A Model Reduction Method for Bladed Disks With Large Geometric Mistuning Using a Partially Reduced Intermediate System Model

2020 ◽  
Author(s):  
Lukas Schwerdt ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Reduction Method ◽  
Axial Compressor ◽  
Reduction Process ◽  
Computational Effort ◽  
System Model ◽  
Bladed Disks ◽  
Element Mesh ◽  
Modal Expansion ◽  
Reduced Order ◽  
Intermediate System

Abstract Reduced order models (ROMs) are widely used to enable efficient simulation of mistuned bladed disks. ROMs based on projecting the system dynamics into a subspace spanned by the modes of the tuned structure work well for small amounts of mistuning. When presented with large mistuning, including changes of geometry and number of finite element mesh nodes, advanced methods such as the the pristine-rogue-interface modal expansion (PRIME) are necessary. PRIME builds a reduced model from two full cyclic symmetric analyses, one for the nominal and one for the modified type of sector. In this paper a new reduced order model suitable for large mistuning with arbitrary mesh modifications is presented. It achieves higher accuracy than PRIME, while saving approximately 25% computational effort during the reduction process, when using the same number of cyclic modes. The new method gains its efficiency by recognizing that large modifications from damage or repair are unlikely to be exactly the same for multiple blades. It works by building a partially reduced intermediate model: All nominal sectors are reduced using cyclic modes of the tuned structure. The single modified sector is kept as the full model. For this reason, the new reduction method is called Partially Reduced Intermediate System Model (PRISM) method. The accuracy of the PRISM method is demonstrated on an axial compressor blisk and an academic blisk geometry.

A Model Reduction Method for Bladed Disks with Large Geometric Mistuning Using a Partially Reduced Intermediate System Model

2020 ◽  
Author(s):  
Lukas Schwerdt ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Reduction Method ◽  
Axial Compressor ◽  
Reduction Process ◽  
Computational Effort ◽  
System Model ◽  
Bladed Disks ◽  
Element Mesh ◽  
Modal Expansion ◽  
Reduced Order ◽  
Intermediate System

Abstract Reduced order models (ROMs) are widely used to enable efficient simulation of mistuned bladed disks. ROMs based on projecting the system dynamics into a subspace spanned by the modes of the tuned structure work well for small amounts of mistuning. When presented with large mistuning, including changes of geometry and number of finite element mesh nodes, advanced methods such as the the pristine-rogue-interface modal expansion (PRIME) are necessary. PRIME builds a reduced model from two full cyclic symmetric analyses, one for the nominal and one for the modified type of sector. In this paper a new reduced order model suitable for large mistuning with arbitrary mesh modifications is presented. It achieves higher accuracy than PRIME, while saving approximately 25% computational effort during the reduction process, when using the same number of cyclic modes. The new method gains its efficiency by recognizing that large modifications from damage or repair are unlikely to be exactly the same for multiple blades. It works by building a partially reduced intermediate model: All nominal sectors are reduced using cyclic modes of the tuned structure. The single modified sector is kept as the full model. For this reason, the new reduction method is called Partially Reduced Intermediate System Model (PRISM) method. The accuracy of the PRISM method is demonstrated on an axial compressor blisk and an academic blisk geometry.

Reduced-Order Modeling of Bladed Disks Considering Small Mistuning of the Disk Sectors

2018 ◽  
Vol 141 (5) ◽  
Author(s):  
Lukas Schwerdt ◽  
Sebastian Willeke ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Reduction Method ◽  
Order Reduction ◽  
Bladed Disks ◽  
Small Disk ◽  
Model Order ◽  
Reduced Order ◽  
Mass Matrices ◽  
Dense Matrices ◽  
The Individual ◽  
Order Reduction Method

A model order reduction method based on the component mode synthesis for mistuned bladed disks is introduced, with one component for the disk and one component for each blade. The interface between the components at the blade roots is reduced using the wave-based substructuring (WBS) method, which employs tuned system modes. These system modes are calculated first, and used subsequently during the reduction of the individual components, which eliminates the need to build a partially reduced intermediate model with dense matrices. For the disk, a cyclic Craig–Bampton (CB) reduction is applied. The deviations of the stiffness and mass matrices of individual disk sectors are then projected into the cyclic basis of interior and interface modes of the disk substructure. Thereby, it is possible to model small disk mistuning in addition to large mistuning of the blades.

scholarly journals Sensitivity and Forced Response Analysis of Anisotropy-Mistuned Bladed Disks With Nonlinear Contact Interfaces

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Adam Koscso ◽  
Evgeny Petrov
Keyword(s):  
Reduction Method ◽  
Computational Effort ◽  
Forced Response ◽  
Response Analysis ◽  
Nonlinear Friction ◽  
Material Anisotropy ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Nonlinear Contact ◽  
Blade Model

AbstractA new method has been developed for the analysis of nonlinear forced response of bladed disks mistuned by blade anisotropy scatter and for the forced response sensitivity to blade material anisotropy orientations. The approach allows for the calculation of bladed disks with nonlinear friction contact interfaces using the multiharmonic balance method. The method uses efficient high-accuracy model reduction method for the minimization of the computational effort while providing required accuracy. The capabilities of the developed methods are validated and demonstrated using a two-blade model. A thorough study of the influence of the material anisotropy mistuning and its sensitivity on the characteristics of the forced response is carried out using finite element (FE) modes of anisotropy mistuned realistic bladed disk with nonlinear friction joints of blade roots and shroud contacts. The dependency of the nonlinear forced response on excitation level and contact pressure values has been carried out for anisotropy mistuned bladed disks.

Reduced-Order Modeling of Bladed Disks Considering Small Mistuning of the Disk Sectors

2018 ◽  
Author(s):  
Lukas Schwerdt ◽  
Sebastian Willeke ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Reduction Method ◽  
Order Reduction ◽  
Bladed Disks ◽  
Small Disk ◽  
Model Order ◽  
Reduced Order ◽  
Mass Matrices ◽  
Dense Matrices ◽  
The Individual ◽  
Order Reduction Method

A model order reduction method based on the Component Mode Synthesis for mistunend bladed disks is introduced, with one component for the disk and one component for each blade. The interface between the components at the blade roots is reduced using the wave-based substructuring method, which employs tuned system modes. These system modes are calculated first, and used subsequently during the reduction of the individual components, which eliminates the need to build a partially reduced intermediate model with dense matrices. For the disk, a cyclic Craig-Bampton reduction is applied. The deviations of the stiffness and mass matrices of individual disk sectors are then projected into the cyclic basis of interior and interface modes of the disk substructure. Thereby it is possible to model small disk mistuning in addition to large mistuning of the blades.

scholarly journals A Comparison between Two Reduction Strategies for Shrouded Bladed Disks

2018 ◽  
Vol 8 (10) ◽  
pp. 1736
Author(s):  
Alessandro Sommariva ◽  
Stefano Zucca
Keyword(s):  
Degrees Of Freedom ◽  
Computational Effort ◽  
Life Assessment ◽  
Test Cases ◽  
Cyclic Symmetry ◽  
Bladed Disks ◽  
Reduced Order ◽  
Sector Model ◽  
Bladed Disk ◽  
Reduction Strategies

Shrouded bladed disks exhibit a nonlinear dynamic behavior due to the contact interfaces at shrouds between neighboring blades. As a result, reduced order models (ROMs) are mandatory to compute the response levels during the design phase for high cycle fatigue (HCF) life assessment. In this paper, two reduction strategies for shrouded bladed disk reduction are presented. Both approaches rely on: (i) the cyclic symmetry of the linear bladed disk with open shrouds to perform only single sector calculations, (ii) the Craig–Bampton (CB) method to reduce the number of physical degrees of freedom (dofs). The two approaches are applied to a set of test cases in order to evaluate and compare their accuracy and the associated computational effort. Although both approaches allow for generating accurate ROMs, it is found that the numerical efficiency of the two methods depends on the ratio of the number of nodes at the inter-sector interfaces over the number of inner nodes of the elementary sector model.

Parametric Reduced Order Models for Bladed Disks With Mistuning and Varying Operational Speed

2018 ◽  
Author(s):  
Eric Kurstak ◽  
Ryan Wilber ◽  
Kiran D’Souza
Keyword(s):  
Forced Response ◽  
Reduced Order Models ◽  
Order Model ◽  
Small Frequency ◽  
Bladed Disks ◽  
Modal Expansion ◽  
Reduced Order ◽  
Finite Element Calculations ◽  
Different Types ◽  
Reduced Space

A considerable amount of research has been conducted to develop reduced order models of bladed disks that can be constructed using single sector calculations when there is mistuning present. A variety of methods have been developed to efficiently handle different types of mistuning ranging from small frequency mistuning, which can be modeled using a variety of methods including component mode mistuning (CMM), to large geometric mistuning, which can be modeled using multiple techniques including pristine rogue interface modal expansion (PRIME). Research has also been conducted on developing reduced order models that can accommodate the variation of specific parameters in the reduced space; these models are referred to as parametric reduced order models (PROMs). This work introduces a PROM for bladed disks that allows for the variation of rotational speed in the reduced space. These PROMs are created by extracting information from sector models at three rotational speeds, and then the appropriate reduced order model is efficiently constructed in the reduced space at any other desired speed. This work integrates these new PROMs for bladed disks with two existing mistuning methods, CMM and PRIME, to illustrate how the method can be readily applied for a variety of mistuning methods. Frequencies and forced response calculations using these new PROMs are compared to the full order finite element calculations to demonstrate the effectiveness of the method.

Parametric Reduced Order Models for Bladed Disks With Mistuning and Varying Operational Speed

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Eric Kurstak ◽  
Ryan Wilber ◽  
Kiran D'Souza
Keyword(s):  
Finite Element ◽  
Forced Response ◽  
Reduced Order Models ◽  
Small Frequency ◽  
Bladed Disks ◽  
Modal Expansion ◽  
Reduced Order ◽  
Finite Element Calculations ◽  
Different Types ◽  
Reduced Space

A considerable amount of research has been conducted to develop reduced order models (ROMs) of bladed disks that can be constructed using single sector calculations when there is mistuning present. A variety of methods have been developed to efficiently handle different types of mistuning ranging from small frequency mistuning, which can be modeled using a variety of methods including component mode mistuning (CMM), to large geometric mistuning, which can be modeled using multiple techniques including pristine rogue interface modal expansion (PRIME). Research has also been conducted on developing ROMs that can accommodate the variation of specific parameters in the reduced space; these models are referred to as parametric reduced order models (PROMs). This work introduces a PROM for bladed disks that allows for the variation of rotational speed in the reduced space. These PROMs are created by extracting information from sector models at three rotational speeds, and then the appropriate ROM is efficiently constructed in the reduced space at any other desired speed. This work integrates these new PROMs for bladed disks with two existing mistuning methods, CMM and PRIME, to illustrate how the method can be readily applied for a variety of mistuning methods. Frequencies and forced response calculations using these new PROMs are compared to the full order finite element calculations to demonstrate the effectiveness of the method.

scholarly journals A hyper-reduction method using adaptivity to cut the assembly costs of reduced order models

2021 ◽  
Vol 380 ◽  
pp. 113723
Author(s):  
Jack S. Hale ◽  
Elisa Schenone ◽  
Davide Baroli ◽  
Lars A.A. Beex ◽  
Stéphane P.A. Bordas
Keyword(s):  
Reduction Method ◽  
Reduced Order Models ◽  
Reduced Order

Simulation and Simulation Software Development of the Braking Process of a Subway Train

2014 ◽  
Vol 556-562 ◽  
pp. 294-301 ◽  
Author(s):  
Long Han ◽  
Chun Tian ◽  
Yan Wang ◽  
Meng Ling Wu ◽  
Zhuo Jun Luo
Keyword(s):  
Computational Effort ◽  
Simulation Software ◽  
System Model ◽  
Brake System ◽  
Railway Vehicle ◽  
Model Parameters ◽  
Modeling Process ◽  
Time Simulation ◽  
Subway Train ◽  
Braking Process

This paper deals with the problem of braking process modeling. A subway train braking process simulation software is built, which composes of a GUI and a underlying model. The underlying model consists of a train model and a brake system model. The train model is simplified and built by assembling subcomponent element models of a railway vehicle. The brake system model is simplified and built based on experimental data in order to reduce computational effort. The GUI of the software can be use to input model parameters, display simulation results, and store simulation data. As a result of the simplifications of the modeling process, the developed software can perform real time simulation.

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