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.

scholarly journals A New Flexibility Based Damage Index for Damage Detection of Truss Structures

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
M. Montazer ◽  
S. M. Seyedpoor
Keyword(s):  
Damage Detection ◽  
Modal Analysis ◽  
Structural Damage ◽  
Damage Index ◽  
Truss Structures ◽  
Structural Elements ◽  
Reliable Tool ◽  
Flexibility Matrix ◽  
Strain Change ◽  
Flexibility Index

A new damage index, called strain change based on flexibility index (SCBFI), is introduced to locate damaged elements of truss systems. The principle of SCBFI is based on considering strain changes in structural elements, between undamaged and damaged states. The strain of an element is evaluated using the columnar coefficients of the flexibility matrix estimated via modal analysis information. Two illustrative test examples are considered to assess the performance of the proposed method. Numerical results indicate that the method can provide a reliable tool to accurately identify the multiple-structural damage for truss structures.

scholarly journals Identification of Damage on Sluice Hoist Beams Using Local Mode Evoked by Swept Frequency Excitation

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6357
Author(s):  
Qingyang Wei ◽  
Hao Xu ◽  
Yifei Li ◽  
Li Chen ◽  
Drahomír Novák ◽  
...  
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Large Scale ◽  
Damage Index ◽  
Three Dimensional ◽  
Element Model ◽  
Local Mode ◽  
Structural Systems ◽  
Significant Shift ◽  
Frequency Excitation

As a global vibration characteristic, natural frequency often suffers from insufficient sensitivity to structural damage, which is associated with local variations of structural material or geometric properties. Such a drawback is particularly significant when dealing with the large scale and complexity of sluice structural systems. To this end, a damage detection method in sluice hoist beams is proposed that relies on the utilization of the local primary frequency (LPF), which is obtained based on the swept frequency excitation (SFE) technique and local resonance response band (LRRB) selection. Using this method, the local mode of the target sluice hoist beam can be effectively excited, while the vibrations of other components in the system are suppressed. As a result, the damage will cause a significant shift in the LPF of the sluice hoist beam at the local mode. A damage index was constructed to quantitatively reflect the damage degree of the sluice hoist beam. The accuracy and reliability of the proposed method were verified on a three-dimensional finite element model of a sluice system, with the noise resistance increased from 0.05 to 0.2 based on the hammer impact method. The proposed method exhibits promising potential for damage detection in complex structural systems.

Network-Conscious Damage Tracing Method for Beam Structures Based on Measurements Acquired by Distributed MEMS Gyroscopes

Aerospace ◽  
2004 ◽  
Author(s):  
Arata Masuda ◽  
Akira Sone
Keyword(s):  
Damage Index ◽  
Mode Shapes ◽  
Beam Structures ◽  
Vibratory Gyroscopes ◽  
Damage Indices ◽  
Mode Separation ◽  
Modal Flexibility ◽  
Mems Gyroscopes ◽  
Evaluation Algorithm ◽  
Tracing Method

The aim of this conceptual paper is to develop a damage tracing method to detect and track the evolution of structural damages in aerospace structures, in particular, large beam structures, considering the applicability in a decentralized computing environment of wireless sensor networks. We first present a modal flexibility-based damage indices that have simple and intuitive physical interpretation. Since the damage indices are computed using angular mode shapes of the lowest several modes, vibratory gyroscopes are adopted as the sensing device in this approach. The damage evaluation algorithm is then modified to a decentralized form, which is to be implemented as the local computation of mode separation at each sensor unit and the global computation of the damage index at the central monitoring station. Some illustrative experiments simulating both stationary damages and sudden damages are conducted to show that the proposed method is capable to indicate the location of the damages and the time when they occur.

scholarly journals Output-Only Damage Detection in Plate-Like Structures Based on Proportional Strain Flexibility Matrix

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6862
Author(s):  
Kang Yun ◽  
Mingyao Liu ◽  
Jiangtao Lv ◽  
Jingliang Wang ◽  
Zhao Li ◽  
...  
Keyword(s):  
Damage Detection ◽  
Damage Index ◽  
Identification Accuracy ◽  
Mode Shapes ◽  
Engineering Structures ◽  
Strain Mode ◽  
Flexibility Matrix ◽  
Construction Procedure ◽  
Output Only ◽  
Strain Mode Shapes

For engineering structures, strain flexibility-based approaches have been widely used for structural health monitoring purposes with prominent advantages. However, the applicability and robustness of the method need to be further improved. In this paper, a novel damage index based on differences in uniform load strain field (ULSF) is developed for plate-like structures. When estimating ULSF, the strain flexibility matrix (SFM) based on mass-normalized strain mode shapes (SMSs) is needed. However, the mass-normalized strain mode shapes (SMSs) are complicated and difficult to obtain when the input, i.e., the excitation, is unknown. To address this issue, the proportional strain flexibility matrix (PSFM) and its simplified construction procedure are proposed and integrated into the frames of ULSF, which can be easily obtained when the input is unknown. The identification accuracy of the method under the damage with different locations and degrees is validated by the numerical examples and experimental examples. Both the numerical and experimental results demonstrate that the proposed method provides a reliable tool for output-only damage detection of plate-like structures without estimating the mass-normalized strain mode shapes (SMSs).

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.

scholarly journals Structural Damage Detection by Using Single Natural Frequency and the Corresponding Mode Shape

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Bo Zhao ◽  
Zili Xu ◽  
Xuanen Kan ◽  
Jize Zhong ◽  
Tian Guo
Keyword(s):  
Damage Detection ◽  
Natural Frequency ◽  
Mode Shape ◽  
Structural Damage ◽  
Bending Moment ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Structural Damage Detection ◽  
Damage Scenarios ◽  
Flexibility Matrix

Damage can be identified using generalized flexibility matrix based methods, by using the first natural frequency and the corresponding mode shape. However, the first mode is not always appropriate to be used in damage detection. The contact interface of rod-fastened-rotor may be partially separated under bending moment which decreases the flexural stiffness of the rotor. The bending moment on the interface varies as rotating speed changes, so that the first- and second-modal parameters obtained are corresponding to different damage scenarios. In this paper, a structural damage detection method requiring single nonfirst mode is proposed. Firstly, the system is updated via restricting the first few mode shapes. The mass matrix, stiffness matrix, and modal parameters of the updated system are derived. Then, the generalized flexibility matrix of the updated system is obtained, and its changes and sensitivity to damage are derived. The changes and sensitivity are used to calculate the location and severity of damage. Finally, this method is tested through numerical means on a cantilever beam and a rod-fastened-rotor with different damage scenarios when only the second mode is available. The results indicate that the proposed method can effectively identify single, double, and multiple damage using single nonfirst mode.

Use of LU Decomposition of Modal Flexibility in Structural Damage Detection: Numerical Validation

2013 ◽  
Vol 569-570 ◽  
pp. 986-993
Author(s):  
Yong Hui An ◽  
Jin Ping Ou
Keyword(s):  
Structural Damage ◽  
Numerical Study ◽  
Damage Index ◽  
Triangular Matrix ◽  
Mathematical Tool ◽  
Lu Decomposition ◽  
Flexibility Matrix ◽  
Modal Flexibility ◽  
The Matrix ◽  
Upper Triangular Matrix

The flexibility can be approximately synthesized with the first several measured modal parameters, i.e. the so called modal flexibility. The modal flexibility matrix will change with damage in a structure, and the change of modal flexibility should contain the information of damage. It is important to find a damage index that can pick up damage from the change of modal flexibility. To address this issue, the mathematical tool LU decomposition is introduced to deal with the modal flexibility matrix in order to find damage clearly. After decomposition, the modal flexibility is decomposed into a lower triangular matrix L and an upper triangular matrix U. Numerical results of both single and multiple damage cases under white noise excitation indicate that the matrix U has enough information of damage; and the proposed new technique can be utilized to locate the damage accurately. The present numerical study will lay a foundation for the application of real-time structural health monitoring in experiments and engineering.

scholarly journals Development of a Novel Damage Detection Framework for Truss Railway Bridges Using Operational Acceleration and Strain Response

Vibration ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 422-445
Author(s):  
Md Riasat Azim ◽  
Mustafa Gül
Keyword(s):  
Damage Detection ◽  
Damage Identification ◽  
Numerical Study ◽  
Damage Index ◽  
Strain Analysis ◽  
Time History ◽  
Principal Component ◽  
Element Model ◽  
Railway Bridges ◽  
Truss Bridge

Railway bridges are an integral part of any railway communication network. As more and more railway bridges are showing signs of deterioration due to various natural and artificial causes, it is becoming increasingly imperative to develop effective health monitoring strategies specifically tailored to railway bridges. This paper presents a new damage detection framework for element level damage identification, for railway truss bridges, that combines the analysis of acceleration and strain responses. For this research, operational acceleration and strain time-history responses are obtained in response to the passage of trains. The acceleration response is analyzed through a sensor-clustering-based time-series analysis method and damage features are investigated in terms of structural nodes from the truss bridge. The strain data is analyzed through principal component analysis and provides information on damage from instrumented truss elements. A new damage index is developed by formulating a strategy to combine the damage features obtained individually from both acceleration and strain analysis. The proposed method is validated through a numerical study by utilizing a finite element model of a railway truss bridge. It is shown that while both methods individually can provide information on damage location, and severity, the new framework helps to provide substantially improved damage localization and can overcome the limitations of individual analysis.

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