No abstract

Reliability and durability of proton exchange membrane fuel cells (PEMFCs) are one of the most complex issues in real applications' environment. Especially, when it subjects to the various mechanical loads and vibrations. This topic requires more attention for research and experimental works. In this study, the effect of mechanical loads was investigated on an open‐cathode PEMFC in operating state. Several long time vibration tests have been applied on non‐operating PEMFC, and the performance of the fuel cell was evaluated during the test. Hydrogen leakage as a key parameter was investigated in performance monitoring instead of measuring torque on compression bolts. The vibration tests were consisted of sine, shock and random for X, Y and Z axes in operating state and random vibration in non‐operating state of PEMFC. The experimental results in operating state were indicated that the fuel cell performance has not been affected by the proposed vibrations. Furthermore, the test results of non‐operating state have been shown that the performance of PEMFC reduces about 0.6% in each four‐hour step of the vibration test. In addition, the experiments reveal that if the mechanical loads and vibrations cause physical damage on the fuel cell components, they can change the performance and reliability of the fuel cell.

In this paper, small scale resistance seam welding (SSRSEW) of 304 stainless steel sheet with a thickness of 0.1 mm with a capacitor discharge (CD) welding machine is investigated. The effect of the main parameters such as discharged energy, electrode force, and electrode speed on the quality of the weld seam was investigated. In order to control the speed of the electrode, the electrode wheel was mounted on a CNC machine. Mechanical tests such as tensile-shear and peel tests were used to evaluate the quality of the weld seam. Also, the failure modes were investigated in different welding conditions. The results show that the discharged energy has more effect on the weld seam strength and the maximum strength in the peel test is usually lower than the strength of the tensile-shear test. Also, discharge energy level of 14 ws and electrode force of 20 N and electrode speeds of 200 and 300 mm/min are the optimum welding condition for welding the 304 stainless steel sheets with a thickness of 0.1 mm.

No abstract

One of the most important challenges in increasing the performance, reliability and lifetime of fuel cells is the mechanical load effects that occur on real applications. Therefore, the vibration model of fuel cell that predicts the behavior of various fuel cell layouts is very useful. The fuel cell is made up of different adjacent layers that may have semi opposite mechanical properties. This special structure leads to occurrence of non‐linear behavior of fuel cell under dynamic mechanical vibrations and so, a black box method is selected for modeling of its vibration behavior. In this study, the mechanical load experiments in various shape and axes were applied on five layouts of proposed fuel cell and the vibration of its body measure by some accelerometers. The NNARXM neural network is created and trained with the experimental data of three layouts of the fuel cell. Then, the prediction error of this neural network, validated with the two other experimental data of fuel cell layouts, by correlation coefficients and histogram of prediction errors. Neural network validation shows the well prediction of both untrained layout and suitable estimation for any desired layout.