The Buckling And Reliability Analysis Of Imperfect Shells

In the processing and manufacturing process, there will inevitably be some initial imperfection in the members of the actual engineering structure. And there will be local damage when the actural structure in the process of the use. The structure with intial imperfection and localized damage is imperfect structure. In the design, construction and use of the structure, it is crucial that the structure has sufficient strength. In order to do this, uncertainty analysis of the past and reliability analysis of the perfect structure are not enough. We need further research on imperfect structural reliability problems.This thesis carried out the research of initial imperfection influence and localized damage influence on thin shell structural reliability. Based on the study of a number of references, the analytical solution of buckling load of thin wall cylinder shell loaded axially with localized imperfection was derived. Based on this analytical solution, the safety margin equation of cylinder shell with localized imperfection was founded. According the typical depression model of the cylinder shell impacted or crashed by the collision, the safety margin equation of cylinder shell with localized damage was founded. And the reliability analysis of the cylinder shell with intial imperfection and localized damage was carried out. In this thesis, finite element method was used to study the ultimate strength of pressure spherical shells. The ultimate strength of pressure spherical shells under different thickness-radius is studied, as well as the effect of the initial imperfection. Finally, critical buckling safety margin of thin hemisphere shell structure with initial imperfection under external pressure has been founded and its reliability analysis was carried out.The study of influence of typical imperfection on thin shell structural buckling reliability can be regarded as the engineering guidline. It also lays the theoretical foundation for further study of imperfect structural buckling design based on structural reliability.