We perform finite element analysis of the mechanical response of random RVEs representing the microstructure of a unidirectional (UD) fibre composite, predicting its anisotropic stiffness and damping properties and their sensitivity to temperature and frequency, using as inputs only the measured response of the constituents. The simulations are validated by DMTA measurements on a UD composite; then, the numerical predictions are compared to those of previously published theoretical models. New equations are proposed to predict the viscoelastic constants, providing better accuracy than existing models. The accuracy of these new equations is tested, over wide ranges of fibre volume fractions and stiffness ratios of the constituents, against the numerical predictions

The hysteresis behaviour of metal rubber particles has been characterised. A quasi-static experiment was conducted to measure the damping behaviour of metal rubber particles. The effects of imposed displacement and filling density were examined. A mathematic model has been established to characterise the damping behaviour of metal rubber particles. A single-helix spring model was used to represent the microelement of the metal rubber material. This was composed of three contact states: open, slipping and sticking. The stiffness properties for the three cases were derived. The arrangement and spatial distribution of the microsprings were assumed to be uniform and periodic inside the metal rubber particles component. The test results were compared with the simulation results which showed a good correspondence.

One of the highly effective Layered damping methods is Constraining Layer Damping (CLD), wehrein a layer of viscoelastic (VE) material is sandwiched between the host structure and a stiff Constraining Layer (CL). Traditional CLD uses metallic Cls and hence all the damping comes from the VE layer. However, Cls of certain nonmetallic and/or anisotropic materials with significant inherent damping can be considered to enhance the net damping performance. A single degree of freedom (SDOF) model is presented here to investigate the performance of layered damping coatings comprising a VE layer and a stiff CL. The proposed model considers both the bending and extensional stiffness of the host structure and constraining layer separately, in addition to the shear stiffness of the VE layer. This facilitates the incorporation of some anisotropic stiffness effects and a study of its influence on the damping. The Complex stiffness is used to model the damping in individual components. Structural loss factors are obtained as a function of suitable dimensionless stiffness parameters. The useful range of modulus and the thickness of the layers/coatings are identified to obtain desired level of damping for different material loss factors enabling proper choice of the materials and/or thickness of damping treatments. The model can be reduced to represent conventional free or CLD coatings. The proposed model is validated by comparing the results with those from closed form solutions for traditional CLD systems and finite element results for anisotropic systems.