Research on the burst failure analysis method of type IV cylinders based on the fiber strength reduction effect

Composite material hydrogen storage cylinders are the most effective solution for high-pressure gaseous hydrogen storage. The carbon fiber fully wrapped plastic liner cylinder (Type IV cylinder) is the most important potential in the development of hydrogen storage. Accurately predicting the burst pressure and failure mode of Type IV cylinders is basement for the lightweight design of these cylinders. Current burst failure prediction methods are developed base on traditional laminated structural models, where the influence of fiber bundles cross undulation that occurs during the helical winding process are not considered. This paper comprehensively investigated the influence of fiber bundles cross undulation on the fiber strength by combining numerical and experimental approaches, and a failure prediction method which takes into account of the strength knock-down effect was developed for Type IV cylinders. The burst pressures and failure locations of three different types of IV cylinders were predicted and compared with the ones that predicted by traditional method which does not consider the strength knock-down effect. The physical bursting experiments were conducted, and the results validate that the numerical analysis method considering the strength knock-down effect can give more accurate prediction of the failure location and reduce the prediction error of the bursting pressure, the maximum error is reduced from +15.42% to +6.07%.