Non-Fourier thermoelastic interaction of two collinear cracks in a functionally graded layer

Designed with a predetermined composition profile, functionally graded materials receive much attention in serving as the thermal barrier coating to resist severe thermal loading. By means of the dual-phase-lag theory, the non-Fourier effect is considered in establish-ing the theoretical thermoelastic model of the cracked layer under sudden thermal shocks. The novelty of the present work lies in revealing the interaction effects of two collinear Griffith cracks embedded in a functionally graded layer on the transient temperature and thermal stress fields under harsh conditions. Via employing the Fourier sine and cosine transforms, coupled with the Laplace transform, the dynamic mixed mode crack problem is transformed into a group of Cauchy-type singular integral equations. Numerical calcula-tions are implemented to evaluate the transient temperature and stress intensity factors. The influences of the crack spacing, the nonhomogeneous parameters, and the thermal lags on the thermal and stress concentrations are explored. The results indicate that both mode I and II thermal stress intensity factors of the outer crack tips are noticeably higher than those of the inner crack tips, even up to 71% and 128%, respectively. A larger fracture risk may occur with the closer two adjacent cracks.& COPY; 2023 Elsevier Inc. All rights reserved.

Automated summary

By utilizing the dual-phase-lag theory, this study establishes a theoretical thermoelastic model of a cracked layer in functionally graded materials to unveil the interaction effects of two collinear Griffith cracks under harsh conditions. Numerical calculations evaluate the transient temperature and stress intensity factors, while exploring the influences of crack spacing, nonhomogeneous parameters, and thermal lags on thermal and stress concentrations. The results show significantly higher thermal stress intensity factors at the outer crack tips compared to the inner crack tips, with differences up to 71% and 128% for mode I and II, respectively. These findings suggest a higher risk of fracture with closer adjacent cracks.