Structural Design And Analysis On Cutout Zone Of Composite Rear Pressure Bulkhead

Rear stress bulkhead is not only front bulkhead of rear fuselage,butalso delimitation bulkhead between sealed cabin and rear equipmentcompartment. As for its high ratioes of strength and stiffness,compositematerial has been widely used in aviation and aerospace industry such asA340,A380 and B787. Because of the checking,repairing and the pipegetting across,the structure should have a series of holes. For compositelaminate,holes existing will cut the fiber and lower the load–carryingcapacity.we should strengthen the area around the hole to recoverstructure's load-carrying capacity.This dissertation mainly research on cutout zone of rear stressbulkhead.Its main object is to select correct reinforcement type and defineadjust reinforcement zone,base on which,Reinforcement to the struct hasan effective result.First, through creating crude meal model of rear stressbulkhead, calculating by finite element analysis,analyzing displacementand stress distribute,we can transfer the cutout zone to a rectanglelaminate under biaxial tension load.Second,when rectangle plate withcentral circular cutout is under unixial tension load and biaxial tensionload,we do some theoretical and numerical research.And based on testingresult, the factors that affect stress concentration,such as layup and widthto diameter(W/D) of plate,can be further studied.The result show thatSCF near cutout will be lower while increase the proportion of 45°ply.In this part,it's an important conclution:mesh control equation.Whenapplying it to finite element analysis of laminate plate,its result is verifiedwell to testing one.Third,research is done on cutout reinforcement ofrectangle laminate. Though comparing numerial results of separatereinforcement,submerged reinforcement and inner bush,it finally definesubmerged reinforcement as object type not only for its reinformentefficiency,but for its ability to anti- delamination.Then,four reinforcement types are researched further.Here,geometry dimensions for reinforcementefficiency are anlysised,and list some reinforcement ratio scope fordifferent type.Beside of above,ply thickness also is defined.On thebalance,throuth designing reinforcement adjustly,SCF can be reducedlargely while the whole struct strength highly increast. After designinglayup and selecting reinforcement mode,some numerial work was doneon rear stress bulkhead under uplift pressure though OptiStruct.At thesame time,sphere is futher improved by using two methods Hoffmancriterion and constraint strain level.The result shows that the reinforcement of rear stress bulkhead canobviously raise struct stress. The design method can be widely used.Notonly in the composite planar,but also in some curved surface structurewith similar structural feature and loading situation.