Experimental study and numerical modeling of vibrational characteristics of a 500W PEM fuel cell stack

A PEM fuel cell is considered a system with a complex mechanical structure due to a large number of components with different dimensions and materials. Understanding this structure is essential to design fuel cells against dynamic loads such as shock and vibration. In this paper, modal analysis of a 500 W fuel cell with an active area of 225 cm2 has been performed. The fuel cell has been excited in transverse and longitudinal directions, and the outputs of the sensors were recorded at several points. Using the Poly reference least-squares complex frequency-domain method, the first ten transverse and longitudinal natural frequencies and mode shapes of the model were determined. Modal analysis revealed that the lack of structural integrity, the layered structure, and the layer connection type results in the formation of mode shapes that do not match conventional predictions. Comparison of the numerical and experimental results showed a maximum difference of 15%. Furthermore, the results illustrated that changing geometrical and mechanical properties of the membrane by 45% have a negligible effect on the natural frequency of the fuel cell. Allowing for this fact will result in a significant reduction in the computational cost of large-scale fuel cells analysis.