A CONTRIBUTION TO THE NONLINEAR-ANALYSIS OF COMPOUND SHELL STRUCTURES

Finite element formulation providing solution of geometrically and mat erially nonlinear problems is presented. The geometrically nonlinear t heory of small rotation and elastic-plastic material model based on th e isotropic strain hardening and Von Mises yield criterion were applie d. The effect of geometric and material nonlinearity on the internal f orce distribution in an internally pressurized torispherical shell was investigated. It was found out that the geometric nonlinearity increa ses with increase in the ratio of cylindrical shell diameter to wall t hickness which, in turn, yields lower stress resultants and moments in relation to linear analysis. The spreading of plastic regions has no significant influence on these differences. In the case of bending mom ents the differences in the values obtained by geometrically linear an d nonlinear computations tend to some increase with an increase of pla stic regions, which in case of hoop stress resultants even a relative decrease regarding the elastic response may occur. Nonlinear analysis contributes to an optimization of presented compound shell structures.