Vibration-based Damage Detection Techniques Research Articles

Vibration-based damage detection techniques used for health monitoring of structures: a review

Structural health monitoring (SHM) techniques have been studied for several years. An effective approach for SHM is to choose the parameters that are sensitive to the damage occurring in the structure but not sensitive to operational or environmental damages. This paper deals with a comparative study among the different vibration-based damage detection methods: fundamental modal examination, local diagnostic method, non-probabilistic methodology and the time series method. All these strategies contemplate different parameters of a structure to recognize damage. Out of the study made, time series analysis proves to more successfully in damage identification than the rest of the methods.

Performance of Vibration Based Damage Detection Algorithms for Detection of Disbond in Stiffened Metallic Plates

Though vibration based health monitoring has been the focus of attention for quite some time, there exist a strong requirement for an extensive and comprehensive study on the relative performance of different damage detection algorithms under different damage scenarios. To fulfill this objective, a stiffened aluminium plate has been selected to make a comparative study on the performance of several vibration based damage detection techniques, namely, Modal Curvature, Gapped Smoothing Method/Modal Curvature, Generalized Fractal Dimension and Uniform Load Surface Curvature based on four different criteria: variation of damage intensity (i.e., disbond length), position of stiffener and disbond, the effect of noise and capability to detect multiple damage. In addition to this, a new approach, based on the curvature of wavelet coefficients, has been presented. It is found that this novel approach is extremely effective in determining the presence and location of damage under different situations. The entire numerical modelling is done in ANSYS 14.0 and the damage detection algorithms written in MATLAB codes have been used to generate the required damage indices using the modal data retrieved from ANSYS. The study ultimately enlightens inherent characteristics of the various damage detection algorithms under different damage conditions.

Vibration-based Damage Detection of the Reinforced Concrete Column

The article discusses the damage localization of concrete columns by means of vibration analysis techniques. The method for detecting and locating damage is based on the analysis of the dynamic characteristics of a structure, such as eigenfrequencies, mode shapes and modal damping. The article discusses the comparison of the diagnostic results of a full-scale experiment performed on the construction site with the finite element model of column. This article considers the damage localization technique of the reinforced concrete column based on the determination of the structure damage index. The article contains the review of the damage localization results with the different positions of the mono-axial accelerometer sensors along the column. During the research a software was developed to perform an automated diagnosis of reinforced concrete structures with the optimized arrangement of the accelerometer sensors using ANSYS Multiphysics to perform the finite element analysis of the structure and to determine their eigenfrequencies and mode shapes. The finite element analyses demonstrated that increasing the number of sensor locations allows determination of the location of the damage is more accurate, while the use of additional modes for structure shaping provides little advantage and can sometimes lead to a deterioration in the performance of the vibration-based damage detection techniques.

Optimal selection of autoregressive model coefficients for early damage detectability with an application to wind turbine blades

Data-driven vibration-based damage detection techniques can be competitive because of their lower instrumentation and data analysis costs. The use of autoregressive model coefficients (ARMCs) as damage sensitive features (DSFs) is one such technique. So far, like with other DSFs, either full sets of coefficients or subsets selected by trial-and-error have been used, but this can lead to suboptimal composition of multivariate DSFs and decreased damage detection performance. This study enhances the selection of ARMCs for statistical hypothesis testing for damage presence. Two approaches for systematic ARMC selection, based on either adding or eliminating the coefficients one by one or using a genetic algorithm (GA) are proposed. The methods are applied to a numerical model of an aerodynamically excited large composite wind turbine blade with disbonding damage. The GA out performs the other selection methods and enables building multivariate DSFs that markedly enhance early damage detectability and are insensitive to measurement noise.

Health Monitoring of Welded Steel Pipes by Vibration Analysis

In the present work, structure health monitoring (SHM) of welded steel pipes was used to diagnosis their state via vibration based damage detection techniques. The dynamic quantities such as Frequency Response Functions (FRFs), mode shapes and modal parameters from structural vibration to detect damage were measured, set on linear averaging mode, with a maximum frequency of analysis of 3.2 kHz. Two most commonly used welding techniques were used, namely: shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). Static tests were performed to assure the quality of welded steel pipes such as three point bending test (3PB), face bending, and tensile testing. In addition, X- ray, liquid penetration inspection methods were utilized as a NDT. The results show for non-cracked pipes, the first three modes, the higher the damping frequency and lower the damping ratio. This reflects the difficulty of dissipating energy at higher frequency. Also, it was found that SMAW to give higher damping ratio (7.418%) as compared with GTAW joints (7.220). So, the latter joints have higher stiffness than the former ones. However, cracked pipes welded lay 85 A seem to are highest damping for all the tested pipes (8.110%). The results demonstrated that the FRFs technique is a potentially powerful tool for damage detection, health monitoring of welded steel structural pipes

A vibration-based strategy for health monitoring of offshore pipelines' girth-welds.

This study presents numerical simulations and experimental verification of a vibration-based damage detection technique. Health monitoring of a submerged pipe's girth-weld against an advancing notch is attempted. Piezoelectric transducers are bonded on the pipe for sensing or actuation purposes. Vibration of the pipe is excited by two means: (i) an impulsive force; (ii) using one of the piezoelectric transducers as an actuator to propagate chirp waves into the pipe. The methodology adopts the empirical mode decomposition (EMD), which processes vibration data to establish energy-based damage indices. The results obtained from both the numerical and experimental studies confirm the integrity of the approach in identifying the existence, and progression of the advancing notch. The study also discusses and compares the performance of the two vibration excitation means in damage detection.

An investigation of the changes in the natural frequency of a pile affected by scour

Scour around bridge foundations is one of the leading causes of bridge failure. Up until recently, the monitoring of this phenomenon was primarily based around using underwater instrumentation to monitor the progression of scour holes as they develop around foundation systems. Vibration-based damage detection techniques have been used to detect damage in bridge beams. The application of these vibration based methods to the detection of scour has come to the fore in research in recent years. This paper examines the effect that scour has on the frequency response of a driven pile foundation system, similar to those used to support road and rail bridges. The effect of scour on the vibration characteristics of the pile is examined using laboratory and field testing. It is clear that there is a very clear reduction in the natural frequency of the pile as the severity of scour increases. It is shown that by combining state-of-the-art geotechnical techniques with relatively simple finite element modelling approaches, it is possible to accurately predict the natural frequency of the pile for a given scour depth. Therefore, the paper proposes a method that would allow the estimation of scour depth for a given observed pile frequency.

Effect of Temperature on Daily Modal Variability of a Steel-Concrete Composite Bridge

Vibration-based damage detection techniques typically use changes of modal characteristics of bridges as a possible indication of damage. However, structural damages are not the only cause of these changes. This study investigates the effect of temperature variations on modal characteristics of a two span steel-concrete composite bridge in North Carolina, and addresses the extent and reason of the daily changes observed in its dynamic properties. The field testing included measuring vibration responses, deflections, and temperatures of the bridge throughout a summer day. The dynamic characteristics of the bridge, derived from measurements at different times of the day, were compared with each other. Recorded temperatures and deflections of the bridge deck were used to address the observed changes in the natural frequencies of the bridge. Results of the field testing showed that temperature variations can induce modal variability on a daily cycle. A primary reason for this observation can be attributed to the temperature gradients measured on the bridge deck from night to noon.

Damage Detection of Bridge using Wireless Sensors

Bridges are essential links in any surface transportation network. A damage to an important bridge may result in enduring economic loss due to partial or complete closure of the route in addition to the cost of repair or replacement. Also, survival of bridges are of utmost importance in the aftermath of a devastating earthquake in order to facilitate rescue operations. Therefore, it has become customary to carry out a critical assessment of safety and integrity of bridges in regular intervals as well as immediately after disastrous events such as an earthquake. The prevalent practice of bridge inspection requires checking of each and every component, which is experience-based, highly time consuming and an expensive process, often enforcing disruption in traffic flow. As a result, the wireless sensor-based inspection methodology is gaining popularity in recent times. This paper a presents a study to show the efficiency of a multi-hopped wireless sensor network (WSN) for remote health monitoring of bridge. Various vibration-based and feature-based output-only damage detection techniques are applied to show their efficacy in terms of determining the location and severity of damages using the data collected from the bridge under damaged and undamaged conditions.

Vibration-Based Damage Detection of Pipeline System by HHT Method

Pipelines are regarded as the most cost-effective and the safest choice for transporting oil in bulk. In this study, the significance and necessity of conducting damage detection for onshore pipelines is firstly stated. Then, the limitations of current measures in use in pipeline industry and the inherent difficulty of applying vibration-based damage detection techniques (VBDT) to pipeline structures are addressed. This study focuses on exploring the applicability of an advanced VBDT method, HHT method, to the condition assessment of onshore pipelines. The feasibility and effectiveness of HHT method is verified through numerical study. The result shows that for the cases with single or multi segments of damage which are of the same type or of different types coexist in the structure, the HHT method is capable of providing very good results for the damage detection of pipeline system under ambient excitations. The obtained Hilbert spectrum gives very explicit presentation of the structural response’s energy distribution in both time and frequency domain, the marginal spectrum offers satisfactory result not only for locating the damaged area but also for a rough estimate of damage severity.

New methodology for the application of vibration-based damage detection techniques

Vibration-based damage detection (VBDD) comprises a promising set of techniques for damage detection and health monitoring of civil engineering structures. However, the successful application of these methods to real structures is still a challenging task, due primarily to the large size of such structures and the relatively high levels of variability in their dynamic response under operational load conditions. In this paper, a new methodology is introduced for the application of VBDD techniques, with the goal of enhancing their effectiveness for identifying and locating low damage levels and improving their applicability to the continuous or periodic health monitoring of structures. The basic features of the methodology include the use of a controlled and consistent excitation force, the use of operational deflection shapes (ODSs) at all measured frequency increments rather than only at natural frequencies, the use of a logarithmic scale for representing the ODS amplitudes at each frequency increment and the establishment of a threshold level for damage detection that accounts for experimental variability. The performance of the proposed methodology is verified and demonstrated by applying several Level 1 (damage detection) and Level 2 (damage localization) VBDD techniques using experimental data measured on a steel girder taken from a railway bridge. The proposed approach is shown to perform very well at detecting, locating and monitoring the growth of damage. Copyright © 2011 John Wiley & Sons, Ltd.

Using Geophones for Nondestructive Evaluation of Full-Scale Bridges

Nondestructive damage identification for civil engineering structures has received the attention of many researchers over the past several years. Vibration-based damage detection is a nondestructive structural health-monitoring approach that focuses on changes in the dynamic characteristics of a structure as indicators of damage. All vibration-based damage detection techniques require high signal-to-noise vibration data for analysis; thus the sensors used to measure vibrations are an important consideration. The objective of this study is to demonstrate the use of inexpensive geophones for determining the modal parameters of bridges to be used with vibration-based damage detection techniques. A geophone is a velocity transducer commonly used by seismologists for subsurface exploration. Researchers typically use accelerometers to measure bridge vibrations. However, compared with geophones, accelerometers are relatively expensive, have lower sensitivity, and require additional electronics for signal conditioning. To validate the use of geophones for modal parameter identification, a simple beam experiment was conducted, and the results were compared with theoretical values and a finite element model. Modal parameters identified from a full-scale bridge test are presented, and the effects of parapet rails and temperature change on the bridge's modal parameters are discussed. For successful implementation of the proposed methodology in a remote, wireless approach, a solar-powered, cell phone modem–based data acquisition system is demonstrated. This study makes an important contribution because the cost of the sensors needed for implementation of vibration-based damage detection on a large scale is substantially reduced with the use of high-sensitivity geophones.

Structural Health Monitoring of Precast Concrete Box Girders Using Selected Vibration-Based Damage Detection Methods

Precast, prestressed concrete box girders are commonly used as superstructure components for short and medium span bridges. Their configuration and typical side-by-side placement make large portions of these elements inaccessible for visual inspection or the application of nondestructive testing techniques. This paper demonstrates that vibration-based damage detection (VBDD) is an effective alternative for monitoring their structural health. A box girder removed from a dismantled bridge was used to evaluate the ability of five different VBDD algorithms to detect and localize low levels of spalling damage, with a focus on using a small number of sensors and only the fundamental mode of vibration. All methods were capable of detecting and localizing damage to a region within approximately 1.6 times the longitudinal spacing between as few as six uniformly distributed accelerometers. Strain gauges configured to measure curvature were also effective, but tended to be susceptible to large errors in near support damage cases. Finite element analyses demonstrated that increasing the number of sensor locations leads to a proportional increase in localization accuracy, while the use of additional modes provides little advantage and can sometimes lead to a deterioration in the performance of the VBDD techniques.

Damage detection of a steel–concrete composite frame by a multilevel approach: Experimental measurements and modal identification

AbstractStructural Health Monitoring (SHM) and Experimental Modal Analysis (EMA) have revealed to be really efficient tools for the damage detection of structures and structural elements in many engineering fields (Shock Vib. Dig. 1998; 30(2):91–105; Philos. Trans. R. Soc. A 2007; 365(1851):303–315; Mech. Syst. Signal Process. 2003; 17(1):133–142; Philos. Trans. R. Soc.: Math. Phys. Eng. Sci. 2001; 359(1778): 131–149; Struct. Control Health Monit. 2006; 14:1083–1100; Mech. Syst. Signal Process. 2004; 17(1): 83–89). Unfortunately the great variety of morphologies, construction materials and structural schemes makes these techniques not easily applicable to buildings, due to inherent problems related to the location and the extent of damage, the sensitivity of the dynamic response to damage, the choice of damage indexes to be used, the sensors' location, etc.On the other hand, the modern seismic capacity design of buildings in earthquake‐prone areas tends to locate dissipative zones in well‐determined portions of structures (CEN, European Committee for Standardization, EN 1998‐1. Eurocode 8: Design of Structures for Earthquake Resistance. Part 1: General Rules, Seismic Actions and Rules for Buildings, European Community, Brussels, Belgium, 2005); thus, the application of vibration‐based damage detection techniques to earthquake‐resistant structures seems to be very promising even if nowadays there are only few studies on these arguments.The present paper reports the experiences of a vibration‐based damage identification study applied to a steel–concrete composite frame structure, suitably designed to be high ductile according to Eurocode 8 and localizing the seismic energy dissipation in the beam‐to‐column joints. The structure was subjected to series of pseudo‐dynamic (PsD) and cyclic tests with increasing peak ground acceleration at the European Laboratory for Structural Assessment of Joint Research Centre at Ispra (VA, Italy). The damaging phenomena, caused by PsD tests, were assessed and quantified by means of a multi‐level vibration‐based approach suitably designed in order to evaluate the changes in the global dynamic structural response and to experimentally estimate the reduction in joint stiffness. Copyright © 2008 John Wiley & Sons, Ltd.

Assessment of vibration-based damage detection for an integral abutment bridge

Vibration-based damage detection (VBDD) comprises a family of nondestructive testing methods in which changes to signature dynamic characteristics are used to track the condition of a structure. Although VBDD methods have been successfully applied to various mechanical systems and to simple beam-like structures, significant challenges remain in extending this technology to complex, spatially distributed structures such as bridges. In the present study, numerical simulations using a calibrated finite element model were used to investigate the use of VBDD methods to detect small-scale damage on a two-span, integral abutment overpass structure located in Saskatoon, Saskatchewan. Five different VBDD techniques were evaluated, as were the effects of sensor spacing, mode shape normalization, and uncertainty in the measured mode shapes. It was found that localized damage to the top concrete cover of the bridge deck could be reliably detected and located if the sensors were located sufficiently close to the damage and if uncertainty in the mode shapes was attenuated through the use of a sufficient number of repeated trials. Furthermore, preliminary studies indicate that it may be possible to detect damage using sensors that are placed well away from the damaged area.Key words: vibration-based damage detection, structural health monitoring, integral abutment bridge, numerical modelling, field testing.

Development in vibration-based structural damage detection technique

This paper presents a general summary and review of state-of-the-art and development of vibration-based structural damage detection. Various structural damage detection methods based on structural dynamic characteristic parameters are summarised and evaluated. The principle of intelligent damage diagnosis and its application prospects in structural damage detection are introduced, and the development trends of structural damage detection are also put forward.