Bimorph

About: Bimorph is a research topic. Over the lifetime, 3339 publications have been published within this topic receiving 51880 citations.

Design and validation of a fuzzy logic controller for a smart projectile fin with a piezoelectric macro-fiber composite bimorph actuator

Abstract: This paper focuses on the design and validation of a fuzzy logic controller for the smart fin of a projectile. The hollow fin is actuated by a cantilevered piezoelectric bimorph that is completely enclosed within it. A linear model of the actuator and fin is identified experimentally by exciting the system using a chirp signal. A procedure for designing a genetic algorithm (GA)-based fuzzy logic controller for the fin is presented. The controller is validated using simulation and experimental testing that is conducted in the subsonic wind tunnel at the University of Nevada, Las Vegas (UNLV). Results show that the proposed controller accomplishes the desired fin angle control under various operating conditions.

Mosaic adaptive bimorph mirror

Abstract: The invention pertains to the field of adaptive optics and can be used for the static and dynamic guidance of a wave front in a variety of optical devices and systems including astronomical telescopes, industrial laser systems and optical guidance and tracking systems. In the proposed mosaic adaptive bimorph mirror, multilayered local bimorph structures in the form of piezo-electric elements are used to deform the reflecting surface. The piezo-electric elements in question each comprise at least two piezo-ceramic plates (4) fixed on the bottom of a housing (1) the interior cavity of which is filled with an elastic sealant (9).

On graded elements for multiphysics applications

Abstract: Recently, the functionally graded material (FGM) concept has been explored in piezoelectric materials to improve properties and to increase the lifetime of bimorph piezoelectric actuators. For instance, elastic, piezoelectric, and/or dielectric properties may be graded along the thickness of a piezoceramic. Thus, the gradation of piezoceramic properties influences the performance of piezoactuators. The usual FGM modelling using traditional finite element formulation and discretization into layers gives a highly discontinuous stress distribution, which is undesirable. In this work, we focus on nonhomogeneous piezoelectric materials using a generalized isoparametric formulation based on the graded finite element concept, in which the properties change smoothly inside the element. This approach provides a continuum material distribution, which is appropriate to model FGMs. Both four-node quadrilaterals and eight-node quadrilaterals for piezoelectric FGMs were implemented using the graded finite element concept. A closed form two-dimensional analytical model of piezoelectric FGMs is also developed to check the accuracy of these finite elements and to assess the influence of material property gradation on the behavior of piezoelectric FGMs. The paper discusses and compares the behavior of piezoelectric graded elements under four loading conditions with respect to the analytical solutions (derived in this work) considering exponential variation of elastic, piezoelectric, and dielectric properties separately. The analytical solutions provide benchmark problems to verify numerical procedures (such as the finite element method and the boundary element method).

Generation-X mirror technology development plan and the development of adjustable x-ray optics

Abstract: Generation-X is being studied as an extremely high resolution, very large area grazing incidence x-ray telescope. Under a NASA Advanced Mission Concepts Study, we have developed a technology plan designed to lead to the 0.1 arcsec (HPD) resolution adjustable optics with 50 square meters of effective area necessary to meet Generation-X requirements. We describe our plan in detail. In addition, we report on our development activities of adjustable grazing incidence optics via the fabrication of bimorph mirrors. We have successfully deposited thin-film piezo-electric material on the back surface of thin glass mirrors. We report on the electrical and mechanical properties of the bimorph mirrors. We also report on initial finite element modeling of adjustable grazing incidence mirrors; in particular, we examine the impact of how the mirrors are supported - the boundary conditions - on the deformations which can be achieved.

Fluid flow nozzle energy harvesters

Abstract: Power generation schemes that could be used downhole in an oil well to produce about 1 Watt average power with long-life (decades) are actively being developed. A variety of proposed energy harvesting schemes could be used to extract energy from this environment but each of these has their own limitations that limit their practical use. Since vibrating piezoelectric structures are solid state and can be driven below their fatigue limit, harvesters based on these structures are capable of operating for very long lifetimes (decades); thereby, possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. An initial survey [1] identified that spline nozzle configurations can be used to excite a vibrating piezoelectric structure in such a way as to convert the abundant flow energy into useful amounts of electrical power. This paper presents current flow energy harvesting designs and experimental results of specific spline nozzle/ bimorph design configurations which have generated suitable power per nozzle at or above well production analogous flow rates. Theoretical models for non-dimensional analysis and constitutive electromechanical model are also presented in this paper to optimize the flow harvesting system.