Residual Stress Characteristics of Functionally Gradient Joint

Abstract

The residual stresses of functionally gradient materials induced by a bonding process were analyzed by comparison with the direct bonding joints between different materials. In this paper, firstly, the gradation joints of stabilized zirconia/nickel based alloy composites were chosen for a finite element method analysis of residual stress distributions.
It was verified that the residual stresses produced by uniform heating process decreased by use of the gradation techniques. Especially, the stress singularities at the edge of the interface of the direct bonding ioints could be disanneared in case of the gradation joints.
Secondly, the effects of the gradation geometry and material constants, such as Young's modulus and thermal expansion coefficients on the residual stresses were investigated. As a result, it was found that the residual stresses could be effectively analyzed by application of a dimensionless parameter, which is σ(1-μ₁)/(E₁(α₁-α₂)ΔT) (σ; residual stress, μ₁, μ₂; Poisson's ratio, E₁; Young's modulus of material 1, (α₁-α₂); difference of thermal expansion coefficients between material 1 and material 2, ΔT ; temperature difference) in case of the gradation joints, and there was a tendency of decreasing the dimensionless residual stress with increasing the gradation thickness.