Dynamic stability of a hemispherical shell with shape imperfections

The nonlinear dynamic analysis of imperfect hemispherical shell under pressure was executed. finite element model hemisphere in the software NASTRAN built. wall form three-cornered and four-cornered net presented. Shape imperfection as a lower buckling (Buckling) perfect action static modelled. Value amplitude set proportionally to thickness. Two boundary conditions rigid hinged supports on nodes edge were considered. Excitation external pressure, which linearly depended time uniform distributed elements modal with different thicknesses modelled shape imperfections by Lanczos method using computational procedure task natural vibrations (Normal Modes) (Nonlinear Direct Transient) N’yumark Influence critical values loading appropriate deformation forms investigated.
 It discovered that same type effective. A significant influence load (55 %) observed. Also, our opinion, presented can be used assess design reliability loads Bolotin probabilistic approach.