A General Method for a Piezothermoelastic Plate of Crystal Class 6mm Subjected to Axisymmetric Loading

1999 ◽  
Author(s):  
Xiangqing Wang ◽  
Om Prakash Agrawal
Keyword(s):  
Cadmium Selenide ◽  
Solution Method ◽  
Piezoelectric Materials ◽  
Electrical Potential ◽  
Special Cases ◽  
Crystal Class ◽  
Piezoelectric Solids ◽  
And Control ◽  
Electrical Equilibrium ◽  
General Method

Abstract Applications of piezoelectric materials for the development of “intelligent” structural and mechanical systems through sensing, actuation, and control have received considerable recent interest. In this document, we present a general solution method for piezothermoelasticity for hexagonal piezoelectric solids of class 6 mm. In the formulation presented, potential functions are introduced to represent the coupled thermal, elastic, and mechanical fields, which satisfy the thermal, mechanical, and electrical equilibrium and prescribed boundary conditions. The formulation is similar to those presented by Ashida, Tauchert, and Noda (1993, 1994), however, it is simpler and direct, and it eliminates the need to discuss special cases. To demonstrate applications of the technique, a piezothermoelasticity problem subjected to axisymmetric thermal, electrical and mechanical loads on a plate is considered. Numerical calculations for the stresses and the electrical potential are carried out for a cadmium selenide body exhibiting class 6mm symmetry. Results of these calculations are presented graphically.

Axisymmetric Thermal Stresses of a Piezoelectric Poroelastic Circular Solid Plate

2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Ali Abjadi ◽  
Mohsen Jabbari ◽  
Ahmad Reza Khorshidvand
Keyword(s):  
Cadmium Selenide ◽  
Material Properties ◽  
Thermal Stresses ◽  
Separation Of Variables ◽  
Electrical Potential ◽  
Material Symmetry ◽  
Exponential Functions ◽  
Cylindrical Coordinates ◽  
Solid Plate ◽  
Electrical Loads

Abstract This paper presents the steady-state thermoelasticity solution for a circular solid plate is made of an undrained porous piezoelectric hexagonal material symmetry of class 6 mm. The porosities of the plate vary through the thickness; thus, material properties, except Poisson's ratio, are assumed as exponential functions of axial variable z in cylindrical coordinates. Having axisymmetric general form, external thermal and electrical loads are acted on the plate and the piezothermoelastic behavior of the plate is investigated. Using a full analytical method based on Bessel Fourier's series and separation of variables, the governing partial differential equations are derived. A formulation is given for the displacements, electric potential, thermal stresses, and electric displacements resulting from prescribed the general form of thermal, mechanical, and electric boundary conditions. Finally, the application of the derived formulas is illustrated by an example for a cadmium selenide solid, the results of which are presented graphically. Also, the effects of material property indexes, the porosity, and Skempton coefficients are discussed on the displacements, thermal stresses, electrical potential function, and electric displacements.

Sensing and Control of Thermally Induced Vibrations of Stationary Blades Using Piezoelectric Materials

2017 ◽  
Vol 43 (3) ◽  
pp. 1301-1311 ◽  
Author(s):  
K. S. Al-Athel ◽  
H. M. Al-Qahtani ◽  
M. Sunar ◽  
L. Malgaca ◽  
A. Omar
Keyword(s):  
Piezoelectric Materials ◽  
Thermally Induced ◽  
Thermally Induced Vibrations ◽  
And Control

Modeling and stabilization of current-controlled piezo-electric beams with dynamic electromagnetic field

2020 ◽  
Vol 26 ◽  
pp. 8
Author(s):  
Ahmet Özkan Özer ◽  
Kirsten A. Morris
Keyword(s):  
Electromagnetic Field ◽  
Piezoelectric Materials ◽  
Electrical Potential ◽  
Gauge Condition ◽  
Current Control ◽  
Magnetic Vector Potential ◽  
Bounded Control ◽  
The Cauchy Problem ◽  
A Current ◽  
Piezo Electric

Piezoelectric materials can be controlled with current (or charge) as the electrical input, instead of voltage. The main purpose of this paper is to derive the governing equations for a current-controlled piezo-electric beam and to investigate stabilizability. The magnetic permeability in piezo-electric materials is generally neglected in models. However, it has a significant qualitative effect on properties of the control system such as stabilizability. Besides the consideration of current control, there are several new aspects to the model. Most importantly, a fully dynamic magnetic model is included. Also, electrical potential and magnetic vector potential are chosen to be quadratic-through thickness to include the induced effects of the electromagnetic field. Hamilton’s principle is used to derive a boundary value problem that models a single piezo-electric beam actuated by a current (or charge) source at the electrodes. Two sets of decoupled system of partial differential equations are obtained; one for stretching of the beam and another one for bending motion. Since current (or charge) controller only affects the stretching motion, attention is focused on control of the stretching equations in this paper. It is shown that the Lagrangian of the beam is invariant under certain transformations. A Coulomb type gauge condition is used. This gauge condition decouples the electrical potential equation from the equations of the magnetic potential. A semigroup approach is used to prove that the Cauchy problem is well-posed. Unlike voltage actuation, a bounded control operator in the natural energy space is obtained. The paper concludes with analysis of stabilizability and comparison with other actuation approaches and models.

Stability and Vibrations of Compressed, Aeolotropic, Composite Cylindrical Shells

1982 ◽  
Vol 49 (4) ◽  
pp. 843-848 ◽  
Author(s):  
J. B. Greenberg ◽  
Y. Stavsky
Keyword(s):  
Fiber Orientation ◽  
Vibration Analysis ◽  
Solution Method ◽  
Cylindrical Shells ◽  
Critical Buckling Load ◽  
Method Of Solution ◽  
The Stability ◽  
Winding Angle ◽  
General Method ◽  
Composite Cylindrical Shells

A general method of solution, based on a complex finite Fourier transform, is adopted for the stability and vibration analysis of compressed, aeolotropic, composite cylindrical shells. A major feature of the solution method is its ability to handle both uniform and nonuniform conditions that hold at the boundaries of finite-length cylindrical shells. For the various shells investigated, an optimum winding angle was found for which a maximum frequency response and highest critical buckling load is attainable. Similar optimization was also discovered to be possible by controlling both/either shell heterogeneity and/or fiber orientation.

Micro-Structronics and Control of Hybrid Electrostrictive/Piezoelectric Thin Shells

Aerospace ◽  
2003 ◽  
Author(s):  
W. K. Chai ◽  
H. S. Tzou ◽  
S. M. Arnold
Keyword(s):  
Curie Point ◽  
Piezoelectric Materials ◽  
Constitutive Relations ◽  
Ferroelectric Materials ◽  
Polar Phase ◽  
Free Energy Function ◽  
Generic Theory ◽  
And Control ◽  
Electrostrictive Effect ◽  
Piezoelectric Characteristics

Certain ferroelectric materials possess dual electrostrictive and piezoelectric characteristics, depending on their specific Curie temperatures. These materials exhibit piezoelectric characteristics in the ferroelectric phase when the temperature is below the Curie point. However, they become electrostrictive in the paraelectric phase (non-polar phase) as the temperature exceeds the Curie point. The (direct) electrostrictive effect is a quadratic dependence of stress or strain on applied electric field. The nonlinear electromechanical effect of electrostrictive materials provides stronger actuation performance as compared with that of piezoelectric materials. Due to the complexity of the generic ferroelectric actuators, micro-electromechanics and control characteristics of generic electrostrictive/piezoelectric dynamics system deserve an in-depth investigation. In this study, electro-mechanical dynamic system equations and generic boundary conditions of hybrid electrostrictive/piezoelectric double-curvature shell continua are derived using the energy-based Hamilton’s principle, elasticity theory, electrostrictive/piezoelectric constitutive relations, and Gibb’s free energy function. Moreover, the second converse electrostrictive effect and the direct piezoelectric effect are all considered in the generic governing equations. Simplifications of the generic theory to other common geometries or specific materials are demonstrated and their electromechanical characteristics are also evaluated.

scholarly journals Quantum key distribution with correlated sources

2020 ◽  
Vol 6 (37) ◽  
pp. eaaz4487 ◽  
Author(s):  
Margarida Pereira ◽  
Go Kato ◽  
Akihiro Mizutani ◽  
Marcos Curty ◽  
Kiyoshi Tamaki
Keyword(s):  
Quantum Key Distribution ◽  
Key Distribution ◽  
The Other ◽  
Correlated Sources ◽  
Information Theoretic ◽  
Security Proofs ◽  
Information Theoretic Security ◽  
Special Cases ◽  
New Framework ◽  
General Method

In theory, quantum key distribution (QKD) offers information-theoretic security. In practice, however, it does not due to the discrepancies between the assumptions used in the security proofs and the behavior of the real apparatuses. Recent years have witnessed a tremendous effort to fill the gap, but the treatment of correlations among pulses has remained a major elusive problem. Here, we close this gap by introducing a simple yet general method to prove the security of QKD with arbitrarily long-range pulse correlations. Our method is compatible with those security proofs that accommodate all the other typical device imperfections, thus paving the way toward achieving implementation security in QKD with arbitrary flawed devices. Moreover, we introduce a new framework for security proofs, which we call the reference technique. This framework includes existing security proofs as special cases, and it can be widely applied to a number of QKD protocols.

Enumeration of Singular Configurations for Robotic Manipulators

1991 ◽  
Vol 113 (3) ◽  
pp. 272-279 ◽  
Author(s):  
H. Lipkin ◽  
E. Pohl
Keyword(s):  
Joint Angle ◽  
Robotic Manipulators ◽  
Systematic Procedure ◽  
Singular Configurations ◽  
Special Cases ◽  
Angle Space ◽  
Six Degree Of Freedom ◽  
Kinematic Singularities ◽  
And Control ◽  
Space Approach

Kinematic singularities are important considerations in the design and control of robotic manipulators. For six degree-of-freedom manipulators, the vanishing of the determinant of the Jacobian yields the conditions for the primary singularities. Examining the vanishing of the minors of the Jacobian yields further singularities which are special cases of the primary ones. A systematic procedure is presented to efficiently enumerate all possible singular configurations. Special geometries of representative manipulators are exploited by expressing the Jacobian in terms of vector elements. In contrast to using a joint-angle space approach, the resulting expressions yield direct physical interpretations.

Another Look at Nonholonomic Systems

1973 ◽  
Vol 40 (1) ◽  
pp. 101-104 ◽  
Author(s):  
C. E. Passerello ◽  
R. L. Huston
Keyword(s):  
Analytical Methods ◽  
Classical Problem ◽  
Nonholonomic Systems ◽  
Constraint Forces ◽  
Advantages And Disadvantages ◽  
Arbitrary Choice ◽  
Special Cases ◽  
Dependent Variables ◽  
Automatic Elimination ◽  
General Method

The relative advantages and disadvantages of various analytical methods for nonholonomic systems are briefly presented and discussed. The techniques of Kane’s method are then used to develop a derivation of a general method which consolidates and employs the advantages of the various classical methods. These advantages include the automatic elimination of nonworking constraint forces while avoiding the computation of vector components of acceleration. The method also provides for the arbitrary choice of dependent variables so that it may be adapted to a variety of nonholonomic systems. Two special cases are considered and the method is then illustrated in the classical problem of the rolling coin.

scholarly journals Concerning RNA-guided gene drives for the alteration of wild populations

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Kevin M Esvelt ◽  
Andrea L Smidler ◽  
Flaminia Catteruccia ◽  
George M Church
Keyword(s):  
Invasive Species ◽  
Herbicide Resistance ◽  
Wild Populations ◽  
Genomic Changes ◽  
Ecological Problems ◽  
Political Borders ◽  
And Control ◽  
Gene Drives ◽  
Careful Assessment ◽  
General Method

Gene drives may be capable of addressing ecological problems by altering entire populations of wild organisms, but their use has remained largely theoretical due to technical constraints. Here we consider the potential for RNA-guided gene drives based on the CRISPR nuclease Cas9 to serve as a general method for spreading altered traits through wild populations over many generations. We detail likely capabilities, discuss limitations, and provide novel precautionary strategies to control the spread of gene drives and reverse genomic changes. The ability to edit populations of sexual species would offer substantial benefits to humanity and the environment. For example, RNA-guided gene drives could potentially prevent the spread of disease, support agriculture by reversing pesticide and herbicide resistance in insects and weeds, and control damaging invasive species. However, the possibility of unwanted ecological effects and near-certainty of spread across political borders demand careful assessment of each potential application. We call for thoughtful, inclusive, and well-informed public discussions to explore the responsible use of this currently theoretical technology.

A Strain Model for Piezoelectric Materials Operating in Highly Hysteretic Regimes

2011 ◽  
Author(s):  
Zhengzheng Hu ◽  
Ralph C. Smith
Keyword(s):  
Piezoelectric Materials ◽  
Material Behavior ◽  
Macroscopic Model ◽  
Optimization And Control ◽  
Homogenized Energy Model ◽  
Energy Relations ◽  
Stress Dependent ◽  
And Control ◽  
Strain Model

Piezoelectric materials exhibit hysteresis in the field-strain relation at essentially all drive levels. Furthermore, this non-linear relation is dependent upon both prestresses and dynamic stresses generated during employment of the materials. The accurate characterization of this nonlinear and hysteretic material behavior is critical for material characterization, device design, and model-based control design. In this paper, we will discuss the characterization of hysteresis using the homogenized energy model (HEM) framework. At the mesoscale, energy relations characterizing field and stress-dependent 90 and 180 degree switching are used to develop fundamental kernels or hysterons. Material and field nonhomogeneities are subsequently incorporated by assuming that certain parameters are manifestations of underlying densities. This yields a macroscopic model that accurately characterizes the fundamental material behavior yet is sufficiently efficient for optimization and control implementation. Attributes of the model will be illustrated through comparison to experimental data.

Sign in / Sign up

Export Citation Format

Share Document