Selective Sensitivity for Model Updating With Modal Data

1995 ◽  
Author(s):  
Muzio M. Gola ◽  
Aurelio Somà
Keyword(s):  
Degrees Of Freedom ◽  
Model Updating ◽  
Structural Parameters ◽  
Selection Procedure ◽  
Element Model ◽  
Degree Of Freedom ◽  
Data Set ◽  
Minimum Number ◽  
Selective Sensitivity ◽  
Updating Procedure

Abstract In the present work a criterion for the minimum measured data set (modes and degree of freedom) required for a successful updating is established in the case of the inverse sensitivity method. The finite element model is used as a tool for the pre-analysis in order to plan the modal experiments, the selection of modes and degree of freedom to put into play in the updating procedure are obtained though the evaluation covariance matrix of the estimated parameters. A two stage procedure is proposed, in the first part of the work the modal sensitivity problem is reviewed in order to illustrate a systematic procedure capable of enucleating the set of modes that effectively contributes to the updating procedure. Then the procedure is extended to the determination of the minimum number of degrees of freedom to be measured in relation to a desired upper limit for the standard deviation of the structural parameters which are to be updated. Simple frame structures with different parameter locations are used as examples, the convergence on two parameters maps is used as demonstration of the powerful of the selection procedure to predict the chances of the successful updating.

scholarly journals Sensitivity Analysis of the Influence of Structural Parameters on Dynamic Behaviour of Highly Redundant Cable-Stayed Bridges

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
B. Asgari ◽  
S. A. Osman ◽  
A. Adnan
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Structural Parameters ◽  
Element Model ◽  
Structural Behavior ◽  
Model Tuning ◽  
The Finite Element Model ◽  
Cable Stayed Bridges

The model tuning through sensitivity analysis is a prominent procedure to assess the structural behavior and dynamic characteristics of cable-stayed bridges. Most of the previous sensitivity-based model tuning methods are automatic iterative processes; however, the results of recent studies show that the most reasonable results are achievable by applying the manual methods to update the analytical model of cable-stayed bridges. This paper presents a model updating algorithm for highly redundant cable-stayed bridges that can be used as an iterative manual procedure. The updating parameters are selected through the sensitivity analysis which helps to better understand the structural behavior of the bridge. The finite element model of Tatara Bridge is considered for the numerical studies. The results of the simulations indicate the efficiency and applicability of the presented manual tuning method for updating the finite element model of cable-stayed bridges. The new aspects regarding effective material and structural parameters and model tuning procedure presented in this paper will be useful for analyzing and model updating of cable-stayed bridges.

scholarly journals Parameter identification for a point-supported cross laminated timber slab based on experimental and numerical modal analysis

2020 ◽  
Author(s):  
Michael Kawrza ◽  
Thomas Furtmüller ◽  
Christoph Adam ◽  
Roland Maderebner
Keyword(s):  
Modal Analysis ◽  
Model Updating ◽  
Dynamic Properties ◽  
Element Model ◽  
Mode Shapes ◽  
Cross Laminated Timber ◽  
Numerical Studies ◽  
Robust Parameter ◽  
Updating Procedure ◽  
Sensor Positions

AbstractIn this paper, the dynamic properties of a point-supported cross-laminated timber slab are studied in order to determine the elastic material parameters on this basis. A detailed experimental modal analysis of the slab with dimensions 16.0 m x 11.0 m is performed, and seven modes including the natural frequencies, damping ratios and mode shape components at 651 sensor positions are identified. The found mode shapes are complex due to environmental influences that occurred during the two-day measurement campaign. This error is corrected by eliminating these influences. A finite element model of the slab is presented, whose parameters in terms of material properties and boundary conditions are determined by a model updating procedure. Based on the modal properties of the seven experimentally identified modes, an accurate and robust parameter set is obtained, which can be used in further numerical studies of the considered CLT to check serviceability limit criteria.

scholarly journals Finite element model updating using Lagrange interpolation

2019 ◽  
Vol 23 (1) ◽  
pp. 228-232
Author(s):  
F. Asma
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Model Updating ◽  
Element Model ◽  
Truss Structures ◽  
Finite Element Model Updating ◽  
Initial Model ◽  
Information Matrices ◽  
Matrix Interpolation

Abstract In this paper, an iterative finite element model updating method in structural dynamics is proposed. This uses information matrices and element connectivity matrices to reconstruct the corrected model by reproducing the frequency response at measured degrees of freedom. Indicators have been proposed to quantify the mismodelling errors based on a development in Lagrange matrix interpolation. When applied on simulated truss structures, the model gives satisfactory results by detecting and quantifying the defaults of the initial model.

Distributed Friction and Microslip in Mechanical Joints With Varying Degrees-of-Freedom

2001 ◽  
Author(s):  
D. Dane Quinn
Keyword(s):  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
External Forcing ◽  
Reduced Order ◽  
Mechanical Joints ◽  
Starting Point ◽  
Minimum Number ◽  
Frictional Forces ◽  
Distributed Friction ◽  
Structural Interfaces

Abstract This work considers the effect of distributed friction on the dynamics arising from a simple model for a jointed structure. A hierarchy of models is developed, parameterized by the degree-of-freedom n, which physically corresponds to the number of possible slip zones. When the resulting system is subjected to harmonic forcing, numerical simulations indicate that the instantaneous power dissipated by the frictional forces is sensitive to n. However, the frictional work per unit forcing cycle is, surprisingly, relatively insensitive to the degree-of-freedom, provided n is greater that some minimum number which depends on the amplitude of the external forcing as well as the maximum frictional force. Finally, representative simulations are shown as both the amplitude and frequency of the external forcing are varied. This model provides a starting point for the development of reduced-order models of structural interfaces.

scholarly journals Modeling and Stochastic Model Updating of Bolt-Jointed Structure

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Ming Zhan ◽  
Qintao Guo ◽  
Lin Yue ◽  
Baoqiang Zhang
Keyword(s):  
Finite Element ◽  
High Resolution ◽  
Material Properties ◽  
Model Updating ◽  
Computational Cost ◽  
Three Dimensional ◽  
Element Model ◽  
Joint Interface ◽  
Unknown Parameters ◽  
Updating Procedure

Bolt-jointed structure is widely used in engineering fields. The dynamic characteristics of bolt-jointed structure are complex, and there is a variety of uncertainties in the jointed structure. In this study, modeling and updating of a typical bolt-jointed structure are investigated. In modeling terms, three-dimensional brick elements are used to represent the substructures, and thin-layer elements with virtual material properties are employed to represent the joint interface. Modal tests and experimental modal analysis of substructures and built-up structure are performed. A hierarchical model updating strategy based on Bayesian inference is applied to identify the unknown parameters in the substructures model and those in the overall model. Radial basis function (RBF) models are used as surrogates of time-consuming finite element model with high resolution to avoid the enormous computational cost. The results indicate that the updated model can reproduce modal frequencies used in updating and can predict those not used in the updating procedure.

Structure Statics Finite Element Model Updating Based on Response Surface Methodology

2011 ◽  
Vol 255-260 ◽  
pp. 1939-1943 ◽  
Author(s):  
Miao Yi Deng ◽  
Guang Hui Li
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Response Surface ◽  
Model Updating ◽  
Structural Parameters ◽  
Optimization Procedure ◽  
Element Model ◽  
Surface Model ◽  
Model Parameters ◽  
Finite Element Model Updating

Employing response surface method, the complicated implicit relationship between bridge structural static-load responses and structural parameters is approximately represented by the simple explicit function. Based on this response surface model (function), the structural finite element model parameters can be easily updated by selected optimization procedure. By a numerical example of a two-span continuous beam, the essential theory and implementation of structural static response surface based finite element model updating are presented in the paper.

Experimental validation of a FRF-based model updating method

2016 ◽  
Vol 24 (8) ◽  
pp. 1570-1583 ◽  
Author(s):  
Fariba Shadan ◽  
Faramarz Khoshnoudian ◽  
Daniel J Inman ◽  
Akbar Esfandiari
Keyword(s):  
Measurement Errors ◽  
Model Updating ◽  
Structural Parameters ◽  
Element Model ◽  
Lumped Mass ◽  
Sensitivity Equation ◽  
Modeling Errors ◽  
Incomplete Measurement ◽  
Aluminum Beam

In this paper, a finite element model updating method using frequency response functions is experimentally validated. The method is a sensitivity-based model updating approach which utilizes a pseudo-linear sensitivity equation. The method is robust against the adverse effects of incomplete measurement, measurement errors and modeling errors. The experimental setup consists of a free-free aluminum beam, where changes are introduced by reducing the stiffness and attaching lumped mass at certain parts of the beam. The method is applied to identify the location and amount of the changes in structural parameters. The results indicate that the location and the size of different level of changes in the structure can be properly identified by the method. In addition, a study is done on the influence of the number of impacts and sensors on the quality of the identified parameters.

scholarly journals Structural model updating based on metamodel using modal frequencies

2021 ◽  
Vol 15 (58) ◽  
pp. 114-127
Author(s):  
Jutao Wang ◽  
Zhenzhong Liu ◽  
Liju Xue
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Structural Model ◽  
Model Updating ◽  
Element Model ◽  
Kriging Model ◽  
Frame Structure ◽  
Updating Procedure ◽  
The Finite Element Model

Modal frequencies are often used in structural model updating based on the finite element model, and metamodel technique is often applied to the corresponding optimization process. In this work, the Kriging model is used as the metamodel. Firstly, the influence of different correlation functions of Kriging model is inspected, and then the approximate capability of Kriging model is investigated via inspecting the approximate accuracy of nonlinear functions. Secondly, a model updating procedure is proposed based on the Kriging model, and the samples for constructing Kriging model are generated via the method of Optimal Latin Hypercube. Finally, a typical frame structure is taken as a case study and demonstrates the feasibility and efficiency of the proposed approach. The results show the Kriging model can match the target functions very well, and the finite element model can achieve accurate frequencies and can reliably predict the frequencies after model updating.

Design of Passive Reconfigurable Manipulation Assistive Aids

2001 ◽  
Author(s):  
Xichun Nie ◽  
Venkat Krovi
Keyword(s):  
Task Performance ◽  
Degrees Of Freedom ◽  
Structural Parameters ◽  
Mechanical Systems ◽  
Degree Of Freedom ◽  
Mechanical Constraints ◽  
The Creation

Abstract Multi-jointed mechanical systems typically possess excess degrees-of-freedom, which often are neither required nor used in performing typical manipulation tasks. These excessive degrees of freedom then need to be reduced by application of constraints, either actively by suitable control or passively in hardware, prior to task performance. Our interest is in creating articulated manipulation assistive aids, which combine the motion flexibility due to the multiple articulations with the simplicity of reduced degree-of-freedom control and actuation due to the presence of hardware mechanical constraints. Specifically we investigate the process of design and prototyping of such reduced-degree-of-freedom manipulators to closely approximate desired planar paths. We then examine design enhancements to permit easy reconfiguration for different sets of paths. Finally, special attention is paid to the creation of a prototype with the ability to be reconfigured for multiple sets of paths, by a controlled variation of the principal structural parameters.

scholarly journals A Narrow Deep Learning Assisted Visual Tracking with Joint Features

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Xiaoyan Qian ◽  
Daihao Zhang
Keyword(s):  
Visual Tracking ◽  
Model Updating ◽  
State Of The Art ◽  
Gaussian Mixture ◽  
Background Information ◽  
Robust Tracking ◽  
Data Set ◽  
Tracking Method ◽  
Benchmark Data ◽  
Updating Procedure

A robust tracking method is proposed for complex visual sequences. Different from time-consuming offline training in current deep tracking, we design a simple two-layer online learning network which fuses local convolution features and global handcrafted features together to give the robust representation for visual tracking. The target state estimation is modeled by an adaptive Gaussian mixture. The motion information is used to direct the distribution of the candidate samples effectively. And meanwhile, an adaptive scale selection is addressed to avoid bringing extra background information. A corresponding object template model updating procedure is developed to account for possible occlusion and minor change. Our tracking method has a light structure and performs favorably against several state-of-the-art methods in tracking challenging scenarios on the recent tracking benchmark data set.

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