Experimental vibration dataset collected of a beam reinforced with masses under different health conditions

Vibration signals extracted from structures across diverse health conditions have become indispensable for monitoring structural integrity. These datasets represent a resource for real-time condition monitoring, enabling the precise detection and diagnosis of system anomalies. This paper aims to enrich the scientific community's database on structural dynamics and experimental methodologies pertinent to system modelling. Leveraging experimental measurements obtained from mass-reinforced beams, these datasets validate numerical models, refine identification techniques, quantify uncertainties, and continuously foster machine learning algorithms' evolution to monitor structural integrity. Furthermore, the beam dataset is data-driven and can be used to develop and test innovative structural health monitoring strategies, specifically identifying damages and anomalies within intricate structural frameworks. Supplemental datasets like Mass-position and damage index introduce parametric uncertainty into experimental and damage identification metrics. Thereby offering valuable insights to elevate the efficacy of monitoring and control techniques. These comprehensive tests also encapsulate paramedic uncertainty, providing robust support for applications in uncertainty quantification, stochastic modelling, and supervised and unsupervised machine learning methodologies.

Laser ultrasonics for nondestructive testing of composite materials and structures: A review

This paper presents a comprehensive overview of Laser Ultrasonic Testing (LUT) and its applications in composite materials. The working principles of LUT are thoroughly explained, and an assessment of its advantages and drawbacks is provided. The mechanisms of wave generation and detection are described, along with their influence on the capabilities and limitations of LUT. The paper includes an inclusive overview of each LUT application in composite materials, highlighting their potential, challenges, and research gaps. LUT is a noncontact and nondestructive technique that utilizes lasers to generate and detect ultrasonic waves, with the material itself acting as an emitting transducer. This unique noncontact approach offers an accurate, versatile, convenient, and rapid method for inspecting and characterizing materials. However, some challenges and research gaps have hindered its widespread adoption. One significant challenge in LUT is the low signal-to-noise ratio (SNR), which becomes more pronounced in composite materials due to their low ablation threshold and high wave attenuation. Furthermore, the characterization and inspection of composite materials are more intricate due to their anisotropy and complex damage patterns. Despite these challenges, the combination of ultrasonic waves capable of characterizing and inspecting materials, coupled with the capabilities of lasers and optics for noncontact and real-time operation, presents a promising outlook for the widespread implementation of LUT in Smart Industries and harsh industrial environments, including those with high temperatures, high pressures, or radioactive conditions. This paper contributes to the understanding of LUT's potential and limitations, paving the way for further advancements in its applications.

Dataset for damage detection retrieved from a monitored bridge pre and post verified damage

The Vänersborg Bridge in southwest Sweden is a single-leaf bascule bridge carrying railway traffic over a canal. The load consists of passing commuter trains, occasional freight trains and leaf openings to allow ships to pass on the canal. The bridge constructed from 1914 to 1916 was built by riveted truss members in steel. Over the years, several assessments and maintenance actions have been performed to keep the bridge in service. During autumn 2021, a long-term monitoring campaign was initiated with the installation of sensors to register the load effect and possible changes in the behaviour. In March 2023, the cloud-based service employed detected an abrupt change of behaviour. An emergency inspection revealed a large crack in one of the truss members in the counter-weight part. The published dataset contains sensor data from 64 registered bridge openings, comprising accelerations, strains, inclinations, and weather conditions. Data from before the fracture, during, and after are provided. During the bridge opening events, the data was recorded continuously with a sampling rate of 200 Hz. The evidence of damage in a real case scenario makes the dataset valuable for testing and evaluation of data-driven routines for infrastructure surveillance.

Seismic assessment of bridges through structural health monitoring: a state-of-the-art review

The present work offers a comprehensive overview of methods related to condition assessment of bridges through Structural Health Monitoring (SHM) procedures, with a particular interest on aspects of seismic assessment. Established techniques pertaining to different levels of the SHM hierarchy, reflecting increasing detail and complexity, are first outlined. A significant portion of this review work is then devoted to the overview of computational intelligence schemes across various aspects of bridge condition assessment, including sensor placement and health tracking. The paper concludes with illustrative examples of two long-span suspension bridges, in which several instrumentation aspects and assessments of seismic response issues are discussed.

Spatial mapping of the DNA adducts in cancer

DNA adducts and strand breaks are induced by various exogenous and endogenous agents. Accumulation of DNA damage is implicated in many disease processes, including cancer, aging, and neurodegeneration. The continuous acquisition of DNA damage from exogenous and endogenous stressors coupled with defects in DNA repair pathways contribute to the accumulation of DNA damage within the genome and genomic instability. While mutational burden offers some insight into the level of DNA damage a cell may have experienced and subsequently repaired, it does not quantify DNA adducts and strand breaks. Mutational burden also infers the identity of the DNA damage. With advances in DNA adduct detection and quantification methods, there is an opportunity to identify DNA adducts driving mutagenesis and correlate with a known exposome. However, most DNA adduct detection methods require isolation or separation of the DNA and its adducts from the context of the nuclei. Mass spectrometry, comet assays, and other techniques precisely quantify lesion types but lose the nuclear context and even tissue context of the DNA damage. The growth in spatial analysis technologies offers a novel opportunity to leverage DNA damage detection with nuclear and tissue context. However, we lack a wealth of techniques capable of detecting DNA damage in situ. Here, we review the limited existing in situ DNA damage detection methods and examine their potential to offer spatial analysis of DNA adducts in tumors or other tissues. We also offer a perspective on the need for spatial analysis of DNA damage in situ and highlight Repair Assisted Damage Detection (RADD) as an in situ DNA adduct technique with the potential to integrate with spatial analysis and the challenges to be addressed.

On acoustic fields of complex scatters based on physics-informed neural networks

This paper proposes a modeling method for scattered acoustic fields under complex structures based on Physics-informed Neural Networks (PINNs), with particular attention to the acquisition of training sets and the embedding of physical governing equations. First, using acoustic simulation softwares to obtain the scattered acoustic field under various models, and select the scattered acoustic field data at several moments as the training sets. Then, according to the characteristics of the simulated model, the corresponding physical equations have been embedded in the loss function of the network. We tested the method by predicting the propagation of ultrasonic waves and the scattering of acoustic fields with various simple scatterers. Furthermore, we also use PINN to simulate the scattered acoustic field of the real complex damaged structure. The results show that the mean square error (MSE) between prediction and ground truth is in the order of 10^-4, which illustrate PINN can effectively simulate the propagation and reflection of ultrasonic waves, and can also simulate the scattered acoustic field of complex structures accurately. The meshless and accurate characteristics of PINN provide a reliable alternative for the theoretical prediction of complex and continuous scattered acoustic fields.

Imaging of sub-surface defect in CFRP laminate using A0-mode Lamb wave: Analytical, numerical and experimental studies

Lamb wave propagation in the anisotropic material is characterized by the prominent directivity of wave energy transfer governed by the fiber direction. Due to this anisotropic behavior, it is difficult to define the location of defects by using the arriving time of reflected signals. In this article, A₀-mode Lamb wave-based damage detection technique has been illustrated which can detect the overlapping region of incident and scattered wave in the vicinity of the finite defect region in CFRP composite plate-like structure. A 5-cycle Hanning windowed tone burst of 30 kHz has been allowed to propagate through a 2 mm thickness [0/90]_4S CFRP plate with subsurface cylindrical defect. In the near field region of the defect, the incoming and reflected wave overlaps and the dynamic shear strains of the out-of-plane displacement evaluated consequently. A covariance matrix is developed consisting of the shear strains. The proposed technique can detect the overlapping regions by measuring the determinant of covariance matrix, thus the image of the defect can be reconstructed. In this article, the analytical model of the proposed wavelet-based technique for the subsurface cylindrical defect is discussed and their physical meanings are investigated through numerical and experimental studies in a cross-ply laminate.

Health assessment of dams under various environmental conditions using structural health monitoring techniques: a state-of-art review

Over a while, changes in the environment, such as climate, weather, pollution, will have a more significant impact on the structures in different ways. Hence, continuous monitoring of the structures plays a vital role in order to have a predefined prediction of the structural damages that can be caused by the change in the environment. Structural health monitoring (SHM) is critical in determining the life expectancy of civil structures. The advancement of various sensors and data acquisition systems (DAQ) has enabled more accurate prediction of the life span of civil structures subjected to static and dynamic loading conditions. Hence, SHM is a critical area of research to understand the condition and lifetime of structures such as dams. This article provides detailed insight into the base failures in dam structures such as soil erosion, toe erosion, and gully formation. Also, scouring's impact on the dam structures was discussed in this review article. This review article investigates in detail the detection and analysis of dam structure damage.

Spectral element modeling of ultrasonic guided wave propagation in optical fibers

Recent advancements in fiber optic methods have enabled their use for guided wave sensing. It opens up new possibilities for Structural Health Monitoring. The aim of this paper is to provide insight for the physics related to guided wave propagation and coupling between the optical fiber and solid structure. For this purpose, a new approach for non-matching interface based on Lagrange multipliers and the time domain spectral element method was developed. A parallelized code has been implemented in order to simulate the guided wave propagation in the structure, its coupling into the optical fiber and the propagation in the fiber in a computationally efficient way. The paper presents four studies showing the efficacy of the modeling approach. The paper first shows the improvement in the computation speed through the use of parallelization and a more efficient implementation. Then the results of the simulation of wave propagation in the fiber are compared with results from previous simulation studies using commercially available software. The third study shows that the spectral element method is able to capture the directional sensitivity of optical fiber based sensors. Lastly, the simulation is used for detection of simulated damage using the spectral element method based simulation. The results indicate that indeed the spectral element implementation is able to recreate the wave coupling phenomena, capture the physics of the system including directional sensitivity and reflections from damage.

Dataset on full ultrasonic guided wavefield measurements of a CFRP plate with fully bonded and partially debonded omega stringer

The fourth dataset dedicated to the Open Guided Waves platform [1] presented in this work aims at a carbon fiber composite plate with an additional omega stringer at constant temperature conditions. The dataset provides full ultrasonic guided wavefields. Two types of signals were used for guided wave excitation, namely chirp signal and tone-burst signal. The chirp signal had a frequency range of 20-500 kHz. The tone-burst signals had a form of sine modulated by Hann window with 5 cycles and carrier frequencies 16.5 kHz, 50 kHz, 100 kHz, 200 kHz, 300 kHz. The piezoceramic actuator used for this purpose was attached to the center of the stringer side surface of the core plate. Three scenarios are provided with this setup: (1) wavefield measurements without damage, (2) wavefield measurements with a local stringer debond and (3) wavefield measurements with a large stringer debond. The defects were caused by impacts performed from the backside of the plate. As result, the stringer feet debonds locally which was verified with conventional ultrasound measurements.

Acceleration time history dataset for a 3D miniature model of a shear building with structural damage

The dynamics of short-to-medium height frame buildings closely resembles with a shear building. The vibrational response from a shear building model will help to understand and carry out a detailed study over the behaviour of these buildings. This data article provides acceleration time history response from a laboratory-based small-scaled (scale 1:20) three-dimensional six-storey shear building model. The article presents model specification, its assembly and experimental set-up for acquiring these data. The dataset contains free vibrational responses from the structure under both undamaged and damaged conditions. This laboratory model and corresponding experimental data are a valuable asset for the researchers working on analytical and numerical model generation, particularly in the field of structural health monitoring, in order to experimentally verify their newly developed methodologies for damage identification. The authors have provided this data to assist and contribute so as to benefit the state-of-the-art. All the datasets can be accessed via the repository link provided in the specification table. The article also provides a complete model assembly and experimentation video to its readers for a better insight into the data acquisition steps.

Shear horizontal wave transducers for structural health monitoring and nondestructive testing: A review

Shear horizontal (SH) waves are of great importance in structural health monitoring (SHM) and nondestructive testing (NDT), since the lowest order SH wave in isotropic plates is non-dispersive. The SH waves in plates, circumferential SH waves and torsional waves in pipes have remarkable resemblances in dispersion characteristics and wave structures, so the latter two can also be called as SH waves in pipes. This paper reviews the state-of-the-art research on SH wave transducers for SHM and NDT. These transducers are grouped into the following categories: Lorentz-force-based electromagnetic acoustic transducers (EMATs), magnetostrictive EMATs, shear wave piezoelectric wedge transducers, thickness-shear piezoelectric transducers and face-shear piezoelectric transducers. The working principles, applications, merits and limitations of different kinds of SH wave transducers are summarized, with a focus on discussing the various configurations for exciting and receiving directional, omnidirectional SH waves in plates and torsional waves in pipes. This paper is expected to greatly promote the applications of SH waves in SHM, NDT and the related areas such as elastic metamaterials.

Lamb waves and electro-mechanical impedance based damage detection using a mobile PZT transducer set

Lamb waves and electro-mechanical impedance (EMI) based methods are increasingly used in damage detection owing to their high sensitivity to small structural defects. Lamb wave based methods are effective in detecting damages in a large area and electro-impedance based methods are suitable for characterizing the identified damage. Based on these two methods, a novel combined damage detection method is presented in this research. To achieve this, first, a mobile transducer set is developed, which can be used for both the Lamb waves and EMI based methods. Then, a baseline-free damage detection strategy that combines the Lamb waves and EMI methods is presented. Finally, a laboratory-sized test piece is used to validate the effectiveness of the proposed approach. The results achieved with the application of the presented combined method for characterizing an L-shape crack in an aluminum plate show better location accuracy and detection efficiency than those obtained by applying only one method.

Modeling of nonlinear interactions between guided waves and fatigue cracks using local interaction simulation approach

This article presents a parallel algorithm to model the nonlinear dynamic interactions between ultrasonic guided waves and fatigue cracks. The Local Interaction Simulation Approach (LISA) is further developed to capture the contact-impact clapping phenomena during the wave crack interactions based on the penalty method. Initial opening and closure distributions are considered to approximate the 3-D rough crack microscopic features. A Coulomb friction model is integrated to capture the stick-slip contact motions between the crack surfaces. The LISA procedure is parallelized via the Compute Unified Device Architecture (CUDA), which enables parallel computing on powerful graphic cards. The explicit contact formulation, the parallel algorithm, as well as the GPU-based implementation facilitate LISA's high computational efficiency over the conventional finite element method (FEM). This article starts with the theoretical formulation and numerical implementation of the proposed algorithm, followed by the solution behavior study and numerical verification against a commercial finite element code. Numerical case studies are conducted on Lamb wave interactions with fatigue cracks. Several nonlinear ultrasonic phenomena are addressed. The classical nonlinear higher harmonic and DC response are successfully captured. The nonlinear mode conversion at a through-thickness and a half-thickness fatigue crack is investigated. Threshold behaviors, induced by initial openings and closures of rough crack surfaces, are depicted by the proposed contact LISA model.

Minimum variance imaging based on correlation analysis of Lamb wave signals

In Lamb wave imaging, MVDR (minimum variance distortionless response) is a promising approach for the detection and monitoring of large areas with sparse transducer network. Previous studies in MVDR use signal amplitude as the input damage feature, and the imaging performance is closely related to the evaluation accuracy of the scattering characteristic. However, scattering characteristic is highly dependent on damage parameters (e.g. type, orientation and size), which are unknown beforehand. The evaluation error can degrade imaging performance severely. In this study, a more reliable damage feature, LSCC (local signal correlation coefficient), is established to replace signal amplitude. In comparison with signal amplitude, one attractive feature of LSCC is its independence of damage parameters. Therefore, LSCC model in the transducer network could be accurately evaluated, the imaging performance is improved subsequently. Both theoretical analysis and experimental investigation are given to validate the effectiveness of the LSCC-based MVDR algorithm in improving imaging performance.

Combined analytical FEM approach for efficient simulation of Lamb wave damage detection

Lamb waves have been widely explored as a promising inspection tool for non-destructive evaluation (NDE) and structural health monitoring (SHM). This article presents a combined analytical finite element model (FEM) approach (CAFA) for the accurate, efficient, and versatile simulation of 2-D Lamb wave propagation and interaction with damage. CAFA used a global analytical solution to model wave generation, propagation, scattering, mode conversion, and detection, while the wave-damage interaction coefficients (WDICs) were extracted from harmonic analysis of local FEM with non-reflective boundaries (NRB). The analytical procedure was coded using MATLAB, and a predictive simulation tool called WaveFormRevealer 2-D was developed. The methodology of obtaining WDICs from local FEM was presented. Case studies were carried out for Lamb wave propagation in a pristine plate and a damaged plate. CAFA predictions compared well with full scale multi-physics FEM simulations and experiments with scanning laser Doppler vibrometry (SLDV), while achieving remarkable performance in computational efficiency and computer resource saving compared with conventional FEM.

High-frequency lowest torsional wave mode ultrasonic inspection using a necked pipe waveguide unit

We propose an effective method to transmit only the non-dispersive lowest torsional wave mode at a high frequency range even above the cutoff frequency of the third torsional mode. Unlike existing methods that tune the wavelength or phase of the target wave mode, the proposed method is based on the thickness change and the cutoff phenomenon. A specially configured necked waveguide, consisting of three regions of which the middle region is thinner than the so-called cutoff thickness, is put in end-to-end contact with a test pipe to transmit only the first torsional wave mode to a test pipe. After explaining the underlying role of the proposed necked waveguide, we propose a technique to mainly transmit the lowest torsional wave mode at a frequency where higher modes can also propagate. Numerical simulations and damage detection experiments were carried out to show the effectiveness of the proposed method.

Detection and quantification of pipe damage from change in time of flight and phase

The use of ultrasonic guided waves for damage detection in pipes is continuously increasing. Generally longitudinal (axial symmetric) modes are excited and detected by PZT (Lead Zirconate Titanate) transducers in transmission mode for this purpose. In most studies the change in the received signal strength with the extent of damage has been investigated while in this study the change in the phase and the time-of-flight (TOF) of the propagating wave modes with the damage size is investigated. The cross-correlation technique is used to record the small changes in the TOF as the damage size varies in steel pipes. Dispersion curves are calculated to carefully identify the propagating wave modes. Differential TOF is recorded and compared for different propagating wave modes. Feature extraction techniques are used for extracting phase and time-frequency information. The main advantage of this approach is that unlike the recorded signal strength the TOF and the phase are not affected by the bonding condition between the transducer and the pipe. Therefore, if the pipe is not damaged but the transducer-pipe bonding is deteriorated then although the received signal strength is altered the TOF and phase remain same avoiding the false positive alarms of damage.

Robust ultrasonic damage detection under complex environmental conditions using singular value decomposition

Guided wave ultrasonics is an attractive monitoring technique for damage diagnosis in large-scale plate and pipe structures. Damage can be detected by comparing incoming records with baseline records collected on intact structure. However, during long-term monitoring, environmental and operational conditions often vary significantly and produce large changes in the ultrasonic signals, thereby challenging the baseline comparison based damage detection. Researchers developed temperature compensation methods to eliminate the effects of temperature variation, but they have limitations in practical implementations. In this paper, we develop a robust damage detection method based on singular value decomposition (SVD). We show that the orthogonality of singular vectors ensures that the effect of damage and that of environmental and operational variations are separated into different singular vectors. We report on our field ultrasonic monitoring of a 273.05 mm outer diameter pipe segment, which belongs to a hot water piping system in continuous operation. We demonstrate the efficacy of our method on experimental pitch-catch records collected during seven months. We show that our method accurately detects the presence of a mass scatterer, and is robust to the environmental and operational variations exhibited in the practical system.