Multi-material junctions with functionally graded materials

Paggi, Marco and Carpinteri, Alberto Multi-material junctions with functionally graded materials. In: AIMETA 2005 : atti del XVII Congresso dell’Associazione italiana di meccanica teorica e applicata : Firenze, 11-15 settembre 2005. Firenze University Press. ISBN 88-8453-313-9 (2005)

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Abstract

Composites frequently involve situations where nonhomogeneous materials are either present naturally, or used intentionally to attain a required mechanical performance. Starting from Bogy (1968), bi- and multi-material junctions between different homogeneous materials have been characterized from the stress-singularity point of view. In these studies, the material parameters were assumed to be constant inside each material region and an abrupt discontinuity of the elastic properties at the interfaces was allowed. More recently, another class of materials, conventionally referred to as functionally graded materials (FGMs), has been proposed, which involves materials whose elastic properties vary continuously. When two materials are joined together, an abrupt discontinuity of the elastic parameters, which is usually assumed for analytical purposes, does not exist in reality. On the contrary, materials in the proximity of the interface possess continuous, rapidly varying elastic moduli (Eischen (1987), Paulino (2002)). In this paper the problem of stress-singularity due to multi-material junctions composed of angularly nonhomogeneous elastic wedges in plane elasticity is addressed. For this new type of grading the governing equation for the Airy stress function is derived and, by applying the eigenfunction expansion method, a fourth order ODE with nonconstant coefficients for the eigenequation is obtained. The solution to this ODE permits to formulate an eigenvalue problem similar to that valid for material junctions between homogenous different materials. Moreover, it is mathematically demonstrated that the angular grading influences the order of the stresssingularity. The potentials of the use of this new class of materials in joining technology are carefully investigated and some illustrative examples involving three-material junctions are deeply discussed. Comparisons

Item Type: Book Section 17th AIMETA Congress of Theoretical and Applied Mechanics, Firenze, Italy, September 11-15, 2005 Multi-material junctions; Interfaces; Functionally graded materials; Asymptotic analysis; Stress-singularity; Fracture. T Technology > TJ Mechanical engineering and machinery Computer Science and Applications Prof Marco Paggi 22 Nov 2013 11:19 09 Oct 2014 09:20 http://eprints.imtlucca.it/id/eprint/1931