CRITICAL AND COINCIDENCE FREQUENCIES OF FLAT PANELS

Critical and coincidence frequencies of panels are important in studyi ng their behaviour under acoustic excitation. Most spacecraft structur al panels are of honeycomb sandwich construction and many of them have face sheets made of composite material. The critical and coincidence frequencies of such panels an discussed here. Expressions for critical and coincidence frequencies of thick isotropic and thin as well as th ick symmetric composite panels are derived. It is shown that the ortho tropic behaviour and transverse shear flexibility of the panels affect s the critical and coincidence frequencies. The critical frequency of a typical composite honeycomb sandwich panel obtained using the above expressions match well with experimental results. (C) 1997 Academic Pr ess Limited.