In this paper,a phenomenological continuum theory of surface piezoelectricity accounting for the linear superficial interplay between electricity and elasticity is formulated primarily for elastic dielectric materials...In this paper,a phenomenological continuum theory of surface piezoelectricity accounting for the linear superficial interplay between electricity and elasticity is formulated primarily for elastic dielectric materials.This theory is inspired by the physical idea that once completely relaxed,an insulating free dielectric surface will sustain a nontrivial spontaneous surface polarization in the normal direction together with a tangential self-equilibrated residual surface stress field.Under external loadings,the surface Helmholtz free energy density is identified as the characteristic function of such surfaces,with the in-plane strain tensor of surface and the surface free charge density as the independent state variables.New boundary conditions governing the surface piezoelectricity are derived through the variational method.The resulting concepts of charge-dependent surface stress and deformationdependent surface electric field reflect the linear electromechanical coupling behavior of nanodielectric surfaces.As an illustrative example,an infinite radially polarizable piezoelectric nanotube with both inner and outer surfaces grounded is investigated.The novel phenomenon of possible surface-induced polarity inversion is predicted for thin enough nanotubes.展开更多
In the framework of continuum thermodynamics, the present paper presents the thermo-hyperelastic models for both the surface and the bulk of nanostructured materials, in which the residual stresses are taken into acco...In the framework of continuum thermodynamics, the present paper presents the thermo-hyperelastic models for both the surface and the bulk of nanostructured materials, in which the residual stresses are taken into account. Due to the existence of residual stresses, different configuration descriptions of the surface (or the bulk) thermo-hyperelastic constitutive equations are not the same even in the cases of infinitesimal deformation. As an example, the effective thermal expansion coefficient of spherical nanoparticles is analyzed.展开更多
基金supports from the National Natural Science Foundation of China(Grant Nos. 10772093,10972121,and 10732050)the National Basic Research Program of China(Grant Nos. 2007CB936803 and 2010CB-631005)
文摘In this paper,a phenomenological continuum theory of surface piezoelectricity accounting for the linear superficial interplay between electricity and elasticity is formulated primarily for elastic dielectric materials.This theory is inspired by the physical idea that once completely relaxed,an insulating free dielectric surface will sustain a nontrivial spontaneous surface polarization in the normal direction together with a tangential self-equilibrated residual surface stress field.Under external loadings,the surface Helmholtz free energy density is identified as the characteristic function of such surfaces,with the in-plane strain tensor of surface and the surface free charge density as the independent state variables.New boundary conditions governing the surface piezoelectricity are derived through the variational method.The resulting concepts of charge-dependent surface stress and deformationdependent surface electric field reflect the linear electromechanical coupling behavior of nanodielectric surfaces.As an illustrative example,an infinite radially polarizable piezoelectric nanotube with both inner and outer surfaces grounded is investigated.The novel phenomenon of possible surface-induced polarity inversion is predicted for thin enough nanotubes.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60936001, 10772180, 10902111)the National Basic Research Program of China (Grant No. 2007CB310500)the Foundamental Research Funds for the Central Universities (Grant No. 2010ZY33)
文摘In the framework of continuum thermodynamics, the present paper presents the thermo-hyperelastic models for both the surface and the bulk of nanostructured materials, in which the residual stresses are taken into account. Due to the existence of residual stresses, different configuration descriptions of the surface (or the bulk) thermo-hyperelastic constitutive equations are not the same even in the cases of infinitesimal deformation. As an example, the effective thermal expansion coefficient of spherical nanoparticles is analyzed.
