scholarly journals FRF Sensitivity-Based Damage Identification Using Linkage Modeling for Limited Sensor Arrays

2018 ◽  
Vol 18 (08) ◽  
pp. 1840002 ◽  
Author(s):  
Van Vu Nguyen ◽  
Jianchun Li ◽  
Emre Erkmen ◽  
Mehrisadat Makki Alamdari ◽  
Ulrike Dackermann
Keyword(s):  
Degrees Of Freedom ◽  
Damage Identification ◽  
Model Updating ◽  
Sensor Arrays ◽  
Successful Implementation ◽  
Fe Model ◽  
Stiffness Reduction ◽  
Stiffness Matrices ◽  
Novel Method ◽  
Linkage Model

This paper presents a novel method to localize and quantify damage in a jack arch structure by introducing a linkage modeling technique to overcome issues caused by having limited sensors. The main strategy in the proposed Frequency Response Function (FRF)-based sensitivity model updating approach is to divide the specimen into partitions. The Young’s modulus of each partition is then updated to detect stiffness reduction caused by damage. System Equivalent Reduction Expansion Process (SEREP) is used to reduce the full finite element (FE) model to a linkage model. The number of measured degrees of freedom (DOFs) is then expanded to the linkage model using the mass and stiffness matrices of the linkage model for the synthesis of interpolated FRFs. The FRF sensitivities are then formulated using the linkage model along with the interpolated FRFs to iteratively calculate the values of the updating parameters until convergence is achieved. The methodology and theory behind this procedure are discussed and verified using a numerical and experimental study. The successful implementation of this method has the potential to detect the location and severity of damage where sensor placement is limited.

scholarly journals Vision-Based Structural FE Model Updating Using Genetic Algorithm

2021 ◽  
Vol 11 (4) ◽  
pp. 1622
Author(s):  
Gun Park ◽  
Ki-Nam Hong ◽  
Hyungchul Yoon
Keyword(s):  
Genetic Algorithm ◽  
Model Updating ◽  
Structural Parameters ◽  
Fe Model ◽  
Structural Members ◽  
Stiffness Reduction ◽  
Before And After ◽  
Scale Test ◽  
Fe Model Updating ◽  
Story Building

Structural members can be damaged from earthquakes or deterioration. The finite element (FE) model of a structure should be updated to reflect the damage conditions. If the stiffness reduction is ignored, the analysis results will be unreliable. Conventional FE model updating techniques measure the structure response with accelerometers to update the FE model. However, accelerometers can measure the response only where the sensor is installed. This paper introduces a new computer-vision based method for structural FE model updating using genetic algorithm. The system measures the displacement of the structure using seven different object tracking algorithms, and optimizes the structural parameters using genetic algorithm. To validate the performance, a lab-scale test with a three-story building was conducted. The displacement of each story of the building was measured before and after reducing the stiffness of one column. Genetic algorithm automatically optimized the non-damaged state of the FE model to the damaged state. The proposed method successfully updated the FE model to the damaged state. The proposed method is expected to reduce the time and cost of FE model updating.

scholarly journals Rotor Model Updating and Validation for an Active Magnetic Bearing Based High-Speed Machining Spindle

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Adam C. Wroblewski ◽  
Jerzy T. Sawicki ◽  
Alexander H. Pesch
Keyword(s):  
Transfer Functions ◽  
Model Updating ◽  
Dynamic Properties ◽  
Magnetic Bearing ◽  
Mode Shapes ◽  
Model Parameters ◽  
Successful Implementation ◽  
Fe Model ◽  
Rotor Model ◽  
Machining Spindle

This paper presents an experimentally driven model updating approach to address the dynamic inaccuracy of the nominal finite element (FE) rotor model of a machining spindle supported on active magnetic bearings. Modeling error is minimized through the application of a numerical optimization algorithm to adjust appropriately selected FE model parameters. Minimizing the error of both resonance and antiresonance frequencies simultaneously accounts for rotor natural frequencies as well as for their mode shapes. Antiresonance frequencies, which are shown to heavily influence the model’s dynamic properties, are commonly disregarded in structural modeling. Evaluation of the updated rotor model is performed through comparison of transfer functions measured at the cutting tool plane, which are independent of the experimental transfer function data used in model updating procedures. Final model validation is carried out with successful implementation of robust controller, which substantiates the effectiveness of the model updating methodology for model correction.

Review and Prospect on Dynamic FE Model Updating Methods of Footbridge Structures Based on Ambient Excitation

2011 ◽  
Vol 291-294 ◽  
pp. 1572-1577
Author(s):  
Rui Zhao ◽  
Yi Gang Zhang
Keyword(s):  
Structural Damage ◽  
Optimization Design ◽  
Damage Identification ◽  
Model Updating ◽  
Target Function ◽  
Optimization Theory ◽  
Empirical Method ◽  
Fe Model ◽  
Fe Model Updating ◽  
Ambient Excitation

The discrete finite element (FE) model often cannot reflect structure characteristics accurately due to imply more idealistic assumptions and simplifications. Therefore, it is necessary to update FE model for structural damage identification, response calculation, safety evaluation, optimization design, and so on. This article will illustrate respectively three key steps of updating parameters selection, target function selection and optimization method in process of dynamic FE model updating of footbridge structures based on ambient excitation, and put forward a feasible updating method: combine empirical method with sensitivity analysis method to select updating parameters; joint natural frequencies, MAC and modal flexibility as target function; adopt optimization algorithm based on the optimization theory.

Output-Only Modal Analysis of an Internal Unreachable Module Embedded in a Space Electronic Equipment

2012 ◽  
Author(s):  
Lassaad Ben Fekih ◽  
Georges Kouroussis ◽  
David Wattiaux ◽  
Olivier Verlinden ◽  
Christophe De Fruytier
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Transverse Direction ◽  
Mode Shapes ◽  
Fe Model ◽  
Fe Method ◽  
Numeric Model ◽  
Stiffness Matrices ◽  
Output Only

An approach is proposed to identify the modal properties of a subsystem made up of an arbitrary chosen inner module of embedded space equipment. An experimental modal analysis was carried out along the equipment transverse direction with references taken onto its outer housing. In parallel, a numerical model using the finite element (FE) method was developed to correlate with the measured results. A static Guyan reduction has led to a set of master degrees of freedom in which the experimental mode shapes were expanded. An updating technique consisting in minimizing the dynamic residual induced by the FE model and the measurements has been investigated. A last verification has consisted in solving the numeric model composed of the new mass and stiffness matrices obtained by means of a minimization of the error in the constitutive equation method.

Multi-Objective Model Updating Optimization Considering Orthogonality

2019 ◽  
Vol 14 (6) ◽  
Author(s):  
Braden T. Warwick ◽  
Il Yong Kim ◽  
Chris K. Mechefske
Keyword(s):  
Mode Shape ◽  
Degrees Of Freedom ◽  
Pareto Front ◽  
Model Updating ◽  
Current Model ◽  
Physical Reality ◽  
Frequency Error ◽  
Fe Model ◽  
Multi Objective ◽  
Objective Model

The coordinate orthogonality check (CORTHOG) and multi-objective optimization considering pseudo-orthogonality as an objective function are introduced to overcome several limitations present in current model updating methods. It was observed that the use of the CORTHOG to remove four inaccurate degrees-of-freedom (DOF) was able to increase the orthogonality between mode shape vectors. The multi-objective model updating process generated a Pareto front with 38 unique optimal solutions. Four critical points were identified along the Pareto front, of which decreased the natural frequency error by greater than 2.84% and further increased the orthogonality between mode shape vectors. Therefore, it has been demonstrated that both steps of the methodology are critical to significantly reduce the overall errors of the system and to generate a finite element (FE) model that best describes physical reality. Additionally, the methodology introduced in this work generated a feasible computational runtime allowing for it to be easily adapted to widespread applications.

Application of Bayesian statistical method in sensitivity-based seismic damage identification of structures: Numerical and experimental validation

2018 ◽  
Vol 17 (5) ◽  
pp. 1255-1276 ◽  
Author(s):  
Maryam Vahedi ◽  
Faramarz Khoshnoudian ◽  
Ting Yu Hsu
Keyword(s):  
Statistical Method ◽  
Structural Damage ◽  
Damage Identification ◽  
Model Updating ◽  
Least Square Method ◽  
Element Model ◽  
Least Square ◽  
Detection Methods ◽  
Sensitivity Equation ◽  
Stiffness Reduction

Most of the developed sensitivity-based damage detection methods are based on the application of external excitations which could be prohibitive due to infeasible excitation of all structural degrees of freedom. In this regard, identification of damage properties using seismic structural response would be advantageous. In this research, sensitivity-based finite element model updating method is proposed to identify structural damage by earthquake response in the frequency domain and the transfer function of the structure due to ground excitation. The obtained sensitivity equation is solved by linear least square method through defining constraints on the design variables. Since the attainable measured data are restricted by limits on the instrumentations and preciseness of the measurements and due to the fact that only a few of the lower modes of a structure can generally be determined with confidence, a Bayesian statistical method is utilized to enhance the reliability of the predicted damage properties. The proposed technique is applied to a numerical frame model and an experimental six-story steel structure with various scenarios of story stiffness reduction. The results are indicative of the capability of the proposed method for identification of damage location and severity.

Response Surface Method for Updating Dynamic Finite Element Models

Volume 2 ◽  
2004 ◽  
Author(s):  
Kun-Nan Chen ◽  
Cheng-Tien Chang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Response Surface ◽  
Damage Identification ◽  
Model Updating ◽  
Response Prediction ◽  
Element Model ◽  
General Purpose ◽  
Frame Structure ◽  
Fe Model

A finite element model of a structure can be updated as certain criteria based on experimental data are satisfied. The updated FE model is considered a better model for future studies in dynamic response prediction, structural modification, and damage identification. A finite element model updating technique incorporating the concept of response surface approximation (RSA) requires no sensitivity calculations and is much easier to implement with a general-purpose finite element code. The proposed updating method was incorporated with MSC. Nastran to solve the updating problem for an H-shaped frame structure. The updated results show that the predicted and experimental modes are correlated well with high MAC values and with a maximum frequency difference of 1.5%. Moreover, the updated parameters provide a physical insight to the modeling of bolted and welded joints of the H-frame structure.

Substructure-Joint Based Approach to Damped FE Model Updating of Complex Assembly Structure

2012 ◽  
Vol 463-464 ◽  
pp. 1169-1174
Author(s):  
Parivash Soleimanian ◽  
Morteza H.Sadeghi ◽  
Akbar Tizfahm
Keyword(s):  
Finite Element ◽  
Model Updating ◽  
Element Model ◽  
Modal Testing ◽  
Fe Model ◽  
Complex Assembly ◽  
Modal Data ◽  
Damping Matrix ◽  
Stiffness Matrices ◽  
Assembly Structure

Model updating techniques are used to update the finite element model of a structure, so that updated model can be predicted the dynamic behavior of an actual assembly structure more accurately. Most of the model updating techniques neglects damping and so amplitudes of vibration at resonance and antiresonance frequencies cannot be predicted by using of these updated models. In dynamic design of structures predicting of these properties is necessary. This paper presents a new technique to create an accurate finite element (FE) updated model of complex assembly structures consisting of substructures and real joint by considering damping of them. Given the fact that modal testing of real joints (such as bolt with some washers) are almost impossible. The updated model of assembly structure is obtained in four steps. In the first step, mass and stiffness matrix of substructures, joint and assembly structure are updated using modal data and Eigen-sensitivity approach. In the second step, damping of assembly structure is identified using complex modal data and updated mass and stiffness matrices which are obtained in first step. In the third step, the effect of damping of joint on frequency response functions (FRFs) extracted from updated model was shown. In the forth step, damping matrix of joint is updated by using FRF-based model updating method and finally damped updated model of assembly structure compared with measured data.

Structural Damage Identification Based on Model Updating

2006 ◽  
Author(s):  
T. Yin ◽  
L. Yu ◽  
H. P. Zhu
Keyword(s):  
Objective Function ◽  
Structural Damage ◽  
Damage Identification ◽  
Model Updating ◽  
Frame Structure ◽  
Mode Shapes ◽  
Fe Model ◽  
Portal Frame ◽  
Structural Damage Identification ◽  
Portal Frame Structure

This paper presents a new method for structural damage identification based on the finite element (FE) model updating techniques. First, an objective function is defined as minimizing the sum of differences between the experimental and analytical modal data (natural frequencies and mode shapes), which is set as a nonlinear least-squares problem with bound-constrains. The trust-region approach is then used to solve the minimization problem in order to make this optimization process more robust and reliable. In addition, the expansion and weighting of the original objective function are investigated so that the presented method can be well applied into the damage identification of more real structures. Finally, a numerical simulation model of two-story portal frame structure is adopted to evaluate the efficiency of the proposed technique when both the single and multiple damage cases are set up in the model. Some important issues are also discussed in this paper. The illustrated results show that the single and multiple damages on the two-story portal frame structure can be well identified by the proposed method.

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