scholarly journals Three Case Studies in Finite Element Model Updating

1995 ◽  
Vol 2 (2) ◽  
pp. 119-131 ◽  
Author(s):  
M. Imregun
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Case Studies ◽  
Model Updating ◽  
Mathematical Formulation ◽  
Element Model ◽  
Computational Effort ◽  
Fe Model ◽  
Sensitivity Matrix ◽  
General Applicability

This article summarizes the basic formulation of two well-established finite element model (FEM) updating techniques for improved dynamic analysis, namely the response function method (RFM) and the inverse eigensensitivity method (IESM). Emphasis is placed on the similarities in their mathematical formulation, numerical treatment, and on the uniqueness of the resulting updated models. Three case studies that include welded L-plate specimens, a car exhaust system, and a highway bridge were examined in some detail and measured vibration data were used throughout the investigation. It was experimentally observed that significant dynamic behavior discrepancies existed between some of the nominally identical structures, a feature that makes the task of model updating even more difficult because no unequivocal reference data exist in this particular case. Although significant improvements were obtained in all cases where the updating of the FE model was possible, it was found that the success of the updated models depended very heavily on the parameters used, such as the selection and number of the frequency points for RFM, and the selection of modes and the balancing of the sensitivity matrix for IESM. Finally, the performance of the two methods was compared from general applicability, numerical stability, and computational effort standpoints.

Finite Element Model Updating of Large Structures by the Clustering of Parameter Sensitivities

2006 ◽  
Vol 5-6 ◽  
pp. 85-92 ◽  
Author(s):  
H. Shahverdi ◽  
Cristinel Mares ◽  
W. Wang ◽  
C.H. Greaves ◽  
John E. Mottershead
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Mass Density ◽  
Element Model ◽  
Finite Element Model Updating ◽  
Sensitivity Matrix ◽  
Large Structures ◽  
New Development ◽  
Bending Modes

Finite element model updating of a Westland Lynx XZ649 helicopter tail is presented. Eigenvalue sensitivities with respect to Young’s modulus and mass density are used. Large groups based on material input data were divided to form smaller subgroups so that those parts of the model responsible for errors in the predicted eigenvalues were located. A particular new development was the use of parameter clustering based on the similarity of different columns of the sensitivity matrix. Finally the finite element model was updated successfully with regard to the lower frequency tail-bending modes.

scholarly journals Clustering of Parameter Sensitivities: Examples from a Helicopter Airframe Model Updating Exercise

2009 ◽  
Vol 16 (1) ◽  
pp. 75-87 ◽  
Author(s):  
H. Shahverdi ◽  
C. Mares ◽  
W. Wang ◽  
J.E. Mottershead
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Large Scale ◽  
Structural Changes ◽  
Model Updating ◽  
Mass Density ◽  
Main Tool ◽  
Element Model ◽  
Sensitivity Matrix ◽  
Comparative Results

The need for high fidelity models in the aerospace industry has become ever more important as increasingly stringent requirements on noise and vibration levels, reliability, maintenance costs etc. come into effect. In this paper, the results of a finite element model updating exercise on a Westland Lynx XZ649 helicopter are presented. For large and complex structures, such as a helicopter airframe, the finite element model represents the main tool for obtaining accurate models which could predict the sensitivities of responses to structural changes and optimisation of the vibration levels. In this study, the eigenvalue sensitivities with respect to Young's modulus and mass density are used in a detailed parameterisation of the structure. A new methodology is developed using an unsupervised learning technique based on similarity clustering of the columns of the sensitivity matrix. An assessment of model updating strategies is given and comparative results for the correction of vibration modes are discussed in detail. The role of the clustering technique in updating large-scale models is emphasised.

A Meta-Modeling Procedure for Updating the Finite Element Model of an Arch Bridge Model

2013 ◽  
Vol 540 ◽  
pp. 79-86
Author(s):  
De Jun Wang ◽  
Yang Liu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Analysis ◽  
Large Scale ◽  
Model Updating ◽  
Element Model ◽  
Fe Model ◽  
Large Scale Structures ◽  
Bridge Model ◽  
Scale Structures

Finite element (FE) model updating of structures using vibration test data has received considerable attentions in recent years due to its crucial role in fields ranging from establishing a reality-consistent structural model for dynamic analysis and control, to providing baseline model for damage identification in structural health monitoring. Model updating is to correct the analytical finite element model using test data to produce a refined one that better predict the dynamic behavior of structure. However, for real complex structures, conventional updating methods is difficult to be utilized to update the FE model of structures due to the heavy computational burden for the dynamic analysis. Meta-model is an effective surrogate model for dynamic analysis of large-scale structures. An updating method based on the combination between meta-model and component mode synthesis (CMS) is proposed to improve the efficiency of model updating of large-scale structures. The effectiveness of the proposed method is then validated by updating a scaled suspender arch bridge model using the simulated data.

Investigation of a Software for Finite Element Model Updating of Bridges Based on Interface Technology between VC++ and MATLAB

2013 ◽  
Vol 540 ◽  
pp. 1-10
Author(s):  
Yang Liu ◽  
Zhan Lv ◽  
Hong Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Element Model ◽  
Steel Tube ◽  
Finite Element Model Updating ◽  
Fe Model ◽  
Arch Bridge ◽  
Fe Model Updating

To develop an effective software for finite element (FE) model updating of bridges, the interface technology between VC++ and MATLAB was investigated firstly, and then a software for updating FE model of bridges, named Doctor for Bridges (version 1.0) was developed. Finally, a model ofconcrete-filled steel tube arch bridge was applied to verify the performance and effectiveness of the proposed software.

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.

Finite Element Model Updating Based on Direct Optimization Technique

2010 ◽  
Vol 163-167 ◽  
pp. 2804-2810 ◽  
Author(s):  
Bei Dou Ding ◽  
Heng Lin Lv ◽  
Yong Sheng Ji
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Objective Function ◽  
Optimization Algorithm ◽  
Model Updating ◽  
Optimization Technique ◽  
Element Model ◽  
Mode Shapes ◽  
Fe Model ◽  
Direct Optimization

Setting up of an objective function, update parameters and use of robust optimization algorithm are three crucial steps in FE model updating. In order to calculate the gradient of the objective function, analytic optimization algorithm is not easy to be achieved, while the direct optimization algorithm may achieve the objective function optimization simply by comparing the size of the objective function to move the iteration point. In this paper, the eigenvalues and mode shapes are used as the optimization objective function, the direct optimization algorithm is adopted, an updated finite element model is achieved, and a numerical example is given.

Structural Dynamic Modifications Using Damped Updated Finite Element Model Updating

2013 ◽  
Author(s):  
V. Arora
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Element Model ◽  
Fe Model ◽  
Structural Damping ◽  
Structural Dynamic ◽  
Structural Modifications ◽  
Damping Matrix ◽  
Fe Model Updating

An accurate finite element model of a structure is essential for predicting reliably its dynamic characteristics. Such a model can be used to predict the effects of structural modifications for dynamic design of the structure. These structural modifications may be imposed by design alterations for operating reasons. Most of the model updating techniques neglect damping and so these updated models can’t be used for accurate prediction of vibration amplitudes. This paper deals with the basic formulation of finite element model updating method having identified structural damping matrix, and its use for structural dynamic modifications. A case involving actual measured data for the case of F-shaped test structure, which resembles the skeleton of a drilling machine is used to evaluate the effectiveness of FE model updating method incorporating identified structural damping matrix for accurate prediction of the vibration levels and thus its use for structural dynamic modifications. Design modifications in terms of mass and stiffener modifications are introduced to evaluate the effectiveness updated model incorporating damping matrices for structural dynamic modifications. It has been concluded that the FE model updating incorporating identified structural damping matrix can be used for structural dynamic modifications with confidence.

Fatigue Assessment of a Slender Footbridge Based on an Updated Finite Element Model

2018 ◽  
Vol 774 ◽  
pp. 589-594
Author(s):  
J. Pérez-Aracil ◽  
A.M. Hernandez-Díaz ◽  
J.F. Jiménez-Alonso ◽  
F.J. Puerta-Lopez
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fatigue Damage ◽  
Model Updating ◽  
Numerical Models ◽  
Vertical Direction ◽  
Element Model ◽  
Modal Parameters ◽  
Fe Model ◽  
Fatigue Assessment

Finite element model updating is a well-known technique to better characterize the real behaviour of civil engineering structures. The updated numerical model can be used to perform a more accurate structural assessment. Herein, its effectiveness is validated through the fatigue assessment of a lively footbridge considering two different numerical models: (i) a preliminary finite element (FE) model and (ii) an updated version of the preliminary model based on the modal parameters of the footbridge identified experimentally. For this purpose, the Malecon footbridge (Murcia, Spain) has been considered. This footbridge, a cable-stayed structure, is prone to vibrate in vertical direction under continuous walking pedestrian flows so fatigue damage might be expected on its supporting cables. A detailed FE model of the footbridge has been performed and subsequently updated based on the experimental modal parameters of the structure. The behaviour of the pedestrian flows was characterized by field observations. Finally, a comparison is performed between the fatigue damage of some cables of the footbridge considering the two mentioned FE models. The safe life method was used to assess such damage. As result, a maximum relative difference around 52 % was obtained between the two numerical models.

scholarly journals Parameter Selection Strategies in Finite Element Model Updating

1997 ◽  
Vol 119 (1) ◽  
pp. 37-45 ◽  
Author(s):  
H. Ahmadian ◽  
G. M. L. Gladwell ◽  
F. Ismail
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Element Model ◽  
Measured Data ◽  
Finite Element Model Updating ◽  
Fe Model ◽  
Selection Strategies ◽  
Design Changes ◽  
Fe Model Updating

In FE model updating, as in any identification procedure, we select some parameters in the model, and try to fine-tune them to minimize the discrepancy between the model predictions and the measured data. The paper compares the performance of the generic element matrices, recently introduced by the authors, with other selection strategies for finite element model updating. The updated models obtained from these methods are compared with the measured data and rated according to their ability to produce the measured data within and beyond the frequency range used in the updating, and more importantly, according to their ability to predict the effect of design changes.

Required Precision and Valid Methodologies for Dynamic Finite Element Model Updating

1998 ◽  
Vol 120 (3) ◽  
pp. 733-741 ◽  
Author(s):  
R. I. Levin ◽  
T. P. Waters ◽  
N. A. J. Lieven
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Model ◽  
Model Updating ◽  
Element Model ◽  
Fe Analysis ◽  
Finite Element Model Updating ◽  
Fe Model ◽  
Lower Mode ◽  
Dynamic Finite Element

This paper investigates the effects of adjusting the system matrices of a Finite Element (FE) model on the eigen-properties of the model for the purposes of dynamic model updating. It is shown that minor modifications to the connectivity of the model can cause unexpectedly significant eigenvalue perturbations of the lower modes, especially if the physical location of the modification is near an antinode of vibration of a lower mode. These modifications can be introduced either by non-parametric updating techniques or unwittingly by truncation of the FE structural matrices. It is proposed that model updating techniques specifically avoid introducing such changes to the model either directly or indirectly. A mathematical bound has been established which gives a limit on eigenvalue perturbations. From this bound it has been deduced that a definable degree of computational precision is necessary for FE analysis for the purposes of model updating.

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