Appendix: Overview of Some Sensors and Actuators Used for Smart Structure Applications

1999 ◽  
Vol 604 ◽  
Author(s):  
Alison B. Flatau ◽  
Marcelo J. Dapino ◽  
Frederick T. Calkins

AbstractThis paper provides an overview of magnetostrictive transducer technology. The bi-directional coupling between the magnetic and mechanical states of a magnetostrictive material provides a transduction mechanism that can be used both for actuation and sensing. The current interest in design of adaptive smart structures, coupled with the advent of materials that exhibit high sensor figures of merit, such as Metglas and giant magnetostrictive materials such as Terfenol-D has lead to a renewed interest in the engineering of optimized magnetostrictive transducer designs. A survey of recent applications for giant magnetostrictive materials as both sensors and actuators and their use in smart structure applications will be presented along with a brief discussion of some pertinent device design issues. Examples of magnetostrictive actuation used to produce displacements, force and acoustic waves are summarized. Magnetostrictive sensor configurations that measure motion, stress or force, torque, magnetic fields and target characteristics are discussed. A very brief look at transducer modeling and experimental results is included and schematics of a number of actuator and sensor configurations are presented.


Author(s):  
Marcelo J. Dapino

Ultrasonic additive manufacturing (UAM), a form of 3D printing based on ultrasonic metal welding, allows for room-temperature fabrication of adaptive structures with seamlessly embedded sensors and actuators. UAM combines solid-state welding of metallic foils, automated additive foil layering, and CNC machining. The most recent UAM systems utilize 9 kW of ultrasonic power for improved build strength and quality over low power systems, leading to previously unfeasible smart structures. Current UAM efforts in this area are focused on embedding smart materials, fiber optics, and cooling channels into metallic matrices. Since UAM process temperatures do not exceed one half of the melting temperature of the matrix, various alloys such as NiTi and FeGa, and polymers such as PVDF, have been successfully embedded without degradation of the smart material or the matrix. This paper aims to demonstrate the benefits of UAM, with particular emphasis on smart components for vehicle design. Example concepts include stiffness-tunable structures, thermally invariant composites, and materials with embedded cooling channels.


2017 ◽  
Vol 14 (2) ◽  
pp. 165-172
Author(s):  
Lebied Abdelaziz ◽  
Necib Brahim ◽  
Sahli Mohamed Lakhdar

Purpose Safety improvement and cost reduction have a strong influence on the way to achieve maintenance operations of complex structures, in particular in air transportation, in civil engineering and others. In this case, piezoelectric ceramics such as sensors and actuators have been used. The advantages of piezoelectric materials include high achievable bandwidth, reliability, compactness, lightness and ease of implementation, thus making them well-suited to be used as actuators and sensors in the case of onboard structures. In this context, this study based around the examination of health and deformation of smart structures, taking into consideration the mechanical and piezoelectric behaviour of sensors and actuators, mechanical contact as well as the initial conditions and the imposed boundary conditions. This paper aims to present an approach for modeling of an intelligent structure by the finite element method. This structure is of aluminum type beam with elastic behaviur where piezoelectric rectangular pellets discreetly spread on the surface of the beam are instrumented. The numerical results were computed and compared to the experimental tests available in the literature and the results show the effectiveness of these piezoelectric (PZT) elements, depending on their positions, and to control the deformed structure, good agreement has been found between the experimental data and numerical predictions. Design/methodology/approach Numerical modeling by finite elements model for the measurement of the deformation and the change in shape of a clamped-free structure composed of both elastic and piezoelectric materials have been given by using the Ansys® software. The numerical results were valid by comparisons with analytical and experimental results find in the literature. Findings The numerical results showing a good correlation and agree very well. It was also concluded that the actuator and the sensor will be better placed at the housing because it is the position or the actuator that has the greatest impact and where the sensor gives the greatest signal. They are said to be co-located as glues one below the other on either side of the beam. Originality/value These materials have an inverse piezoelectric effect allowing them to control the form and present any noise or vibration at any time or position on the structure. The study presented in this paper targets the modeling of a PZT beam device for deform generation by transforming electrical energy into usable load. In this paper, a unimorph piezoelectric cantilever with traditional geometry is investigated for micromanipulation by using the software Ansys®.


Author(s):  
Fernando J. O. Moreira ◽  
José Roberto de França Arruda ◽  
Daniel J. Inman

Abstract In this paper the design of a low order controller for a high-order, smart structural system is presented. The application considered here is a model of a solar panel dynamically similar to those used on satellites. Smart structure refers here to the use of integrated piezoceramic materials as sensors and actuators in the structural system in order to implement the control. The theoretical contribution is made be extending well known robust control theory by relating the high frequency robustness condition to the residual uncertainty, removing a trial and error step in the normal robust control design. The procedure is applied experimentally to a one-meter long frame that is coupled in bending and torsion. Both numerical and experimental results are given.


Aerospace ◽  
2004 ◽  
Author(s):  
Wai Leung Chan ◽  
Soren Solari ◽  
Robert E. Skelton

Tensegrity is a special class of tension-trusses. Strings play an important role in the deployment and shape changing of these structures. A simple class-1 tensegrity unit consists of 3 bars and 9 strings. This unit can be arranged to form a tower or a flat plate. With the integration of sensors and actuators, the tower and plate can be a smart structure. In this paper, we demonstrate the shape changing of a 7-unit tensegrity structure from a flat plate to a parabolic dish by controlling the length of strings in each unit. This provides a feasible structure for a next generation shape changing antenna and space telescope.


2015 ◽  
Vol 31 (6) ◽  
pp. 671-682 ◽  
Author(s):  
R. Xu ◽  
D.-X. Li ◽  
J.-P. Jiang ◽  
W. Liu

ABSTRACTThe vibration control of smart structure is considered in this paper. Membrane SAR antenna structure with piezoelectric sensors and actuators is taken as an example. The dynamic model is build up based on vector form intrinsic finite element (VFIFE) method. The four nodes membrane element, sensor element and actuator element for VFIFE are presented. By decentralized control stratagem, the bending and torsional vibrations of the membrane SAR antenna can be decoupled on measurement and driving control. The fuzzy control and adaptive fuzzy control are applied to suppress the bending and torsional vibrations of the membrane SAR structure. In the numerical experiment section, form finding is first carried out, then vibration control simulations are studied. The results demonstrate that adaptive fuzzy control algorithm can suppress the vibrations more effectively than the fuzzy control algorithm.


Author(s):  
Stephen J. Furst ◽  
Rohan Hangekar ◽  
Stefan Seelecke

Many “smart materials” have the capacity to be used simultaneously as both an actuator and sensor. For example, SMA actuator wires can be heated by Joule heating to induce contraction; at the same time, the resistance across the SMA wire can be measured to give the user some indication of the strain in the wire. This multi-functional capability enables the design of applications requiring extremely light-weight and streamlined embedded sensors and actuators. One such “smart structure” application is the flexible nozzle used in the Smart Inhaler system under development at North Carolina State University. The Smart Inhaler allows a doctor to control the locations within the pulmonary system that are medicated by controlling the location at which medication is injected into an inhaled airflow. This can reduce the amount of healthy tissue that is exposed to potentially toxic medications, such as those used to treat lung cancer. However, the practical challenge of injecting medication into a flow without disturbing the flow requires a highly controllable yet non-obstructive nozzle. This paper presents a scheme that correlates the resistance measurement across an SMA actuator wire to the wire strain and the resulting deformation of the flexible nozzle. The relationship between resistance and nozzle deformation is nonlinear and hysteretic; however, the repeatability of the relationship allows the user to calibrate the feedback measurement. This enables the wire to be used as both position sensor and positioning actuator. The results represent the first experiments that exploit the multi-functional capabilities of SMA wires in the context of a practical embedded sensor and actuator application.


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