The paper describes experimental tests carried out on three ring-reinforced circular conical shel... more The paper describes experimental tests carried out on three ring-reinforced circular conical shells that suffered plastic general instability under uniform external pressure. In this mode, the entire ring-shell combination buckles bodily in its flank. The cones were carefully machined from EN1A mild steel to a very high degree of precision. The paper also provides a design chart using the results obtained from these three vessels, together with the results of nine other vessels obtained from other tests. All 12 vessels failed by general instability. The design chart allows the possibility of obtaining a plastic knockdown factor, so that the theoretical elastic buckling pressures for perfect vessels can be divided by the plastic knockdown factor, to give the predicted buckling pressure. This method can also be used for the design of full-scale vessels.
The paper presents new experimental results on the collapse of unstiffened aluminum alloy circula... more The paper presents new experimental results on the collapse of unstiffened aluminum alloy circular cylinders suffering elastic and plastic nonsymmetric bifurcation buckling under external hydrostatic pressure. These results complement the results given in two previous Marine Technology papers written by the senior author, which were intended for the structural design of near-perfect unstiffened and ring-stiffened circular conical shells under external hydrostatic pressure. The present paper presents a structural design chart for geometrically imperfect circular cylinders under uniform external pressure, which is more likely to be used than the design charts for the previous near-perfect vessels because it represents the more "usual" case. In addition to an experimental analysis, theoretical analyses were also carried out. An analytical solution by von Mises was used, together with a finite element analysis solution, using the Shell 93 element of the ANSYS computer package....
ABSTRACT The paper presents theoretical and experimental investigations on three varying thicknes... more ABSTRACT The paper presents theoretical and experimental investigations on three varying thickness circular cylinders, which were tested to destruction under external hydrostatic pressure. The five buckling theories that were presented were based on inelastic shell instability. Three of these inelastic buckling theories adopted the finite element method and the other two theories were based on a modified version of the much simpler von Mises theory. Comparison between experiment and theory showed that one of the inelastic buckling theories that was based on the von Mises buckling pressure gave very good results while the two finite element solutions, obtained by dividing the theoretical elastic instability pressures by experimentally determined plastic knockdown factors gave poor results. The third finite element solution which was based on material and geometrical non-linearity gave excellent results. Electrical resistance strain gauges were used to monitor the collapse mechanisms and these revealed that collapse occurred in the regions of the highest values of hoop stress, where considerable deformation took place.
Proceedings of the Ninth International Conference on Computational Structures Technology, 2000
The paper reports on the buckling of twelve thin-walled geometrically imperfect tubes, which were... more The paper reports on the buckling of twelve thin-walled geometrically imperfect tubes, which were tested to destruction under uniform external hydrostatic pressure. The paper also reports on other similar tests to destruction, carried out on a large number of geometrically ...
The theoretical investigation was carried out using the finite element analysis to model both the... more The theoretical investigation was carried out using the finite element analysis to model both the structure and the fluid. The theoretical investigation used two different programs, one of which was the giant computer program ANSYS and the other was an in-house program ...
ABSTRACT The paper reports on the buckling of three ring-stiffened prolate domes under external h... more ABSTRACT The paper reports on the buckling of three ring-stiffened prolate domes under external hydrostatic pressure. The study was partly theoretical and partly experimental, where in the case of the latter, the finite element was used. Comparison between experiment and theory was good. The effect of ring stiffening the domes was to increase their buckling resistances by factors varying from 4.43 to 5.72.
The paper describes experimental tests carried out on three ring-reinforced circular conical shel... more The paper describes experimental tests carried out on three ring-reinforced circular conical shells that suffered plastic general instability under uniform external pressure. In this mode, the entire ring-shell combination buckles bodily in its flank. The cones were carefully machined from EN1A mild steel to a very high degree of precision. The paper also provides a design chart using the results obtained from these three vessels, together with the results of nine other vessels obtained from other tests. All 12 vessels failed by general instability. The design chart allows the possibility of obtaining a plastic knockdown factor, so that the theoretical elastic buckling pressures for perfect vessels can be divided by the plastic knockdown factor, to give the predicted buckling pressure. This method can also be used for the design of full-scale vessels.
The paper presents new experimental results on the collapse of unstiffened aluminum alloy circula... more The paper presents new experimental results on the collapse of unstiffened aluminum alloy circular cylinders suffering elastic and plastic nonsymmetric bifurcation buckling under external hydrostatic pressure. These results complement the results given in two previous Marine Technology papers written by the senior author, which were intended for the structural design of near-perfect unstiffened and ring-stiffened circular conical shells under external hydrostatic pressure. The present paper presents a structural design chart for geometrically imperfect circular cylinders under uniform external pressure, which is more likely to be used than the design charts for the previous near-perfect vessels because it represents the more "usual" case. In addition to an experimental analysis, theoretical analyses were also carried out. An analytical solution by von Mises was used, together with a finite element analysis solution, using the Shell 93 element of the ANSYS computer package....
ABSTRACT The paper presents theoretical and experimental investigations on three varying thicknes... more ABSTRACT The paper presents theoretical and experimental investigations on three varying thickness circular cylinders, which were tested to destruction under external hydrostatic pressure. The five buckling theories that were presented were based on inelastic shell instability. Three of these inelastic buckling theories adopted the finite element method and the other two theories were based on a modified version of the much simpler von Mises theory. Comparison between experiment and theory showed that one of the inelastic buckling theories that was based on the von Mises buckling pressure gave very good results while the two finite element solutions, obtained by dividing the theoretical elastic instability pressures by experimentally determined plastic knockdown factors gave poor results. The third finite element solution which was based on material and geometrical non-linearity gave excellent results. Electrical resistance strain gauges were used to monitor the collapse mechanisms and these revealed that collapse occurred in the regions of the highest values of hoop stress, where considerable deformation took place.
Proceedings of the Ninth International Conference on Computational Structures Technology, 2000
The paper reports on the buckling of twelve thin-walled geometrically imperfect tubes, which were... more The paper reports on the buckling of twelve thin-walled geometrically imperfect tubes, which were tested to destruction under uniform external hydrostatic pressure. The paper also reports on other similar tests to destruction, carried out on a large number of geometrically ...
The theoretical investigation was carried out using the finite element analysis to model both the... more The theoretical investigation was carried out using the finite element analysis to model both the structure and the fluid. The theoretical investigation used two different programs, one of which was the giant computer program ANSYS and the other was an in-house program ...
ABSTRACT The paper reports on the buckling of three ring-stiffened prolate domes under external h... more ABSTRACT The paper reports on the buckling of three ring-stiffened prolate domes under external hydrostatic pressure. The study was partly theoretical and partly experimental, where in the case of the latter, the finite element was used. Comparison between experiment and theory was good. The effect of ring stiffening the domes was to increase their buckling resistances by factors varying from 4.43 to 5.72.
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Papers by Andrew Little