Damage detection in instrumented structures without baseline modal parameters

2010 ◽  
Vol 32 (6) ◽  
pp. 1715-1722 ◽  
Author(s):  
Ramsés Rodríguez ◽  
J. Alberto Escobar ◽  
Roberto Gómez
Keyword(s):  
Damage Detection ◽  
Modal Parameters

EFFECTIVENESS OF OPERATIONAL MODAL ANALYSIS (OMA) FOR DAMAGE DETECTION IN FIBERGLASS REINFORCED EPOXY

2015 ◽  
Vol 76 (8) ◽  
Author(s):  
Haizuan Abd Rahman ◽  
Ahmad Azlan Mat Isa ◽  
Abdul Rahim Bahari
Keyword(s):  
Finite Element Method ◽  
Boundary Condition ◽  
Composite Material ◽  
Damage Detection ◽  
Modal Analysis ◽  
Detection Method ◽  
Small Deviation ◽  
Operational Modal Analysis ◽  
Modal Parameters ◽  
Fiber Glass

This study attempts to apply vibration-based damage detection method specifically Operational Modal Analysis (OMA) on fiberglass reinforced epoxy plate. OMA is used on healthy fiber glass reinforced epoxy plate to extract the modal parameters and the procedure is extended to damaged fiberglass reinforced epoxy plate. Both healthy and damaged composite material are tested under different boundary conditions i.e. free-free on 4 edges, 1 edge clamped, 2 edges clamped, 3 edges clamped and 4 edges of free-free boundary condition. The result of frequency from OMA was compared analytically with Finite Element Method (FEM). Nastran software is employed in this study. The FEM using Nastran shows that the result obtained is not accurate enough compared to OMA. Therefore, another method was applied to look at the effectiveness of OMA method using Experimental Modal Analysis (EMA). It was observed that both EMA and OMA methods gave small deviation and good correlation.

Photogrammetry-based structural damage detection by tracking a visible laser line

2019 ◽  
Vol 19 (1) ◽  
pp. 322-336 ◽  
Author(s):  
Yongfeng Xu
Keyword(s):  
Finite Element ◽  
Damage Detection ◽  
Structural Damage ◽  
Detection Method ◽  
Element Model ◽  
Target Line ◽  
Laser Line ◽  
Modal Parameters ◽  
Structural Damage Detection ◽  
Visible Laser

Research works on photogrammetry have received tremendous attention in the past few decades. One advantage of photogrammetry is that it can measure displacement and deformation of a structure in a fully non-contact, full-field manner. As a non-destructive evaluation method, photogrammetry can be used to detect structural damage by identifying local anomalies in measured deformation of a structure. Numerous methods have been proposed to measure deformations by tracking exterior features of structures, assuming that the features can be consistently identified and tracked on sequences of digital images captured by cameras. Such feature-tracking methods can fail if the features do not exist on captured images. One feasible solution to the potential failure is to artificially add exterior features to structures. However, painting and mounting such features can introduce unwanted permanent surficial modifications, mass loads, and stiffness changes to structures. In this article, a photogrammetry-based structural damage detection method is developed, where a visible laser line is projected to a surface of a structure, serving as an exterior feature to be tracked; the projected laser line is massless and its existence is temporary. A laser-line-tracking technique is proposed to track the projected laser line on captured digital images. Modal parameters of a target line corresponding to the projected laser line can be estimated by conducting experimental modal analysis. By identifying anomalies in curvature mode shapes of the target line and mapping the anomalies to the projected laser line, structural damage can be detected with identified positions and sizes. An experimental investigation of the damage detection method was conducted on a damaged beam. Modal parameters of a target line corresponding to a projected laser line were estimated, which compared well with those from a finite element model of the damaged beam. Experimental damage detection results were validated by numerical ones from the finite element model.

Damage detection based on system identification of concrete dams using an extended finite element–wavelet transform coupled procedure

2017 ◽  
Vol 24 (18) ◽  
pp. 4226-4246 ◽  
Author(s):  
Sajjad Pirboudaghi ◽  
Reza Tarinejad ◽  
Mohammad Taghi Alami
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wavelet Transform ◽  
System Identification ◽  
Damage Detection ◽  
Cohesive Crack ◽  
Modal Parameters ◽  
Concrete Dams ◽  
Extended Finite Element ◽  
Element Method

The aim of the present study is to propose a procedure for seismic cracking identification of concrete dams using a coupling of the extended finite element method (XFEM) based on cohesive crack segments (XFEM-COH) and continuous wavelet transform (CWT). First, the dam is numerically modeled using the traditional finite element method (FEM). Then, cracking capability is added to the dam structure by applying the XFEM-COH for concrete material. The results of both the methods under the seismic excitation have been compared and identified to damage detection purposes. In spite of predefined damage in some of the structural health monitoring (SHM) techniques, there is an advantage in the XFEM model where the whole dam structure is potentially under damage risk without initial crack, and may not crack at all. Finally, in order to evaluate any change in the system, that is, specification of any probable crack effects and nonlinear behavior, the structural modal parameters and their variation have been investigated using system identification based on the CWT. The results show that the extended finite element–wavelet transform procedure has high ability for the online SHM of concrete dams that by analysis of its results, the history of physical changes, cracking initiation time, and exact damage localization have been performed from comparing the intact (FEM) and damaged (XFEM) modal parameters of the structural response. In addition, any small change in the system is observable while the final crack profile and performance simulation of the dam body under strong seismic excitations have obtained.

scholarly journals Sensitivity of Parameter Changes in Structural Damage Detection

1997 ◽  
Vol 4 (1) ◽  
pp. 27-37 ◽  
Author(s):  
C. H. Jenkins ◽  
L. Kjerengtroen ◽  
H. Oestensen
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Structural Response ◽  
Theoretical Models ◽  
Modal Parameters ◽  
Complex Structures ◽  
Static Deflection ◽  
Structural Damage Detection ◽  
Dynamic Measurements ◽  
Static Deflection Measurements

Structural damage detection by nondestructive methods is highly desirable. Changes in modal parameters such as frequency, damping, and mode shape are particularly inviting. Evidence is presented here that reveals that static deflection can, in many cases, be a more sensitive predictor of structural damage than frequency. The reasons for this are illuminated within, and hinge on very fundamental issues about the very nature of structural response. Furthermore, static deflection measurements are often easier to make, with higher levels of accuracy than dynamic measurements. Comparisons are made between theoretical models and experimental results for simple structures, with extensions given to more complex structures.

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