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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Table 2. Normalized mode-I and mode-II SIFs obtained by DCT and ANSYS (2016) for Case-A, a=1.0 mm. t (s) ( ) * DCT I K ( ) * ANSYS(2016) I K %  ( ) * DCT II K ( ) ( ) * ANSYS 2016 II K %  0.2 -0.04149 -0.04141 0.19703 0.041151 0.040483 1.650756 0.4 -0.01282 -0.01274 0.58803 0.081534 0.080756 0.963413 0.8 -0.00512 -0.00506 1.253383 0.079166 0.078469 0.888449 1 -0.00428 -0.00422 1.384043 0.073952 0.073305 0.88292 2 -0.00268 -0.00264 1.492113 0.050534 0.050094 0.878961

Fig. 3. The influence of crack length on (a) Normalized mode-I SIF vs time, (b) Normalized mode-II SIF vs time, (c) Total energy release rate vs time, (d) Phase angle vs time in a cold thermal shock Case-A configuration.

Fig. 4. Temperature contours in the coating system for cold thermal shock at time t=1.0s for Case-A configuration (a) = 0.5 , (b) = 1.0 , (c) = 1.5 , (d) = 2.0 . However, there is almost no decrease in  for small crack, i.e. 0.5 , a mm = which means crack-tip stress field is always shear dominant. In Fig. 4, temperature contours are presented for the cold shock in Case-A at t=1.0s for various values of crack length such as a = 0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm. The lowest temperature values are observed around the close vicinity of the crack at the surface of the coating since crack faces are assumed to be thermally insulated. Fig. 5 displays the corresponding fracture parameters of the coating system under the effect of hot shock. Mode I and Mode II SIFs are increased for larger lengths of crack. Again, as the crack length is increased, total energy release rate is increased. It is worthy to say that the level of energy release rate is larger in hot shock when compared to that in cold shock. Hence, hot thermal shock is more critical in this case. The phase angle is decreasing as shock time is