ABSTRACT
Seldom in real life is a structure subjected only to static loads. More often products and structures are subjected to vehicular, impact, crash, earthquake, handling, or fabricating dynamic loads. In the linear-elastic range, dynamic effects can be divided into two categories: natural vibrations and forced vibrations, and the latter can be further subdivided into one-time events or receiving loads. The chapter describes that the water reduces the natural frequencies dramatically. L. S. Ramachandra and H. R. Meyer-Piening investigated frequencies of sandwich panels in contact with water and simply supported on all four edges. Sandwich construction is being used increasingly for plate and shell constructions in structures such as space vehicles, deep submergence vehicles, pressure vessels, and many others. For sandwich plates composed of composite materials, orthotropy must be accounted for, and in addition, the effect of transverse shear deformation must be included.
