Prediction of all-steel CNG cylinder fracture under impact using a damage mechanics approach

In this paper, a damage mechanics approach is used to investigate the effect of crash and damage caused by impact in a steel cylinder filled by compressed natural gas (cng). the canadian standard association (csa) for cng cylinders is used as a damage detection criterion, and the cylinders' capability of reuse. the johnson-cook damage model is used to compute cylinder failures. simulations are carried out in different impact directions, and the effect of cylinder internal pressure, collision velocity and fall height are analyzed. also, failure due to collisions in various situations is studied and discussed. investigations for cases including crash and drop tests showed that the maximum damage in a cylinder is created in the case of normal impact and, by changing impact direction from normal to the side, the amount of damage will be decreased. also, by eliminating failed elements and comparing the damage depth caused by collision using the csa standard, it was observed that in most cases of normal accidents and drop tests, damaged cylinders lose their ability for reuse. however, in the case of side impact, the cylinder remains intact or can be reused after repair.