Plastic response of conical shells with stiffeners to blast loading

The inelastic response of circular conical shells to the blast loading is studied. The impact loading is applied at the initial time moment and it is removed at a certain instant of time. The load intensity depends of the coordinate of the shell. The material of the shell is a perfect plastic one obeying the Johansen yield condition and the associated flow law. It is assumed that the frustum of the cone is furnished with ring stiffeners made of the same material. A theoretical method for the evaluation of the stress strain state of the shell and for determination of maximal residual deflections is developed.

Active Structural-Acoustic Control of Laminated Composite Truncated Conical Shells Using Smart Damping Treatment

This article deals with the active structural-acoustic control of composite truncated circular conical shells using active constrained layer damping (ACLD) treatment. The constraining layer of the ACLD treatment is made of vertically/obliquely reinforced 1–3 piezoelectric composite (PZC) material. A finite element model of smart laminated truncated conical shells backed by the acoustic cavity and integrated with the patches of such ACLD treatment has been developed to demonstrate the performance of these patches for active structural-acoustic control of symmetric and antisymmetric cross-ply and antisymmetric angle-ply truncated conical laminated shells. Both velocity and pressure rate feedback control laws have been implemented to activate the patches. Particular emphasis has also been placed on investigating the effect of variation of piezoelectric fiber orientation angle in the constraining layer on the performance of the patches.

Plastic General Instability of Ring-Stiffened Conical Shells under External Pressure

The paper describes experimental tests carried out on three ring-stiffened circular conical shells that suffered plastic general instability under uniform external pressure. The cones were carefully machined from EN1A mild steel to a very high degree of precision. The end diameters of the cones, together with their thicknesses were the same, but the size of their ring stiffeners was different for each of the three vessels. In the general instability mode of collapse, the entire ring-shell combination buckles bodily in its flank. The paper also provides three design charts using the results obtained from these three vessels, together with the results obtained for twelve other vessels from other tests. All 15 vessels failed by general instability. One of these design charts was based on conical shell theory and two of the design charts were based on the general instability of ring-stiffened circular cylindrical shells, using Kendrick’s theory, which were made equivalent to ring-stiffened circular conical shells suffering from general instability under uniform external pressure. The design charts allowed the possibility of obtaining plastic knockdown factors, so that the theoretical elastic buckling pressures, for perfect vessels, could be divided by the appropriate plastic knockdown factor, to give the predicted buckling pressure. The theoretical work is based on the solutions of Kendrick, together with the finite element program of Ross, namely RCONEBUR and the commercial finite element package ANSYS. This method can also be used for the design of full-scale vessels.

Plastic General Instability of Ring—Reinforced Conical Shells Under Uniform External Pressure

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.