Nonlinear forced vibration of carbon fiber/epoxy prepreg composite beams: Theory and experiment

In the present work, a nonlinear forced vibration model for fiber reinforced composites was developed with varying fiber orientations and laminate sequences. A nonlinear viscoelastic beam model was developed using nonlinear von Kármán strains and Kelvin-Voigt stress-strain relationship to model viscoelasticity. The effect of fiber orientation and laminate sequence was included in the model using classic laminated plate theory. Method of multiple time scales was used to solve the resulting nonlinear equation and an inverse problem approach was used to extract the model parameters from experimental data. Theoretical model parameters were calculated and compared to experimentally determined values for different fiber orientations and laminate sequences, and a nominally good qualitative agreement was observed. Finally, the experimentally extracted model parameters were substituted in the analytical model, and the model predictions in terms of frequency shifts were compared against experimental observations. Nominally good agreement was observed for 45° and 90° fiber orientations, however the experimental observations didn't match well for 0°.