ANALYZIS OF THE FATIGUE LIFE OF HYDROGEN HIGH PRESSURE TANKS
Nevertheless, in order to respond to the economic a nd environmental criteria, hydrogen production and storage have to be improved. This wo rk focuses on gaseous storage under high pressure (700 bar) using a type III vessel (figure 1) that is to say composed of a metal liner – which prevents gas diffusion – and of a composite l aminate wrapped by filament winding – which is used as a mechanical strengthening piece. Th problem with this type of high pressure vessel is the early explosion when it is t ested to cyclic pressures. To solve this problem, the components – liner and composite – hav e to be well-proportioned.
Optimal design of a Type 3 hydrogen vessel: Part I—Analytic modelling of the cylindrical section
The present paper aims to study the cylindrical section of a Type 3 high-pressure hydrogen storage vessel, combining an aluminium liner which prevents gas diffusion and an overwrapped composite devoted to reinforce the structure. Today, this technique is widely used but still requires consistent time investments whenever a competitive solution, involving to definitely increase weight efficiency, is needed. The laminate composite is assumed to be an elasto-damage material whereas the liner behaves as an elasto-plastic material. Based on the classical laminate theory and on Hill's criterion to take into account the anisotropic plastic flow of the liner, the model provides an exact solution for stresses and strains on the cylindrical section of the vessel under thermomechanical static loading. Part I focuses on the theoretical background. The effect of the stacking sequence on the gap occurrence, on the residual stress magnitude and on the structure stiffness may then be investigated. This will be done and be compared with results of experiments which are carried out on prototypes in the second part of this paper before an optimization is performed.
A computational study in optimum formulations of optimization problems on laminated cylindrical shells for buckling II. Shells under external pressure
The paper deals with different formulations of optimization problems on bucking of multi-layered composite cylindrical shells under axial compression. The problem is posed on searching the global extremum and local extrema of the buckling load such that are maximum close to the global extremum (or practically the same) and more convenient for the design and production of real shells. A comparison is done for uni-, two- and multi-dimensional formulations of optimization problems for the shells including different number of the layers. It is shown that, for most practical cases, there is no gain in increasing the number of the layers above four and the number of variable parameters above two. Recommendations are given on the selection of rational structures for two- and three-layered shells. Known rules are studied for different intervals of shell dimensions and material characteristics.