scholarly journals Dynamic Identification Techniques to Numerically Detect the Structural Damage

2013 ◽  
Vol 7 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Dora Foti
Keyword(s):  
Finite Element ◽  
Damage Detection ◽  
Structural Damage ◽  
Model Updating ◽  
Element Model ◽  
Mode Shapes ◽  
Dynamic Identification ◽  
Engineering Structures ◽  
Bridge Model ◽  
Modal Curvature

Damage detection in civil engineering structures using changes in measured modal parameters is an area of research that has received notable attention in literature in recent years. In this paper two different experimental techniques for predicting damage location and severity have been considered: the Change in Mode Shapes Method and the Mode Shapes Curvature Method. The techniques have been applied to a simply supported finite element bridge model in which damage is simulated by reducing opportunely the flexural stiffness EI. The results show that a change in modal curvature is a significant damage indicator, while indexes like MAC and COMAC – extensively and correctly used for finite element model updating - lose their usefulness in order to damage detection.

New structural damage-identification method using modal updating and model reduction

2014 ◽  
Vol 229 (6) ◽  
pp. 1041-1059 ◽  
Author(s):  
Mir M Ettefagh ◽  
Hossein Akbari ◽  
Keivan Asadi ◽  
Farshid Abbasi
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Damage Detection ◽  
Model Reduction ◽  
Traditional Method ◽  
Structural Damage ◽  
Model Updating ◽  
Element Model ◽  
Detection Algorithm ◽  
Detection Methods

Early prediction of damages using vibration signal is essential in avoiding the failure in structures. Among different damage-detection approaches, the finite-element model updating and modal analysis-based methods are of most importance due to their applicability and feasibility. Owing to some restrictions in nodal measurements in experimental cases, finite-element model reduction is an indispensable part of fault-detection methods. Even though model reduction of dynamic systems leads to the less complicated models, an improved convergence rate and acceptable accuracy are highly required for a successful structural health monitoring of the real complex systems. In this paper, the aim is to design a damage-detection algorithm based on a new model updating method, which has a faster rate of convergence and higher accuracy. Then the proposed method is applied on a simulated damaged beam considering different noise levels to see how capable the method is in dealing with noise-corrupted data. Finally, the experimentally extracted data from a cracked beam in a real noisy condition are used to evaluate the efficiency of the proposed method in identifying the damages in a beam-like structure. It is concluded that the identification of the damages by the proposed method is encouraging and robust to the noise compared with the traditional method. Also, the proposed method converges faster and is more accurate in identifying damage than the traditional method.

IDENTIFICATION OF DAMAGE FOR A THIN PLATE JOINTED STRUCTURE

2015 ◽  
Vol 76 (8) ◽  
Author(s):  
M. A. Yunus ◽  
M. N. Abdul Rani ◽  
A. A. M Isa ◽  
W. M. W. Sulaiman ◽  
R. Hassan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Damage Detection ◽  
Dynamic Characteristic ◽  
Model Updating ◽  
Element Model ◽  
Bolted Joints ◽  
Mode Shapes ◽  
Metal Sheets ◽  
Body In White

The dynamic characteristics of automotive structures are largely influenced by joints. The complex structures such as car a body-in-white is made from thin metal sheets and joined together by several types of joints such as spot welds and bolted joints. The integrity and dynamic characteristic of the structure are highly dependent on these joints. The defective and inaccurate tightening of the bolts during the assembly process could degrade the integrity of the structure and alter the dynamic characteristic of the vehicles. Early detection of the presence of damage in the structure is very important so that necessary actions can be taken to prevent further problems to the structure. In this paper, the damage detection via vibration based damage detection is used to identify the presence of damage in a bolted joints structure. In order to check the validity of the proposed method, natural frequencies and mode shapes of the initial finite element model of the undamaged structure and the finite element model of the damaged structure are compared with the experimental counterparts. The model updating method is used to improve the initial finite element model of the undamaged structure and the damaged structure as close as possible to the measured data.

FEM Free Damage Detection of Beam Structures Using the Deflections Estimated by Modal Flexibility Matrix

2021 ◽  
pp. 2150128
Author(s):  
Wen-Yu He ◽  
Wei-Xin Ren ◽  
Lei Cao ◽  
Quan Wang
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Damage Index ◽  
Element Model ◽  
Mode Shapes ◽  
Beam Structures ◽  
Flexibility Matrix ◽  
Damage Quantification ◽  
Modal Flexibility ◽  
The Cost

The deflection of the beam estimated from modal flexibility matrix (MFM) indirectly is used in structural damage detection due to the fact that deflection is less sensitive to experimental noise than the element in MFM. However, the requirement for mass-normalized mode shapes (MMSs) with a high spatial resolution and the difficulty in damage quantification restricts the practicability of MFM-based deflection damage detection. A damage detection method using the deflections estimated from MFM is proposed for beam structures. The MMSs of beams are identified by using a parked vehicle. The MFM is then formulated to estimate the positive-bending-inspection-load (PBIL) caused deflection. The change of deflection curvature (CDC) is defined as a damage index to localize damage. The relationship between the damage severity and the deflection curvatures is further investigated and a damage quantification approach is proposed accordingly. Numerical and experimental examples indicated that the presented approach can detect damages with adequate accuracy at the cost of limited number of sensors. No finite element model (FEM) is required during the whole detection process.

L1 Regularized Model Updating for Structural Damage Detection

2018 ◽  
Vol 18 (12) ◽  
pp. 1850157 ◽  
Author(s):  
Yu-Han Wu ◽  
Xiao-Qing Zhou
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Model Updating ◽  
Regularization Parameter ◽  
Structural Vibration ◽  
Mode Shapes ◽  
Modal Data ◽  
Vibration Data ◽  
Stiffness Reduction ◽  
Regularized Model

Model updating methods based on structural vibration data have been developed and applied to detecting structural damages in civil engineering. Compared with the large number of elements in the entire structure of interest, the number of damaged elements which are represented by the stiffness reduction is usually small. However, the widely used [Formula: see text] regularized model updating is unable to detect the sparse feature of the damage in a structure. In this paper, the [Formula: see text] regularized model updating based on the sparse recovery theory is developed to detect structural damage. Two different criteria are considered, namely, the frequencies and the combination of frequencies and mode shapes. In addition, a one-step model updating approach is used in which the measured modal data before and after the occurrence of damage will be compared directly and an accurate analytical model is not needed. A selection method for the [Formula: see text] regularization parameter is also developed. An experimental cantilever beam is used to demonstrate the effectiveness of the proposed method. The results show that the [Formula: see text] regularization approach can be successfully used to detect the sparse damaged elements using the first six modal data, whereas the [Formula: see text] counterpart cannot. The influence of the measurement quantity on the damage detection results is also studied.

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