Integrally Bladed Rotor Mistuning Identification and Model Updating Using Geometric Mistuning Models

2020 ◽  
Author(s):  
Joseph A. Beck ◽  
Jeffrey M. Brown ◽  
Daniel L. Gillaugh ◽  
Emily B. Carper ◽  
Alex A. Kaszynski
Keyword(s):  
Elastic Modulus ◽  
Model Updating ◽  
Element Model ◽  
Analytical Models ◽  
Optical Scanners ◽  
Reduced Order ◽  
Optical Scanning ◽  
Numerical Predictions ◽  
Simulated Test ◽  
Bladed Rotor

Abstract Non-uniform manufacturing variations and uneven usage wear and damage, referred to as mistuning, can drastically alter the dynamic response of Integrally Blade Rotors (IBR)s. Optical scanners, combined with Finite Element Model (FEM) mesh metamorphosis algorithms, have provided capabilities to create analytical models that reduce the effect of geometrical uncertainties in numerical predictions. However, deviations in material properties cannot be obtained via optical scanning, so additional approaches are needed. A geometric mistuning Reduced-Order Model (ROM) is developed and modified to solve for unknown IBR sector eigenvalues that are linearly proportional to Elastic modulus. The developed approach accounts for both proportional and non-proportional mistuning and allows updating of the Elastic modulus for each sector in the ROM. Different tuned and mistuned modal reduction procedures are employed to understand the implications of each for identifying mistuning. Simulated test data with known inputs indicate the efficiency and accuracy of the method and improvements over using a traditional, tuned mode approach. The developed methods are then extended to bench-level traveling wave excitation data to discern how sector frequencies vary due to geometry and modulus mistuning.

Integrally Bladed Rotor Mistuning Identification and Model Updating Using Geometric Mistuning Models

2021 ◽  
Author(s):  
Joseph Beck ◽  
Jeffrey Brown ◽  
Daniel Gillaugh ◽  
Emily Carper ◽  
Alex Kaszynski
Keyword(s):  
Elastic Modulus ◽  
Model Updating ◽  
Element Model ◽  
Analytical Models ◽  
Optical Scanners ◽  
Reduced Order ◽  
Optical Scanning ◽  
Numerical Predictions ◽  
Simulated Test ◽  
Bladed Rotor

Abstract Non-uniform manufacturing variations and uneven usage wear and damage, referred to as mistuning, can drastically alter the dynamic response of Integrally Bladed Rotors (IBRs). Optical scanners, combined with Finite Element Model mesh metamorphosis algorithms, have provided capabilities to create analytical models that reduce the effect of geometrical uncertainties in numerical predictions. However, deviations in material properties cannot be obtained via optical scanning, so additional approaches are needed. A geometric mistuning Reduced-Order Model (ROM) is developed and modified to solve for unknown IBR sector eigenvalues that are linearly proportional to Elastic modulus. The developed approach accounts for both proportional and non-proportional mistuning and allows updating of the Elastic modulus for each sector in the ROM. Different tuned and mistuned modal reduction procedures are employed to understand the implications of each for identifying mistuning. Simulated test data with known inputs indicate the efficiency and accuracy of the method and improvements over using a traditional, tuned mode approach. The developed methods are then extended to bench-level traveling wave excitation data to discern how sector frequencies vary due to geometry and modulus mistuning.

Improved Inverse Eigensensitivity Method for Structural Analytical Model Updating

1995 ◽  
Vol 117 (2) ◽  
pp. 192-198 ◽  
Author(s):  
R. M. Lin ◽  
M. K. Lim ◽  
H. Du
Keyword(s):  
Analytical Model ◽  
Model Updating ◽  
Element Model ◽  
Small Error ◽  
Analytical Models ◽  
Engineering Structures ◽  
Modal Data ◽  
Existing Problems ◽  
Practical Engineering ◽  
True Values

In order to update analytical models of practical engineering structures, inverse eigensensitivity method (IEM) has been developed. Though it has nowadays been widely accepted, the classical inverse eigensensitivity method does have some drawbacks such as the assumption of small error magnitudes and slow speed of convergence due to the fact that the sensitivity coefficients are calculated purely based on modal data of analytical model. In the present paper, an improved inverse eigensensitivity method, which avoids the existing problems of classical inverse eigensensitivity method, has been developed. The improved method employs both analytical and experimental modal data to calculate the required eigensensitivity coefficients which are very close to their true values. The method has been further extended to the case where measured coordinates are incomplete. Practical applicability of the method has been assessed by its application to the updating of the finite element model of a plane truss structure.

Prediction of Geometrically Induced Localization Effects Using a Subset of Nominal System Modes

2019 ◽  
Author(s):  
Thomas Maywald ◽  
Christoph R. Heinrich ◽  
Arnold Kühhorn ◽  
Sven Schrape ◽  
Thomas Backhaus
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Reduced Order Model ◽  
Vibration Measurement ◽  
Mode Shapes ◽  
Compressor Stage ◽  
Order Model ◽  
Reduced Order ◽  
Numerical Predictions

Abstract It is widely known that the vibration characteristics of blade integrated discs can dramatically change in the presence of manufacturing tolerances and wear. In this context, an increasing number of publications discuss the influence of the geometrical variability of blades on phenomena like frequency splitting and mode localization. This contribution is investigating the validity of a stiffness modified reduced order model for predicting the modal parameters of a geometrically mistuned compressor stage. In detail, the natural frequencies and mode shapes, as well as the corresponding mistuning patterns, are experimentally determined for an exemplary rotor. Furthermore, a blue light fringe projector is used to identify the geometrical differences between the actual rotor and the nominal blisk design. With the help of these digitization results, a realistic finite element model of the whole compressor stage is generated. Beyond that, a reduced order model is implemented based on the nominal design intention. Finally, the numerical predictions of the geometrically updated finite element model and the stiffness modified reduced order model are compared to the vibration measurement results. The investigation is completed by pointing out the benefits and limitations of the SNM-approach in the context of geometrically induced mistuning effects.

Estimation of Forcing Function for a Geometrically Mistuned Bladed Rotor Via Modified Modal Domain Analysis

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Vinod Vishwakarma ◽  
Alok Sinha
Keyword(s):  
Estimation Algorithm ◽  
Element Model ◽  
Domain Analysis ◽  
Dynamic Responses ◽  
Function Estimation ◽  
Mass Model ◽  
Reduced Order ◽  
Bladed Disk ◽  
Forcing Function ◽  
Bladed Rotor

Modified modal domain analysis (MMDA) is a method to generate an accurate reduced-order model (ROM) of a bladed disk with geometric mistuning. An algorithm based on the MMDA ROM and a state observer is developed to estimate forcing functions for synchronous (including integer multiples) conditions from the dynamic responses obtained at few nodal locations of blades. The method is tested on a simple spring-mass model, finite element model (FEM) of a geometrically mistuned academic rotor, and FEM of a bladed rotor of an industrial-scale transonic research compressor. The accuracy of the forcing function estimation algorithm is examined by varying the order of ROM and the number of vibration output signals.

Finite Element Model Updating of Space Grid Structures

2011 ◽  
Vol 243-249 ◽  
pp. 116-119
Author(s):  
Tian Yin Xiao ◽  
Jian Gang Han ◽  
Hong Bo Gao
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Numerical Models ◽  
Time History ◽  
Element Model ◽  
Vibration Test ◽  
Modal Shape ◽  
Numerical Predictions ◽  
Space Grid

The aim of updating models is to generate improved numerical models which may be applied in order to predict actual dynamic behaviors of the structure. The approach of numerical predictions to the behavior of a physical system is limited by the assumptions used in the development of the mathematical model. Model updating is about correcting invalid assumptions by processing vibration test results. Updating by improving the physical meaning of the model requires the application of considerable physical insight in the choice of parameters to update and the arrangement of constraints, force inputs and response measurements in the vibration test. The choice of updating parameters is the most important and the numerical predictions should be sensitive to small changes in the parameters. So methods used in model updating places a demand that the mass, stiffness and damping terms should be based on physically meaningful parameters. Using the structure frequency and local modal shape acquired from structural time-history responses, a model updating method of space grid structures was established in this paper. A numerical example is provided to prove the accuracy of this method. The results show that the method can be effectively used to correct the finite element model of space grid structures.

Estimation of Forcing Function for a Geometrically Mistuned Bladed Rotor via Modified Modal Domain Analysis

2015 ◽  
Author(s):  
Vinod Vishwakarma ◽  
Alok Sinha
Keyword(s):  
Estimation Algorithm ◽  
Element Model ◽  
Domain Analysis ◽  
Reduced Order Model ◽  
Dynamic Responses ◽  
Order Model ◽  
Mass Model ◽  
Reduced Order ◽  
Forcing Function ◽  
Bladed Rotor

Modified Modal Domain Analysis (MMDA) is a method to generate an accurate reduced order model (ROM) of a bladed disk with geometric mistuning. An algorithm based on MMDA ROM and a state observer is developed to estimate forcing functions for synchronous (including integer multiples) conditions from the dynamic responses obtained at few nodal locations of blades. The method is tested on a simple spring-mass model, finite element model (FEM) of a geometrically mistuned academic rotor and FEM of a bladed rotor of an industrial scale transonic research compressor. The accuracy of the forcing function estimation algorithm is examined by varying the order of reduced-order model and the number of vibration output signals.

The Finite Element Model Updating Based on Multi-Case Displacement Measurement

2013 ◽  
Vol 353-356 ◽  
pp. 3378-3381
Author(s):  
Ye Yan Liu ◽  
Jun Xiao ◽  
Yu Xin Zhang
Keyword(s):  
Genetic Algorithm ◽  
Inverse Problem ◽  
Finite Element ◽  
Elastic Modulus ◽  
Model Updating ◽  
Element Model ◽  
Finite Element Model Updating ◽  
Improved Genetic Algorithm ◽  
Numerical Examples ◽  
The Finite Element Model

Elastic modulus is an important parameter in structural analysis. This paper identifys the structural elastic modulus with measured displacements, which is an inverse problem. The improved genetic algorithm combined with multi-cases measurement is applied in the solution. Numerical examples have proved that the method is available.

Reduced Order Model of a Multistage Bladed Rotor With Geometric Mistuning via Modal Analyses of Finite Element Sectors

2011 ◽  
Vol 134 (4) ◽  
Author(s):  
Yasharth Bhartiya ◽  
Alok Sinha
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Element Model ◽  
Reduced Order Model ◽  
Statistical Distributions ◽  
Order Model ◽  
Two Stage ◽  
Reduced Order ◽  
Bladed Rotor ◽  
The Finite Element Model

An algorithm to generate a reduced order model of a multistage rotor in which each stage has a different number of blades has been developed. It is shown that a reduced order model can be developed on the basis of tuned modes of certain bladed disks which can be easily obtained via sector analyses. Further, it is shown that the reduced order model can also be obtained when blades are geometrically mistuned. This algorithm is similar to the modified modal domain analysis, which has been recently developed for a single-stage bladed rotor with geometric mistuning. The validity of this algorithm is shown for the finite element model of a two-stage bladed rotor. In addition, the statistical distributions of peak maximum amplitudes and natural frequencies of a two-stage rotor are generated via Monte Carlo simulations for different patterns of geometric mistuning.

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