Effect of Compositional Distribution Profile on the Thermal Stress Mitigating Properties in Functionally Gradient Materials

• Published in: Transactions of the Japan Society of Mechanical Engineers Series A Vol. 57; no. 542; pp. 2427 - 2431
• Main Authors: KATO, Shinichiro, HASHIDA, Toshiyuki, TAKAHASHI, Hideaki
• Format: Journal Article
• Language: English; Japanese
• Published: The Japan Society of Mechanical Engineers 1991
• Subjects: Ceramics; Composite Material; Finite-Element Method; Law of Mixture; Numerical Analysis; Thermal Stress
• ISSN: 0387-5008; 1884-8338
• DOI: 10.1299/kikaia.57.2427

This paper presents some results of transient heat-transfer and thermal-stress analyses of functionally gradient materials (FGMs) subject to rapid heating. The objective of this study is to examine the effect of changing compositional distribution profiles in FGMs on the transient thermal stresses. Finite-element analysis are conducted on FGMs which posess different compositional gradients with varying mixture ratios of ZrO2 and NiCrAIY deposited on a copper substrfte. The thermal boundary conditions used for the analysis simulate the thermal load encountered in the thrust chamber of a rocket engine. A two-dimensional, axisymmetric model is used for the numerical computations, where the outer ZrO2 surface is subject to a heat flux and the inner copper surface temperature is kept at 0°C. It is shown that the hoop and axial stress in the FGMs are compressive, and the maximum tensile stress is the radial direction is induced at the interface between the coating layer and substrate, regardless of the different compositional profiles. It is further demonstrated that the gradient composition cas mitigate both the in-plane compressive stresses and interfacial radial tensile stress which are responsible for the cracking and delamination of the coating layers.