Thermal Residual Stress Analysis of Ni–Al2O3, Ni–TiO2, and Ti–SiC Functionally Graded Composite Plates Subjected to Various Thermal Fields

Abstract

This study investigates the thermal elastic residual stresses occurring in Ni–Al2O3, Ni–TiO2, and Ti–SiC functionally graded plates due to uniform, linear, and parabolic temperature fields through the plate thickness. A 3D eight-noded isoparametric layered (no limit layer number) finite element with three degrees of freedom at each node was implemented to the residual stress problem analogous to the shell elements proposed by Ahmad et al. (Ahmad, S., Irons, B.M. and Zienkiewicz, O.C. (1970). Analysis of Thick and Thin Shell Structures by Curved Finite Elements, Int. J. of Numerical Methods in Engineering, 2: 419–451.) and Yunus and Khonke (Yunus, S.M. and Khonke, P.C. (1989). An Efficient Through-Thickness Integration Scheme in an Unlimited Layer Doubly Curved Isoparametric Composite Shell Element, Int. J. of Numerical Methods in Engineering, 28: 2777– 2793.). The longitudinal stresses (11, 22) and transverse shear stresses (13, 23) were dominant. The shear stresses become important especially at the free edges of the plate. As the compositional gradient was increased the normal and shear stresses increased. Whereas the normal stresses become tensile in both ceramic-rich and metal-rich regions; the shear stresses, which are not severe in both the regions, change their directions and become a maximum inside the plate. The thermal and mechanical properties of constituents played an important role on the stress magnitudes rather than on the profiles of the through-thickness variations of normal and shear stresses. Thus, the difference of the coefficients of thermal expansion of the ceramic and metal phases affected the magnitudes of the normal and shear stresses. In addition, the continuous temperature fields through the plate thickness resulted in similar normal and shear stress variations.