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Effect of interface morphology on the residual stress distribution in solid oxide fuel cell
International Journal of Energy Research ( IF 4.3 ) Pub Date : 2020-02-03 , DOI: 10.1002/er.5036
Qiangqiang Li 1 , Guojun Li 1 , Ganglin Cao 1 , Xiongwen Zhang 1 , Mincan Cheng 1 , Yanfei Ma 1
Affiliation  

Solid oxide fuel cell directly and efficiently converts chemical energy to electrical energy. However, the necessity for high operating temperatures can result in mechanical failure. Fuel cell is a multilayer system and its stress distribution is greatly affected by the interface morphology. In this work, cosine interfaces with different amplitudes are used to approximate the fluctuation of actual interface. The effects of interface morphology on stress state, energy release rate of crack and creep behavior have been investigated. The results show that if the interface is planar, the residual normal stress component is zero on the interface, while the nonplanarity of interface can cause the normal stress Sn and shear stress St on the interface. When the amplitude is relatively small, the max values of Sn and St on the interfaces vary linearly with increasing amplitudes in both anode and cathode. Above a certain value, nonlinearity of the interface becomes important. Max tensile Sn always occurs at the peak of convex interface, but the position of max compressive Sn varies. Max shear stress is prone to occur at 1/4 of the wavelength at small amplitude and moves towards 1/2 of the wavelength when the amplitude increases. Fracture mechanics analysis shows that the surface crack possibly penetrates into the anode function layer and then is constrained by the stiff electrolyte. On the other hand, the horizontal crack likely penetrates into the electrolyte layer when the interface is not planar. Creep analysis shows that 11 800 hours of continuous operation at high temperature cannot remove stress undulation introduced by nor‐planar interface but can make max value of Sn and St decrease around 30%.

中文翻译:

界面形态对固体氧化物燃料电池残余应力分布的影响

固体氧化物燃料电池直接有效地将化学能转化为电能。但是,高工作温度的必要性会导致机械故障。燃料电池是多层系统,其应力分布受界面形态的影响很大。在这项工作中,使用具有不同幅度的余弦界面来近似实际界面的波动。研究了界面形态对应力状态,裂纹能量释放率和蠕变行为的影响。结果表明,如果界面是平面的,则界面上的残余法向应力分量为零,而界面的非平面性会导致法向应力S n和剪切应力S t在界面上。当幅度相对较小时,界面上S nS t的最大值随阳极和阴极中幅度的增加而线性变化。超过一定值,界面的非线性变得很重要。最大拉伸力S n总是出现在凸形界面的峰值处,但是最大压缩力S n的位置不同。最大剪切应力倾向于在小幅度的波长的1/4处发生,并且在幅度增加时会向波长的1/2移动。断裂力学分析表明,表面裂纹可能会渗透到阳极功能层中,然后受到硬质电解质的约束。另一方面,当界面不是平坦的时,水平裂缝可能渗透到电解质层中。蠕变分析表明,在高温下连续运行11800小时不能消除非平面界面引入的应力波动,但可使Sn和St的最大值降低30%左右。
更新日期:2020-02-03
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