Wave finite element-based superelements for forced response analysis of coupled systems via dynamic substructuring

2015 ◽  
Vol 107 (6) ◽  
pp. 453-476 ◽  
Author(s):  
Priscilla Brandão Silva ◽  
Jean-Mathieu Mencik ◽  
José Roberto de Franca Arruda
Keyword(s):  
Finite Element ◽  
Forced Response ◽  
Coupled Systems ◽  
Response Analysis ◽  
Dynamic Substructuring

Explicit Finite Element Models of Friction Dampers in Forced Response Analysis of Bladed Discs

2007 ◽  
Author(s):  
E. P. Petrov
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Dynamic Properties ◽  
Forced Response ◽  
Response Analysis ◽  
Contact Interactions ◽  
Contact Interface ◽  
Explicit Finite Element ◽  
Friction Dampers ◽  
Time Dynamic

A generic method for analysis of nonlinear forced response for bladed discs with friction dampers of different design has been developed. The method uses explicit finite element modelling of dampers, which allows accurate description of flexibility and, for the first time, dynamic properties of dampers of different design in multiharmonic analysis of bladed discs. Large-scale finite element damper and bladed disc models containing 104–106 DOFs can be used. These models, together with detailed description of contact interactions over contact interface areas, allow for any level of refinement required for modelling of elastic damper bodies and for modelling of friction contact interactions. Numerical studies of realistic bladed discs have been performed with three different types of underplatform dampers: (i) a ‘cottage-roof’ (called also ‘wedge’) damper; (ii) seal wire damper; and (iii) a strip damper. Effects of contact interface parameters and excitation levels on damping properties of the dampers and forced response are extensively explored.

Forced Response Analysis of a Transonic Fan

2012 ◽  
Author(s):  
Parthasarathy Vasanthakumar ◽  
Paul-Benjamin Ebel
Keyword(s):  
Finite Element ◽  
Flow Field ◽  
Forced Response ◽  
Navier Stokes ◽  
Response Analysis ◽  
Aerodynamic Damping ◽  
Forcing Function ◽  
Transonic Fan ◽  
Work Done ◽  
Highly Loaded

The forced response of turbomachinery blades is a primary source of high cycle fatigue (HCF) failure. This paper deals with the computational prediction of blade forced response of a transonic fan stage that consists of a highly loaded rotor along with a tandem stator. In the case of a transonic fan, the forced response of the rotor due to the downstream stator assumes significance because of the transonic flow field. The objective of the present work is to determine the forced response of the rotor induced as a result of the unsteady flow field due to the downstream stator vanes. Three dimensional, Navier-Stokes flow solver TRACE is used to numerically analyse the forced response of the fan. A total of 11 resonant crossings as identified in the Campbell diagram are examined and the corresponding modeshapes are obtained from finite element modal analysis. The interaction between fluid and structure is dealt with in a loosely coupled manner based on the assumption of linear aerodynamic damping. The aerodynamic forcing is obtained by a nonlinear unsteady Navier-Stokes computation and the aerodynamic damping is obtained by a time-linearized Navier-Stokes computation. The forced response solution is obtained by the energy method allowing calculations to be performed directly in physical space. Using the modal forcing and damping, the forced response amplitude can be directly computed at the resonance crossings. For forced response solution, the equilibrium amplitude is reached when the work done on the blade by the external forcing function is equal to the work done by the system damping (aerodynamic and structural) force. A comprehensive analysis of unsteady aerodynamic forces on the rotor blade surface as a result of forced response of a highly loaded transonic fan is carried out. In addition, the correspondence between the location of high stress zones identified from the finite element analysis and the regions of high modal force identified from the CFD analysis is also discussed.

Explicit Finite Element Models of Friction Dampers in Forced Response Analysis of Bladed Disks

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
E. P. Petrov
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Dynamic Properties ◽  
Forced Response ◽  
Response Analysis ◽  
Contact Interactions ◽  
Contact Interface ◽  
Bladed Disks ◽  
Explicit Finite Element ◽  
Friction Dampers

A generic method for analysis of nonlinear forced response for bladed disks with friction dampers of different designs has been developed. The method uses explicit finite element modeling of dampers, which allows accurate description of flexibility and, for the first time, dynamic properties of dampers of different designs in multiharmonic analysis of bladed disks. Large-scale finite element damper and bladed disk models containing 104−106 degrees of freedom can be used. These models, together with detailed description of contact interactions over contact interface areas, allow for any level of refinement required for modeling of elastic damper bodies and for modeling of friction contact interactions. Numerical studies of realistic bladed disks have been performed with three different types of underplatform dampers: (i) a “cottage-roof” (also called “wedge”) damper, (ii) seal wire damper, and (iii) a strip damper. Effects of contact interface parameters and excitation levels on damping properties of the dampers and forced response are extensively explored.

Analysis of Forced Response for Bladed Disks Mistuned by Material Anisotropy Orientation Scatters

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Chaoping Zang ◽  
Yuanqiu Tan ◽  
E. P. Petrov
Keyword(s):  
Finite Element ◽  
Monte Carlo ◽  
High Accuracy ◽  
Forced Response ◽  
Response Analysis ◽  
High Fidelity ◽  
Fe Model ◽  
Material Anisotropy ◽  
Bladed Disks ◽  
Bladed Disk

A new method is developed for the forced response analysis of mistuned bladed disks manufactured from anisotropic materials and mistuned by different orientations of material anisotropy axes. The method uses (i) sector finite element (FE) models of anisotropic bladed disks and (ii) FE models of single blades and allows the calculation of displacements and stresses in a mistuned assembly. A high-fidelity reduction approach is proposed which ensures high-accuracy modeling by introducing an enhanced reduction basis. The reduction basis includes the modal properties of specially selected blades and bladed disks. The technique for the choice of the reduction basis has been developed, which provides the required accuracy while keeping the computation expense acceptable. An approach for effective modeling of anisotropy-mistuned bladed disk without a need to create a FE model for each mistuning pattern is developed. The approach is aimed at fast statistical analysis based on Monte Carlo simulations. All components of the methodology for anisotropy-mistuned bladed disks are demonstrated on the analysis of models of practical bladed disks. Effects of anisotropy mistuning on forced response levels are explored.

scholarly journals Cyclic Symmetry Finite Element Forced Response Analysis of a Distortion Tolerant Fan with Boundary Layer Ingestion

2018 ◽  
Author(s):  
James B. Min ◽  
Tondapu S. Reddy ◽  
Milind A. Bakhle ◽  
Rula M. Coroneos ◽  
George L. Stefko ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Finite Element ◽  
Forced Response ◽  
Response Analysis ◽  
Cyclic Symmetry

A Forced Response Method for Annular Combustors Excited by Traveling Acoustic Pressure Waves

2008 ◽  
Author(s):  
Sanghum Baik ◽  
Mehmet Dede
Keyword(s):  
Finite Element ◽  
Pressure Wave ◽  
Acoustic Pressure ◽  
Response Prediction ◽  
Element Model ◽  
Forced Response ◽  
Response Analysis ◽  
Element Analysis ◽  
Variable Theory ◽  
Response Method

Recent progress in the development of an industry level tool for computing forced response of annular combustors is presented. Hereby, in addressing productivity issues caused by huge finite element model of full-wheel combustor, the theoretical framework of cyclic symmetry is introduced. The complex-variable theory, which originated for capturing natural frequency and mode shape characteristics of rotationally periodic structure, was extended for real-number-based finite element analysis (FEA) to solve forced response problem; specifically, a systematic method was developed to create cyclic domain replica of traveling pressure wave loading on full-wheel combustor. In this paper, theoretical descriptions of the physics-based, practical forced response analysis technique will be provided, and its implementation into building the tool of industrial level will be discussed. The technology developed herein will be verified using a simple cylindrical structure that is excited by acoustic pressure wave that travels in circumferential direction with a certain number of nodal diameter. In the end, a practical application to forced response prediction of a combustor component will be presented.

Time-Linearized Forced Response Analysis of a Counter Rotating Fan: Part II — Analysis of the DLR CRISP2 Model

2014 ◽  
Author(s):  
Io Eunice Gómez Fernández ◽  
Michael Blocher
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Structural Integrity ◽  
Forced Response ◽  
Nonlinear Finite Element ◽  
Response Analysis ◽  
Dynamic Stresses ◽  
Campbell Diagram ◽  
Aerodynamic Damping ◽  
Operating Points

Over the last 3 years, several Institutes of the German Aerospace Center (DLR) investigated the possible gains of a counter rotating fan arrangement manufactured from CFRP designed with an automated optimization tool chain. While counter rotating fans promise aerodynamic efficiency improvements, they might suffer from aerodynamic exitation phenomena as well. The wakes, potential fields and shocks on the blade suction sides might cause blade vibrations leading to high cycle fatigue. Therefore, numerical investigations into aerodynamic excitation are necessary to estimate the amplitude of induced vibrations. At the Institute of Aeroelasticity, a time-linearized loosely coupled approach was used to determine the aerodynamic forcing of the blade rows of this counter rotating fan arrangement. A finite element model consisting of shell elements was created for the blades in order to be able to model the CFRP material properties. Subsequently, nonlinear finite element load calculations (inertia and blade surface pressure) with a modal analysis in the last step were performed to generate a Campbell diagram of the rotor blades. Critical operating points were identified from the Campbell diagram. Nonlinear steady CFD simulations of these operating points were performed. Based on these calculations, time-linearized unsteady simulations at the crititcal inter-blade phase angle were performed with forced blade motion to determine the aerodynamic damping. Similarly, time-linearized unsteady simulations were performed with gust boundary conditions to determine the aerodynamic forcing. The results of aerodynamic damping and aerodynamic forcing simulations were combined to yield the predicted forced response amplitude of the eigenmode shape that is going to be excited at the respective critical operating point. As a last step, a nonlinear finite element displacement simulation is conducted to determine the static and dynamic stresses and strains during a forced response vibration. These static and dynamic stresses and strains are then compared to the material properties of the CFRP material to determine if the blades will keep their structural integrity over time. The results of these calculations are presented and discussed.

The Forced Response Analysis of Heavy Duty Vehicle’s Cab

2014 ◽  
Vol 599-601 ◽  
pp. 503-506
Author(s):  
Jun Liang Liu ◽  
Yu Hong Long ◽  
Wen Shang Li ◽  
Jie Cai
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Theoretical Basis ◽  
Element Model ◽  
Forced Response ◽  
Response Analysis ◽  
Heavy Duty ◽  
Inherent Frequency ◽  
The Impact ◽  
Response Region

An automobile will sustain various incentives from the outside and inside in the process of being driven, in which the impact of the wheel and the vibration of engine mainly dominates. This paper gets the inherent frequency through modal analysis on finite element model in a heavy vehicle’s driving cab. And then it conducts the forced response analysis on finite element model by modeling a condition where the vibration of driving cab is caused by outside incentive. Through analyzing, it finds the main response region generated in driving cab when affected by outside incentive. At the same time, it can provide certain theoretical basis for controlling the noise of driving cab in the future.

scholarly journals A Finite Element Approach to the Analysis of Rotating Bladed-Disk Assemblies Coupled With Flexible Shaft

1994 ◽  
Author(s):  
Wen Zhang ◽  
Wenliang Wang ◽  
Hao Wang ◽  
Jiong Tang
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Coupled System ◽  
Equation Of Motion ◽  
Coupled Systems ◽  
The Finite Element Method ◽  
Bladed Disk ◽  
Modal Synthesis ◽  
Element Approach ◽  
Final Equation

A method for dynamic analysis of flexible bladed-disk/shaft coupled systems is presented in this paper. Being independant substructures first, the rigid-disk/shaft and each of the bladed-disk assemblies are analyzed separately in a centrifugal force field by means of the finite element method. Then through a modal synthesis approach the equation of motion for the integral system is derived. In the vibration analysis of the rotating bladed-disk substructure, the geometrically nonlinear deformation is taken into account and the rotationally periodic symmetry is utilized to condense the degrees of freedom into one sector. The final equation of motion for the coupled system involves the degrees of freedom of the shaft and those of only one sector of each of the bladed-disks, thereby reducing the computer storage. Some computational and experimental results are given.

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