An h-p finite element vibration analysis of open conical sandwich panels and conical sandwich frusta

The vibration study of a general three-layer conical sandwich panel based o n the h-p version of the finite element method is presented in this paper. No restriction is placed on the degree of curvature of the shell, thereby r elaxing the strictures associated with shallow shell theory. The methodolog y incorporates a new set of trigonometric functions to provide the element p-enrichment, and elements may be joined together to model either open coni cal panels, or complete conical frusta (circumferentially connected, but op en at each end). The full range of classical boundary conditions, which inc ludes free, clamped, simply supported and shear diaphragm edges, may be app lied in any combination to open and closed panels, thereby facilitating the study of a wide range of conical sandwich shells. The convergence properti es of this element have been established for different combinations of the h- and p-parameters, thereby assuring its integrity for more general use. S ince very little work has been reported on the vibration characteristic of either circumferentially closed or open conical sandwich panels, the main t hrust of this work has been to present and validate an efficient modelling technique, rather than to perform numerous parameter and/or sensitivity stu dies. To this end, some new results are presented and subsequently validate d using a commercially available finite element package. It is shown that f or results of comparable accuracy, models constructed using the h-p formula tion require significantly fewer degrees of freedom than those assembled us ing the commercial package. Some preliminary experimental results are also included for completeness. (C) 1999 Academic Press.