A nine-node isoparametric plate element in conjunction with first-order shear deformation theory is used for free vibration analysis of rectangular plates with central cutouts. Both thick and thin plate problems are solved for various aspect ratios and boundary conditions. In this article. primary focus is given to the effect of rotary inertia on natural frequencies of perforated rect... https://thegreensjunglebeautyshops.shop/product-category/eye-care-set/