Finite element analysis of thermal residual stresses at graded ceramic-metal interfaces. Part II. Interface optimization for residual stress reduction

Abstract

An elastic-plastic finite element method numerical model previously developed (see Part I of this article) for predicting thermal residual stresses at graded ceramic-metal interfaces has been applied to determine interface conditions favorable for achieving residual stress reductions. Using Al2O3-Ni as a model system, and for a fixed specimen geometry, a study was performed to investigate the effects of different interlayer thicknesses and nonlinear composition profiles on strain and stress distributions established during cooling from an assumed elevated bonding temperature. For each interface condition, relative stress reductions were evaluated by comparing the magnitude of specific stress and strain components important for controlling interface failure with those predicted for a sharp (nongraded) interface. For the geometry considered, stress was reduced by thick graded interlayers and nonlinear composition profiles that distributed the largest property changes over the interlayer region having low elastic modulus and high plasticity. In contrast to the Part I results for a linear composition profile, the optimized interlayer condition effectively reduced the peak near-surface axial stress component.

Functional Biomimetic Dental Restoration

“…Drake et al The power distribution law was utilized to prove that significant stress and plastic strain reduction can be accomplished through increasing the ceramic materials thickness gradient and tailoring the exponent to create a compositional change gradient close to the parts showing high modulus and little plasticity [81]. Matsuo et al [82] fabricated functionally graded dental post (FGDP) using laser lithography, one of the photo-curing type computer-aided design/computer-aided manufacturing (CAD/ CAM).…”

Joining of Tungsten Armor Using Functional Gradients

“…In order to estimate the elastic and plastic properties of the different composites used as interlayer a modified rule of mixtures (ROM) was used. This ROM works well for functionally graded materials [8][9][10]. Figure 7 shows a schematic representation of this ROM.…”

“…The value of q used in the current model, -4.5 GPa, was based on earlier work [8,9] for the elastic-plastic system Al 2 O 3 -Ni. Williamson et al showed that the stress is not very sensitive to changes in the transfer coefficient [8].…”

“…For the Cu rich and W rich graded interlayers the following power law equation previously applied by Drake et al and Torres et al [9,14] was used: (9) where x is the distance from the W to the position in thickness, t is the total thickness of the graded region and p is an arbitrary exponent. Discrete layers are used to approximate the gradient.…”

Fabrication of Functionally Graded Composite Material using Powder Metallurgy Route, An Overview

“…Later on the stress singularity at the interface of a composite can be eliminated and thus bonding strength enhanced. Studies show that, the thermal residual stresses can be drastically reduced by using FGM [11][12][13].…”