Bimorph

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

The constitutive equations of a piezoelectric duo-bimorph

Abstract: This paper describes the behaviour of a two-degrees-of-freedom piezoelectric actuator; based on piezoelectric bimorphs. The constitutive equations of the actuator are established, with a model derived from material resistance. They link external parameters (applied voltages; applied torque, force and distributed loads) and the internal variables (deflexion, slopes and volume displaced).

Piston control with adaptive optics in stellar interferometry - Application to the GI2T interferometer and bimorph mirrors

Abstract: The general purpose of an adaptive optics system is to correct for the wavefront corrugations due to atmospheric turbulence. When applied to a stellar interferometer, care must be taken in the control of the mean optical path length, commonly called differential piston. This paper defines a general formalism for the piston control of a deformable mirror in the linear regime. It is shown that the usual filtering of the piston mode in the command space is not sufficient, mostly in the case of a bimorph mirror. Another algorithm is proposed to cancel in the command space the piston produced in the pupil space. This analysis is confirmed by simulations in the case of the GI2T interferometer located on Plateau de Calern, France. The contrast of the interference fringes is severely reduced in the case of a classical wavefront correction, even in short exposures, but is negligible with our algorithm, assuming a realistic calibration of the mirror. For this purpose, a simple concept for the calibration of the piston induced by a deformable mirror is proposed.

Smart material actuators as a means of UAV flight control

Abstract: The use of piezo-ceramic actuators for UAV ight control has been shown to be e ective both in the wind tunnel and in ight test. Macro ber composite (MFC) actuators are a high strain variant of the lead zirconate titanate (PZT) actuator, and have been employed in a bimorph con guration to cause morphing camber control of aerodynamic surfaces in less than 0.5 m wingspan UAV applications. One of the challenges of operating these conformal actuators is to quantify the voltage input/displacement output relationship given hysteresis and aerodynamic loading e ects. The work presented provides a framework for the practical implementation of these actuators by using both open and closed loop feedback systems for displacement control. Results are presented for thick airfoil designs where only the trailing edge is de ected using smart materials. The two main sources of non-linear behavior include dynamic pressure and actuator hysteresis, and knowledge of these parameters can be used for reasonably good open loop displacement control. Results are presented for 2-D airfoil section testing.

A positionable element driving circuit

Abstract: A positionable element driving circuit for driving a positionable element compensates the supplied voltage-position characteristics of a bimorph type piezoelectric element which is used in a track following type video tape recorder/reproducer and which displaces the position of a video head. The supplied voltage to the bimorph type piezoelectric element is generated by an operational circuit which detects the track position of the video head. The circuit of the present invention compensates for the non-linearity and maintains the track following when the video tape recorder/reproducer is switched from one mode to another, e.g. from a still motion mode to a quick motion mode.