Nonlinear buckling analysis of a semi-elliptical dome: Numerical and experimental investigations

In this paper, non-linear buckling performance of a semi-elliptical steel dome under uniform external pressure is investigated numerically and experimentally. Numerical buckling analysis is performed on an ellipsoidal dome with various nonlinearities including geometric (GN) and material non-linearity (MN) to obtain the critical pressure. The option ``Arc length method'' available in ANSYS is implemented to solve the nonlinear differential equations. Further, an experimental testing is performed on the prototype ellipsoidal dome subjected to external hydrostatic pressure to obtain the critical pressure. The effectiveness of the developed numerical modelling is demonstrated by comparing the critical buckling load evaluated using the present non-linear analysis with those available in literature and experimental analysis. Imperfections such as Force Induced Dimple (FID) and eigen affine imperfections are considered in the ellipsoidal dome to investigate their effects on collapse load. Non-linear (NL) buckling analysis of stringer reinforced semi-elliptical dome is performed to investigate the effect of stringers on critical buckling pressure. Various parametric studies are also performed to study the effect of the nature of imperfection, location of imperfection, aspect ratio on critical buckling pressure of the dome. It was observed that an increase in the amplitude of eigen affine imperfection significantly reduces the critical buckling pressure. FID at an apex of the dome causes a reduction in buckling pressure whereas FID located at the middle and bottom of dome do not affect the critical load significantly. It was also demonstrated that stringer reinforcement on semi-elliptical dome without modifying the mass of overall structure significantly increases the critical buckling pressure. The effect of geometric nonlinearity and material nonlinearity on the critical buckling pressure of the semi-elliptical dome is observed to be more significant in stringer reinforced domes.