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Prediction of Crack Path Based on Geometrical Parameters for Si3N4 Ceramics
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SYSNO ASEP 0435049 Document Type O - Others R&D Document Type Others Title Prediction of Crack Path Based on Geometrical Parameters for Si3N4 Ceramics Author(s) Chlup, Zdeněk (UFM-A) RID, ORCID
Hadraba, Hynek (UFM-A) RID, ORCID
Kozák, Vladislav (UFM-A) RID, ORCID
Dlouhý, Ivo (UFM-A) RID, ORCID
Petráš, Roman (UFM-A)Year of issue 2014 Language eng - English Country NO - Norway Keywords Silicon nitride ; Ceramic ; Crack path Subject RIV JL - Materials Fatigue, Friction Mechanics Institutional support UFM-A - RVO:68081723 Annotation The high fracture toughness of silicon nitride ceramic is given by reinforcement of microstructure by elongated beta silicon nitride grains. The effect of reinforcement is dependent on many factors as grain aspect ratio, glassy phase, presence of so called “snowflakes” etc. Present computation capacities enable modelling of fracture processes undergoing in such materials on the microstructure level. However, the complexity of the microstructure causes difficulties with the crack propagation modelling. Especially the interfacial grain decohesion energy is not simple to determine. The indentation technique for fracture microstructural parameters determination was used because of its simplicity and straight forward application for any other material. An Extensive fractographic analysis was employed to determine fracture patterns. Mainly the observation using scanning electron microscopy showed behaviour of individual grains where inter-granular and trans-granular fracture was clearly distinguished. The statistical analysis was employed to find the most reliable and robust parameters governing the fracture process with respect to the condition that no additional material characteristic will be needed. Based on the obtained results the damage model describing behaviour of the crack of the grain boundaries was developed. The robust parameters describing the fracture process were selected based on the statistical multifactor analysis. The stochastic nature of the acting fracture mechanisms was taken into account for the damage model development trough incorporating the three-parameter Weibull distribution function. The newly proposed damage model obtained from indentation cracks determine geometrical parameters controlling fracture for given material. Based on the statistical evaluation of geometrical situation on the crack tip it is possible to determine crack path. This approach can be easily accommodated to the FEM calculations. Workplace Institute of Physics of Materials Contact Yvonna Šrámková, sramkova@ipm.cz, Tel.: 532 290 485 Year of Publishing 2015
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