Investigation of non-linear free vibrations of fully clamped symmetrically laminated carbon-fibre-reinforced PEEK (AS4/APC2) rectangular composite panels

In an earlier publication, the optimum parameters for ultrasonic welding of carbon-fibre/PEEK (AS4/APC-2) composites have been determined; the physico-chemical properties and fracture surface morphology of modes I and 11 have been described. The objective of this paper is further to extend our understanding of the dynamic behaviour of the AS4/APC-2 by the theoretical modelling of its geometrically non-linear dynamic behaviour at large vibration amplitudes. In previous work, a theoretical model based on Hamilton's principle and spectral analysis has been used to study the non-linear free vibration of CFRP (carbon-fibre-reinforced plastic) and hybrid composite panels. The present paper investigates the first non-linear mode shape of symmetrically laminated AS4/APC2 composite panels. The large vibration amplitudes problem, reduced to a set of non-linear algebraic equations, is solved numerically. Results are summarised for various plate aspect ratios and vibration amplitudes, giving the dependence of the first non-linear mode shape and associated frequencies on the amplitudes of vibration, and showing higher bending stresses near to the clamps at large deflections, compared with those predicted by linear theory. (C) 2002 Published by Elsevier Science Ltd.