skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: FRACTURE FAILURE CRITERIA OF SOFC PEN STRUCTURE

Abstract

Thermal stresses and warpage of the PEN are unavoidable due to the temperature changes from the stress-free sintering temperature to room temperature and mismatch of the coefficients of thermal expansion (CTE) of various layers in the PEN structures of solid oxide fuel cells (SOFC) during the PEN manufacturing process. In the meantime, additional mechanical stresses will also be created by mechanical flattening during the stack assembly process. The porous nature of anode and cathode in the PEN structures determines presence of the initial flaws and crack on the interfaces of anode/electrolyte/cathode and in the interior of the materials. The sintering/assembling induced stresses may cause the fracture failure of PEN structure. Therefore, fracture failure criteria for SOFC PEN structures is developed in order to ensure the structural integrity of the cell and stack of SOFC. In this paper, the fracture criteria based on the relationship between the critical energy release rate and critical curvature and maximum displacement of the warped cells caused by the temperature changes as well as mechanical flattening process is established so that possible failure of SOFC PEN structures may be predicted deterministically by the measurement of the curvature and displacement of the warped cells.

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
960326
Report Number(s):
PNNL-SA-53375
AA2530000; TRN: US200923%%398
DOE Contract Number:
AC05-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: Advances in Solid Oxide Fuel Cells III; 31st International Conference on Advanced Ceramics and Composites; Ceramic Engineering and Science Proceedings, 28(4):389-402
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; ANODES; CATHODES; CERAMICS; DEFECTS; FRACTURES; MANUFACTURING; SINTERING; SOLID OXIDE FUEL CELLS; STRESSES; THERMAL EXPANSION; THERMAL STRESSES; fracture criteria, SOFC, PEN

Citation Formats

Liu, Wenning N., Sun, Xin, Khaleel, Mohammad A., and Qu, Jianmin. FRACTURE FAILURE CRITERIA OF SOFC PEN STRUCTURE. United States: N. p., 2007. Web.
Liu, Wenning N., Sun, Xin, Khaleel, Mohammad A., & Qu, Jianmin. FRACTURE FAILURE CRITERIA OF SOFC PEN STRUCTURE. United States.
Liu, Wenning N., Sun, Xin, Khaleel, Mohammad A., and Qu, Jianmin. Mon . "FRACTURE FAILURE CRITERIA OF SOFC PEN STRUCTURE". United States. doi:.
@article{osti_960326,
title = {FRACTURE FAILURE CRITERIA OF SOFC PEN STRUCTURE},
author = {Liu, Wenning N. and Sun, Xin and Khaleel, Mohammad A. and Qu, Jianmin},
abstractNote = {Thermal stresses and warpage of the PEN are unavoidable due to the temperature changes from the stress-free sintering temperature to room temperature and mismatch of the coefficients of thermal expansion (CTE) of various layers in the PEN structures of solid oxide fuel cells (SOFC) during the PEN manufacturing process. In the meantime, additional mechanical stresses will also be created by mechanical flattening during the stack assembly process. The porous nature of anode and cathode in the PEN structures determines presence of the initial flaws and crack on the interfaces of anode/electrolyte/cathode and in the interior of the materials. The sintering/assembling induced stresses may cause the fracture failure of PEN structure. Therefore, fracture failure criteria for SOFC PEN structures is developed in order to ensure the structural integrity of the cell and stack of SOFC. In this paper, the fracture criteria based on the relationship between the critical energy release rate and critical curvature and maximum displacement of the warped cells caused by the temperature changes as well as mechanical flattening process is established so that possible failure of SOFC PEN structures may be predicted deterministically by the measurement of the curvature and displacement of the warped cells.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Apr 30 00:00:00 EDT 2007},
month = {Mon Apr 30 00:00:00 EDT 2007}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • Due to the mismatch of thermal expansion coefficients (TEC) of the various layer materials in SOFC, the internal stresses are unavoidable under temperature differential. In order to create the reliable cell and stack of solid oxide fuel cell (SOFC), it is necessary to develop a failure criterion for SOFC PEN structures for the initial failures occurred during cell/stack assembly. In this paper, a global failure criterion is developed for the initial design against mechanical failure of the PEN structure in high temperature SOFCs. The relationship of the critical energy release rate and critical curvature and maximum displacement of the warpagemore » of the cells caused by the temperature differential is established so that the failure reliability of SOFC PEN structures may be determined by the measurement of the curvature and displacement of the warpaged cells.« less
  • Two criteria are implemented in a piping reliability analysis code to assess the stability of crack growth in pipes. One is the critical net section stress criterion. It is simple and convenient but its application is limited to very ductile materials. The other is the tearing modulus stability criterion. This criterion has a solid technical base. However, calculating the J-integral, J, and the associated tearing modulus, T, usually requires a complicated finite element method (FEM). In this piping reliability code, existing J and T solutions in tabular or formula form instead of the FEM are used for computational efficiency. Thesemore » two failure criteria are discussed and compared in terms of their effects on the estimation of pipe failure probability. 5 refs., 9 figs.« less
  • The objective of this project is to develop first-order failure criteria to be used for the initial design, material selection and optimization against thermomechanical failure of the PEN structure in high temperature SOFCs.
  • One of the major problems of SOFC is the sintering of Ni particles operation which causes the degradation of fuel electrode. To suppress the sintering of Ni particles, the authors have been trying to achieve homogeneous dispersion of Ni particles and fix them in the film. Ni/YSZ powder composed of Ni particles strongly combined with YSZ(Yttria Stabilized Zirconia) particles by mechanical milling techniques, etc., were studied, and some of powders proved to be effective for the suppression of the sintering of Ni particles.
  • In Part 1 of this paper, Gurson`s mixed hardening plasticity model with strain and stress-controlled nucleations, was used in large deformation finite element program to study the plastic flow and damage in the uniaxial compression of cylinders under sticking friction. Due to low stress triaxiality at the bulge of the cylinders, it was found that localization may occur before void coalescence. In this paper, necessary conditions of localizations are analyzed for the axial compression of porous cylinders under sticking friction. Shear band type of localization with a normal mode of fracture has been predicted for the majority of the casesmore » studied. Various existing localization conditions and fracture criteria are assessed using the results form the simulation. The maximum shear stress at failure is approximately constant and a constant critical damage can not be found.« less