Graphite fracture models

Burchell, T.D., A microstructurally based fracture model for polygranular graphites. Carbon, 1996, 34(3), 297 316. 

Rose and Tucker applied their fracture model to Sleeve graphite, an extmded, medium-grain, pitchcoke nuclear graphite used for fuel sleeves in the UK AGR (see Chapter 13). The performance of the model was disappointing the predicted... 

Fig. 17. Graphite microstructure as conceived in the Burchell fracture model.

T. D. Burchell. A Microstructurally Based Fracture Model for Nuclear Graphites. In Proc. IAEA Specialist s Meeting on Status of Graphite Development for Cos Cooled Heac/ors, Told-Mura, Japan, Sept 1991, IAEA TECDOC No. 690, Pub. IAEA, Vienna, 1993, pp. 49 58. 

T. D. Burchell and J. P. Strizak. The Performance of a Fracture Model for Graphites. In Proc. Carbon 94, Granada, Spain. Published Spanish Carbon Society, 1994, pp. 128 129. 

Burchell T.D., A Microstructurally based Fracture Model for Polygranular Graphites, Carbon 2AO) 1996, 297 316... 

N. McLachlan. The Modelling of Polycrystalline Graphite Fracture and Deformation Properties, Ph.D. Thesis, University of Exeter, UK, 1992. 

Several additional, non-microstructural, inputs are required for the fracture model (i) Particle critical stress intensity factor, KIc. Here, the value determined in a previous study (Klc = 0.285 MPa in )[3] was adopted for all four graphites studied. This value is significantly less than the bulk Klc of graphites (typically -0.8-1.2 MPa rn). However, as discussed in the previous section, when considering fracture occurring in volumes commensurate in size with the process zone a reduced value of Klc is appropriate (ii) the specimen volume, taken to be the stressed volume of the ASTM tensile test specimens specimen used to determine the tensile strength distributions and (iii) the specimen breadth, b, of a square section specimen. For cylindrical specimens, such as those used here, an equivalent breadth is calculated such that the specimen cross sectional area is identical, i.e.,... 

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