1 Fuel Cell Safety & Failure Modes in Light Duty Vehicles Principal Investigators: Dr. Keith Williams Dr. Beth Todd Dr. Steve Shepard Department of Mechanical Engineering The University of Alabama Researchers: Matt Blackwood, Josh Baurichter, Blair Clinton Matt Fitzgerald, Courtney Graham

2 Objectives in Studying Fuel Cell Safety Examine the effects of large dynamic inputs, such as those caused during a vehicle collision, on a fuel cell in a light duty vehicle. Types of dynamic inputs include both mechanical loads as well as sudden changes in electrical loading. Determine how the behavior of the fuel cell and other support components impact passenger safety during such events.

3 Project Overview Fuel Cell Power Unit Lumped Parameter Modeling Subcomponents Vehicle Frame FCPU Finite ElementFinite Element Identify CriticalIdentify Critical Components Components Hydrogen Leakage IssuesHydrogen Leakage Issues ID Failure ModesID Failure Modes Critical Loads, Paths, and Response Levels and Response Levels H2H2 Simulations ExperimentalEfforts H2H2 023 Crash Impulse Road Response A better understanding of the safety issues and failure modes of light duty vehicles incorporating fuel cells will provide information critical to public policy for transportation.

4 Extreme Loading Simulations 10 W Fuel Cell 15 ksi Using ANSYS Finite Element Analysis Software, stresses and deflections experienced by the fuel cell end plate are predicted. Loading is through the supporting bolts. Fuel Cell Plate Rear View Maximum Stress Occurs in 4 Symmetrical Locations Fuel Cell Plate Front View Maximum Deflection Occurs in 4 Symmetrical Locations Fuel Cell Plate Graphite Plate

5 Dynamic Behavior Analysis Using ANSYS Finite Element Analysis Software, the first several vibration mode shapes and natural frequencies of the fuel cell’s graphite plates are predicted. Natural frequencies are compared to vehicle characteristics, such as vehicle speed, engine speed, suspension hop and tramp. Graphite Plate Front View Rear View First Mode Shape Second Mode Shape Third Mode Shape

6 Fuel Cell Power Characteristics Extreme dynamic & electrical conditions, which might occur during a collision, must be simulated by varying the load connected to the fuel cell. As the load changes, so does the power output by the fuel cell. The power generated by the Nexa Power Module by Ballard Systems depends on the load impedance.

7 Variable Electrical Load The load “seen” by the fuel cell is varied by turning the solid state relays “on” and “off.” As different equivalent loads are generated, the fuel cell’s power output varies, providing a method to test the dynamic electrical response of the fuel cell. Aluminum Bus Bar Fast Recovery Diode Power Resistors Solid State Relay

8Acknowledgements This work is being conducted at the Center for Advanced Vehicle Technologies and sponsored by the National Highway Traffic Safety Administration and the U.S. Department of Transportation under Grant #DTNH22-04-H-01411: Research on Fuel Cells and Hybrid Electric Vehicles