Within this study, metal–plastic composites with highly dissipating shear sensitive cores have been used to experimentally determine the damping values with varying amplitudes. The results show a significance of this parameter already for small deflection within the geometrically linear range. The derived nonlinearity is further described by an exponential approach and parametrized by a regression analysis. Furthermore, the amplitude sensitivity is retraced to the contributions of the layered material by a detailed numerical analysis of the stress states. Therefrom, the mean strain energy density per material is derived as an amplitude criterion for the nonlinear damping model. The resulting model can be further applied to the finite element analysis to improve the determination of vibrations as well as structure borne sound of such acoustically improved materials.