13th International Conference on Fracture June 16–21, 2013, Beijing, China -8- 5. Concluding Remarks This work is focused on the effects of cooling rate on the thermal stress intensity factors (TSIFs) at the tips of parallel edge cracks of alternating lengths in an FGM plate. The cooling rates at the surfaces of the FGM plate are described by a linear ramp function. The TSIFs are obtained using a closed-form, short-time temperature solution and an integral equation method. Numerical results for an Al2O3/Si3N4 FGM system show that the peak TSIFs at the tips of both long and short cracks decrease with a decrease in cooling rate. The variations of the peak TISF for the long and short cracks with the cooling rate and crack length ratio exhibit a complex pattern due to the interactions between the long and short cracks. References [1] A. Kawasaki, R. Watanabe, Fabrication of disk-shaped functionally gradient materials by hot pressing and their thermomechanical performance, in: J.B. Holt, M. Koizumi, T. Hirai, Z.A. Munir (Eds.), Ceramic Transactions, Vol. 34, American Ceramic Society, Westerville, OH, 1993, pp. 157–164. [2] K. Kokini, J. DeJonge, S. Rangaraj, B. Beardsley, Thermal shock of functionally graded thermal barrier coatings, in: K. Trumble, K. Bowman, I. Reimanis,S. Sampath (Eds.), Ceramic Transactions, Vol. 114, American Ceramic Society, Westerville, OH, 2001, pp. 213-221. [3] S. Rangaraj, K. Kokini, Multiple surface cracking and its effect on interface cracks in functionally graded thermal barrier coatings under thermal shock. ASME Journal of Applied Mechanics, 70 (2003) 234-245. [4] H.C. Han, B.L. Wang, Thermal shock resistance enhancement of functionally graded materials by multiple cracking. Acta Materialia, 54 (2006) 963-973. [5] Z.H. Jin, Y.Z. Feng, Thermal fracture resistance of a functionally graded coating with periodic edge cracks. Surface & Coatings technology, 202 (2008) 4189-4197. [6] Z.H. Jin, Y.Z. Feng, Effects of multiple cracking on the residual strength behavior of thermally shocked functionally graded ceramics. International Journal of Solids and Structures, 45 (2008) 5973-5986. [7] S. Nemat-Nasser, L.M. Keer, K.S. Parihar, Unstable growth of thermally induced interacting cracks in brittle solids. International Journal of Solids Structures, 14 (1978) 409-430. [8] H.A. Bahr, H.J. Weiss, H.G. Maschke, F. Meissner, Multiple crack propagation in a strip caused by thermal shock. Theoretical and Applied Fracture Mechanics, 10 (1988) 219-226. [9] Z.H. Jin, Y.Z. Feng, An array of parallel edge cracks with alternating lengths in a strip subjected to a thermal shock. Journal of Thermal Stresses, 32 (2009) 431-447. [10] Y.Z. Feng, Z.H. Jin, Thermal fracture of a functionally graded plate with parallel surface cracks. Acta Mechanica Solida Sinica, 22 (2009) 453-464. [11] Y.Z. Feng, Z.H. Jin, Thermal shock damage and residual strength behavior of a functionally graded plate with surface cracks of alternating lengths. Journal of Thermal Stresses, 35 (2012) 30-47. [12] Z.H. Jin, Heat conduction in a functionally graded plate subjected to finite cooling/heating rates: An asymptotic solution. Materials, 4 (2011) 2108-2118.
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