PSI - Issue 61

Mehmet N. Balci et al. / Procedia Structural Integrity 61 (2024) 331–339 Balci and Yalcin / Structural Integrity Procedia 00 (2019) 000 – 000

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5. Conclusions Thermal shock loading problem for homogenous coating-bond coat-substrate system was examined numerically based on Finite Element Method (FEM) using Displacement Correlation Technique (DCT). Two different crack configurations were studied under the effect of both cold and hot thermal shock loading. Mode-I and II SIFs and Energy Release Rate (G) were calculated and values of energy release rate (G) obtained based on DCT were compared with those acquired by J-integral. A good agreement was observed between results. The main limitation of this study is assuming the material properties of bond coat same as those used for either coating or substrate depending on the crack configuration. If this assumption was not considered, material properties at upper and lower faces of the crack would be different, which results in an oscillatory behaviour of singularity at the crack tip and complex SIFs. The following conclusions can be drawn from this study: • For the larger length of the crack, both mode-I, mode-II SIFs and Energy Release Rate (G) are greater under the effect of both cold and hot thermal shock loadings. • While phase angle ( ∅ ) reaches steady level after t=2s for cold thermal shock, it displays a remarkable decreasing behaviour for hot thermal shock, indicating different failure (shear/opening mode) behaviour. • Values of mode-I and mode-II SIFs generated for hot thermal shock condition are greater than those computed for cold thermal shock. • Increase in the elastic modulus of the surface coating leads to a decrease in mode-I and mode-II SIFs. Phase angle ( ∅ ) is greater for larger values of sc s E E which indicates shear dominant result at crack tip stress field. References ANSYS, 2016. ANSYS Basic Analysis Procedures Guide, Release 17.1. ANSYS Inc., Canonsburg, PA, USA. Białas, M. 2008. Finite element analysis of stress distribution in thermal barrier coatings. Surf. Coat. Technol. 202, 6002 – 6010. Bumgardner, C., Croom, B., Li, X. 2017. High-temperature delamination mechanisms of thermal barrier coatings: In situ digital image correlation and finite element analyses, Acta Mater. 128, 54-63. Clarke, D.R., Phillpot, S.R. 2005. Thermal barrier coating materials. Mater. Today 8, 22 – 29. Clarke, D.R., Oechsner, M., Padture, N.P. 2012. Thermal-barrier coatings for more efficient gas-turbine engines. MRS Bull . 37, 891 – 898. Dag, S., Ilhan, K.A. 2008. Mixed-mode fracture analysis of orthotropic functionally graded material coatings using analytical and computational methods. J. App. Mech.-Transactions of ASME 75, p.051104 1-9. Dundurs, J. 1969. Edge-bonded dissimilar orthogonal elastic wedges. J. Appl. Mech. 36, 650-652. Eischen, J.W. 1987. Fracture of non-homogenous materials. Int. J. Fract. 34, 3-22. Fan, X., Xu, R., Wang, T.J. Interfacial delamination of double-ceramic-layer thermal barrier coating system. Ceram. Int. 40, 13793-13802. Hutchinson, J.W., Suo, Z. 1991. Mixed Mode Cracking in Layered Materials. Adv. Appl. Mech. 29, 63-187. Jin, Z.H., Noda, N. 1994. Crack tip singular fields in non-homogenous materials. ASME J. Appl. Mech. 61(3), 738-740. Kim, J.-H., Paulino, G.H. 2002. Finite element evaluation of mixed mode stress intensity factors in functionally graded materials. Int. J. Numer. Meth. Eng. 53, 1903-1935. Li, W., Li, J., Song, F., 2020. Biot number effect and non-Fourier effect on temperature field and stress intensity factor of a cracked strip under thermal shock loading. Eng. Fract. Mech. 228, 106923. Ping-wei, C., Shao-ming, W., Feng-Hui, W. 2015. Fracture analysis of Thermal Barrier Coating Delamination under Thermal Shock. 2014 Asia Pacific International Symposium on Aerospace Technology APISAT2014 Procedia Engineering 99, 344-348. Padture, N.P., Gell, M. Jordan, E.H. 2002. Thermal barrier coatings for gas-turbine engine applications. Science 296, 280 – 284. Padture, N.P. 2016. Advanced structural ceramics in aerospace propulsion. Nat. Mater. 15, 804 – 809. Stolarski, T., Nakasone Y., Yoshimoto S. 2018. Application of ANSYS to stress analysis in “ Engineering Analysis with ANSYS Software (Second Ed.) ”. Butterworth- Heinemann, pp. 51-163. Yildirim, B., Dag, S., Erdogan, F. 2005. Three dimensional fracture analysis of FGM coatings under thermomechanical loading. Int. J. Frac. 132, 369-395. Yildirim, B., Erdogan, F. 2010. Edge Crack Problems in Homogenous and Functionally Graded Material Thermal Barrier Coatings Under Uniform Thermal Loading. J. Therm. Stresses 27(4): 311-329. Zhao, M. Pan, W., Wan, C., Qu, Z., Li, Z., Yang, J. 2017. Defect engineering in development of low thermal conductivity materials: a review. J. Eur. Ceram. Soc. 37, 1 – 13. Zok, F.W. 2016. Ceramic-matrix composites enable revolutionary gains in turbine engine efficiency. Am. Ceram. Soc. Bull. 95, 22 – 28.