Browsing by Subject "Finite-element method"

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Open Access
Homogenization of size-dependent multiphysics behavior of nanostructured piezoelectric composites with energetic surfaces
(Elsevier, 2022-07-16) Chen, Q.; Chatzigeorgiou, G.; Javili, Ali
Surface piezoelectricity considering the extended Gurtin–Murdoch coherent interface model has been incorporated into the composite cylinder assemblage (CCA), generalized self-consistent method (GSCM), as well as the multiphysics finite-element micromechanics (MFEM), for simulating the size-dependent multiphysics response of nanoporous materials wherein interface stress and electric displacement prevail. In the case of the CCA/GSCM model, the coherent interface model is implemented through the generalized Young–Laplace equations that govern the variation of the surface stress and the surface electric displacement. Three loading modes are utilized to identify the closed-form solutions for a complete set of Hill's moduli, and piezoelectric and dielectric constants. In the case of the MFEM, surface piezoelectricity is incorporated directly through additional surface energies associated with the elements that stretch along the interface. In order to assess the accuracy of the developed computational approaches, the generalized Kirsch problem under far-field transverse electric displacement loading is developed for recovering electric displacement concentration in the vicinity of the pore boundary. Homogenized properties are generated and critically examined for a broad variety of parameters and dimensions, predicted by the CCA/GSCM and MFEM methods. It is shown that all the predicted effective properties of these two families of homogenization techniques are similar except for the transverse shear moduli where they show marked differences that are reminiscent of what has been observed in the absence of surface electricity. © 2022 Elsevier Masson SAS
Open Access
Phononic crystals with archimedean-like tiling: band structure and the transformation of sound
(Taylor & Francis, 2021-12-01) Ozer, Z.; Mamedov, Amirullah M.; Ozbay, Ekmel
In this study, we investigate acoustic wave propagation in 3 D phononic crystal (PnC) slabs wherein scatterers have different cross sections by using the finite-element method. The PnC consists of scatterers embedded in the host material arranged in a square lattice and honeycomb lattice in different patterns (bathroom and ladybug tiling in Archimedean-like tiling). By determining the eigenmodes and band gaps, complete and accurate band structures and transmission spectra are obtained. Compared to traditional square lattice PnCs, it has been observed that the bands obtained in pattern structures may have some advantages in terms of width and position. It was also shown that the low-frequency response of two Archimedean-like structures was similar with respect to the traditional square lattice.