Papers by Keyword: Smart Structure

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Authors: In Pil Kang, Gyeong Rak Choi, Joo Yung Jung, Yong Hoon Chang, Yeon Sun Choi, Mark J. Schulz
Abstract: This paper experimentally investigates the power generation property of carbon nanotubes in an aqueous environment. Carbon nanotube based films are investigated in this paper as a new method for power generation based on ionic conductivity of the fluid. It is demonstrated that a carbon nanotube film that is bonded onto a structure vibrating with an electrolyte on the surface produces an alternating current without a net fluid flow. The power produced is smaller than for a piezoelectric material of the same size, but the CNT power generator is lightweight and has no moving parts, and does not require the structure to be immersed in an electrolyte. There are various possible applications for nanotube power generators.
Authors: In Pil Kang, Hyo Byung Chae, Ki Hoon Park, Kwang Joon Yoon, Li Li Xin, Tae Sam Kang
Abstract: A smart material actuator is required for a smart structure having multifunctional performance. Among the smart material actuators, piezoelectric actuator is known for its excellent large force generation in broad bandwidth in a compact size. However it needs relatively large actuation voltage requiring a bulky hardware system. This study is mainly concerned to develop a self-powered miniaturized piezoelectric actuator driver (MIPAD) controlled by a radio controller for small sized piezoelectric smart structures. It can receive command from other microprocessors or a remote radio controller. We designed a real hardware and it demonstrated good performances even though the driving system was very small. The MIPAD is expected to minimize the weight and size of the piezoelectric actuator system and it can be easily embedded into mobile smart structures.
Authors: Nuan Song, Yi Wu, Wei Quan, Wei Zheng
Abstract: The key problem for improving the precision of grating sensor is the subdivision technolgy. According to the instable condition of traditional monostable trigger subdivision circuit works on fast condition, this paper adopts CPLD to judge the logic signal, can identify direction, subdivide and count. In addition, we have introduction of the exterior synchronous clock .The technology not only overcome the instable situation but also improve anti-jamming of circuit system .It has been proved that the method get the better effort in practice.
Authors: En Yu Jiang, Xiao Jin Zhu, Yong Shao, Zheng Liang Wang
Abstract: Though with its big restoring force and large deformation characteristic, shape memory alloy (SMA) is commonly used in the research of active vibration control for smart structure, the presence of its thermal hysteresis often leads to bad control performance. A vibration control method based on alternate multichannel driving SMA is proposed to improve the SMA based smart structural vibration control performance by reducing the effect of thermal hysteresis of SMA. The technical methods, the design of the experimental structure, the construction of the experimental platform is illustrated, with the principle and operating process of the experiment and experimental results described. By embedding the SMA driving elements into the epoxy substrate and mounted epoxy plate into the framework of the aircraft prototype, experimental analysis and verification is done. The experimental results show that alternate multichannel driving of SMA for vibration suppression of smart structure is feasible, and the performance is improved to a certain extent.
Authors: Mohammad Reza Bemanian, Mohammadjavad Mahdavinejad, Ali Karam, Shahabeddin Ramezani
Abstract: Suitable applications of smart structures for multifunctional spaces are going to be found by this paper. Logical argumentation research method is applied to identify a special smart structure which its features match to architectural requirements of multifunctional spaces. Hence, the smartness of architectural structures has two distinct scales: nanoscale and real scale, the application of these structures is based on two scales. Nanoscale smart structures have the capabilities which differ from real-scale smart structures. The analysis of features of multifunctional spaces shows that these kinds of spaces require structures which are smart both in nanoscale and real scale. As a result, combined-scale smart structures are recommended for multifunctional spaces.
Authors: Daniele Zonta, Matteo Pozzi, Hua Yong Wu, Daniele Inaudi
Abstract: This paper presents the laboratory validation of a prototype optic-fiber instrumented structural element. The element is a reduced-scale reinforced concrete beam, of dimensions 3.8×0.3×0.5m that can be pre-stressed by an internal Dywidag bar. The sensing technology is based on a multiplexed version of the SOFO strain sensor, prepared in the form of a 3-field smart composite bar; in-line multiplexing is obtained by separating each measurement field through broadband FBGs. The experiment aims to identify the response of the sensors to differing damage conditions artificially produced in the element, including cracking and loss of prestressing. A numerical algo-rithm, based on Bayesian logic, is applied to real-time diagnosis: by processing the sensor meas-urements and prior information, the method assigns a posterior probability to each assumed damage scenario, as well as the updated probability distributions for each relevant structural parameter. With respect to classical damage detection approaches, the merit of those based on Bayesian logic is to provide not only information on the damage, but also the degree of confidence in this informa-tion. The paper discusses the ability of the system to identify the differing damage conditions. The reported test clearly shows that an occurrence such as a loss of prestressing can be recognized early with a high degree of reliability based on the strain data acquired.
Authors: Yasuhide Shindo, Fumio Narita
Abstract: We present numerical and experimental results on the nonlinear bending behavior due to domain wall motion in functionally graded piezoelectric actuator under alternating current (ac) electric fields. A nonlinear finite element method is employed to analyze the dynamic response of functionally graded piezoelectric actuator. A phenomenological model of domain wall motion is used in computation, and the effects of ac electric field amplitude and frequency, number of layers, and property gradation on the deflection of the cantilever actuators are examined. Experimental results, which verify the model, are presented using a functionally graded bimorph. The numerical results agree very well with the experimental values.
Authors: Scott D. Moss, Ian Powlesland, Michael Konak, Alex Barry, Steve C. Galea, Gregory Carman
Abstract: The certification of retro-fitted structural health monitoring (SHM) systems for use on aircraft raises a number of challenges. One critical issue is determining the optimal means of supplying power to these systems, given that access to the existing aircraft power-system is likely to be problematic. Other conventional options such as primary cells can be difficult to certify and would need periodic replacement, which in an aircraft context would pose a serious maintenance issue. Previously, the DSTO has shown that a structural-strain based energy harvesting approach can be used to power a device for SHM of aircraft structures. Acceleration-based energy harvesting from airframes is more demanding (than a strain based approach) since the vibration spectrum of an aircraft structure varies dynamically with flight conditions, and hence a frequency agile or (relatively) broad-band device is often required to maximize the energy harvested. This paper reports on the development of a prototype vibro-impacting energy harvester with a ~59 gram flying mass and two piezoelectric bimorph-stops. Over the frequency range 29-41 Hz using a continuous-sine 450 milli-g r.m.s. excitation, the harvester delivers an average of 5.1 mW. From a random band-passed 25-45 Hz excitation with r.m.s. 450 milli-g, the average harvester output is 1.7 mW.
Authors: Satish Nagarajaiah, Shirley Dyke, Jerome P. Lynch, Andrew Smyth, Anil Agrawal, Michael Symans, Erik Johnson
Abstract: Structural Health Monitoring (SHM) is an important and growing field in civil engineering. The goal of SHM techniques is to identify, quantify and locate damage in structures. In light of the aging infrastructure and recent failures of important bridges, long-term monitoring techniques are being increasing investigated and adopted. In addition to SHM, structural control (SC) is increasingly adopted in modern structures around the world. In the past two decades a number of SC techniques, including, passive, semi-active, and active control methods have been developed and adopted in civil engineering–particularly, in infrastructure such as important tall buildings, critical facilities, and long span bridges. Both SHM and SC technology face significant challenges due to the size and scale of civil engineering structures. In response of these challenges researchers in the U.S.A and around the world have developed new and innovative techniques.This paper summarizes some of the ongoing research in the U.S.A. in the area of monitoring, damage detection and control in civil engineering structures.
Authors: Hideaki Murayama, Kazuro Kageyama, Isamu Ohsawa, Makoto Kanai, Kiyhoshi Uzawa, Tsuyoshi Matsuo
Abstract: We have developed a novel fiber-optic vibration sensors and applied commercially available strain and temperature sensors to health monitoring of composite structures. In this study, we constructed an optical fiber network integrating four types of optical fiber sensor into a carbon reinforced plastic (CFRP) panel. These four sensors were the vibration sensor developed by our laboratory, two distributed sensors based on Brillouin and Raman backscattering and Fiber Bragg Grating (FBG) sensors. By dealing the data obtained from the measurement systems corresponding to these four sensors, strain/stress and temperature distributions throughout the panel can be monitored. Vibration and elastic waves transmitting on the panel are also detected at several sensing points. Furthermore, we will be able to determine damage locations and modes by processing the wave signals. To make the panel with the optical fiber sensor network more sensitive and smarter, we are developing some techniques that can improve the performance of the sensors and can assess the structural integrity by analyzing measurement results. In this paper, the development of the first generation of our smart composite panel with the optical fiber sensors is described and the techniques making the panel more sensitive and smarter are also described.
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