About selection of the rational wall thickness of a liner high pressure metal compound cylinder | Mekhanika | kompozitsionnykh | materialov i konstruktsii
> Volume 25 > №1 / 2019 / Pages: 97-109

About selection of the rational wall thickness of a liner high pressure metal compound cylinder

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Abstract:

The design features of lightweight metal-composite cylinders are considered, the main requirements for pressure vessels are formulated. The principal part of them are include strength and resistance to cyclic pressure change. On the basis of the analysis of requirements, it has been established that the main factor preventing the achievement of mass perfection is the metal sealing shell – liner. Since the main load is perceived by the composite material, to weight savings, it is necessary to minimize the thickness of the wall of the liner, that is limited by technological possibilities. In addition, the presence of metal requires an increase in the amount of the composite layer to eliminate the fatigue failure of the liner. When calculating the design of the cylinder, the basic boundary criteria are taken: the strength and the admissible strains, which prevents the metal from falling into the plastic state. As a result of the analysis of the technological cycle of fabrication and testing of the metal-composite pressure vessel, the additional technologies stresses that affect the final range of strains are established to arise in the structure. Based on the known approaches to the calculation of combined cylinders, a calculation technique which takes into account the influence of technological stresses is proposed. The refined calculation made from the cylinder from the strength conditions and the absence of plastic strains in the metal for different combinations of materials at different wall thicknesses of the liner. It is established that in most cases the limiting factor is the requirement to limit metal strains. The account of technological stresses has a significant effect on the estimated mass of the cylinder, because in some cases, the thickness of the liner has a positive effect on the strains of the combined pressure vessel. The ration of metal and composite which ensure the minimum mass of the balloon are obtained. It is established that the correlation between the mass of the vessel and the thickness of the liner has a nonlinear character and in certain combinations of materials the tendency to minimize the metal is inexpedient.

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