Theoretical And Numerical Analysis Of The Strength Of The Heterogeneous Material Interface

It was found that stress singularities which caused by discontinuous of geometry or mechanical properties of heterogeneous materials exist on interface corners or edges. Singular stress field is a significant factor which leading immature failure for bonded junctions. To analysis the stress singularities field of singular point is a meaningful learning for enhancing the strength of heterogeneous materials junctions. This paper derived the complex variable function method and Airy stress function method in detail to solve heterogeneous material stress singularities problem.It is known that eigenvalues are influenced by the Young’s modulus, Poisson’s ratio and interface angles. This paper uses Airy stress function method, talking about bi-and tri-material junctions stress singularities by changing the elastic modulus of the bonding material, Poisson’s ratio, and bonding angle, respectively. Used steel, aluminum, polycarbonate (PC), polymethylmethacrylate(PMMA) bonding models, to compare stress singularities influenced by changing of the interface bonding angle θ from0°to180°. Preliminary selecting90°,75°,60°,49°(53°) as the experimental interface bond angles. And all these heterogeneous materials junctions adopt four-point bending test in the further research.For three materials ideal interfaces bonding models, selecting steel, aluminum, ceramic materials and epoxy as bonding matching combinations. Using Airy stress function method, solve stress singularities influenced by changing interface angle of the tri-material junction. This paper solved distributions of angular functions around interface end corresponding bi-material and tri-material junctions for90°and135°interface angles differently. It can be known that stress functions in softer materials vary slower than in harder materials with increasing θ. But for the displacements values in softer materials vary much more rapidly than in harder materials. All these performances are consistent with mechanical behavior of materials. Comparing examples of bi-material and tri-material junctions, it can be readily known that for the given combination of material junctions, bi-material junction is easier to eliminate stress singularities than tri-material junction by varying interface angles.Stress singularities are difference between3-D and2D problem.3-D problem can be solved by plane stress functions after fillet. Solved eigenvalues of bi-material junction combine of steel, ceramics and epoxy, aiding by finite element software. According to the theory and numerical solution, design the sample model with and without arc chamfering cases, and solved stress singularities of these models used numerical method. Using PC-AL sample to test interface strength by verifying intersect dimension and interface angle. By doing so to provide a reference for the next step work that is for fillet sample experiments.