The Computation Of High Temperature Creep Damage And Failure Probability Of Solid Oxide Fuel Cell

The solid oxide fuel cell(SOFC)is widely applied in different industries due to the clean and efficient advantages,such as the large-scale power station,distributed power supply system and military.But the creep deformation and damage become the main failure mode for the SOFC at the high temperature.In this paper,taking the SOFC rigid sealant as the object,the creep behavior and damage evolution were extensively researched under working conditions,and a novel time-dependence failure probability prediction method was established to provide the theoretical guidance for the high temperature strength theory design of the SOFC.The conclusions drawn in this paper were listed as following:(1)The distribution of creep damage was analyzed by the finite element method based on a famous Wen-Tu creep damage constitutive model,and the role of uniaxial creep failure strain of glass ceramic on whole structure was discussed in detail.The results show that the maximum equivalent creep strain(CEEQ)and damage values were located in the glass ceramic sealing layer when the SOFC continuously worked for 50000 h at 600?.However,the maximum CEEQ and damage was not in the same position due to the effect of the stress multiaxiality.In addition,with the increase of the uniaxial creep failure strain of glass ceramic,the CEEQ and damage decrease significantly.(2)A novel time-dependence failure probability model was proposed by modifying the traditional Weibull failure probability calculation model.And the time-dependence failure probability of the SOFC was calculated by the subroutine compiled Fortran language,which was incorporated into the finite element code ABAQUS.The study found that the largest failure probability is observed at the glass ceramic sealing layer when the SOFC worked for 50000 h at 600?.Furthermore,with the characteristic creep strain and Weibull modulus of the glass ceramic increase,the failure probability of the SOFC stack decrease.And the characteristic strain should be larger than 0.01 and Weibull modulus should be larger than 8.0 of the glass ceramic to ensure the high temperature integrity of the SOFC stack,(3)The role of geometric dimensions and operating temperature on creep damage and failure probability of the SOFC were detailedly discussed.The results show that the CEEQ,damage distribution and failure probability represent a slightly decreased tendency with the increase of the cathode thickness.The thickness of the electrolyte,anode and window frame has significant influence on the CEEQ,damage distribution and failure probability,i.e.,with the increase of their thickness,the CEEQ,damage and failure probability all increased dramatically.As the key position of the SOFC,the geometric dimensions of the glass ceramic sealant mainly dominate the strength of whole structure,i.e.,as the thickness and width increase,the CEEQ,damage distribution and failure probability decrease.With the increase of the working temperature,the stress of the SOFC stack decrease,which results in a obvious decrease of the CEEQ,damage distribution and failure probability.