DEPP Co-Extruded Functionally Graded Piezoceramics

Aerospace ◽  
2005 ◽  
Author(s):  
Paul W. Alexander ◽  
Diann Brei ◽  
John W. Halloran
Keyword(s):  
Electric Field ◽  
Piezoelectric Actuator ◽  
Stress Reduction ◽  
Gradient Method ◽  
High Stress ◽  
Layered Material ◽  
Functionally Graded ◽  
Reliability Testing ◽  
Micro Fabrication ◽  
Complex Electric Field

Functionally Graded Piezoceramics (FGP) offer performance similar to conventional piezoceramic actuators while reducing the problems associated with their bonded construction (high stress levels, large stress discontinuities, delamination, etc.). This paper presents the Dual Electro/Piezo Property (DEPP) gradient method and the tools necessary for designing, modeling, and producing DEPP FGP actuators including: material property gradient maps, a Micro-Fabrication by Co-eXtrusion (MFCX) process, and experimentally validated analytic and numeric performance and stress modeling methodologies that account for continuous and layered material gradients and complex electric field profiles. These models predict a dramatic internal stress reduction achieved by the DEPP method. Preliminary reliability testing confirm this with an increase in piezoelectric actuator lifetimes over 1010 cycles, improvement of almost four orders of magnitude compared to conventional piezoceramic actuation.

The Design Tradeoffs of Linear Functionally Graded Piezoceramic Actuators

Aerospace ◽  
2003 ◽  
Author(s):  
Paul W. Alexander ◽  
Diann Brei
Keyword(s):  
Material Properties ◽  
High Stress ◽  
Functionally Graded ◽  
Homogeneous Material ◽  
Stress Concentrations ◽  
Practical Applications ◽  
Complex Electric Field ◽  
Design Tradeoffs ◽  
A Minor ◽  
The Cost

It is common practice to reduce the voltage level within piezoelectric actuators by utilizing multiple layers, typically bonded together. Unfortunately, this has a tendency to result in device failure due to delamination. For example, with benders the typical lifetime is 105 to 106 cycles, limiting its use in practical applications. This poses an interesting design tradeoff: the stroke is increased due to sharper gradients between material layers; however, the higher gradients lead to high stress concentrations at those interfaces. One approach to reducing these stresses is to grade the material properties through a monolithic piece of piezoceramic so that no interfaces or bonding elements exist, but this comes at the cost of stroke. This paper explores the design tradeoff inherent to monolithic functionally graded piezoelectrics. An analytical free-displacement model for a monolithic piezoceramic beam with a generic gradient is derived. Key to this is the inclusion of the complex electric field distribution which rises from the non-homogeneous material properties. This model is used along with finite element models to examine the effect of continuous linear and stepwise material gradients on the displacement performance as well as the stress levels. The study shows that using monolithic functionally graded piezocermics can significantly reduce the stresses with only a minor impact on the device stroke.

Application of functionally graded material for reducing electric field on electrode and spacer interface

2010 ◽  
Vol 17 (1) ◽  
pp. 256-263 ◽  
Author(s):  
Muneaki Kurimoto ◽  
Katsumi Kato ◽  
Masahiro Hanai ◽  
Yoshikazu Hoshina ◽  
Masafumi Takei ◽  
...  
Keyword(s):  
Electric Field ◽  
Functionally Graded Material ◽  
Functionally Graded ◽  
Graded Material

scholarly journals Study of electric field stress on the surface contour and at the triple junction in three phase GIS with FGM spacer under the depression defect

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Janaki Pakalapati ◽  
Venkata N. Kumar Gundavarapu ◽  
Deepak Chowdary Duvvada ◽  
Sravana Kumar Bali
Keyword(s):  
Electric Field ◽  
Triple Junction ◽  
Dielectric Strength ◽  
Functionally Graded ◽  
Uniform Electric Field ◽  
Filler Materials ◽  
Field Stress ◽  
As Doping ◽  
Three Phase ◽  
Graded Material

AbstractNow days, the establishment of spacers is in wide usage in three-phase Gas Insulated Busduct (GIB) for providing mechanical support and better insulation to the conductors. The region of the intersection of SF6 gas, enclosure end and the spacer is one of the weakest links in GIB, so the major concentration is done on minimization of electric field stress at this junction by using Functionally Graded Material (FGM) technique. The other incidents of insulation failures are due to several defects like depression, delamination etc. reduces the dielectric strength of the spacers. In this paper, an FGM post type spacer has been designed for a three-phase GIB under depression and further electric field stress at Triple Junction (TJ) is reduced by introducing a metal insert (MI) nearer to the TJ. Several filler materials are used as doping materials for obtaining different permittivity values using FGM technique to achieve uniform electric field stress. Simulation is carried out for the designed spacer at various operating voltages with different types of FGM gradings. The effect of depression with different dimensions and positions is analyzed before and after inserting MI to the FGM post type spacer in three-phase GIB.

Functionally Graded Polymeric Composites Having Micro-Tailored Structure Formed by Electric Field

Materials ◽  
2003 ◽  
Author(s):  
Geun Hyung Kim ◽  
Daniel K. Moeller ◽  
Yuri M. Shkel
Keyword(s):  
Mechanical Properties ◽  
Electric Field ◽  
Functionally Graded Materials ◽  
Applied Electric Field ◽  
Polymeric Composites ◽  
Functionally Graded ◽  
Graded Materials ◽  
Functionally Graded Composites ◽  
Liquid Suspensions ◽  
Redistribution Effect

A solid composite having locally micro-tailored structure can be produced by curing liquid polymeric suspensions in an electric field. The redistribution effect of the field-induced forces exceeds the effect of centrifugation, presently employed to manufacture functionally graded materials. Moreover, unlike centrifugational sedimentation, one can electrically rearrange the inclusions in desired targeted areas. The applied electric field can be employed to produce a composite having uniformly oriented structure or only modify the material in selected regions. This technology enables polymeric composites to be locally micro-tailored for given design objectives. We discuss electrical and rheological inteactions in liquid suspensions. Relationships between microstructure and mechanical properties of the obtained functionally graded composites are presented.

Wide-Viewing-Angle Hybrid Aligned Nematic Liquid Crystal Cell Controlled by Complex Electric Field

2002 ◽  
Vol 41 (Part 1, No. 7A) ◽  
pp. 4571-4576 ◽  
Author(s):  
Seung Ho Hong ◽  
Hyang Yul Kim ◽  
Jae-Hyung Kim ◽  
Sang-Hee Nam ◽  
Myong-Hoon Lee ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Nematic Liquid Crystal ◽  
Liquid Crystal Cell ◽  
Viewing Angle ◽  
Crystal Cell ◽  
Wide Viewing Angle ◽  
Complex Electric Field

Bending Behavior of Functionally Graded Piezoelectric Laminated Actuators under Electric Fields

2007 ◽  
Vol 336-338 ◽  
pp. 2619-2623
Author(s):  
Yasuhide Shindo ◽  
Fumio Narita
Keyword(s):  
Domain Wall ◽  
Electric Fields ◽  
Piezoelectric Actuator ◽  
Wall Motion ◽  
Domain Wall Motion ◽  
Functionally Graded ◽  
Experimental Results ◽  
Nonlinear Bending ◽  
Bending Behavior ◽  
Functionally Graded Piezoelectric

We present numerical and experimental results on the nonlinear bending behavior due to domain wall motion in functionally graded piezoelectric actuator under alternating current (ac) electric fields. A nonlinear finite element method is employed to analyze the dynamic response of functionally graded piezoelectric actuator. A phenomenological model of domain wall motion is used in computation, and the effects of ac electric field amplitude and frequency, number of layers, and property gradation on the deflection of the cantilever actuators are examined. Experimental results, which verify the model, are presented using a functionally graded bimorph. The numerical results agree very well with the experimental values.

scholarly journals Multi-octave, CEP-stable source for high-energy field synthesis

2020 ◽  
Vol 6 (7) ◽  
pp. eaax3408
Author(s):  
Ayman Alismail ◽  
Haochuan Wang ◽  
Gaia Barbiero ◽  
Najd Altwaijry ◽  
Syed Ali Hussain ◽  
...  
Keyword(s):  
Electric Field ◽  
Coherent Control ◽  
Average Power ◽  
High Energy ◽  
Energy Field ◽  
Electro Optic ◽  
Free Induction ◽  
Complex Electric Field ◽  
Stable Source

The development of high-energy, high-power, multi-octave light transients is currently the subject of intense research driven by emerging applications in attosecond spectroscopy and coherent control. We report on a phase-stable, multi-octave source based on a Yb:YAG amplifier for light transient generation. We demonstrate the amplification of a two-octave spectrum to 25 μJ of energy in two broadband amplification channels and their temporal compression to 6 and 18 fs at 1 and 2 μm, respectively. In this scheme, due to the intrinsic temporal synchronization between the pump and seed pulses, the temporal jitter is restricted to long-term drift. We show that the intrinsic stability of the synthesizer allows subcycle detection of an electric field at 0.15 PHz. The complex electric field of the 0.15-PHz pulses and their free induction decay after interaction with water molecules are resolved by electro-optic sampling over 2 ps. The scheme is scalable in peak and average power.

Optimization of Wall Electrodes for Electro-Hydrodynamic Control of Natural Convection Effects During Solidification

Materials ◽  
2003 ◽  
Author(s):  
Marcelo J. Colac¸o ◽  
George S. Dulikravich ◽  
Thomas J. Martin
Keyword(s):  
Natural Convection ◽  
Electric Field ◽  
Solid Phase ◽  
Charged Particles ◽  
Numerical Procedure ◽  
Functionally Graded ◽  
Navier Stokes ◽  
Graded Materials ◽  
Shape Distribution ◽  
B Splines

This paper presents a numerical procedure to reduce and possibly control the natural convection effects in a cavity filled with a molten material by applying an external electric field whose intensity and spatial distributions are obtained by the use of a hybrid optimizer. This conceptually new approach to manufacturing could be used in creation of layered and functionally graded materials and objects. In the case of steady electro-hydrodynamics (EHD), the flow-field of electrically charged particles in a solidifying melt is influenced by an externally applied electric field while the existence of any magnetic field is neglected. Solidification front shape, distribution of the charged particles in the accrued solid, and the amount of accrued solid phase in such processes can be influenced by an appropriate distribution and orientation of the electric field. The intensities of the electrodes along the boundaries of the cavity were described using B-splines. The inverse problem was then formulated to find the electric boundary conditions (the coefficients of the B-splines) in such a way that the gradients of temperature along the horizontal direction are minimized. For this task we used a hybrid optimization algorithm which incorporates several of the most popular optimization modules; the Davidon-Fletcher-Powell (DFP) gradient method, a genetic algorithm (GA), the Nelder-Mead (NM) simplex method, quasi-Newton algorithm of Pshenichny-Danilin (LM), differential evolution (DE), and sequential quadratic programming (SQP). The transient Navier-Stokes and Maxwell equations were discretized using the finite volume method in a generalized curvilinear non-orthogonal coordinate system. For the phase change problems, we used the enthalpy method.

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