A Crack Model Around Junctions in WC/Co Composite
The presence of the elastic-plastic interface material, i.e. Co binder, in the composite structure is the reason for initiation of technological defects – mainly material porosity. During material loading pores start to coalesce and finally one can observe creation of microcracks system distributed along interfaces.
The aim of the paper is to show the previously formulated model ,  of the polycrystalline composite to be extended towards cracks development around the junctions of the interfaces. The obtained numerical results indicate that in the junctions high stress concentrations were observed, which leads to crack initiation and its further unstable propagation, and finally the composite failure.
Results indicate that the first crack appears close to the junction and that the load carrying capacity of the sample is overestimated if a crack model in the interfaces is not assumed.
Sadowski T., Hardy S., Postek E., Prediction of the mechanical response of polycrystalline ceramics containing metallic intergranular layers under uniaxial tension, Computational Materials Science, 34(1): 46–63, 2005, doi: 10.1016/j.commatsci.2004.10.005.
Postek E., Sadowski T., Assessing the Influence of Porosity in the Deformation of Metal-Ceramic Composites, Composite Interfaces, 18(1): 55–76, 2011, doi: 10.1163/092764410X554049.
Siegl L.S., Exner H.E., Experimental study of the mechanics of fracture in WC-Co alloys, Metallurgical Transactions A, 18(7): 1299–1308, 1987, doi: 10.1007/BF02647199.
Dalgleish B.J., Lu M.C., Evans A.G., The strength of ceramics bonded with metals, Acta Metallurgica, 36(8): 2029–2035, 1988, doi:10.1016/0001-6160(88)90304-5.
Sadowski T., Samborski S., Development of damage state in porous ceramic under compression state, Computational Materials Science, 43(1): 75–81, 2008, doi: 10.1016/j.commatsci.2007.07.041.
Ravichandran K.S., Fracture toughness of two phase WC-Co cermets, Acta Metallurgica et Materialia, 42(1): 143–150, 1994, doi: 10.1016/0956-7151(94)90057-4.
Dalgleish B.J., Trumble K.P., Evans A.G., The strength and fracture of alumina bonded with aluminium alloys, Acta Metallurgica, 37(7): 1923–1931, 1989, doi: 10.1016/0001-6160(89)90077-1.
Abaqus 6.13. User’s Manual.
Felten F., Schneider G.A., Sadowski T., Estimation of R-curve in WC/Co cermet by CT test, International Journal of Refractory Materials and Hard Materials, 26(1): 55–60, 2008, 10.1016/j.ijrmhm.2007.01.005.
Camanho P.P., Dávila C.G., Mixed-mode decohesion finite elements for the simulation of delamination in composite materials, NASA Scientific and Technical Infomlation (STI) Program, NASA/TM-2002-211737, 2002. ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20020053651.pdf.
Zavattieri P.D., Hector L.G., Bower A.F., Cohesive zone simulations of crack growth along a rough interface between two elastic-plastic solids, Engineering Fracture Mechanics, 75(15): 4309–4332, 2008, doi: 10.1016/j.engfracmech.2007.11.007.
Kachanov L.M., Introduction to Continuum Damage Mechanics, Martinun Nijhoff Publishers, Dordrecht, 1986.
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