Optimal stiffening of square plates subjected to air-blast loading

Abstract

Studies carried out to determine the free and forced vibration responses of a square clamped plate with three different stiffener patterns are described. The aim is to arrive at an optimal lay-out of the stiffeners for a given mass. To achieve this objective, the response of an equivalent solid (unstiffened) plate are compared with those of the three stiffened plates. At the outset, it is shown that blast loads induce only the fundamental symmetric mode. Then, the eight lowest natural frequencies and mode shapes, as well as the blast responses, are determined for stiffened and unstiffened plates. For a given mass the plate, which has maximum fundamental natural frequency and minimum blast response, is deemed to be superior to the rest. The results obtained facilitate the conclusion that a plate with a rhombus rib is superior to one with conventional bi-directional orthogonal stiffener for the resistance of blast loads.