Load Carrying Capacity Of Shells Research Articles

Effect of joint stiffness on the load-carrying capacity of single-layer cylindrical reticulated shell with improved bolt-column (IBC) joint

To enlarge the application of single-layer reticulated shells, this study proposes an innovative semi-rigid joint based on the original bolt-column (OBC) joint, referred to as the improved bolt-column (IBC) joint. The mechanical behavior of the IBC joint under the pure load and the coupling effect of bending and axial force is investigated using numerical tests. Then, the practical analytical model of IBC joint is developed based on a three-parameters power model and component method. Subsequently, a mechanical model considering joint stiffness is developed to establish semi-rigidly connected single-layer cylindrical reticulated shell. A total of 456 numerical models of shells are conducted to examine the impact of different kinds of joint stiffness on the load-carrying capacity of shells systematically. The results demonstrate that (i) weak axis bending stiffness and axial stiffness significantly affect the load-carrying capacity of shells by approximately 19 % and 14 % on average respectively; (ii) strong axis bending stiffness and torsional stiffness have relatively minor effects on the critical load of shells, with average decline ratios of only 5 % and 6 % respectively; (iii) out-of-plane shear stiffness and in-plane shear stiffness exhibit negligible impacts on the load-carrying capacity of shells, with an average effect not exceeding 1 %. Finally, the findings of numerical simulation considering all stiffness of IBC joint reveal insights into both varying laws of load-carrying capacity and failure modes for shells. It is observed that the mean critical load can reach up to 59 % of the one of rigidly-connected shells, which is significantly higher than those observed in shells with pinned joints.

Bend-free design of super ellipsoids of revolution composite pressure vessels

Shells are thin-walled curved structures that are widely used in many engineering applications because of their structural performance in reacting transverse loads via generating membrane stresses. However, bending deformations and stresses are also generated, yet, alleviating them can result in more efficient use of material and improvement of load carrying capacity of shells. Ideally, a bend-free design provides scope for exploiting the full potential of load carrying in shell structures because of the uniform load distribution through the thickness. In this study, a family of so-called super ellipsoids of revolution are designed to have bend-free states under uniform internal pressure. Super ellipsoids of revolution have several advantages compared to conventional geometries such as higher packing efficiency, smoother stress flow variation, alleviating stress concentrations and cost associated with assembly processes. In this work, a new generalised set of governing equations representing bend-free states in composite super ellipsoids of revolutions are developed and solved analytically. Stiffness tailoring via tow steering is used to realise bend-free states. A parametric study is performed on several super ellipsoids of revolution for finding the required distribution of fibre orientations. The analytical solution is verified by finite element modelling and results are compared with an isotropic baseline.

Load-carrying capacity of a spherical shell with circular holes

The load-carrying capacity of spherical shells loaded by external pressure with circular holes is investigated. The problem is solved with the use of a numerical variant of the experiment-the-oretic method. Computations were carried out using an ANSYS/LS-DINA 11.0 finite-element package. Semianalytic formulas were obtained for computation of critical loads. The effect of sizes of the circular hole on the load-carrying capacity of shells studied is investigated.

Stability and Load-Carrying Capacity of Elastic Reinforced Cylindrical Shells

By using the equilibrium equations in displacements, we develop an analytic method for the evaluation of upper critical loads in elastic cylindrical shells with transverse reinforcement. As a result, we deduce analytic expressions for the evaluation of critical stresses in momentless shells and propose a procedure for the evaluation of the lower limit of the load-carrying capacity of shells based on the application of the method of reduced stiffness. The numerical results are compared with the available theoretical and experimental data.

Effect of the Stress State on the Critical Load and Load-Carrying Capacity of Shells with Axisymmetrical Dents

A method of approximate determination of critical stresses in elastic near-cylindrical shells with the use of equations in terms of displacements is proposed. Analytical expressions to estimate critical stresses in membrane unstiffened shells were obtained. Two distributions of internal forces, namely, the forces constant and variable in magnitude, were analyzed.

The stability and load-carrying capacity of incomplete shells

The survey is devoted to problems on the stability and load-carrying capacity of imperfect shells in a nonhomogeneous stress-strain state. Methods recently developed at the Institute of Mechanics (Kiev, Ukraine) are briefly described. The approaches proposed are based on the generalized Euler criterion. Special attention is focused on numerical methods. The stability and load-carrying capacity of shells with symmetric and asymmetric, local and regular imperfections are considered. The data presented are compared with the well-known theoretical results and experimental data. At the end of the review, an analytical method (of reduced stiffness) is presented for predicting the lower bounds of sensitivity to imperfection in elastic buckling of longitudinally compressed stiffened shells with a nearly cylindrical shape.

Experimental investigation of the load-carrying capacity of shells with combined static loading and local thermal shock

Experimental investigation of the load-carrying capacity of shells with combined static loading and local thermal shock

Deformability and load-carrying capacity of shells made on an expanding mandrel

Deformability and load-carrying capacity of shells made on an expanding mandrel