Bimorph

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

High reliability ceramic bender

Abstract: A piezoelectric ceramic hammern of the bimorph bender-type is improved by providing an outer foil layer of stainless steel, or the like, to increase the tensile and compression strength at the surface of a layer of polycrystalline piezoelectric material.

A piezoelectric fan using pzt ceramics

Abstract: A fan consisting of a piezoelectric bimorph tipped with an additional flexible blade is introduced. Since the flexible blade resonates in a large amplitude but the bimorph vibrates in a very small amplitude, the fan can supply sufficient and constant air flow without any structural destruction for a long time. The fan case has two air outlets which are directed oppositely each other. The fan with such outlets can supply an air flow of 4 m3/hr at an applied voltage of 140 Vp–p. Another type of a piezoelectric fan using multi-layered PZT ceramic elements produced by a thick film printing technique is introduced. This fan is suitable for low voltage operation and it can supply an air flow of 1 m3/hr at an applied voltage of 17Vp–p.

Lightweight High Voltage Electronic Circuits for Piezoelectric Composite Actuators

Abstract: The purpose here is to enable peak-to-peak actuation of piezocomposite devices to perform shape control of structures, specifically bimorph variable-camber control surfaces on small aircraft. One of the major drawbacks in implementing control with piezocomposite actuation is its asymmetry in the positive and negative voltage directions. To remedy this situation, a novel, solid-state electrical circuit employing diodes and resistors is proposed. The circuit allows a single bipolar amplifier to control a bimorph composed of two piezoceramic composite actuators known as Macro-Fiber Composite (MFC). The MFCs have an asymmetric actuation range of -500 to 1500 V; hence an MFC bimorph with conventional serial or parallel electrical connection limits the actuation to the -500 to 500 V range. The proposed circuit allows the division of the input voltage so that: (1) The MFC that is in extension receives 1500 V, and (2) The MFC that is in compression receives -500 V. The circuit also allows the actuation in the opp...

Bimorph Silk Microsheets with Programmable Actuating Behavior: Experimental Analysis and Computer Simulations

Abstract: Microscaled self-rolling construct sheets from silk protein material have been fabricated, containing a silk bimorph composed of silk ionomers as an active layer and cross-linked silk β-sheet as the passive layer. The programmable morphology was experimentally explored along with a computational simulation to understand the mechanism of shape reconfiguration. The neutron reflectivity shows that the active silk ionomers layer undergoes remarkable swelling (eight times increase in thickness) after deprotonation while the passive silk β-sheet retains constant volume under the same conditions and supports the bimorph construct. This selective swelling within the silk-on-silk bimorph microsheets generates strong interfacial stress between layers and out-of-plane forces, which trigger autonomous self-rolling into various 3D constructs such as cylindrical and helical tubules. The experimental observations and computational modeling confirmed the role of interfacial stresses and allow programming the morphology o...

Electromechanical Modeling of Cantilevered Piezoelectric Energy Harvesters for Persistent Base Motions

Abstract: This chapter investigates electromechanical modeling of cantilevered piezoelectric energy harvesters excited by persistent base motions. The modeling approaches are divided here into two sections as lumped parameter modeling and distributed parameter modeling. The first section discusses the amplitude-wise correction of the existing lumped parameter piezoelectric energy harvester model for base excitation. For cantilevers operating in the transverse and longitudinal vibration modes, it is shown that the conventional base excitation expression used in the existing lumped parameter models may yield highly inaccurate results in predicting the vibration response of the structure. Dimensionless correction factors are derived to improve the predictions of the coupled lumped parameter piezoelectric energy harvester model. The second section of this chapter presents coupled distributed parameter modeling of unimorph and bimorph cantilevers under persistent base excitations for piezoelectric energy harvesting. Closed-form solutions are obtained by considering all vibration modes and the formal representation of the direct and converse piezoelectric effects. Steady state electrical and mechanical response expressions are derived for arbitrary frequency excitations. These multi-mode solutions are then reduced to single-mode solutions for excitations around the modal frequencies. Finally, the analytical expressions derived here are validated experimentally for a cantilevered bimorph with a proof mass.