Numerical simulation of CNG fuel tank behavior made of epoxy/glass composite in design mode considering constant and variable thicknesses under burst pressure test

In the present study, failure strength of the type-IV CNG fuel tank under burst pressure test in both constant and variable thicknesses was analized using finite element simulation. Afterward, optimal fiber twist angle was optimized to achieve maximum resistance to burst pressure in both models. To this end, the test specifications stated in NECE R 110: 2016 standard and von Mises yield criterion were used to determine the critical area which is prone to failure in the tank. The simulation results showed that the separation occurred in the lower flange of the tank and the location of the low curvature shell in the tank with the constant and variable thicknesses, respectively. Validation of presented finite element simulation for prediction of burst pressure in both design modes, including constant and variable thicknesses, using the technique of comparison with experimental results showed that an acceptable agreement was established between the experimental and numerical results. Also, the results showed that the optimal fiber twist angle to achieve maximum resistance to burst pressure for both design cases (constant and variable thicknesses) was 23° (670 bar) and 15° (780 bar), respectively. Finally, applying the results of this study can lead to a 22% increase in the failure strength of the type-IV composite tank.