No abstract

A design is robust when it is not sensitive to variations in noise parameters such as manufacturing tolerances, material properties, environmental temperature, humidity, etc. In recent years several robust design concepts have been introduced in an effort to obtain optimum designs and minimize the variation in the product characteristics. Increasing the pressure on a PEM (Proton Exchange Membrane) fuel cell’s MEA (Membrane Electrode Assembly) leads to increasing the electric conductivity and reducing the permeability of the assembly. In this study, a probabilistic FEA analysis was performed on a simplified fuel cell stack in order to identify the effect of material and manufacturing variations on the MEA’s pressure distribution. The bi-polar flow plate thickness, the modulus of elasticity and the end plate bolt loading were considered as randomly varying parameters with given mean and standard deviation. The normal stress uniformity of the MEA was determined in terms of the probabilistic input variables. The methodology for implementing robust design used in this research effort is summarized in a reusable workflow diagram.

In typical Proton Exchange Membrane fuel cells, a compressed gasket provides a sealing barrier between cell and cooler bipolar plate interfaces. The gasket initially bears the entire bolt load, and its resisting reaction load depends on the cross-sectional shape of the gasket, bipolar plate’s groove depth, and the hyperelastic properties of the gasket material. A nonlinear, finite element analysis (FEA) model with various hyperelastic material models, large deformations, and contact was used to evaluate the load-gap curves. The deformed shapes and the distributions of stress, strain, and deflections are presented. Mooney-Rivlin and Arruda-Boyce hyperelastic material models were used, and a comparison of load-gap curves is shown. A process is presented that couples the computer-aided design geometry with the nonlinear FEA model that was used to determine the gasket’s cross-sectional shape, which achieves the desired reaction load for a given gap.