To simulate the nonlinear behavior of ferroelectric structures and devices under non-uniform electromechanical loadings,a domain-switching embedded electromechanical finite element method is developed in this paper.Fo...To simulate the nonlinear behavior of ferroelectric structures and devices under non-uniform electromechanical loadings,a domain-switching embedded electromechanical finite element method is developed in this paper.Following continuum assumption,the electromechanical behavior of each representative material point can be obtained by averaging the behavior of the local corresponding microstructure,e.g.42 domains used in this work.A new Double Gibbs free energy criterion for domain-switching is proposed to ensure the convergence and stability of the simulations on ferroelectrics under non-uniform field.Several computational examples are given to demonstrate that this nonlinear finite element method can yield reasonable and stable simulation results which can be used to explain some experimental results and assist the design of ferroelectric devices.展开更多
This paper studies the dynamic shell buckling behavior of multi-walled carbon nanotubes(MWNTs) embedded in an elastic medium under step axial load based on continuum mechanics model.It is shown that,for occurrence of ...This paper studies the dynamic shell buckling behavior of multi-walled carbon nanotubes(MWNTs) embedded in an elastic medium under step axial load based on continuum mechanics model.It is shown that,for occurrence of dynamic shell buckling of MWNTs or MWNTs embedded in an elastic medium,the buckling stress is higher than the critical buckling stress of the corresponding static shell buckling under otherwise identical conditions.Detailed results are demonstrated for dynamic shell buckling of individual double-walled carbon nanotubes(DWNTs) or DWNTs embedded in an elastic medium.A phenomenon is shown that DWNTs or embedded DWNTs in dynamic shell buckling are prone to axisymmetric buckling rather than non-axisymmetric buckling.Numerical results also indicate that the axial buckling form shifts from the lower buckling mode to the higher buckling mode with increasing buckling stress,but the buckling mode is invariable for a certain domain of buckling stress.Further,an approximate analytic formula is presented for the buckling stress and the associated buckling wavelength for dynamic axisymmetric buckling of embedded DWNTs.The effect of radii is also examined.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos. 10702034,10732050,90816006 and 10820101048)the National Basic Research Program of China(Grant Nos.2007CB936803 and 2010CB832701)
文摘To simulate the nonlinear behavior of ferroelectric structures and devices under non-uniform electromechanical loadings,a domain-switching embedded electromechanical finite element method is developed in this paper.Following continuum assumption,the electromechanical behavior of each representative material point can be obtained by averaging the behavior of the local corresponding microstructure,e.g.42 domains used in this work.A new Double Gibbs free energy criterion for domain-switching is proposed to ensure the convergence and stability of the simulations on ferroelectrics under non-uniform field.Several computational examples are given to demonstrate that this nonlinear finite element method can yield reasonable and stable simulation results which can be used to explain some experimental results and assist the design of ferroelectric devices.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11172304,11202210,11021262 and 10972010)the National Basic Research Program of China (Grant No. 2012CB937500)
文摘This paper studies the dynamic shell buckling behavior of multi-walled carbon nanotubes(MWNTs) embedded in an elastic medium under step axial load based on continuum mechanics model.It is shown that,for occurrence of dynamic shell buckling of MWNTs or MWNTs embedded in an elastic medium,the buckling stress is higher than the critical buckling stress of the corresponding static shell buckling under otherwise identical conditions.Detailed results are demonstrated for dynamic shell buckling of individual double-walled carbon nanotubes(DWNTs) or DWNTs embedded in an elastic medium.A phenomenon is shown that DWNTs or embedded DWNTs in dynamic shell buckling are prone to axisymmetric buckling rather than non-axisymmetric buckling.Numerical results also indicate that the axial buckling form shifts from the lower buckling mode to the higher buckling mode with increasing buckling stress,but the buckling mode is invariable for a certain domain of buckling stress.Further,an approximate analytic formula is presented for the buckling stress and the associated buckling wavelength for dynamic axisymmetric buckling of embedded DWNTs.The effect of radii is also examined.
