Bimorph

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

Performance of a Piezoelectric Bimorph Harvester with Variable Width

Abstract: This article analyzes the performance of a piezoelectric energy harvester in the flexural mode for scavenging ambient vibration energy. The energy harvester consists of a piezoelectric bimorph plate with a variable width. A theoretical study is performed and the computational results show that the output power density increases initially, reaches a maximum, and then decreases monotonically with the increasing width, underscoring the importance for the width design of the scavenging structure. Further analysis indicates that the peak of output power density is determined by both the bimorph deformation amplitude and the efficiency in scavenging-energy. The analysis for this simplified model piezoelectric harvester provides a framework for further development on design guidelines for piezoelectric energy harvesters of optimal performance.

Bimorph MEMS devices

Abstract: A micro-electromechanical dimensioned bimorph structure includes a first element layer structure, and a second element layer structure. The element layer structures are provided in various combinations, including piezoelectric/piezoelectric, antiferroelectric/antiferroelectric or antiferroelectric/piezoelectric. The layer thickness of the element structure is less than 100 μm. A bonding layer bonds the first element structure directly to the second element structure, and the bonding layer thickness is less than 10 μm. The bimorph structure can be made in various forms including a cantilever or a diaphragm. Microfluidic devices using the bimorph structures may also be constructed.

Adjusting the resonant frequency of a PVDF bimorph power harvester through a corrugation-shaped harvesting structure

Abstract: We propose a corrugated polyvinylidene fluoride (PVDF) bimorph power harvester with the harvesting structure fixed at the two edges in the corrugation direction and free at the other edges. The resonant frequency of a corrugated PVDF bimorph is readily adjusted through changing either its geometrical configuration or the span length, which can keep the harvester operating at the optimal state in environments with different ambient vibrations. The governing equations of a PVDF bimorph with a corrugation shape, are derived from the transfer-matrix technique. Statistical results show that the adaptability of a harvester to the operating environment can be improved greatly by designing the harvesting structure with adjustable resonant frequency.

Modeling and vibration control of an active membrane mirror

Abstract: The future of space satellite technology lies in ultra-large mirrors and radar apertures for significant improvements in imaging and communication bandwidths. The availability of optical-quality membranes drives a parallel effort for structural models that can capture the dominant dynamics of large, ultra-flexible satellite payloads. Unfortunately, the inherent flexibility of membrane mirrors wreaks havoc with the payload's on-orbit stability and maneuverability. One possible means of controlling these undesirable dynamics is by embedding active piezoelectric ceramics near the boundary of the membrane mirror. In doing so, active feedback control can be used to eliminate detrimental vibration, perform static shape control, and evaluate the health of the structure. The overall motivation of the present work is to design a control system using distributed bimorph actuators to eliminate any detrimental vibration of the membrane mirror. As a basis for this study, a piezoceramic wafer was attached in a bimorph configuration near the boundary of a tensioned rectangular membrane sample. A finite element model of the system was developed to capture the relevant system dynamics from 0 to 300 Hz. The finite element model was compared against experimental results, and fair agreement found. Using the validated finite element models, structural control using linear quadratic regulator control techniques was then used to numerically demonstrate effective vibration control. Typical results show that less than 12 V of actuation voltage is required to eliminate detrimental vibration of the membrane samples in less than 15 ms. The functional gains of the active system are also derived and presented. These spatially descriptive control terms dictate favorable regions within the membrane domain for placing sensors and can be used as a design guideline for structural control applications. The results of the present work demonstrate that thin plate theory is an appropriate modeling medium for capturing the relevant system dynamics of an active membrane mirror and can be used effectively to set the framework for the closed-loop vibration control architecture.

Single crystal domain driven bender actuator

Abstract: A single crystal bender actuator for selectively positioning a movable precision optical or acoustical component is described which comprises a single crystal of barium titanate, barium strontium titanate, barium lead titanate, potassium niobate tantalate, lead titanate-lead magnesium niobate or other material in which a special domain structure can be induced to produce a very high strain bimorph configuration, the single crystal operatively interconnecting support structure and the movable component, and means for selectively applying an electric field of controllable field strength to the crystal.