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

Hydrogen fuel cell electric vehicles (FCEV) are attractive due to their lack of exhaust (they produce only heat and water), and the possibility of reducing our dependence on hydrocarbon fuels. One impediment to widespread adoption of hydrogen FCEV has been high production costs, driven in part by the need to over- engineer the carbon-fiber-overwrap-pressure vessels (COPV) which carry the compressed hydrogen fuel. Further, there is no way to continuously monitor the tank’s structural health mile after mile over the vehicle’s life. TDA Research has developed a structural health monitoring system that is lightweight, compact, and inexpensive. The system is entirely external to the tank and does not require any alteration of the composite tank; therefore, no requalification of the tank’s integrity is required. It has no moving parts and can be ruggedized to run on board vehicles. It can detect defect location, size and damage type. Most importantly this technology has the capability to predict when damage requires the tank to be replaced, before it becomes dangerous. TDA novel sensor technology can be used for non-destructive-evaluation (NDE) for inspection of composite tanks and structural carbon fiber composite in addition to COPV structural health monitoring system. In the successful Phase I effort we demonstrated we can detect damage in commercial carbon fiber composites samples. The composites samples were measured in three states; as received conditions (undamaged) and also after they were impacted with a calibrated weight. Our sensors showed that there was a clear damage profile in the location of and around the impact sites. Using data from Phase I, we will design a structural health monitor (SHM) for on-board COPV in hydrogen FCEV. Our preliminary engineering design conducted showed all components are widely available and mass produced. In the Phase II project we will optimize the sensor design and operation. We will demonstrate the structural health monitoring system detects damage on a commercial COPV tanks. We will conduct detailed engineering and design of the structural health monitoring system for composite tanks, and produce a prototype sensor array for COPV. We will conduct an economic analysis to define the SHM system cost and perform a cost benefit analysis. The fuel cell market is expected to reach $12 billion by 2022 and 11 car manufacturers 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 SHM of carbon fibers that provide the strength of the fuel cylinder. The technology also has wide application for NDE of composite used in the aerospace and defense industry.