Seminars

Abstract: This work investigates the elasto-visco-plastic buckling of thick shell structures. Methods to estimate the buckling of thin elasto-visco-plastic shells are proposed in literature. Nevertheless, only few works present experimental results, and none treat experimental elasto-visco-plastic thick shell buckling. A modelling / experimental approach is followed to solve such problem.

A buckling prediction model was developed. It is based on Bodner's approach, and coupled to the corner theory of Christoffersen. This model should be applicable to predict the buckling of thick elasto-visco-plastic shells subjected to non-proportional loading. Bifurcation analysis were performed to estimate buckling critical stresses, strains and times, and buckling modes. The validity and the limitations of the buckling prediction method were discussed. Effect of geometrical and loading imperfections on buckling behaviour were also discussed.

Two test campaigns were performed on two different thick shell geometries. The specimens were manufactured from an alloy with an elasto-visco-plastic behaviour at room temperature. The first buckling test campaign was performed on thick plates subjected to a uni-axial compressive loading and the second one on thick hemi-egg shells subjected to external pressure.

3D digital image correlation was used to measure displacement fields on specimen surfaces during buckling experiments. It is also used in order to extract and investigate the evolution of the buckling modes. The experiments were also modelled through finite element models.

A good correlation between the buckling predictions and the experiments was observed. The good correlation between the buckling predictions and the experiments was observed. The good correlation was noticed on both critical values and buckling modes.