Sobol’s sensitivity analysis for a fuel cell stack assembly model with the aid of structure-selection techniques

Significance Statement

    This work presents a novel method for identifying the main parameters affecting the stress distribution of the components used in assembly modeling of proton exchange membrane fuel cell (PEMFC) stack. This method is a combination of an approximation model and Sobol’s method, which allows a fast global sensitivity analysis for a set of uncertain parameters using only a limited number of calculations.

Seven major parameters, i.e., Young’s modulus of the end plate and the membrane electrode assembly (MEA), the contact stiffness between the MEA and bipolar plate (BPP), the X and Y positions of the bolts, the pressure of each bolt, and the thickness of the end plate, are investigated regarding their effect on four metrics, i.e., the maximum stresses of the MEA, BPP, and end plate, and the stress distribution percentage of the MEA.

The proposed method was demonstrated to be feasible and effective at determining the most influential model parameters. Moreover, it enhances our understanding of the assembly of a PEMFC stack, and provides a valuable tool for a sensitivity analysis of a PEMFC stack assembly model.

The analysis reveals the individual effects of each parameter and its interactions with other parameters on the model performance regarding four metrics. The main findings from the results obtained are summarized as follows:

(1) The position of each bolt has a significant influence on the maximum stresses of the BPP and end plate, whereas the thickness of the end plate has the most crucial role in the maximum stress and stress distribution percentage of the MEA.

(2) The contact stiffness between the MEA and BPP has little effect on the maximum stresses of the BPP and end plate, and on the stress distribution percentage of the MEA. Moreover, it is not the most important factor affecting the maximum stress of the MEA when measured using a total-order sensitivity index. However, the contact stiffness interacting with the thickness of the end plate has a highly sensitive interaction effect on the maximum stress of the MEA.

(3) The parameter interactions contribute to a significant portion of the variation in the metric considering the maximum stress of the BPP. The interaction effects include the following: the thickness of the end plate interacts with its material property as well as the Y position of each bolt, the X position of each bolt interacts with its Y position, and the Y position of each bolt interacts with the pressure. 

Sobol's sensitivity analysis fuel cell stack assembly model with the aid of structure-selection techniques (renewable energy global innovations)

About the author

Dr. Wei Zhang received his B.Eng. in Engineering Mechanics from Hunan University, China in 2005, his M.Eng. and Ph.D. in Mechanical Engineering also from Hunan University, China in 2010 and 2013, respectively. He was an assistant engineer at Special Aircraft Research Institute of China from Aug. 2005 to Jun. 2007, and was a Post-Doctoral fellow at Department of Mechanical Engineering, Inha University, Korea from Nov. 2013 to Nov. 2015.

His research interests are in computational inverse techniques, uncertainty management and bioinspired design in composites. He is currently a research fellow at School of Mechanical & Aerospace Engineering, Queen’s University Belfast, UK. 

About the author

Prof. Chongdu Cho received his B.Eng. in Mechanical Engineering from Seoul National University, Korea in 1983, his M.Eng. in Mechanical Engineering from KAIST, Korea in 1985 and his Ph.D. in Mechanical Engineering from University of Michigan, USA in 1991. He has been a visiting scholar in UCLA, USA from Jul. 2000 to Jul. 2001, and in Cornell University, USA from Aug. 2009 to Aug. 2010, respectively.

He has been developing FEA applications for various engineering products. He has published more than 150 referenced journal papers. Now, he is a fellow professor at Department of Mechanical Engineering, Inha University, Korea. 

Journal Reference

Journal of Power Sources, Volume 301, 2016, Pages 1–10.

Wei Zhang1, Chongdu Cho1, Changhao Piao1, Hojoon Choi2

Show Affiliations
  1. Department of Mechanical Engineering, Inha University, Incheon 402-751, South Korea
  2. Korea Institute of Industrial Technology, Incheon 406-840, South Korea

Abstract

This paper presents a novel method for identifying the main parameters affecting the stress distribution of the components used in assembly modeling of proton exchange membrane fuel cell (PEMFC) stack. This method is a combination of an approximation model and Sobol’s method, which allows a fast global sensitivity analysis for a set of uncertain parameters using only a limited number of calculations. Seven major parameters, i.e., Young’s modulus of the end plate and the membrane electrode assembly (MEA), the contact stiffness between the MEA and bipolar plate (BPP), the X and Y positions of the bolts, the pressure of each bolt, and the thickness of the end plate, are investigated regarding their effect on four metrics, i.e., the maximum stresses of the MEA, BPP, and end plate, and the stress distribution percentage of the MEA. The analysis reveals the individual effects of each parameter and its interactions with the other parameters. The results show that the X position of a bolt has a major influence on the maximum stresses of the BPP and end plate, whereas the thickness of the end plate has the strongest effect on both the maximum stress and the stress distribution percentage of the MEA.

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