A Direct Two Response Approach for Updating Analytical Dynamic Models of Structures With Emphasis on Uniqueness

1990 ◽  
Vol 112 (1) ◽  
pp. 107-111 ◽  
Author(s):  
S. R. Ibrahim ◽  
C. Stavrinidis ◽  
E. Fissette ◽  
O. Brunner
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Normal Modes ◽  
Element Model ◽  
Finite Element Models ◽  
Complex Modes ◽  
Structural Responses ◽  
Stiffness And Damping ◽  
The Finite Element Model

An approach, based on utilizing only two sets of structural responses and the enforcement of the conditions for a unique solution, is presented for the updating of Finite Element Models. The responses required can be any two identified normal modes, any two identified complex modes, or two forced harmonic response vectors in the neighborhood of any two natural frequencies of the structure under test. The mass, stiffness, and damping matrices are interactively and simultaneously corrected in a direct noniterative procedure. A uniqueness factor is automatically computed in the procedure to indicate the correctability of the Finite Element Model under consideration. The number of measurement locations is assumed to be less than the number of degrees of freedom of the analytical model. Provisions for completing and smoothing the measured or identified responses are included to reduce the effects of measurement noise and identification error. Preliminary results on simple models are presented in support of the proposed technique.

A Parallel Solution Strategy for Finite Element Models

1996 ◽  
Author(s):  
Jordan J. Cox ◽  
Jeffrey A. Talbert ◽  
Eric Mulkay
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Decomposition Methods ◽  
Finite Element Models ◽  
Unique Contribution ◽  
Matrix Equations ◽  
Parallel Solution ◽  
The Finite Element Model ◽  
Parallel Fashion

Abstract This paper presents a method for naturally decomposing finite element models into sub-models which can be solved in a parallel fashion. The unique contribution of this paper is that the decomposition strategy comes from the geometric features used to construct the solid model that the finite element model represents. Domain composition and domain decomposition methods are used to insure global compatibility. These techniques reduce the N2 behavior of traditional matrix solving techniques, where N is the number of degrees of freedom in the global set of matrix equations, to a sum of m matrices with n2 behavior, where n represents the number of degrees of freedom in the smaller sub-model matrix equations.

Updating Rotor-Bearing Finite Element Models

1997 ◽  
Author(s):  
Cristinel Mares ◽  
Cecilia Surace
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Parameters Estimation ◽  
Flexible Rotor ◽  
Estimation Errors ◽  
Rotor Bearing ◽  
Bearing Stiffness ◽  
Measured Frequency Response ◽  
Stiffness And Damping ◽  
The Finite Element Model

Abstract In this paper, the possibility of updating the finite element model of a rotor-bearing system by estimating the bearing stiffness and damping coefficients from a few measured Frequency Response Functions using a Genetic Algorithm is investigated. The issues of identifiability and parameters estimation errors, computational costs and algorithm tuning are addressed. A simulated example of a flexible rotor supported by orthotropic bearings is used for illustrating the method.

Identification of Joint Parameters for a Taper Joint

1989 ◽  
Vol 111 (3) ◽  
pp. 282-287 ◽  
Author(s):  
T. R. Kim ◽  
S. M. Wu ◽  
K. F. Eman
Keyword(s):  
Finite Element ◽  
Experimental Verification ◽  
Joint Stiffness ◽  
Element Model ◽  
Damping Characteristics ◽  
Analysis Technique ◽  
Joint Parameters ◽  
Stiffness And Damping ◽  
Taper Joint ◽  
The Finite Element Model

A new methodology of combining the finite element model of a structure with the results of the experimental modal analysis technique was applied to a tool-holder system with a taper joint to identify its joint stiffness and damping characteristics. The underlying background is briefly introduced followed by an experimental verification of the proposed method.

A Complaint Mechanism with Freedom Degrees of One Movement and Two Rotations

2014 ◽  
Vol 551 ◽  
pp. 444-447
Author(s):  
Sheng Lin ◽  
Xi Kong ◽  
Chun Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Finite Element Model ◽  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Compliant Mechanism ◽  
Element Model ◽  
Theory Analysis ◽  
The Finite Element Model

Based on the method of Freedom and Constraint Topology (FACT), a compliant mechanism with 3 degrees of freedom is designed. The 3 DOF are one movement and two rotations, which belongs to Case 3, Type 2. The whole stiffness matrix of the compliant mechanism is obtained. The finite element model is established for statics analysis. The results of theory analysis and finite element method are closed.

Simulation of the Head-On Collision between Heavy Truck and Rigid Guardrail

2013 ◽  
Vol 409-410 ◽  
pp. 1085-1088
Author(s):  
Si Yang Wang ◽  
Yap Ping Zhang ◽  
Yu Wei ◽  
Yong Li Zhang
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Finite Element Models ◽  
Vehicle Speed ◽  
Regular Pattern ◽  
Whole Process ◽  
Collision Safety ◽  
Heavy Truck ◽  
The Finite Element Model ◽  
Setting Parameters

This paper mainly studied the collision between heavy truck and rigid guardrail. The integral finite element models were established via respectively building the finite element model of truck and rigid guardrail and setting parameters of head-on collision. Then the paper did relative simulation and calculation, and analyzed the curves of vehicle speed, accelerated speed and energy in collision process. The whole process above used LS-DYNA to calculate, ANSYS to do pretreatment and LSPREPOST to do post-treatment in order to test collision safety. Compared with relative documents, the established model is basically correct and accords with the regular pattern of collision simulation.

scholarly journals Structural Response of Submerged Air-Backed Plates by Experimental and Numerical Analyses

2000 ◽  
Vol 7 (6) ◽  
pp. 333-341 ◽  
Author(s):  
Lloyd Hammond ◽  
Raphael Grzebieta
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Structural Response ◽  
Time History ◽  
Element Model ◽  
Steel Plates ◽  
Small Scale ◽  
History Of ◽  
Structural Responses ◽  
The Finite Element Model

This paper presents the results of a series of small-scale underwater shock experiments that measured the structural responses of submerged, fully clamped, air-backed, steel plates to a range of high explosive charge sizes. The experimental results were subsequently used to validate a series of simulations using the coupled LS-DYNA/USA finite element/boundary element codes. The modelling exercise was complicated by a significant amount of local cavitation occurring in the fluid adjacent to the plate and difficulties in modelling the boundary conditions of the test plates. The finite element model results satisfactorily predicted the displacement-time history of the plate over a range of shock loadings although a less satisfactory correlation was achieved for the peak velocities. It is expected that the predictive capability of the finite element model will be significantly improved once hydrostatic initialisation can be fully utilised with the LS-DYNA/USA software.

Experimental Study on Flexural Behavior of Damaged RC Beams Strengthened with Prestressed CFRP Plate

2011 ◽  
Vol 250-253 ◽  
pp. 2263-2270
Author(s):  
Rui Zhou ◽  
Mei Zhen Zhang ◽  
Zhou Hong Zong
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Element Model ◽  
Nonlinear Finite Element ◽  
Flexural Behavior ◽  
Finite Element Models ◽  
Rc Beams ◽  
Cfrp Plate ◽  
Sustained Loading ◽  
The Finite Element Model

Strengthening using prestressed CFRP plate is a new developed technology in recent years, which can significantly improve the flexural behavior of reinforced concrete (RC) beams. In this paper, an experimental study including four RC beams stengthened with CFRP plates using self-developed anchorage system was carried out. The nonlinear finite element models of the strengthened beams were constructed to simulate the influence of flexural behavior on RC beams strengthened with CFRP plates under different damage degrees. The experimental results indicated that initial damage degrees have greatly influence on the crack distribution and ductility, deflection and the ultimate flexural strength of the strengthened beams, as well as steel reinforcement strain and CFRP plate strain. Meanwhile, the finite element model can predict accurately performances of strengthened RC beams before CFRP debonding. In addition, the numerical analysis indicated that the sustained loading while strengthening RC beam using prestressed CFRP plates would induce adverse effect, so the live loading should be removed before starting the strengthening works.

scholarly journals ANALYSIS OF FEATURES OF APPLIED SOFTWARE “LIRA” IN CALCULATIONS OF NON-CIRCULAR TUNNEL LININGS

2019 ◽  
pp. 41-50
Author(s):  
V. P. KUPRIY ◽  
O. L. TIUTKIN ◽  
P. YE. ZAKHARCHENKO
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Finite Element Model ◽  
Software Package ◽  
Strain State ◽  
Element Model ◽  
Finite Element Models ◽  
Stress Strain ◽  
Stress Strain State ◽  
The Finite Element Model

Purpose. The article examines the effect on the stress-strain state of the parameters of the finite-element model created in the “Lira” software package in a numerical analysis of non-circular outlined tunnels. Methodology To achieve this goal, the authors developed finite element models of the calotte part of the mine during the construction of a double track railway tunnel using “Lira” software. In each of the models in the “Lira” software package, the interaction zone with temporary fastening was sampled in a specific way. After creation of models, their numerical analysis with the detailed research of his results was conducted. Findings. In the finite element models, the values of deformations and stresses in the horizontal and vertical axes, as well as the maximum values of the moments and longitudinal forces in the temporary fastening were obtained. A comparative analysis of the obtained values of the components of the stress-strain state with a change in the parameters of the finite element model was carried out. The graphs of the laws of these results from the discretization features of the two models were plotted. The third finite element model with a radial meshing in the zone of interaction of temporary support with the surrounding soil massif was investigated. Originality It has been established that in the numerical analysis of the SSS of a tunnel lining of a non-circular outline, its results substantially depend on the shape, size and configuration of the applied finite elements, on the size of the computational area of the soil massif, and also on the conditions for taking into account the actual (elastic or plastic) behavior of the soil massif.  Practical value. The features of discretization and the required dimensions of the computational area of the soil massif were determined when modeling the “lining – soil massif” system, which provide sufficient accuracy for calculating the parameters of the stress-strain state of the lining.

scholarly journals Finite Element Model Updating of Reinforced Concrete Beams with Honeycomb Damage

2012 ◽  
Vol 58 (2) ◽  
pp. 135-151 ◽  
Author(s):  
Z. Ismail
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Finite Element Model ◽  
Model Updating ◽  
Element Model ◽  
Significant Loss ◽  
Reinforced Concrete Beams ◽  
Finite Element Model Updating ◽  
Finite Element Models ◽  
The Finite Element Model

Abstract A method of detecting honeycombing damage in a reinforced concrete beam using the finite element model updating technique was proposed. A control beam and two finite element models representing different severity of damage were constructed using available software and the defect parameters were updated. Analyses were performed on the finite element models to approximate the modal parameters. A datum and a control finite element model to match the datum test beams with honeycombs were prepared. Results from the finite element model were corrected by updating the Young’s modulus and the damage parameters. There was a loss of stiffness of 3% for one case, and a loss of 7% for another. The more severe the damage, the higher the loss of stiffness. There was no significant loss of stiffness by doubling the volume of the honeycombs.

Prediction Capabilities of Damped Updated Finite Element Models

2011 ◽  
Author(s):  
Vikas Arora
Keyword(s):  
Finite Element ◽  
Model Updating ◽  
Dynamic Properties ◽  
Detailed Comparison ◽  
Element Model ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Complex Frequency ◽  
Structural Modifications ◽  
The Finite Element Model

Model updating techniques are used to correct the finite element model of a structure using experimental data such that the updated model more correctly describes the dynamic properties of the structure. One of the applications of such an updated model is to predict the effects of making modifications to the structure. These 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 complex frequency response functions (FRFs) and complex mode shapes. In this paper, a detailed comparison of prediction capabilities of parameter-based and non parameter-based damped updated methods for structural modifications is done. The suitability of paramter-based and non parameter-based damped updated models for predicting the effects of structural modifications is evaluated by laboratory experiment for the case of an F-shape test structure. It is concluded that parameter-based damped updated models are likely to perform better in predicting the effects of structural modifications.

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