Optimization Design And Mechanical Response To Dynamic Impact In Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cell (PEMFC) stack has a promising application in automobile industry due to the advantages of fast starting, long service life and non-pollution to the environment. On the one hand, the of clamping load of a large fuel cell stack and the inside interface pressure homogeneity significantly affect the efficiency, stability and durability of the stack. Fuel cell end plate can provide appropriate package pressure for the stack in coordinate with fasteners and control the distribution of contact pressure. The mechanical property of the end plate has an important effect on the overall performance of the stack. A good end plate should have sufficient strength and stiffness, easy processing, small size and light weight. Traditional end plate design is based on engineering experience. There are no theoretical tools used for the initial conceptual design to ensure the optimal shape and topology. Based on topology optimization theory and finite element method, considering various design parameters, a multi-objective optimization of fuel cell end plate topology model is established in the present thesis. After topology and shape optimization designs, the end plate acquires the best material distribution and shape. The results show that the optimized end plate is lighter than the original structure and can provide more uniform interface contact pressure for the stack. On the other hand, large fuel cell stacks usually undergo vibration or dynamic impact in packing, transportation, and serving time, in particular for those used in the automobiles. This may cause the decay in the performance, and even structure damage of the stack. In the present paper we numerically study the mechanical response of a large fuel stack clamped by steel belts subjected to an impact load based on end plate optimization. It was found that the location of the clamping belts has a great effect on the anti-impact performance of the stack. The cells near the endplates have a worse anti-impact performance than those far from the endplates. We also show that it is the interface slippage among the layers that result in the collapse phenomenon of fuel cell under shock in the perpendicular direction of clamping direction. Using large-sized finite element calculation, we discuss the effect of clamping force, shocking acceleration and friction on the slippage among the layers and analyze the dynamic response of fuel cell under shock. This may have guiding significance to the anti-shock design and failure analysis of large-size fuel cell stack.