The design formulas of pressure vessels made of steel are given in Section VIII and Section III of the ASME Boiler and Pressure Vessel Code for non-lethal and lethal substances, respectively. As similar codes and standards are not available for composite pressure vessels, a method is proposed for use as a design guide in determining the required wall thickness and the optimized winding angle of a composite filament-wound pressure vessel.

The only design formula for determining the optimized fiber winding angle and the required wall thickness of the filament wound vessel was located in the Military Handbook. These equations have the following two major shortcomings:

1) All stresses are assumed to be carried by the fibers. The effect of epoxy on the optimized winding angle design is not considered.

2) The equations are derived based on the failure criterion of the ultimate tensile strength in fibers. Nevertheless, a vessel may also fail when the distortion energy reaches the critical value (the widely used Tsai-Wu failure criterion).

This abstract presents a set of three equations for use in determining the optimized fiber winding angle and the required wall thickness for an initial design of a filament-wound fiber-reinforced composite hydrogen storage vessel. This design method follows the same basic principle given in the Military Handbook, but includes some significant improvements:

1) Effects of both fiber and epoxy on the determination of the optimized fiber winding angle are considered.

2) Three failure criteria: the maximum tensile strength of fiber, the maximum tensile strength of epoxy and the maximum distortion energy are satisfied.

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