Simulation based evaluation of manufacturing process on the performance of composite pressure vessels

Nowadays, hydrogen (H2) offers an advantage to power zero-emissionvehicles in conventional distance ranges delivering a fasttank re-fueling (less than 5 minutes). This gain comes with a new challenge for the onboard fuel storage. Due its low volumetric energy density, H2 must be compressed and kept in vehicles at high pressures of 700 bar, which requires having a very robust fuel tank. The first choice for this application are carbon fiber composite materials due to the superior weight-to-strength ratio. To ensure the tank safety, composite pressure vessels (CPVs) are designed with a safety factor of at least 2.25 bringing the product cost up. Such an overdesign is required to compensate for any possible manufacturing-induced variabilities in the composite microstructure, which could otherwise lead to a premature or unsafe failure.

In this work, the authors will present a methodology for the virtual multi-scale testing of the CPV performance including the effect of several manufacturing influence factors: cure-induced residual stresses, defects (voids) and variability inherited from the composite material and manufacturing process. The simulation workflows are implemented in Siemens Digital Industries Software Simcenter 3D simulation environment. This work is a part of the running Belgian (Flemish) research project OptiVaS which aims to improve the design of a CPV by establishing a manufacturing process that reduces the burst variability and would consequently allow the potential reduction of the required safety factor (determined by legislation).The project is being performed in a close collaboration among industrial and academic partners: Toyota Motor Europe, Plastic Omnium, Siemens Industry Software NV, Departments of Materials Engineering and Mechanical Engineering of KU Leuven.

The authors gratefully acknowledge SIM (Strategic Initiative Materials in Flanders) and VLAIO (Flemish government agency Flanders Innovation & Entrepreneurship) for their support of the ICON project NANOFORCE-OptiVaS “Optimized pressure vessels through composite Variability Simulation” (HBC.2019.0070).