Research On Mechanical Properties And Burst Pressure Of Airbag Used In Launching

Ship launching air bags is a new technique created in china,which has became one of the key techniques to support the development of the Chinese shipbuilding industry.Air bags used for launching are typical flexible composites with high loading ability,combining cord thread and rubber effectively.At present,researching on theory of air bags is not mature.With the increase of ship's size,risk increases accordingly.So it's necessary to do research on air bag s' mechanical properties.Following works:(1)Based on the pressure on air bags,ideal gas status equation is used,combined with the calculating result of the finite element program,vertical stiffness formula is deduced under deformation hypothesis.Then analysis on factors of effect on air bags stress is done.(2)Based on structural features of air bags,thin film laminated theory and netting theory,theoretical formula of internal-force stress,and cord force is deduced.Based on fiber failure criteria,theoretical calculation formula of air bags blasting pressure is deduced.Contrast between theoretical formula and experimental result shows theoretical formula can be used in practice.(3)Using the nonlinear finite element program MSC MARC,based on finite element research for launching air bags,analysis the stress of air bags based on experiment results.The results show that verifying the third failure criterion is suitable.(4)On the basis research of(2)and(3),blasting pressure of the real launching air bags by equalizing pressure were applied with grid combines membrane method,membrane combined failure method and finite element method.Results show that grid combines membrane method to calculate the air bags minimum blasting pressure,finite element method to calculate the air bags blasting pressure maximum,membrane combined failure method,but this three methods have little difference.Through the research of this thesis,a reliable way of determining airbag vertical stiffness,blasting pressure is provided,the accuracy of calculating is enhanced;on the other hand,stress distribution of air bags is obtained,which can point the way to improve and optimize the structure of airbag,and improve the bearing capacity of airbag.