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Micromechanics
About: Micromechanics is a research topic. Over the lifetime, 6000 publications have been published within this topic receiving 162635 citations.
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TL;DR: Based on the mechanics of domain switch and irreversible thermodynamics, a micromechanics-based model that incorporates the effect of polarization strain and electric polariza- tion in the switched domain is developed to predict the evolution of new domain and the associated hysteresis loops of a ferroelectric ceramic as discussed by the authors.
Abstract: Based on the mechanics of domain switch and irreversible thermodynamics, a micromechanics-based model that incorporates the effect of polarization strain and electric polariza- tion in the switched domain is developed to predict the evolution of new domain and the associated hysteresis loops of a ferroelectric ceramic. The new domain concentration cr associated with the remanent polarization Pr, and the new domain concentration cc at the coercive field Ec, are also found in terms of the saturation polarization Ps, the coercive field Ec, and the dielectric permittivity of the parent domain. The theory is developed with a homogenization technique for a coupled, dual-phase electromechanical system with an evolving microstructure, whose driving force arises from the re- duction of Gibbs' free energy and whose resistance force comes from the energy dissipation due to domain wall movement. The developed theory is applied to a lanthanum doped lead zirconate titanate (PLZT), first for the calculation of its hysteresis electric displacement versus electric field (D vs. E) relation and the butterfly-shaped longitudinal strain versus electric field ( vs. E) relation, and then for its nonlinear compressive stress-strain relation and nonlinear depolarization. The results are shown to provide the essential features of the hysteresis behavior and found to be in quantitative ac- cord with the experimental data.
56 citations
TL;DR: In this article, failure mechanisms were studied by reflection light microscopy in a unidirectional silicon carbide/glass-ceramic composite loaded in longitudinal tension, and the results of crack density and stress/strain behavior were compared with predictions based on a modified shear lag analysis.
56 citations
TL;DR: In this paper, a size-dependent Euler-Bernoulli beam model was developed to investigate the vibration characteristics of cracked nano-beams made of nanocrystalline materials.
56 citations
TL;DR: In this article, a micromechanical framework is proposed to predict effective elastic moduli of particle-reinforced composites by making use of the exterior-point Eshelby tensor and the equivalence principle associated with the pairwise particle interactions.
Abstract: A micromechanical framework is proposed to predict effective elastic moduli of particle-reinforced composites. First, the interacting eigenstrain is derived by making use of the exterior-point Eshelby tensor and the equivalence principle associated with the pairwise particle interactions. Then, the near-field particle interactions are accounted for in the effective elastic moduli of spherical-particle-reinforced composites. On the foundation of the proposed interacting solution, the consistent versus simplified micromechanical field equations are systematically presented and discussed. Specifically, the focus is upon the effective elastic moduli of two-phase composites containing randomly distributed isotropic spherical particles. To demonstrate the predictive capability of the proposed micromechanical framework, comparisons between the theoretical predictions and the available experimental data on effective elastic moduli are rendered. In contrast to higher-order formulations in the literature, the proposed micromechanical formulation can accommodate the anisotropy of reinforcing particles and can be readily extended to multi-phase composites.
56 citations
TL;DR: In this article, multi-inclusion models are extended to predict the effective electroelastic properties of multiphase piezoelectric composites. But the modeling of this functional gradient is difficult through micromechanics models without discretizing the gradient into numerous layers of varying properties.
Abstract: Recent work on multifunctional materials has shown that a functionally graded interface between the fiber and matrix of a composite material can lead to improved strength and stiffness while simultaneously affording piezoelectric properties to the composite. However the modeling of this functional gradient is difficult through micromechanics models without discretizing the gradient into numerous layers of varying properties. In order to facilitate the design of these multiphase piezoelectric composites, accurate models are required. In this work, Multi-Inclusion models are extended to predict the effective electroelastic properties of multiphase piezoelectric composites. To evaluate the micromechanics modeling results, a three dimensional finite element model of a four-phase piezoelectric composite was created in the commercial finite element software ABAQUS with different volume fractions and aspect ratios. The simulations showed excellent agreement for multiphase piezoelectric composites, and thus the modeling approach has been applied to study the overall electroelastic properties of a composite with zinc oxide nanowires grown on carbon fibers embedded in the polymer. The results of this case study demonstrate the importance of the approach and show the system cannot be accurately modeled with a homogenized interphase.
56 citations