The Irradiation Efficiency of Simply Supported Beam-Reinforced Plates with Structural Optimization by Genetic Algorithms

摘要

The study of the irradiation efficiency of structural components has been subject of many researches along the years, since its precise understanding provides conditions for predicting the sound pressure field where these components are operating. This is the case of sound pressure generated at the accommodation area in offshore platforms, due to vibrations transmitted throughout the structure, excited by vibrations of large machines. It is known that reinforcing beams affects the irradiation efficiency of plates, which is increased since sound cancellations effects are interrupted in the vicinities of the beams. From the Rayleigh Integral, one can have the sound pressure field on the plate, which is necessary to calculate the irradiation efficiency. Fourier Transforms can solve this integral. When FFT algorithms are used, the integral is resolved in a very fast way, when compared with a numerical integration. This work presents results of irradiation efficiency of plane plates, considering the effects of the flexibility (web and flange own modes) of the reinforcing beams. The velocity distribution is obtained by Finite Elements and considers the real influence of the reinforcement. The results show that increases in the irradiation efficiency occur when the plate is reinforced. Comparisons of irradiation efficiencies will be shown, among simply supported plates and beam-reinforced plates, along with the FFT technique. This work also presents a structural optimization of a plate with one reinforcement, using Genetic Algorithms to select the best beam in order to minimize the irradiation efficiency of the beam-reinforced plate.