Form finding analysis of air cushion of underwater shaking tables

Abstract

An air cushion, in the context of this study, is an inflatable membrane structure made of rubber-coated woven fabric reinforced composites. Inflatable membrane structures have wide application prospects in the waterproofing of underwater moving machineries, such as underwater shaking tables. A refining form finding analysis of a waterproof air cushion was carried out, and the mechanical characteristics in the process of form finding were studied. The air cushion had two layers. The lower layer is acted upon by air pressure, and the upper layer is acted upon by air and water pressure, both of which were theoretically analyzed. The dynamic equilibrium process of the air cushion was simulated by combining the Coupled Eulerian-Lagrangian(CEL) method with the fluid cavity analysis technology. The accuracy of the simulated results was verified by the theoretical analysis results. The dynamic equilibrium process of the air cushion with different initial inflation pressures was analyzed. The results show that the air cushion is most favorable when the initial inflatable pressure is slightly higher than the theoretical analysis result. Higher air pressure leads to higher stress of the air cushion, while lower air pressure will lead to slow stability during form finding. These results will provide a basis for engineering applications of air cushions in underwater shaking tables and in other fields.