Sensitivity-Based Finite Element Model Updating Using Dynamic Condensation Approach

2018 ◽  
Vol 18 (08) ◽  
pp. 1840004 ◽  
Author(s):  
Tianyi Zhu ◽  
Wei Tian ◽  
Shun Weng ◽  
Hanbin Ge ◽  
Yong Xia ◽  
...  

An accurate finite element (FE) model is frequently used in damage detection, optimization design, reliability analysis, nonlinear analysis, and so forth. The FE model updating of large-scale structures is usually time-consuming or even impossible. This paper proposes a dynamic condensation approach for model updating of large-scale structures. The eigensolutions are calculated from a condensed eigenequation and the eigensensitivities are calculated without selection of additional master DOFs, which is helpful to improve the efficiency of FE model updating. The proposed model updating method is applied to an eight-storey frame and the Jun Shan Yangtze Bridge. By employing the dynamic condensation approach, the number of iterations for the eigensensitivities is gradually increased according to the model updating process, which contributes to accelerate the convergence of model updating.

2013 ◽  
Vol 540 ◽  
pp. 79-86
Author(s):  
De Jun Wang ◽  
Yang Liu

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.


Author(s):  
D. V. Nehete ◽  
S. V. Modak ◽  
K. Gupta

Finite element (FE) model updating is now recognized as an effective approach to reduce modeling inaccuracies present in an FE model. FE model updating has been researched and studied well for updating FE models of purely structural dynamic systems. However there exists another class of systems known as vibro-acoustics in which acoustic response is generated in a medium due to the vibration of enclosing structure. Such systems are commonly found in aerospace, automotive and other transportation applications. Vibro-acoustic FE modeling is essential for sound acoustic design of these systems. Vibro-acoustic system, in contrast to purely structural system, has not received sufficient attention from FE model updating perspective and hence forms the topic of present paper. In the present paper, a method for finite element model updating of coupled structural acoustic model, constituted as a problem of constrained optimization, is proposed. An objective function quantifying error in the coupled natural frequencies and mode shapes is minimized to estimate the chosen uncertain parameters of the system. The effectiveness of the proposed method is validated through a numerical study on a 3D rectangular cavity attached to a flexible panel. The material property and the stiffness of joints between the panel and rectangular cavity are used as updating parameters. Robustness of the proposed method under presence of noise is investigated. It is seen that the method is not only able to obtain a close match between FE model and corresponding ‘measured’ vibro-acoustic characteristics but is also able to estimate the correction factors to the updating parameters with reasonable accuracy.


2013 ◽  
Vol 540 ◽  
pp. 1-10
Author(s):  
Yang Liu ◽  
Zhan Lv ◽  
Hong Zhang

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.


Author(s):  
V. Arora

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.


2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Eunjong Yu ◽  
Seung-Nam Kim ◽  
Taewon Park ◽  
Sang-Hyun Lee

Damage of a 5-story framed structure was identified from two types of measured data, which are frequency response functions (FRF) and natural frequencies, using a finite element (FE) model updating procedure. In this study, a procedure to determine the appropriate weightings for different groups of observations was proposed. In addition, a modified frame element which included rotational springs was used to construct the FE model for updating to represent concentrated damage at the member ends (a formulation for plastic hinges in framed structures subjected to strong earthquakes). The results of the model updating and subsequent damage detection when the rotational springs (RS model) were used were compared with those obtained using the conventional frame elements (FS model). Comparisons indicated that the RS model gave more accurate results than the FS model. That is, the errors in the natural frequencies of the updated models were smaller, and the identified damage showed clearer distinctions between damaged and undamaged members and was more consistent with observed damage.


1997 ◽  
Vol 119 (1) ◽  
pp. 37-45 ◽  
Author(s):  
H. Ahmadian ◽  
G. M. L. Gladwell ◽  
F. Ismail

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.


2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Hongrui Cao ◽  
Bing Li ◽  
Zhengjia He

The unknown joint dynamics are the main obstacle that limits the accuracy of the finite element (FE) model of a machine-tool spindle assembly. In this paper, an FE model updating method is proposed to assist industrial engineers in achieving a reliable model that can accurately represent the dynamic characteristics of machine-tool spindle systems. In the proposed FE model updating procedure, the iterative algorithm based on frequency response functions (FRFs) is applied. The joint stiffness parameters are identified through the iteration process, while the FE model is updated simultaneously. The proposed method was applied to update an existing coupled model of a machine-tool spindle system. The experimental results show that the identified joint stiffness parameters are acceptable and the dynamic behavior of the spindle mounted in the machine tool column is predicted reliably.


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