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81
Integrated Structural Health Monitoring
- An International Journal
, 2001
"... Structural health monitoring is the implementation of a damage detection strategy for aerospace, civil and mechanical engineering infrastructure. Typical damage experienced by this infrastructure might be the development of fatigue cracks, degradation of structural connections, or bearing wear in ro ..."
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Cited by 109 (3 self)
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Structural health monitoring is the implementation of a damage detection strategy for aerospace, civil and mechanical engineering infrastructure. Typical damage experienced by this infrastructure might be the development of fatigue cracks, degradation of structural connections, or bearing wear in rotating machinery. The goal of the research effort reported herein is to develop a robust and cost-effective structural health monitoring solution by integrating and extending technologies from various engineering and information technology disciplines. It is the authors' opinion that all structural health monitoring systems must be application specific. Therefore, a specific application, monitoring welded moment resisting steel frame connections in structures subjected to seismic excitation, is described along with the motivation for choosing this application. The structural health monitoring solution for this application will integrate structural dynamics, wireless data acquisition, local actuation, micro-electromechanical systems (MEMS) technology, and statistical pattern recognition algorithms. The proposed system is based on an assessment of the deficiencies associated with many current structural health monitoring technologies including past efforts by the authors. This paper provides an example of the integrated approach to structural health monitoring being undertaken at Los Alamos National Laboratory and summarizes progress to date on various aspects of the technology development.
Structural Health Monitoring Using Statistical Process Control.
- Journal of Structural Engineering
, 2000
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Embedment of Structural Monitoring Algorithms in a Wireless Sensing Unit
- Structural Engineering and Mechanics
, 2003
"... Complementing recent advances made in the field of structural health monitoring and damage detection, the concept of a wireless sensing network with distributed computational power is proposed. The fundamental building block of the proposed sensing network is a wireless sensing unit capable of acqui ..."
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Cited by 31 (21 self)
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Complementing recent advances made in the field of structural health monitoring and damage detection, the concept of a wireless sensing network with distributed computational power is proposed. The fundamental building block of the proposed sensing network is a wireless sensing unit capable of acquiring measurement data, interrogating the data and transmitting the data in real time. The computational core of a prototype wireless sensing unit can potentially be utilized for execution of embedded engineering analyses such as damage detection and system identification. To illustrate the computational capabilities of the proposed wireless sensing unit, the fast Fourier transform and autoregressive time-series modeling are locally executed by the unit. Fast Fourier transforms and autoregressive models are two important techniques that have been previously used for the identification of damage in structural systems. Their embedment illustrates the computational capabilities of the prototype wireless sensing unit and suggests strong potential for unit installation in automated structural health monitoring systems.
Articles A Review of Vibration-based Structural Health Monitoring with Special Emphasis on Composite Materials
, 2006
"... ABSTRACT—Structural health monitoring and damage detection techniques are tools of great importance in the offshore, civil, mechanical and aeronautical engineering communities, both for safety reasons and because of the economic benefits that can result. The need to be able to detect damage in compl ..."
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Cited by 27 (0 self)
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ABSTRACT—Structural health monitoring and damage detection techniques are tools of great importance in the offshore, civil, mechanical and aeronautical engineering communities, both for safety reasons and because of the economic benefits that can result. The need to be able to detect damage in complex structures has led to the development of a vast range of techniques, of which many are based upon structural vibration analysis. In the present article, some of the latest advances in Structural Health Monitoring and Damage Detection are reviewed, with an emphasis on composite structures on the grounds that this class of materials currently has a wide range of engineering applications. FOREWORD—It should be noted that this review is not intended to be a general, all-encompassing review covering the whole range of structural health monitoring (SHM); it was
Structural Damage Detection and Localization Using NETSHM
- In Proc. of IPSN
, 2006
"... Structural health monitoring (SHM) is an important application area for wireless sensor networks. Recent work has examined the design of wireless sensor networks for structural data acquisition systems. The eventual goal of structural monitoring, however, is autonomous detection and localization of ..."
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Cited by 24 (0 self)
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Structural health monitoring (SHM) is an important application area for wireless sensor networks. Recent work has examined the design of wireless sensor networks for structural data acquisition systems. The eventual goal of structural monitoring, however, is autonomous detection and localization of structural damage. Developing practical damage detection and localization schemes is still an area of active research and there exists a large array of techniques. Structural engineers typically implement and test SHM algorithms in a higher level language such as C/Matlab. Practical sensor network based SHM systems, thus, should allow structural engineers to program various SHM schemes in a higher level language that they are familiar with such as C/Matlab without delving into the intricacies of the underlying sensor network. In this paper we describe the design of NETSHM, a programmable, re-usable and evolvable sensor network system that can be used to implement a variety of structural monitoring techniques at a level of abstraction that structural engineers are comfortable with. We validate our design by implementing and evaluating a damage detection techniques and localization techniques on a NETSHM prototype.
Statistical damage classification under changing environmental and operational conditions
- Journal of Intelligent Material Systems and Structures
, 2002
"... ABSTRACT: Stated in its most basic form, the objective of damage diagnosis is to ascertain simply ifdamage is present or not based on measured dynamic characteristics ofa system to be monitored. In reality, structures are subject to changing environmental and operational conditions that affect measu ..."
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Cited by 23 (3 self)
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ABSTRACT: Stated in its most basic form, the objective of damage diagnosis is to ascertain simply ifdamage is present or not based on measured dynamic characteristics ofa system to be monitored. In reality, structures are subject to changing environmental and operational conditions that affect measured signals, and environmental and operational variations of the system can often mask subtle changes in the system’s vibration signal caused by damage. In this paper, a unique combination oftime series analysis, neural networks, and statistical inference techniques is developed for damage classification explicitly taking into account these ambient variations ofthe system. First, a time prediction model called an autoregressive and autoregressive with exogenous inputs (AR-ARX) model is developed to extract damagesensitive features. Then, an autoassociative neural network is employed for data normalization, which separates the effect of damage on the extracted features from those caused by the environmental and vibration variations ofthe system. Finally, a hypothesis testing technique called a sequential probability ratio test is performed on the normalized features to
Power-Efficient Data Management for a Wireless Structural Monitoring System
- In Proceedings of the 4th International Workshop on Structural Health Monitoring
, 2003
"... A low-cost wireless sensing unit for installation in structural monitoring systems is proposed. To eliminate the high cost of installing cables widely used in conventional systems, each wireless sensing unit includes wireless radios for reliable communication of response measurements. With wireless ..."
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Cited by 23 (6 self)
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A low-cost wireless sensing unit for installation in structural monitoring systems is proposed. To eliminate the high cost of installing cables widely used in conventional systems, each wireless sensing unit includes wireless radios for reliable communication of response measurements. With wireless radios consuming large amounts of power, battery preservation can be achieved by limiting the use of the wireless channel. This study explores two approaches to reducing the power demands of the wireless sensing unit. First, embedded engineering analyses are carried out by the sensing unit’s computational core to avoid transmission of long time-history records. Various engineering algorithms are encoded and executed using structural response data to illustrate the power saved in local data interrogation. Second, lossless data compression using Huffman coding is employed to reduce the size of data packets wirelessly transmitted.
Post-seismic damage assessment of steel structures instrumented with self-interrogating wireless sensors
- Proceedings of the 8th National Conference on Earthquake Engineering
, 2006
"... Wireless sensors have been proposed for use in structural health monitoring systems because they offer low-installation costs and automated data processing functionality. A wireless sensor prototype is described for use in large-scale civil structures situated in zones of high seismic activity. When ..."
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Cited by 18 (9 self)
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Wireless sensors have been proposed for use in structural health monitoring systems because they offer low-installation costs and automated data processing functionality. A wireless sensor prototype is described for use in large-scale civil structures situated in zones of high seismic activity. When networked together, the distributed computational resources of the wireless sensor network can be leveraged to automate the process of screening post-seismic ambient response data for signs of structural damage. To validate the performance of the proposed wireless monitoring system, a three-story half-scale steel structure is instrumented with a wireless monitoring system assembled from a network of six wireless sensors. Attached to the wireless monitoring system is a heterogeneous array of sensing transducers including strain gages and accelerometers. White noise and seismic ground motion records are applied to the base of the structure using a shaking table. Autoregressive time series models are calculated by the wireless sensors using structural response data. Pattern classification methods are then adopted to classify the structure as damaged or undamaged using the autoregressive time series coefficients as feature vectors. To simulate damage in the structure, the steel columns are modified at the base of the structure with reduced column sections. The proposed damage detection methodology is shown to be capable of identifying the reduced column sections as damage.
Structural Health Monitoring Using Modular Wireless Sensors
- Journal of Intelligent Material Systems and Structures
, 2003
"... ABSTRACT: System integration ofan online structural health monitoring module was accomplished by coupling commercially available microelectro-mechanical system sensors and a wireless telemetry unit with damage detection firmware. To showcase the capabilities of the integrated monitoring module, a bo ..."
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Cited by 17 (3 self)
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ABSTRACT: System integration ofan online structural health monitoring module was accomplished by coupling commercially available microelectro-mechanical system sensors and a wireless telemetry unit with damage detection firmware. To showcase the capabilities of the integrated monitoring module, a bolted frame structure was constructed, and the preload in one ofthe bolted joints was controlled by a piezoelectric stack actuator to simulate gradual deterioration ofa bolted connection. Two separate damage detection algorithms were used to classify a joint as damaged or undamaged. First, a statistical process control algorithm was used to monitor the correlation ofvibration data from two accelerometers mounted across a joint. Changes in correlation were used to detect damage to the joint. For each joint, data were processed locally on a microprocessor integrated with the wireless module, and the diagnosis result was remotely transmitted to the base monitoring station. Second, a more sophisticated damage detection algorithm combining time series analysis and statistical hypothesis testing was employed using a conventional wired data acquisition system to classify a joint on the
Overview of Wireless Sensors for RealTime Health Monitoring of Civil Structures
- Proceedings of the 4 th International Workshop on Structural Control and Monitoring
"... Wireless monitoring has emerged in recent years as a promising technology that will greatly impact the field of structural health monitoring. This paper is a summary of research efforts that have resulted in the design of numerous wireless sensing unit prototypes explicitly intended for implementati ..."
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Cited by 13 (2 self)
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Wireless monitoring has emerged in recent years as a promising technology that will greatly impact the field of structural health monitoring. This paper is a summary of research efforts that have resulted in the design of numerous wireless sensing unit prototypes explicitly intended for implementation in civil structures. Wireless sensing units integrate wireless communications and mobile computing with sensors to deliver a sensor platform inexpensive to install in large-scale structures. Collocating computational power with sensors is a distinct feature of the wireless sensing paradigm that allows sensors to self-interrogate measurements for signs of structural damage. The paper concludes with a discussion on the future research needs that can further advance wireless sensing as a viable substitute for traditional wire-based structural monitoring systems.
