Onboard Monitoring Method for Detection of Damage to Carbon Fiber Composite Overwrap on Hydrogen Fuel Tanks

Hydrogen fuel cell electric vehicles (FCEV) technology is attractive due to lack of exhaust produced (only heat and water) and the possibility of reducing our dependence on hydrocarbon fuel sources. One impediment to widespread adoption of hydrogen FCEV has been high production costs, driven in part by the need to over-engineer carbon-fiber-overwrap-pressure vessels (COPV) which carry the compressed hydrogen fuel. Improved, non-destructive technologies for evaluating carbon-fiber health are necessary and will be the basis of improvements in carbon fiber manufacture and novel structural health monitoring (SHM) systems for the COPV used in hydrogen FCEV. TDA Research Inc. (TDA) proposes a novel technology for monitoring the structural health of carbon- fibers in COPV. This method can be used on the production floor, and also as the basis of a COPV structural health monitoring system. In Phase I we will show that the magnetic signature of carbon fiber, and of the associated aluminum lining for Type III vessels, can be assessed with our method to identify damage not apparent by visible inspection. In Phase II, we will use data from Phase I to build an array of our small, compact sensors which can be used to indicate damage to the carbon-fiber or aluminum liner and report to an on-board vehicle computer. Demonstration pieces in Phase I will be performed on COPV pieces and vessels provided by our commercial partner who manufactures COPV. The magnetic signature of healthy, virgin carbon fiber materials will be characterized and compared to samples with known types of damage, including impact damage, delamination within the carbon fiber, separation of the liner from the carbon overwrap and damage acquired after drop test and pressurization cycles. Using data from Phase I, we will design an array suitable for integration with on-board COPV in hydrogen FCEV.The fuel cell market is expected to reach $12 billion by 2022 and 11 car manufactures are expected to have hydrogen FCEV offerings by 2021. Widespread adoption of hydrogen FCEV relies on a reduction in unit costs, some of which can be achieved by improved structural health monitoring of carbon fibers by NDE.