小冲杆试验评价平板式固体氧化物燃料电池钎焊密封接头力学性能研究

Evaluating Mechanical Properties of Brazed Seal Joint of Planar Solid Oxide Fuel Cell by Small Punch Test

如何获得钎焊接头钎缝的力学性能一直以来是一个难题。通过小冲杆试验获得了平板式固体氧化燃料电池304不锈钢密封钎焊接头三明治结构弹塑性力学性能,并建立了含有Gurson-Tvergaard-Needleman(GTN)损伤参数的钎焊接头小冲杆试样有限元模型,采用试验与有限元分析结合的方法,利用逆向求解法获得了使用常规试验方法无法得到的接头钎缝的屈服强度、抗拉强度及损伤参数,并通过不同厚度的钎焊焊缝小冲杆试验验证了有限元模型的正确性。同时研究了304不锈钢钎焊接头的断裂行为,结果表明钎缝的强度较母材差,钎缝厚度的增加会使得接头整体的承载能力减小。研究结果能够为平板式固体氧化物燃料电池钎焊自适应密封结构强度研究提供可行的试验方法和数据。

Obtaining the mechanical properties of the brazing seal of brazed joint is always a challenge.The elastoplastic mechanical properties of the whole sandwich structure of 304 stainless steel brazed joint of planar solid oxide fuel cell are obtained by small punch test,and the corresponding finite element model of the small punch specimen with the damage parameter of Gurson-Tvergaard-Needleman(GTN)is established.The method combining experimental and finite element analysis is used to obtain the yield strength,ultimate tensile strength and relevant damage parameters of the brazed joint,which are not able to be obtained by conventional testing methods.The validity of the finite element model is verified by the small punch tests of the brazed joints with different thickness brazing seam.Meanwhile,the fracture behavior of the 304 stainless steel brazed joint are investigated.The results show that the mechanical properties of the brazed joint are weaker than that of the parent metal.The increase of the thickness of the brazing seam will reduce the strength of the integrated brazed joint.The results of the present work are able to provide feasible methods and data for studying the strength of adaptive sealing structure of planar solid oxide fuel cell.