Showing papers in "Structural Health Monitoring-an International Journal in 2012"
TL;DR: In this article, the effect of low-frequency vibration excitation on modulation intensity and associated nonlinear wave interaction mechanisms was investigated experimentally in a cracked aluminum plate, and a clear link between modulations and thermo-elastic coupling was also demonstrated, providing experimental evidence for the recently proposed non-classical, nonlinear vibro-acoustic wave interaction mechanism.
Abstract: Vibro-acoustic nonlinear wave modulations are investigated experimentally in a cracked aluminum plate. The focus is on the effect of low-frequency vibration excitation on modulation intensity and associated nonlinear wave interaction mechanisms. The study reveals that energy dissipation – not opening–closing crack action – is the major mechanism behind nonlinear modulations. The consequence is that relatively weak strain fields can be used for crack detection in metallic structures. A clear link between modulations and thermo-elastic coupling is also demonstrated, providing experimental evidence for the recently proposed non-classical, nonlinear vibro-acoustic wave interaction mechanism.
195 citations
TL;DR: In this paper, an in situ imaging method is presented to detect the impact source location in reverberant complex composite structures using only one passive sensor, which can be used for real-time impact detection.
Abstract: This article presents an in situ imaging method able to detect in real-time the impact source location in reverberant complex composite structures using only one passive sensor. This technique is b...
145 citations
TL;DR: Many bridges worldwide are approaching the end of their lifespan and it is necessary to assess their health condition in order to mitigate risks, prevent disasters, and plan maintenance activities as mentioned in this paper, which can be found in this paper.
Abstract: Many bridges worldwide are approaching the end of their lifespan and it is necessary to assess their health condition in order to mitigate risks, prevent disasters, and plan maintenance activities ...
134 citations
TL;DR: Natural disasters, in particular earthquakes, can cause damage to pipelines with disastrous humanitarian, social, economic, and ecologic consequences as mentioned in this paper, thus, real-time, automatic, or on-demand asses...
Abstract: Natural disasters, in particular earthquakes, can cause damage to pipelines with disastrous humanitarian, social, economic, and ecologic consequences. Thus, real-time, automatic, or on-demand asses...
104 citations
TL;DR: In this paper, the authors monitored fatigue crack growth in plate structures with ultrasonic guided waves generated from piezoelectric transducers and found that cracks initiate in the vicinity of fastener holes due to cyclic in-plane cyclic fatigue cracks.
Abstract: Fatigue crack growth in plate structures is monitored with ultrasonic guided waves generated from piezoelectric transducers. Cracks initiate in the vicinity of fastener holes due to cyclic in-plane...
94 citations
TL;DR: In this article, a multi-physics-based finite element method is used to model the electromechanical behavior of a free piezoelectric wafer active sensor and its interaction with the host structure on which it is bonded.
Abstract: The advancement of composite materials in aircraft structures has led to an increased need for effective structural health monitoring technologies that are able to detect and assess damage present in composite structures. The study presented in this article is interested in understanding self-sensing piezoelectric wafer sensors to conduct electromechanical impe- dance spectroscopy in glass fiber reinforced polymer composite to perform structural health monitoring. For this objec- tive, multi-physics-based finite element method is used to model the electromechanical behavior of a free piezoelectric wafer active sensor and its interaction with the host structure on which it is bonded. The multi-physics-based modeling permits the input and output variables to be expressed directly in electric terms, while the two-way electromechanical conversion is done internally in the multi-physics-based finite element method formulation. The impedance responses are also studied in conditions when the sensor bonding layer is subject to degradation and when the sensor itself is sub- jected to breakage, respectively. To reach the goal of using the electromechanical impedance spectroscopy approach to detect damage, several damage models are generated on simplified orthotropic structure and laminated glass fiber rein- forced polymer structures. The effects of the modeling are carefully studied through experimental validation. A good match has been observed for low and high frequencies.
93 citations
TL;DR: In this article, a new impact localization technique that can pinpoint the location of an impact event within a complex structure using a time-reversal concept, surface-mounted piezoelectric tra...
Abstract: This study presents a new impact localization technique that can pinpoint the location of an impact event within a complex structure using a time-reversal concept, surface-mounted piezoelectric tra...
84 citations
TL;DR: In this article, an in situ structural health monitoring method is proposed to locate the impact source and to determine the flexural Lamb mode A0 velocity in composite structures with unknown lay-up.
Abstract: This article proposes an in situ structural health monitoring method able to locate the impact source and to determine the flexural Lamb mode A0 velocity in composite structures with unknown lay-up...
77 citations
TL;DR: In this paper, a correlation-based nonparametric data analysis approach for detecting and localizing structural changes using strain data under operational loading conditions is presented, which is based on tracking correlation coefficients between strain time histories at different locations.
Abstract: Structural health monitoring systems integrate novel experimental technologies, analytical methods, and information technologies for a number of objectives such as detecting structural changes and damage as well as assessing the condition, safety, and serviceability of the monitored structure. The objective of this article is to present a correlation-based methodology as an effective nonparametric data analysis approach for detecting and localizing structural changes using strain data under operational loading conditions. While several methods have been explored in the literature, the focus of this article is to explore a practical and cost-effective (in terms of sensor, data acquisition, and analysis) methodology to identify structural problems. The methodology presented here is based on tracking correlation coefficients between strain time histories at different locations. After discussing the background, the effectiveness of the methodology is first demonstrated on a laboratory test structure. A unique...
76 citations
TL;DR: In this article, a fiber-optic distributed sensor which can measure strain distributions along fiber Bragg grating (FBG) with the high spatial resolution was developed, which is based on optical frequency domain reflectometry and a long-length FBG whose length is about 100mm can be used.
Abstract: We have developed a fiber-optic distributed sensor which can measure strain distributions along fiber Bragg grating (FBG) with the high spatial resolution This sensing system is based on optical frequency domain reflectometry and a long-length FBG whose length is about 100 mm can be used We can identify the longitudinal strain at an arbitrary position along the FBG using signal processing technology In this study, long-length FBGs were embedded into the adhesive layers of the two single-lap joints and we could successfully measure the strain distributions inside the adhesives In one single-lap joint, the adherends were carbon fiber reinforced plastics and in another one, they were aluminum Theadhesive was epoxy in both cases The measured results were compared with the calculated ones by nonlinear finite element (FE) analysis in which the large displacement and the elasto–plastic response of the adherend or adhesive material were account for We found that in most of the applied loads, the agreement
72 citations
TL;DR: In this article, the authors proposed a damage detection method which is able to deal with temperature variations, where the objective function correlates mode shapes and natural frequencies, and a parallel genetic algorithm handles the inverse problem.
Abstract: Modal parameters such as natural frequencies and mode shapes are sensitive indicators of structural damage. However, they are not only sensitive to damage, but also to the environmental conditions such as, humidity, wind and most important, temperature. For civil engineering structures, modal changes produced by environmental conditions can be equivalent or greater than the ones produced by damage. This article proposes a damage detection method which is able to deal with temperature variations. The objective function correlates mode shapes and natural frequencies, and a parallel genetic algorithm handles the inverse problem. The numerical model of the structure assumes that the elasticity modulus of the materials is temperature-dependent. The algorithm updates the temperature and damage parameters together. Therefore, it is possible to distinguish between temperature effects and real damage events. Simulated data of a three-span bridge and experimental one of the I-40 Bridge validate the proposed methodo...
TL;DR: In this paper, a reinforced concrete slab supported by four steel columns and subjected to earthquake-type dynamic loading on a shake table was analyzed and a good correlation was found between the energy dissipated by the concrete through plastic deformations and the acoustic emissions associated with concrete cracking and friction.
Abstract: This article presents the results and analysis of Acoustic Emission (AE) as recorded in a reinforced concrete (RC) slab supported by four steel columns and subjected to earthquake-type dynamic loading on a shake table. Fifteen seismic simulations were conducted using an accelerogram registered during the Campano-Lucano earthquake (Italy, 1980). The peak acceleration applied to the shake table was increased until the slab reinforcement was on the brink of yielding and slippage of the bars within the concrete occurred. This limit state is commonly associated with low-to-moderate intensity earthquakes in earthquake-prone regions. The evolution of damage to the slab was monitored in terms of AE energy and the history of plastic strain energy was calculated from the acceleration and displacement measurements. A good correlation was found between the energy dissipated by the concrete through plastic deformations and the AE energy associated with concrete cracking and friction. On this basis, a tentative formula...
TL;DR: In this paper, a new approach for fatigue life assessment of bolted steel joints using the equivalent stiffness determined by surface-bonded piezo-impedance transducers is presented.
Abstract: This article presents a new approach for fatigue life assessment of bolted steel joints using the equivalent stiffness determined by surface-bonded piezo-impedance transducers. The piezo transducer ...
TL;DR: In this paper, the Dempster-Shafer (D-S) evidence theory-based approach for structural damage detection is presented, where the damage basic probability assignment (BPA) function of substructures is used.
Abstract: In this study, the Dempster–Shafer (D–S) evidence theory-based approach for structural damage detection is presented. First, the damage basic probability assignment (BPA) function of substructures ...
TL;DR: In this article, a simple and versatile measurement system for structural health monitoring (SHM) based on the electromechanical impedance (EMI) technique is proposed, which allows real-time data acquisition from multiple sensors and includes compensation for temperature effects.
Abstract: This article presents a simple and versatile measurement system for structural health monitoring (SHM) based on the electromechanical impedance (EMI) technique. The proposed system allows real-time data acquisition from multiple sensors and includes compensation for temperature effects, eliminating one cause of incorrect diagnoses in structural monitoring. Besides the low cost compared to conventional impedance analyzers, the hardware and the software are simple and easier to implement than other measurement systems that have been recently proposed. Tests were carried out on an aluminum beam under different temperatures and on an aluminum plate with nine PZT (lead zirconate titanate) patches. The experimental results show conclusively that the proposed methodology is efficient and feasible for real-time SHM.
TL;DR: In this paper, a structural parameter identification and damage detection approach using displacement measurement time series is proposed, and the performance of the approach is validated experimentally with a frusteration system.
Abstract: A structural parameter identification and damage detection approach using displacement measurement time series is proposed, and the performance of the approach is validated experimentally with a fr...
TL;DR: In this paper, a wireless sensing device is embedded into freshly poured concrete to monitor initial curing and subsequent structural health, and the results show that hydrating concrete has an effect on the sensing system and that it is sensitive enough to monitor the strength development of concrete.
Abstract: The application of the electromechanical impedance (EMI) method to monitor the condition of structures is an actively researched area. This article extends the method to allow it to be incorporated into a wireless sensing device, which is embedded into freshly poured concrete to monitor initial curing and subsequent structural health. The results show that the hydrating concrete has an effect on the sensing system and that it is sensitive enough to monitor the strength development of concrete. Initial results also show that the embedded EMI method is sensitive to the removal of formwork. The response of the system to compressive testing is also investigated, and the initial results show a good correlation with previously published reports on compressive testing of concrete. Finally, the ability of the system to be incorporated into a previously developed wireless-sensing platform is investigated. The AD5933 impedance chip offers this possibility, and its response is investigated and compared with the resp...
TL;DR: In this article, a statistical model identification using Bayesian inference when parameters are correlated and observed data have noise and bias is presented. But, the method is explained using the Paris model that describes crack growth in a plate under mode I loading, and the remaining useful life was predicted accurately because the identification errors in correlated parameters were compensated by each other.
Abstract: This paper presents statistical model parameter identification using Bayesian inference when parameters are correlated and observed data have noise and bias. The method is explained using the Paris model that describes crack growth in a plate under mode I loading. It is assumed the observed data are obtained through structural health monitoring systems, which may have random noise and deterministic bias. It was found that strong correlation exists (a) between two model parameters of the Paris model, and (b) between initially measured crack size and bias. As the level of noise increases, the Bayesian inference was not able to identify the correlated parameters. However, the remaining useful life was predicted accurately because the identification errors in correlated parameters were compensated by each other.
TL;DR: In this paper, numerical simulations were conducted in order to examine the influence of distance on the shape distortion of an excited wave inside concrete, and the results showed that classification of cracks based on acoustic emission parameters would be probably misleading in case the separation distance of the sensors is long or the material contains many cracks.
Abstract: Apart from the quantitative parameters of acoustic emission testing, such as the total activity or the location of the sources, much more information can be exploited by qualitative characteristics of the signals. The shape of the waveform strongly depends on the source, supplying information on the type of cracks. Shear cracks which normally follow tensile during fracture, emit signals with longer rise time as well as lower average frequency. However, due to the inherent inhomogeneity of the media, which is enhanced by the nucleation of cracks, each pulse suffers strong dispersion which results in serious alteration of the waveform shape. Therefore, classification of cracks based on acoustic emission parameters would be probably misleading in case the separation distance of the sensors is long or the material contains many cracks. In the present study, numerical simulations were conducted in order to examine the influence of distance on the shape distortion of an excited wave inside concrete. Results are...
TL;DR: Guided wave structural health monitoring offers the potential for efficient defect detection and localization on large plate-like structures as discussed by the authors, and the aim of this article is to demonstrate that the performance of the guided wave health monitoring can be improved.
Abstract: Guided wave structural health monitoring offers the potential for efficient defect detection and localization on large plate-like structures. The aim of this article is to demonstrate that the perf...
Journal Article•
TL;DR: In this article, the applicability of Hilbert transform and HilbertHuang transform on the postprocessing of guided ultrasonic waves for evaluating the condition of relatively complex structural health monitoring applications is presented.
Abstract: The analysis and extraction of the appropriate signal's features in structural health monitoring applications is one of the major challenges on which the robustness of the designed systems relies Many strategies have been developed in the past, which utilise the identification of amplitude-based parameters for the evaluation of structural integrity However, these parameters usually require a baseline reference, which might be extensively affected by noise, environmental or mounting conditions This paper illustrates the applicability of Hilbert transform and HilbertHuang transform on the postprocessing of guided ultrasonic waves for evaluating the condition of relatively complex structural health monitoring applications Two case studies are presented to demonstrate the suitability of the techniques, namely, the damage monitoring of an aluminium repaired panel and the cure level monitoring of symmetric carbon fibreepoxy composite laminates In the first case study, the technique exhibits sensitivity in propagation paths within damaged areas and shows good agreement with the developed damage, enabling the identification of critical areas In the second study, the technique demonstrates a significant advantage over the traditionally adopted approaches and predicts accurately the cure level of the polymeric composite system Copyright 2012 John Wiley & Sons, Ltd
TL;DR: In this paper, fractal theory and R/S analysis were combined to obtain the inherent regularity of observed time series from multi-source data, and its variation tendency was processed quantitatively.
Abstract: For a dam system, its effect quantities of different observed points are related absolutely. To identify evolution tendency of a dam system, it is necessary to find the inherent regularity using observed time series from available multi-source data. Rescaled range analysis (R/S analysis) and fractal theory have been recognized as important tools to assist in the solving of problems of internal correlations in time series of effect quantities in many fields. In this article, fractal theory and R/S analysis were combined to obtain the inherent regularity of observed time series from multi-source data, and its variation tendency was processed quantitatively. By means of building the global time effect model and early-warning criterion of dam deformation and seepage, dam disease diagnosis and early-warning for dam safety can be realized. Deformation analysis of one gravity dam was taken as an example: the time effect monitoring model for this dam deformation was built, based on this, the dam behavior was diag...
TL;DR: In this article, a structural health monitoring (SHM) fastener consisting of a conformable eddy current sensor film that is integrated with a metallic sleeve that goes around the fastener shank was designed.
Abstract: In this study, a structural health monitoring (SHM) fastener consisting of a conformable eddy current sensor film that is integrated with a metallic sleeve that goes around the fastener shank was d...
TL;DR: By analyzing the arrival times of guided waves, the acoustic source in a plate is predicted in this paper, and solving this problem is important for continuous health monitoring of structures. Several techniques bas...
Abstract: By analyzing the arrival times of guided waves, the acoustic source in a plate is predicted. Solving this problem is important for continuous health monitoring of structures. Several techniques bas...
TL;DR: The triboluminescence phenomenon has been proposed as a sensor system for detecting and monitoring damage in aerospace and civil infrastructure systems (CIS), while significant work is being done as mentioned in this paper.
Abstract: The triboluminescence phenomenon has been proposed as a sensor system for detecting and monitoring damage in aerospace and civil infrastructure systems (CIS). While significant work is being done i...
TL;DR: In this article, the identification of data that is unusual or different, is relevant in a wide number of real-world scenarios, ranging from identifying unusual weather conditions to detecting ev...
Abstract: Novelty detection, the identification of data that is unusual or different, is relevant in a wide number of real-world scenarios, ranging from identifying unusual weather conditions to detecting ev...
TL;DR: The Santas Justa and Rufina Gothic Church (fourteenth century) has suffered several physical, mechanical, chemical, and biochemical types of pathologies along its history: rock alveolization, efflo...
Abstract: The Santas Justa and Rufina Gothic church (fourteenth century) has suffered several physical, mechanical, chemical, and biochemical types of pathologies along its history: rock alveolization, efflo...
TL;DR: In this paper, structural health monitoring of civil infrastructure consists of determining, by measured parameters, the location and severity of damage in the structure, and many structural vibration paramea...
Abstract: Ideally, structural health monitoring of civil infrastructure consists of determining, by measured parameters, the location and severity of damage in the structure. Many structural vibration parame...
TL;DR: In this article, the authors report the results of a test-to-failure performed using a real bridge, where the bridge was heavily monitored during the test, using both traditional sensors such as electrical strain gauges and linear variable differential transducers alongside new monitoring systems such as fibre-optic sensors, strain rosette LVD transducers and a novel photographic camera.
Abstract: Full-scale failure tests are rarely performed on structures, primarily due to their high costs and the lack of suitable test objects. This article reports the results of a ‘test-to-failure’ performed using a real bridge. The results obtained in such tests are valuable for assessing analytical models, updating finite element models and investigating the real behaviour of structures. The specific intention in these experiments was to study the shear failure of the bridge, which is a less well-understood mode of failure than is bending. To this end, it was necessary to strengthen the bridge using near-surface-mounted reinforcements made of carbon fibre–reinforced polymer bars in order to prevent bending failure. The bridge was heavily monitored during the test, using both traditional sensors such as electrical strain gauges and linear variable differential transducers alongside new monitoring systems such as fibre-optic sensors, strain rosette linear variable differential transducers and a novel photographic...
TL;DR: In this paper, a stress transfer model focusing on the tip of a crack in concrete, with stress transfer from the host structure to the sensing segment on the attached fiber, was investigated.
Abstract: Stimulated Brillouin-based optical fiber sensors have been receiving increasing attention in recent times because of their ability to measure distributed strain at high spatial resolution. This study presents a methodical approach for understanding the structural behavior from measured strain distribution. A stress-transferring model, focusing on the tip of a crack in concrete, with stress transfer from the host structure to the sensing segment on the attached fiber, was investigated. The loss of information due to the limited spatial resolution of the sensor was also analyzed. An experimental study using a notched concrete prism demonstrated the effectiveness of the proposed model for crack identification, allowing the study to leverage the stimulated Brillouin-based sensor to crack quantification as well as detection and localization.