Investigation of crack initiation during the burst test of hydrogen storage composite overwrapped pressure vessels

Abstract Hydrogen storage composite overwrapped pressure vessels (COPVs), as a core component of fuel cells, are widely used in the new energy vehicles and other fields. However, the service performance of COPVs, especially the burst pressure, has a great dispersion, which may come from the microscopic defects inside the vessels. In this paper, the industrial computed tomography scan was carried out on a type III hydrogen storage COPV with an aluminum alloy liner and a carbon fiber wound layer, and it was found that many delamination defects with random sizes and locations exist inside the fiber wound layer. Among these defects, there are 164 delamination defects with an area of <500 mm2 (accounting for 87.7% of the total number of defects), but the area of the defects only comprises 19.14% of the entire defects area. Delamination defects were the predominant type of manufacturing defect in the fiber wound layer of COPVs. Then the burst test of the COPV was carried out, which showed that the aggregated area of large-sized delamination defects located in the composite layer of the cylindrical part triggered the crack initiation during the burst test. Thus, in turn, directly affected both the burst pressure and the post-burst morphology. Finally, a 3D equivalent model of the laminated structure is proposed to model the expansion of the composite cylinder. By carrying out a finite element simulation of the COPV, the most dangerous area during the loading process of the COPV is confirmed. The experimentally measured burst pressure of the cylinder is 115.5 MPa, which deviates by 18.6% from the pristine model prediction and by 9.09% from the model with delamination defects.