A new method for the determination of viscoelastic properties of composite laminates: a mixed analytical–experimental approach

The present work deals with the determination of the viscoelastic properties of composite laminates based on the assumption of viscoelastic behaviour of the single lamina. A viscoelastic lamination theory is developed assuming the lamina stiffness matrix fully complex and frequency dependent. For the measurement of the complete set of frequency dependent viscoelastic properties of the single lamina (i.e. complex moduli and Poissonʹs ratio) a new methodology has been introduced, based on the free and forced vibration of unidirectional and/or [45/-45.0]composite laminates. All the measurements have been performed in air. Since the vibration amplitude was very small, in order to fulfil linearity requirements, the results do not have any significant dependence on air damping. The effects of experimental errors on the evaluation of the viscoelastic properties of the single lamina have also been discussed analytically.