IHS ESDU Natural frequencies of rectangular singly-curved plates. 87002

ESDU 87002 introduces computer programs and a graphical method for estimating the lower natural frequencies of initially unstressed isotropic plates with either all edges simply-supported or all edges fixed in both rotation and translation. The ratio of length (and width) to thickness should exceed 20, the ratio of width to radius should be less than 1.5, and the graphical method is for aspect ratios of 0.1 to 10. For fixed edge conditions, typical mode shapes are illustrated for a range of aspect ratios and curvatures, and some experimental results for the first modes of one geometry plate are compared with predictions. The two programs, ESDUpacs A8702 and B8702, use energy methods of analysis. ESDUpac A8702 is for edges simply-supported and gives an exact solution to the equations of motion and boundary conditions. ESDUpac B8702 is for fixed edges and uses a Rayleigh-Ritz analysis in which the number of terms in the assumed displacement function can be varied to provide the required accuracy. Worked examples illustrate the use of both graphical and program methods, and application to stiffened structural panels is discussed.