As one type of the important alternative fuel containers, composite cylinders are widely
used in compressed natural gas vehicles (CNGV) all over the world. Compared to traditional metal
containers, the performance of composite cylinders is more complicate because it is difficult to
analyze the material characteristics and the influence of manufacturing process. With the aid of
numerical simulation, the damage tolerance of one type of composite cylinder was investigated in
this paper. Firstly, the usual damage modes and sizes that are generated in the serviced composite
cylinders are classified to illustrate the dangerous parts in the composite cylinders. According to the
manufacturing process of composite cylinders, the fiber material characteristics that account of the
effects of heat and resin are evaluated to conduct the numerical simulation. Under the damage
modes and sizes such as initial flaw, fiber fracture and delamination that are distributed in the
cylinder in terms of the classification, the performance of composite cylinder are carried out. With
the convenience of numerical simulation, the map of the dangerous sites under the elaborate
damage modes and sizes is given to evaluate the running condition of composite cylinders in
practice. The quantitative results are more useful to show the damage tolerance of composite
cylinder than the traditionally qualitative check way and guarantee the running of CNGV.