Modeling the Microslip in the Flange Joint and Its Effect on the Dynamics of a Multistage Bladed Disk Assembly

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Christian M. Firrone ◽  
Giuseppe Battiato ◽  
Bogdan I. Epureanu
Keyword(s):  
Element Model ◽  
Forced Response ◽  
Flange Joint ◽  
Reduced Order ◽  
Bladed Disk ◽  
Simple Geometry ◽  
Bladed Disk Assembly ◽  
Joint Contact ◽  
Turbine Disks ◽  
Complex Architecture

The complex architecture of aircraft engines requires demanding computational efforts when the dynamic coupling of their components has to be predicted. For this reason, numerically efficient reduced-order models (ROM) have been developed with the aim of performing modal analyses and forced response computations on complex multistage assemblies being computationally fast. In this paper, the flange joint connecting two turbine disks of a multistage assembly is studied as a source of nonlinearities due to friction damping occurring at the joint contact interface. An analytic contact model is proposed to calculate the local microslip based on the different deformations that the two flanges in contact take during vibration. The model is first introduced using a simple geometry representing two flanges in contact, and then, it is applied to a reduced finite element model in order to calculate the nonlinear forced response.

Modelling the Microslip in the Flange Joint and its Effect on the Dynamics of a Multi-Stage Bladed Disk Assembly

2016 ◽  
Author(s):  
Christian M. Firrone ◽  
Giuseppe Battiato ◽  
Bogdan I. Epureanu
Keyword(s):  
Forced Response ◽  
Global Dynamics ◽  
Fe Model ◽  
Flange Joint ◽  
Multi Stage ◽  
Simple Geometry ◽  
Bladed Disk Assembly ◽  
Turbine Disks ◽  
The Many ◽  
Complex Architecture

The complex architecture of aircraft engines requires demanding computational efforts to take into account the dynamic coupling of the many components constituting the whole assembly. For this reason numerically efficient Reduced Order Models (ROM) and techniques have been developed with the aim of reproducing the global dynamics of the system being computationally fast at the same time. In particular, ROMs have been presented to perform the modal analysis and the calculation of the forced response of rotating components like turbine bladed disks multi-stage assembly. In order to study the effect that joints may have in terms of nonlinearities due to friction in complex structures, in this paper the flange joint is studied as a source of damping due to microslip occurring at the contact interface between two turbine disks. An analytical contact model is proposed to calculate the local microslip based on the different deformations that the two flanges take during vibration. The model is first introduced using a simple geometry representing two flanges in contact and then it is applied to a reduced FE model in order to calculate the nonlinear forced response.

Rotating Mistuned Bladed Disk Assembly Dynamic Response Prediction Using Component Mode Synthesis Methods With Interface Modes

2005 ◽  
Author(s):  
Francois Duvauchelle ◽  
Duc-Minh Tran ◽  
Roger Ohayon
Keyword(s):  
Response Prediction ◽  
Forced Response ◽  
Component Mode Synthesis ◽  
Synthesis Methods ◽  
Cyclic Symmetry ◽  
Reduced Order ◽  
Bladed Disk ◽  
Static Condensation ◽  
Bladed Disk Assembly ◽  
Reduced Order Methods

Finite element-based reduced order methods are presented with application to the prediction of rotating mistuned bladed disk forced response. These methods have already been applied to tuned non-rotating models having cyclic symmetry. The aim is to reduce significantly the number of interface co-ordinates, which can be very important in classical component mode synthesis methods. The approach is based on the use of the interface modes which result from a static condensation of the whole structure on the whole interface. A first implementation of this procedure and numerical results are presented.

Application of a Reduced Order Modeling Technique for Mistuned Bladed Disk-Shaft Assemblies

2007 ◽  
Author(s):  
Bartolome´ Segui´ ◽  
Euro Casanova
Keyword(s):  
Finite Element ◽  
Synthesis Method ◽  
Element Model ◽  
Reduced Order Modeling ◽  
Forced Response ◽  
Modeling Technique ◽  
Disk Model ◽  
Reduced Order ◽  
Bladed Disk ◽  
Global Dynamic

This paper presents a reduced-order modeling technique, based on a component mode synthesis method specifically tailored for bladed disks, that allows the resulting low-order model to be attached to a shaft. Mistuning is included in the bladed disk model and the shaft is modeled using uniaxial finite elements according to the rotordynamic approach. The proposed formulation is applied to an example finite element model of a bladed disk, for both tuned and mistuned blades. Comparisons are made between the reduced model and the full finite element solution for free and forced responses in order to assess the methodology. The forced response amplitudes of the blades are found to vary significantly with the inclusion of a flexible shaft. This work suggest that stage independent analyses might not be adequate for predicting the global dynamic response of rotating assemblies of turbomachines.

The Effect of Non-Uniform Aerodynamic Loading on the Blade Responses

2007 ◽  
Author(s):  
Abdelgadir M. Mahmoud ◽  
Mohd S. Leong
Keyword(s):  
Turbine Blades ◽  
Forced Response ◽  
Flow Section ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Bladed Disk ◽  
Aerodynamic Loading ◽  
Bladed Disk Assembly ◽  
Flow Generator ◽  
Inlet Flow Distortion

Turbine blades are always subjected to severe aerodynamic loading. The aerodynamic loading is uniform and Of harmonic nature. The harmonic nature depends on the rotor speed and number of nozzles (vanes counts). This harmonic loading is the main sources responsible for blade excitation. In some circumstances, the aerodynamic loading is not uniform and varies circumferentially. This paper discussed the effect of the non-uniform aerodynamic loading on the blade vibrational responses. The work involved the experimental study of forced response amplitude of model blades due to inlet flow distortion in the presence of airflow. This controlled inlet flow distortion therefore represents a nearly realistic environment involving rotating blades in the presence of airflow. A test rig was fabricated consisting of a rotating bladed disk assembly, an inlet flow section (where flow could be controlled or distorted in an incremental manner), flow conditioning module and an aerodynamic flow generator (air suction module with an intake fan) for investigations under laboratory conditions. Tests were undertaken for a combination of different air-flow velocities and blade rotational speeds. The experimental results showed that when the blades were subjected to unsteady aerodynamic loading, the responses of the blades increased and new frequencies were excited. The magnitude of the responses and the responses that corresponding to these new excited frequencies increased with the increase in the airflow velocity. Moreover, as the flow velocity increased the number of the newly excited frequency increased.

Geometric Mistuning Reduced-Order Model Development Utilizing Bayesian Surrogate Models for Component Mode Calculations

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Joseph A. Beck ◽  
Jeffrey M. Brown ◽  
Alex A. Kaszynski ◽  
Emily B. Carper ◽  
Daniel L. Gillaugh
Keyword(s):  
Periodic Structures ◽  
Model Development ◽  
Element Model ◽  
Forced Response ◽  
Mode Shapes ◽  
Order Model ◽  
Mode Localization ◽  
Reduced Order ◽  
Structural Periodicity ◽  
Computationally Intensive

AbstractIntegrally bladed rotors (IBRs) are meant to be rotationally periodic structures. However, unique variations in geometries and material properties from sector-to-sector, called mistuning, destroy the structural periodicity. This results in mode localization that can induce forced response levels greater than what is predicted with a tuned analysis. Furthermore, mistuning and mode localization are random processes that require stochastic treatments when analyzing the distribution of fleet responses. Generating this distribution can be computationally intensive when using the full finite element model (FEM). To overcome this expense, reduced-order models (ROMs) have been developed to accommodate fast calculations of mistuned forced response levels for a fleet of random IBRs. Usually, ROMs can be classified by two main families: frequency-based and geometry-based methods. Frequency-based ROMs assume mode shapes do not change due to mistuning. However, this assumption has been shown to cause errors that propagate to the fleet distribution. To circumvent these errors, geometry-based ROMs have been developed to provide accurate predictions. However, these methods require recalculating modal data during ROM formulations. This increases the computational expense in computing fleet distributions. A new geometry-based ROM is presented to reduce this cost. The developed ROM utilizes a Bayesian surrogate model in place of sector modal calculations required in ROM formulations. The method, surrogate modal analysis for geometry mistuning assessments (SMAGMA), will propagate uncertainties of the surrogate prediction to forced response. ROM accuracies are compared to the true forced response levels and results computed by a frequency-based ROM.

Investigation of Damping Potential of Strip Damper on a Real Turbine Blade

2016 ◽  
Author(s):  
M. Afzal ◽  
I. Lopez Arteaga ◽  
L. Kari ◽  
V. Kharyton
Keyword(s):  
Boundary Conditions ◽  
Dynamic Properties ◽  
Equations Of Motion ◽  
Iterative Solution ◽  
Element Model ◽  
Forced Response ◽  
Contact Forces ◽  
Response Analysis ◽  
Bladed Disk ◽  
Different Types

This paper investigates the damping potential of strip dampers on a real turbine bladed disk. A 3D numerical friction contact model is used to compute the contact forces by means of the Alternate Frequency Time domain method. The Jacobian matrix required during the iterative solution is computed in parallel with the contact forces, by a quasi-analytical method. A finite element model of the strip dampers, that allows for an accurate description of their dynamic properties, is included in the steady-state forced response analysis of the bladed disk. Cyclic symmetry boundary conditions and the multiharmonic balance method are applied in the formulation of the equations of motion in the frequency domain. The nonlinear forced response analysis is performed with two different types of boundary conditions on the strip: (a) free-free and (b) elastic, and their influence is analyzed. The effect of the strip mass, thickness and the excitation levels on the forced response curve is investigated in detail.

Geometric Mistuning Reduced-Order Models for Integrally Bladed Rotors With Mistuned Disk–Blade Boundaries

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Joseph A. Beck ◽  
Jeffrey M. Brown ◽  
Alex A. Kaszynski ◽  
Charles J. Cross ◽  
Joseph C. Slater
Keyword(s):  
Degrees Of Freedom ◽  
Principal Component ◽  
Element Model ◽  
Forced Response ◽  
Solid Model ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Small Areas ◽  
Eigen Analysis ◽  
Connection Type

New geometric mistuning modeling approaches for integrally bladed rotors (IBRs) are developed for incorporating geometric perturbations to a fundamental disk–blade sector, particularly the disk–blade boundary or connection. Reduced-order models (ROMs) are developed from a Craig–Bampton component mode synthesis (C–B CMS) framework that is further reduced by a truncated set of interface modes that are obtained from an Eigen-analysis of the C–B CMS constraint degrees of freedom (DOFs). An investigation into using a set of tuned interface modes and tuned constraint modes for model reduction is then performed, which offers significant computational savings for subsequent analyses. Two configurations of disk–blade connection mistuning are investigated: as-measured principal component (PC) deviations and random perturbations to the interblade spacing. Furthermore, the perturbation sizes are amplified to investigate the significance of incorporating mistuned disk–blade connections during solid model generation from optically scanned geometries. Free and forced response results are obtained for each ROM and each disk–blade connection type and compared to full finite element model (FEM) solutions. It is shown that the developed methods provide accurate results with a reduction in solution time compared to the full FEM. In addition, results indicate that the inclusion of a mistuned disk–blade connection deviations are small or conditions where large perturbations are localized to a small areas of the disk–blade connection.

Computation of the Statistics of Forced Response of a Mistuned Bladed Disk Assembly via Polynomial Chaos

2003 ◽  
Author(s):  
Alok Sinha
Keyword(s):  
Numerical Simulations ◽  
Polynomial Chaos ◽  
Random Variable ◽  
Forced Response ◽  
Bladed Disk ◽  
Bladed Disk Assembly

The method of polynomial chaos has been used to analytically compute the statistics of forced response of a mistuned bladed disk assembly. The model of the bladed disk assembly considers only one mode of vibration of each blade. Mistuning phenomenon has been simulated by treating the modal stiffness of each blade as a random variable. The validity of the polynomial chaos method has been corroborated by comparison with the results from numerical simulations.

scholarly journals Mistuning Analysis of a Detuned Bladed-Disk With Geometrical Nonlinearities

2019 ◽  
Author(s):  
Anthony Picou ◽  
Evangéline Capiez-Lernout ◽  
Christian Soize ◽  
Moustapha Mbaye
Keyword(s):  
Probabilistic Approach ◽  
Element Model ◽  
Deterministic Approach ◽  
Complex Dynamic ◽  
Order Model ◽  
Numerical Application ◽  
Reduced Order ◽  
Bladed Disk ◽  
Geometrical Nonlinearities ◽  
Disk Structure

Abstract This work concerns the nonlinear numerical analysis of mistuned blades for a rotating detuned bladed-disk structure with geometrical nonlinearities. The detuning phenomenon is taken into account through a deterministic approach by modifying material properties of some blades. A nonlinear reduced-order model is obtained by setting up a basis using a double projection method. The mistuning uncertainties are implemented through a nonparametric probabilistic approach for which the level of uncertainties is controlled by a hyperparameter. A numerical application is carried out on a bladed-disk structure made up of 24 blades whose finite element model has about 800,000 dofs exhibiting complex dynamic behaviors.

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