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Electroelastic Analysis of Piezoelectric Composites Using Electro-Echanical Equivalent Inclusion Method:A Micromechanical Approach

Hashemi, Roohollah | 2011

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 41940 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Kargarnovin, Mohammad Hassan; Mohammadi Shodja, Hossein
  7. Abstract:
  8. It is the main idea of present thesis to provide a micromechanical method as a general treatment for several fundamental problems of the piezoelectric inhomogeneities. For initial demonstration of pertinent methodology, a single piezoelectric inhomogeneity of ellipsoidal geometry, under non-uniform far-field loading is considered. Accordingly, it is taken equivalent to elastic and dielectric inclusion problems connected by proper eigenstrain-electric field. This approach is named the electro-mechanical equivalent inclusion method (EMEIM) and requires that the electroelastic fields of the inhomogeneity to be equal to fields of the equivalent inclusions. Afterwards, the complex problem of interacting piezoelectric inhomogeneities of arbitrary size, orientation and material constants, subjected to the non-uniform far-field electro-mechanical loadings is proposed. Based on the extension of the EMEIM, a rigorous and analytical solution of pertinent problem is provided. Next, by utilizing the EMEIM in conjunction with an innovative decomposition approach, a unified method is established for determination of the associated electroelastic fields over a double-phase piezoelectric reinforcement. The methodology is further extended to the piezoelectric multi-inhomogeneity systems, where the particle core is surrounded by many layers of coatings of ellipsoidal shapes. Through consideration of various examples, the validity and applicability of the present theory are thoroughly demonstrated. As a special case encompassed by the presented formulation, the interaction of a single/coated piezoelectric inhomogeneity and a crack/anticrack for two- and three-dimensional problems are addressed. As the ending work, a new robust homogenization scheme for determination of the effective properties of piezoelectric composite with general multi-coated inhomogeneities is developed. In this scheme the coating does not have to be thin, the shape and orientation of the particles and coatings do not have to be identical, their centers do not have to coincide, their properties do not have to remain uniform, and the microstructure can be with the 2-D elliptic or the 3-D ellipsoidal inclusions. To demonstrate its wide range of applicability, we applied it to examine the properties of several piezocomposites
  9. Keywords:
  10. Interaction ; Coverage ; Stress Intensity Factor ; Piezocomposite ; Micromechanics ; Piezoelectric Inhomogeneity ; Electromechanical Equivalent Inclusion Method (EMEIM)

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