On crack growth in functionally graded materials

    Research output: ThesisDoctoral Thesis

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    Abstract

    Stress intensity factors’ behaviour is studied for long plane cracks interacting with a region of functionally graded elastic material. The region is assumed embedded into a large body treated as a homogeneous elastic continuum. The analysis is limited to small deviations of the graded region’s elastic modulus from that of the surrounding body (Poisson’s ratio is kept constant) and analytical solutions are sought using a perturbation technique. Emphasis is laid on the case of an infinite strip, which admits a closed form solution. A cosine change of the modulus of elasticity is treated, furnishing the solution for arbitrary variation in the form of a Fourier’s expansion. Finite element analysis is subsequently performed for investigating the scope of validity of the analytical solution. The results for a set of finite changes of the elastic modulus are compared with the analytical predictions, and a remarkably wide range of validity is demonstrated. New functions, suitable for non-homogeneous material description, are introduced to approach the case of non-constant Poisson’s ratio. The properties and possible applications of these functions are examined.
    Original languageEnglish
    QualificationMaster of Philosophy
    Awarding Institution
    • Luleå University of Technology
    Supervisors/Advisors
    • Ståhle, Per, Supervisor, External person
    Award date7 Feb 2002
    Publisher
    DOIs
    Publication statusPublished - 20 Dec 1999

    Keywords

    • functionally graded materials
    • layered materials
    • composites
    • crack growth
    • stress intensity factors
    • perturbation technique
    • complex potentials
    • finite element method

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