Fiber reinforced vessel design with a damage criterion approach

Current design codes for the design of fiber reinforced vessels are generally based on a quadratic interaction criterion which relies on failure testing of laminas with different fiber orientations. A stress ratio is then imposed for purposes of design. This approach appears to be overly conservative for certain resins and does not account for the onset of damage. An experimental investigation has been conducted to determine the stress at onset of damage in small coupon specimens. The results from the coupon testing were used to develop a damage based design approach that differs from the existing failure based approach. The damage approach was used for the design of a new manway and nozzle on a 2.13 m diameter by 6.55 m tall (7.0 ft diameter by 21.5 ft tall) glass fiber reinforced polymer pressure vessel. The vessel was subsequently tested with acoustic emission to verify the adequacy of the new designs. This paper focuses on the design of these discontinuity regions and provides comparisons between finite element model predictions and measured strain gage data.