Free vibration of doubly curved composite honeycomb rectangular sandwich panels

Sandwich panels have a wide variety of applications in many branches of engineering including aerospace, marine, civil and motorsport. Their very high stiffness-to-weight ratio make them particularly useful in aircraft and typical applications include floor panels, fairings and inlet cowl panels. In the latter case, the geometry of the panels can be considered doubly curved and they are usually constructed with carbon fibre reinforced plastic face plates and a lightweight resin impregnated paper honeycomb core. The free vibration of such panels both experimentally, and theoretically using a commercially available finite element code, has been investigated. Results are presented for the natural frequencies, and the theoretical investigation is extended to cover a variety of configurations in terms of the radius of curvature.