Multi-field Coupling Effect Research Articles

Schottky junction based self-powered photodetectors and their performance modulation by multifield coupling effect

Aiming to overcome the limitation of manufacturing technology at atomic scale, “More than Moore’s law” has been recognized as a promising route to develop the next generation micro-nano electronics in the recent years. These new devices have been designed to minimize the non-digital units to nanoscale and to integrate these units into a multifunctional electronic system. The non-digital units usually contain the power source, sensing units, charge transfer devices, switches, amplifier and etc.

Dynamic response of a generalized piezoelectric-thermoelastic problem under fractional order theory of thermoelasticity

ABSTRACTThe dynamic response of a piezoelectric-thermoelastic rod made of piezoelectric ceramics (PZT-4) subjected to a moving heat source is dealt with in the context of the fractional order theory of thermoelasticity. The piezoelectric-thermoelastic governing equations for the problem are formulated and then solved by means of Laplace transform together with its numerical inversion. The distributions of the considered nondimensional temperature, displacement, stress, and electric potential are obtained and illustrated graphically. The effects of fractional order parameter and the velocity of heat source on the variations of the considered variables are investigated, and the results show that they have significant influence on the variations of the considered variables. The present investigation could be helpful for better understanding the multi-field coupling effect of mechanical, electric, and thermal fields in real piezoelectric ceramics structures, and provide some guidelines in the optimal design of actuators or sensors made of piezoelectric ceramics serving in a thermoelastic environment.

The mixture theory for unsaturated bentonite

Bentonite is a material with low permeability and as such is the preferred material for impervious layer in a refuse landfill. Given the multi-scale structure of the bentonite, contaminant transport in it is a very complex process. In fact, it is coupled with consolidation. The coupling effect affects the contaminant transport by changing the inherent transport feature. In addition, the bentonite clay liner is usually unsaturated. In this article, the mixture theory is used as a framework that describes the transport phenomena and the interactions of the unsaturated bentonite under the multi-field coupling effect. It is also a valuable reference for simulating the contaminant transport in bentonite clay liners.

Photovoltaic and magnetic properties of BiFeO3/TiO2 heterostructures under epitaxial strain and an electric field

First-principles calculations show that the photovoltaic effect of the BiFeO3/TiO2 heterostructures in the visible-light region can be improved by applying epitaxial strain and an electric field. The multi-field coupling effect in the interface makes the heterojunction an intriguing candidate towards fabricating the multifunctional photoelectric devices, and the microscopic mechanism involved is attributed to the spin transfer and charge rearrangement between the Fe 3d and O 2p orbitals in the vicinity of the interface.

Variable kinematics models and finite elements for nonlinear analysis of multilayered smart plates

A variable kinematics approach for moderately large deflection analysis of smart magneto-electro-elastic multilayered plates is presented. The approach is based on the condensation of the electro-magnetic state into the plate kinematics, whose nonlinear strain–displacement relationships are expressed in the von Karman sense. This leads to models resulting in an effective mechanical plate, which takes the multifield coupling effects into account by the plate stiffness, inertia and loading characteristics, consistently defined as combinations of the layers material properties. By a unified approach, both equivalent single layer and layerwise models are developed formulating the associated isoparametric finite elements. Results are presented for different kinematics with through-the-thickness expansion up to the fourth order with the aim of validating the modeling strategy and showing its features for the investigation of smart plates geometrical nonlinear behaviour.

Layer-wise and equivalent single layer models for smart multilayered plates

Layer-wise and equivalent single layer plate models for magneto-electro-elastic multiphysics laminates are presented in a unified framework. They are based on variable kinematics and quasi-static behavior of the electromagnetic fields. The electromagnetic state of each single layer is preliminary determined by solving the corresponding governing equations coupled with the proper interface continuity and external boundary conditions. By so doing, the electromagnetic state is condensed into the plate kinematics and the layer governing equations are inferred by the principle of virtual displacements. This approach identifies effective mechanical layers, which are kinematically equivalent to the original smart layers. These effective layers are characterized by stiffness, inertia and load properties which take the multifield coupling effects into account as their definitions involve the electromagnetic coupling material properties. The layers governing equations are finally assembled enforcing the mechanical interface conditions. This allows to obtain the smart plate resolving system, which involves primary mechanical variables only. Results for thick simply-supported multilayered plates are obtained by an exact closed-form Navier-type solution and compared with benchmark 3D solutions to investigate the features and accuracy of the proposed modeling approach.

Line-integral representations for extended displacements, stresses, and interaction energy of arbitrary dislocation loops in transversely isotropic magneto-electro-elastic bimaterials

In addition to the hexagonal crystals of class 6 mm, many piezoelectric materials (e.g., BaTiO3), piezomagnetic materials (e.g., CoFe2O4), and multiferroic composite materials (e.g., BaTiO3-CoFe2O4 composites) also exhibit symmetry of transverse isotropy after poling, with the isotropic plane perpendicular to the poling direction. In this paper, simple and elegant line-integral expressions are derived for extended displacements, extended stresses, self-energy, and interaction energy of arbitrarily shaped, three-dimensional (3D) dislocation loops with a constant extended Burgers vector in transversely isotropic magneto-electro-elastic (MEE) bimaterials (i.e., joined half-spaces). The derived solutions can also be simply reduced to those expressions for piezoelectric, piezomagnetic, or purely elastic materials. Several numerical examples are given to show both the multi-field coupling effect and the interface/surface effect in transversely isotropic MEE materials.

Refined equivalent single layer formulations and finite elements for smart laminates free vibrations

A family of 2D refined equivalent single layer models for multilayered and functionally graded smart magneto–electro-elastic plates is presented. They are based on variable kinematics and quasi-static behavior for the electromagnetic fields. First, the electromagnetic state of the plate is determined by solving the strong form of the electromagnetic governing equations coupled with the corresponding interface continuity conditions and external boundary conditions. The electromagnetic state is then condensed into the plate kinematics, whose governing equations can be written using the generalized principle of virtual displacements. The procedure identifies an effective elastic plate kinematically equivalent to the original smart plate. The effective plate is characterized by inertia, stiffness and loading properties which take the multifield coupling effects into account through their definitions, which involve the electromagnetic coefficients appearing in the smart materials constitutive law. The proposed model extends the techniques and tools available for the assessment of the mechanical behavior of multilayered composite plates to smart laminates. Additionally, finite elements for the proposed single layer models are formulated and validated against available benchmark 3D solutions.

An Integrated Measurement System for Pyromagnetic Effect of Prefabricated Defects Polymer Materials

There exist multi-field coupling effect in prefabricated defects polymer materials under loading. For understanding the pyromagnetic effect, it is crucial to accurately measure the coupling relations of the key physical quantities about displacement, tensile load, temperature, and magnetic field. To overcome the obstacle in current measurement systems for synchronized measurement, an integrated measurement system for multi-field coupling detection is presented to enable synchronized, automatic detection. This paper introduces the system structure, software design, and the detailed design of varied-speed PID control methods. Test results show that, the system is effective for valid data acquisition for displacement, tension load, temperature and magnetic field of a high polymer Polyvinyl Chloride (PVC) plate sample under constant tensile load, and all test data can be visualized on the software interface. This system provides a good test platform for further research on pyromagnetic effect of PVC plate.

An Integrated Measurement System for Pyromagnetic Effect of Prefabricated Defects Polymer Materials

There exist multi-field coupling effect in prefabricated defects polymer materials under loading. For understanding the pyromagnetic effect, it is crucial to accurately measure the coupling relations of the key physical quantities about displacement, tensile load, temperature, and magnetic field. To overcome the obstacle in current measurement systems for synchronized measurement, an integrated measurement system for multi-field coupling detection is presented to enable synchronized, automatic detection. This paper introduces the system structure, software design, and the detailed design of varied-speed PID control methods. Test results show that, the system is effective for valid data acquisition for displacement, tension load, temperature and magnetic field of a high polymer Polyvinyl Chloride (PVC) plate sample under constant tensile load, and all test data can be visualized on the software interface. This system provides a good test platform for further research on pyromagnetic effect of PVC plate.

The Study of Dynamic Equations of ER Fluids Based on Multi-Field Coupling

Based on the multi-field coupling effect and the theory of electrodynamics, as well as the capture effect of the ER fluids flowing through the control field, by analyzing on the flow characteristics under the electric - power - thermal coupling load environment, the structure-force dynamic coupling mathematical model of ER fluids is derived under multi-field.

An equivalent single-layer approach for free vibration analysis of smart laminated thick composite plates

An equivalent single-layer model for the free vibration analysis of smart laminated plates is presented. The electric and magnetic fields are assumed to be quasi-static, and third order in-plane kinematics is employed to adequately take the shear influence into account when the plate thickness increases. The model governing equations are the plate equations of motion written in terms of mechanical primary variables and effective stiffness coefficients, which take the multi-field coupling effects into account. The model shows that the surface magneto-electric boundary conditions enter the definitions of the laminate forces and moment resultants. Moreover, it reveals that new stiffness terms, which are related to the derivatives of the transverse displacement component and are exclusively associated with the piezoelectric and piezomagnetic couplings, are involved. Free vibration solutions for simply supported plates are presented to validate the model by comparing the present results with benchmark 3D solutions. Comparison of the results obtained by lower order models, namely zero and first order shear deformation theories, is presented and discussed, focusing on the adequateness of the obtained models with respect to the plate thickness. Some characteristic features of smart laminate behavior have also been addressed.

Research of air-cushion isolation effects on high arch dam reservoir

A three-dimensional (3D) finite element model of air-cushion isolated arch dam is presented with the nonlinear gas-liquid-solid multi-field dynamic coupling effect taken into account. In this model, the displacement formulation in Lagrange method, pressure formulation in Euler method, nonlinear contact model based on Coulomb friction law are applied to the air-cushion, reservoir and contraction joint domain, respectively. The dynamic response of Jinping I arch dam with a height of 305 m is analyzed using the seismic records of the Wenchuan Earthquake in 2008. Numerical results show that the air-cushion isolation reduces significantly the hydrodynamic pressure as well as the opening width for the contraction joints of high arch dam.

Modeling and simulation of a condenser microphone

A nodal analysis model of a condenser microphone has been implemented in an IC design environment. The fundamental characteristics, including sensitivity, frequency response and output referred noise are obtained by co-simulation with the microphone and the readout circuit using Cadence/Spectre® simulator. The new model is capable of dealing with the multi-field coupling effects including acoustical, mechanical and electrostatic behavior. Both the numerical analysis and measured data agree with the nodal simulation results. In addition, the implemented readout circuit shows good performance of interfacing a condenser microphone with 63dB SNR and −35dBV/Pa sensitivity. Co-simulating the microphone and readout circuit, enables trade-off analysis between the acoustical-electro-mechanical and electronic design parameters.