The Nonlinear Analysis Of Air-bag Used In Ship Launching

Air-bag launching, originated from China, is the procedure that moves the shipbody by air-bag from the ship building foundation to the water area. Air-bag is one ofthe most important factors of safety performance in ship launching. All around worldhowever, research of this kind of air-bag has been rarely reported and the FiniteElement Analyses of the air-bag is blank. The situation has made a systematic analysisof the air-bag considerably significant. The research promises to provide not only afoundation to the air-bag design but also theory support to air-bag launching, therefore,the research can holds a high social significance and economic value.The components and structural characteristics of air-bag are introduced in thispaper. A preliminary theoretical analysis of the vertical stiffness characteristic of theair-bag is carried out, and the approximate formula for calculating air pressure in theair-bag and counter pressure of the air-bag are obtained. Also the simulation based onfinite element method of a small air-bag used in experiment, is performed in the paper.The results are compared with those of experiment, which verifies the finite elementmethod used in this study. Using finite element method, the study has investigated theimpact on air-bag mechanical performance of string angle, string layer, string distance,air-bag diameter and initial air-bag pressure.In the last part of the paper, a large air-bag model is built and analyzed regardingits mechanical characteristics. The relationship between stress distribution of eachcomponent, air-bag stiffness and working height of the air-bag is obtained.