Damage Identification of a Beam-Like Structure Using Element Modal Strain Energies and Natural Frequencies

2011 ◽  
Vol 94-96 ◽  
pp. 718-723
Author(s):  
Jian Hua Zhao ◽  
Ling Zhang
Keyword(s):  
Natural Frequencies ◽  
Damage Identification ◽  
Identification Algorithm ◽  
Modal Strain Energy ◽  
Second Stage ◽  
Before And After ◽  
Damage Extent ◽  
Frequency Changes ◽  
Potential Damage ◽  
Actual Damage

A two-step damage identification method based on elemental modal strain energies and natural frequencies has been presented for a beam-like structure. In the first stage, this method makes use of the change of elemental modal strain energy before and after damage to locate the potential damage regions. And in the second stage, a damage identification algorithm based on the frequency changes is developed to calculate the damage extent and further determine the actual damage locations. The performance of the proposed method is numerically demonstrated by a simply supported beam with two damage cases. Results indicate that the method can identify the damage location and quantify the damage severity accurately in a beam-like structure.

A Damage Identification Method Using Vibration Modal Parameters Through Finite Element Discretization

2003 ◽  
Author(s):  
Xiaoping Zhou ◽  
Abhijit Gupta
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Least Squares Method ◽  
Modal Testing ◽  
Mode Shapes ◽  
Element Formulation ◽  
Element Discretization ◽  
Damage Indices ◽  
Actual Damage

Natural frequencies and mode shapes of a structure will change whenever the structure has any kind of damage. This paper introduces a technique to quantify and locate the damage when the natural frequencies and mode shapes of undamaged and damaged structure are known. Aluminum beams (with and without damage) are used for numerical simulation and experimental verification. To establish the theoretical basis of this method, finite element formulation is used. A set of undetermined equations involving damage indices and natural frequencies and mode shapes of undamaged and damaged structures are obtained. The damage indices are computed using non-negative least squares method. Impact modal testing was conducted with three aluminum beams and damage indices based on experimental data are compared with actual damage cases to establish the effectiveness of this method to identify the damage.

scholarly journals Localization of Transversal Cracks in Sandwich Beams and Evaluation of Their Severity

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
G. R. Gillich ◽  
Z. I. Praisach ◽  
M. Abdel Wahab ◽  
O. Vasile
Keyword(s):  
Composite Structures ◽  
Damage Identification ◽  
Identification Algorithm ◽  
Vibration Modes ◽  
Bending Vibration ◽  
Global Rigidity ◽  
Crack Location ◽  
Section Shape ◽  
Mathematical Relation ◽  
Frequency Changes

An algorithm to assess transversal cracks in composite structures based on natural frequency changes due to damage is proposed. The damage assessment is performed in two steps; first the crack location is found, and afterwards an evaluation of its severity is performed. The technique is based on a mathematical relation that provides the exact solution for the frequency changes of bending vibration modes, considering two terms. The first term is related to the strain energy stored in the beam, while the second term considers the increase of flexibility due to damage. Thus, it is possible to separate the problems of localization and severity assessment, which makes the localization process independent of the beams cross-section shape and boundary conditions. In fact, the process consists of comparing vectors representing the measured frequency shifts with patterns constructed using the mode shape curvatures of the undamaged beam. Once the damage is localized, the evaluation of its severity is made taking into account the global rigidity reduction. The damage identification algorithm was validated by experiments performed on numerous sandwich panel specimens.

Structural Multi-Damage Identification Based on Modal Strain Energy Equivalence Index Method

2014 ◽  
Vol 14 (07) ◽  
pp. 1450028 ◽  
Author(s):  
Hui Yong Guo ◽  
Zheng Liang Li
Keyword(s):  
Energy Dissipation ◽  
Structural Damage ◽  
Strain Energy ◽  
Damage Identification ◽  
Index Method ◽  
Modal Strain Energy ◽  
Energy Equivalence ◽  
Before And After ◽  
Accurate Expression ◽  
Equivalence Theory

In order to solve structural multi-damage identification problems, a damage detection method based on modal strain energy equivalence index (MSEEI) is presented. First, an accurate expression of modal strain energy (MSE) before and after damage occurs is given. Then, according to the energy equivalence theory that the change in MSE caused by the damage should be equivalent to the energy dissipation caused by the same damage, an energy equivalence equation is deduced. Finally, four roots of the energy equivalence equation are found and a MSEEI is obtained from the four roots. Simulation results demonstrate that the proposed MSEEI method can identify structural damage locations and extent with good accuracy. Identification precision of the proposed method is clearly better than that of the modal strain energy dissipation ratio index (MSEDRI) method.

Damage Identification Research of Cantilever Truss Based on the Principle of Strain Mode

2012 ◽  
Vol 226-228 ◽  
pp. 1432-1435
Author(s):  
Jun Hai Zhang ◽  
Nai Juan Du ◽  
Yue Guo Shen
Keyword(s):  
Structural Damage ◽  
Damage Identification ◽  
Damage Location ◽  
Strain Change ◽  
Before And After ◽  
Force Element ◽  
Damage Extent ◽  
Simulation Results ◽  
Modal Change ◽  
Identification Research

This paper presents a method converting the modal distance of the node into elemental strain based on the special characteristic of two-force element .The strain change before and after damage is applied to the damage identification. The change rule of the relative strain for the same location of the truss occur the various damage extent and the various location of the truss occur the same damage extent, respectively, is obtained according to the strain modal simulation using APDL language. The simulation results show that the strain modal change ratio is sensitive to the cantilever truss damage detection. The damage location and damage extent will be identified. It is an effective nodestructive test way to identify the cantilever truss structural damage.

scholarly journals Damage Identification by the Kullback-Leibler Divergence and Hybrid Damage Index

2014 ◽  
Vol 2014 ◽  
pp. 1-22 ◽  
Author(s):  
Shaohua Tian ◽  
Zhibo Yang ◽  
Zhengjia He ◽  
Xuefeng Chen
Keyword(s):  
Damage Identification ◽  
Damage Index ◽  
Laminated Composite ◽  
Dimensional Structure ◽  
Modal Strain Energy ◽  
One Dimensional ◽  
Leibler Divergence ◽  
Present Technique ◽  
Before And After ◽  
Accurate Performance

The hybrid damage index (HDI) is presented as a mean for the damage identification in this paper, which is on the basis of the Kullback-Leibler divergence (KLD) and its approximations. The proposed method is suitable for detecting damage in one-dimensional structure and delamination in laminated composite. The first step of analysis includes obtaining the mode data of the structure before and after the damage, and then the KLD and its approximations are obtained. In addition, the HDI is obtained on the basis of the KLD and its approximations, utilizing the natural frequencies and mode shape at the same time. Furthermore, the modal strain energy (MSE) method is employed to verify the efficiency of the proposed method. Finally, to demonstrate the capability of the proposed method, examples of the beam and laminated composite are applied for checking the present approaches numerically, and the final results validate the effective and accurate performance of the present technique.

Damage Identification Method of Simply Supported Beam Bridge with Multiple Girders

2013 ◽  
Vol 437 ◽  
pp. 377-381
Author(s):  
Ping Yi Sun ◽  
Yan Hua Wang ◽  
Yan Feng Niu ◽  
Han Bing Liu ◽  
Guo Jin Tan
Keyword(s):  
Numerical Simulation ◽  
Damage Identification ◽  
Identification Algorithm ◽  
Damage State ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Svm Algorithm ◽  
Damage Extent ◽  
Beam Bridge ◽  
T Beam

Considering the complexity of the simply supported beam with multiple girders, a two-step damage identification algorithm for this kind of bridge is presented. This algorithm first locates the damage by means of curvature of flexibility change, and then utilizes the PSO-SVM algorithm to identify the damage extent. At last, a numerical simulation calculation is conducted to identify the damage state of a simply supported T-beam bridge with five girders. The numerical simulation results show that the algorithm proposed is valid, reliable and with high recognition precision.

Structural Damage Detection Based on Strain Energy and Evidence Theory

2011 ◽  
Vol 48-49 ◽  
pp. 1122-1125 ◽  
Author(s):  
Hui Yong Guo ◽  
Zheng Liang Li
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Strain Energy ◽  
Energy Equation ◽  
Damage Identification ◽  
Detection Method ◽  
Evidence Theory ◽  
Modal Strain Energy ◽  
New Energy ◽  
Damage Extent

In order to solve the damage detection problem, a damage detection method based on strain energy and evidence theory is presented in this paper. First, an evidence theory method is proposed to identify structural damage locations. Then, structural modal strain energy is utilized to quantify structural damage extents. In general, structural strain energy dissipation should be equal to the change of modal strain energy, according to this theory, a new energy equation is deduced, and structural damage extent can be obtained through the solution of the equation. The simulation results show that the method can perfectly identify damage locations and extents. Therefore, the proposed method is effective for the structural damage identification.

Multi-crack detection in general cross-section swept wings based on natural frequency changes

2020 ◽  
pp. 107754632096401
Author(s):  
Fatemeh Barzegar ◽  
Saeedreza Mohebpour ◽  
Hekmat Alighanbari
Keyword(s):  
Mathematical Model ◽  
Natural Frequency ◽  
Cross Section ◽  
Crack Detection ◽  
Natural Frequencies ◽  
Detection Method ◽  
Mode Shapes ◽  
Modal Strain Energy ◽  
Torsional Mode ◽  
Frequency Changes

In this article, a multi-crack detection method, which is based on natural frequency changes and the concept of modal strain energy, is for the first time developed for the general cross-section swept tapered wings under coupled bending-torsional vibration and applied to the solid and thin-walled airfoil cross-section wings. The presented method is able to handle the problems with an unknown number of cracks and predicts the number of existent cracks, their locations and depths by optimization of an appropriate objective function. The stress intensity factors of airfoil-shaped crack surfaces are obtained using an approximation method. Inputs of the detection method are natural frequencies of uncracked and cracked wings which are calculated by using a mathematical model and finite element method software ANSYS, respectively, and validated by comparison with former research studies. In the mathematical model, the Rayleigh–Ritz method is used to calculate the coupled bending-torsional mode shapes of the uncracked wing and their corresponding natural frequencies. Results demonstrate that the proposed method has precisely predicted the number, locations and depths of cracks in all case studies.

scholarly journals Sensitivity and Efficiency of the Frequency Shift Coefficient Based on the Damage Identification Algorithm: Modeling Uncertainty on Natural Frequencies

Vibration ◽  
2022 ◽  
Vol 5 (1) ◽  
pp. 59-79
Author(s):  
Anurag Dubey ◽  
Vivien Denis ◽  
Roger Serra
Keyword(s):  
Frequency Shift ◽  
Health Monitoring ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Input Parameter ◽  
Health Surveillance ◽  
Steel Beam ◽  
Identification Algorithm ◽  
Cantilever Beams ◽  
Shift Coefficient

Health surveillance in industries is an important prospect to ensure safety and prevent sudden collapses. Vibration Based Structure Health Monitoring (VBSHM) is being used continuously for structures and machine diagnostics in industry. Changes in natural frequencies are frequently used as an input parameter for VBSHM. In this paper, the Frequency Shift Coefficient (FSC) is used for the assessment of various numerical damaged cases. An FSC-based algorithm is employed in order to estimate the positions and severity of damages using only the natural frequencies of healthy and unknown (damaged) structures. The study focuses on cantilever beams. By considering the minimization of FSC, damage positions and severity are obtained. Artificially damaged cases are assessed by changes in its positions, the number of damages and the size of damages along with the various parts of the cantilever beam. The study is further investigated by considering the effect of uncertainty on natural frequencies (0.1%, 0.2% and 0.3%) in damaged cases, and the algorithm is used to estimate the position and severity of the damage. The outcomes and efficiency of the proposed FSC based method are evaluated in order to locate and quantify damages. The efficiency of the algorithm is demonstrated by locating and quantifying double damages in a real cantilever steel beam using vibration measurements.

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