13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Paper Template for 13th International Conference on Fracture FirstName LastName1,*, Second Author1, Third Author2 Cracking simulation of ceramic materials under thermal shock by a non-local fracture model Li Jia1,*, Song Fan2, Jiang Chiping3 1LSPM, CNRS UPR 3407, Université Paris XIII, Villetaneuse, France; 2State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China; 3Solid Mechanics Research Center, Beijing University of Aeronautics and Astronautics, Beijing, China *Corresponding author: jia.li@univ-paris13.fr Abstract: In this work, we attempted to simulate the cracking process of ceramic beams subjected to quenching from different high temperatures to the ambient one. Based on a non-local damage theory and the linear fracture mechanics, a numerical model was established and implemented into a finite element code. This model is adjusted with two critical situations: it is equivalent to the maximum principal stress criterion when the specimen is subjected to uniform tensile stress and to the Griffith-Irwin criterion for the growth of a macro-crack. By using this numerical model, the initiation and propagation of cracks in quenched ceramic specimens were simulated. It was proved that the proposed damage model is capable to describe the detailed cracking process with high reliability comparing to the experimental results. Several typical characteristics in thermal shock failure such as the multi-cracking procedure, the hierarchical crack distribution, the distances between cracks etc. were faithfully described with high accuracy. Key words: Thermal shock; Crack patterns; Non-local fracture model; Numerical simulations; Ceramics 1. Introduction Ceramic materials exhibit excellent high temperature mechanical properties, corrosion resistance, wear resistance, erosion resistance, oxidation resistance etc. However, they are in general quite vulnerable to thermal shock failure. In general, crack formation is considered as the major reason of failure in thermo-structural engineering. Understanding the mechanisms of cracking process in ceramics under thermal loads has been one of the most importance tasks in the research of this field. The earliest researches on fracture of ceramic materials underwent thermal shock by Kingery [1,2] and Hasselman [3]. Afterward, numerous theoretical and experimental studies on thermal shock failure of ceramics have been reported [4-15]. However, the crack pattern formation under thermal shock is quite a rapid and highly complicated process. This process is difficult to capture with available experimental techniques. Only final crack patterns can easily be observed. This is why direct numerical simulations are particularly interesting in reproducing the cracking process. As results, the failure mechanisms and the control parameters can be better understood. Unfortunately, the direct numerical simulations have rarely been reported in the literature so far due to the inherent complexities in multi-cracking modelling. In this work, a non-local failure criterion was used and implemented into a finite element code and then applied to simulate the crack evolution in ceramic materials subjected to thermal shock. The proposed fracture model is equivalent to the maximum principal stress criterion for a specimen under pure tensile loading, and to the Griffith-Irwin criterion for the crack propagation. Consequently, this non-local fracture model can both predict crack initiation as well as crack
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