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In order to reduce carbon dioxide and air pollution emissions, fuel cell vehicles (FCVs) are being developed, and CFRP pressure vessels have been used as the hydrogen storage systems for the FCVs. Since the FCVs are expected to increase driving distances of at least over 500 km, which is similar to those of conventional gasoline-fueled vehicles, the storage pressure of hydrogen must be raised from 35 to 70 MPa. It is important to decrease the amount of carbon fibers in order to reduce the cost and weight of the CFRP pressure vessels. In this study, a fast fabrication method for the cylindrical-shaped grids (CSG) composed of hoop stiffeners and helical stiffeners was developed with a particular mandrel and a 3-axis filament winding apparatus. Then, the CFRP pressure vessel was inserted into the CSG, and burst tests of the CFRP pressure vessels reinforced with and without the CSG were conducted. Moreover, their experimental results were compared with numerical ones obtained by a FEM analysis, and the mechanical properties and the reinforcement effects of the CFRP pressure vessels reinforced with the CSG were investigated. [ABSTRACT FROM AUTHOR]

Since isogrid structures are composed of triangular grid stiffeners and a surface skin, they have a high specific strength and stiffness. These structures are now being mainly used for aerospace applications. In order to produce a metal isogrid cylindrical shell, most of the thick metal plates must be cut off while the remaining thin surface skins with the stiffeners and both ends of the skins are welded to each other. This process needs a long lead time and a high cost, and unstable behaviors are observed in the joint parts. On the other hand, carbon fiber reinforced plastics (CFRP) isogrid cylindrical shells can be fabricated with an integral method by using a filament winding apparatus. In this study, a fabrication method of the CFRP isogrid cylindrical shells is proposed and their compressive tests are carried out to investigate the reinforcement effect of the grids on the CFRP isogrid cylindrical shells. Furthermore, the results of the static compressive tests are compared with numerical ones obtained by finite element method (FEM). [ABSTRACT FROM AUTHOR]