Modal Identification and Finite Element Model Updating by Adding Known Masses

2013 ◽  
Vol 405-408 ◽  
pp. 808-815 ◽  
Author(s):  
Chang Deng ◽  
Shao Wei Hu ◽  
Pei Ying Gu

This paper focus on the model updating of civil structural systems. Traditional modal test method can identify the frequency of the civil structure accurate, but it is difficult to identify the mass-normalized mode shape. By adding a series of known masses to the structure, measuring the frequency of this mass-modified system, and only using this set of frequency data, the mass-normalized mode shape of the structure can be identified. And the model updating method was developed, which constructed an objective function through the frequency of the measurement and the FE model, corrected the FE model's parameters to minimize the objective function. The example was included to show the capabilities of the technique. The finite element model of the fixed-free beam was updated by the dynamic characteristics which was identified from the modal test, the results show that updated results coincided with the experience of the analyst.

2010 ◽  
Vol 163-167 ◽  
pp. 2804-2810 ◽  
Author(s):  
Bei Dou Ding ◽  
Heng Lin Lv ◽  
Yong Sheng Ji

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.


2016 ◽  
Vol 88 (5) ◽  
pp. 665-675 ◽  
Author(s):  
Bimo Prananta ◽  
Toni Kanakis ◽  
Jos Vankan ◽  
Rien van Houten

Purpose The present paper aims to describe the model updating of a small aircraft dynamic finite element model (FEM) to improve its agreement with ground vibration test (GVT) data. Design/methodology/approach An automatic updating method using an optimization procedure is carried out. Instead of using dedicated updating tools, the procedure is implemented using standard MSC/NASTRAN because of wide availability of the software in small aircraft industries. The objective function is defined to minimize the differences in the natural frequency and the differences in the mode shape between the analytical model and the GVT data. Provision has been made to include the quantification of confidence in both the GVT data and in the initial model. Parameter grouping is carried out to reduce the number of design parameters during the optimization process. Findings The optimization module of standard finite element (FE) software can be effectively used to reduce the differences between the GVT and the FEM in terms of frequency and mode shape satisfactorily. The strategy to define the objective function based on minimizing the mode shape error can reduce the improvement in the frequency error. The required user interference can be kept low. Originality/value The most important contribution of the present paper concerns the combination of strategies to define the objective function and selection of the parameters.


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.


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.


2016 ◽  
Vol 8 (12) ◽  
pp. 168781401668265 ◽  
Author(s):  
Ping-Ping Yuan ◽  
Zuo-Cai Wang ◽  
Wei-Xin Ren ◽  
Xia Yang

Nonlinear behavior is often observed in structural joint system due to external loads. A new technique of nonlinear structural joint model updating with static load test results is proposed in this article to investigate the actual behavior of a joint system. To calibrate the nonlinear parameters of the structural joint system, an appropriate finite element model is first established to characterize the complex nonlinear behavior caused by the joint connections. Combined with the sensitivity analysis, the parameters that describe the nonlinear behavior of the joint connections are selected as the parameters to be updated. Subsequently, an objective function is created in accordance with the residual between experimentally measured static deflections and analytically calculated static deflections through finite element model. The objective function is then optimized to obtain the proper values of the nonlinear force–displacement parameters with the regular simulated annealing algorithm. To validate the efficiency of this updating approach, two numerical examples under static concentrated loads are conducted. The obtained results indicate that the nonlinear joint model parameters can be successfully updated, and the updated new model can further forecast the true deflections of the nonlinear structure with good accuracy and stability.


Sign in / Sign up

Export Citation Format

Share Document