scholarly journals Extension of modal reduction methods to non-linear coupled structure-acoustic problems

2011 ◽  
pp. 227-245
Author(s):  
Youssef Gerges ◽  
Emeline Sadoulet-Reboul ◽  
Morvan Ouisse ◽  
Noureddine Bouhaddi
Keyword(s):  
Numerical Simulations ◽  
Linear Model ◽  
Elastic Plate ◽  
Degrees Of Freedom ◽  
Reduction Method ◽  
Static Response ◽  
Acoustic Cavity ◽  
Modal Reduction ◽  
Non Linear ◽  
Reduction Methods

This paper proposes a robust reduction method dedicated to non-linear vibroacoustic problems in the context of localized geometrical non-linearities. The method consists in enriching the truncated uncoupled modal basis of the linear model by a static response due to unit forces on the non-linear degrees of freedom and by the static response of the fluid due to the interaction with the structure. To show the effectiveness of the proposed method, numerical simulations of responses of an elastic plate closing an acoustic cavity and a hang-on exhaust are performed.

A non-linear model of sulphation of porous stones: Numerical simulations and preliminary laboratory assessments

2008 ◽  
Vol 9 (1) ◽  
pp. 14-22 ◽  
Author(s):  
C. Giavarini ◽  
M.L. Santarelli ◽  
R. Natalini ◽  
F. Freddi
Keyword(s):  
Numerical Simulations ◽  
Linear Model ◽  
Non Linear

On Double Frequency Vibration of a Generator-Bearing System With Asymmetrical Stiffness

2002 ◽  
Author(s):  
Senlin Huang ◽  
Zhansheng Liu ◽  
Jiexian Su
Keyword(s):  
Degrees Of Freedom ◽  
Reduction Method ◽  
Integration Method ◽  
Element Model ◽  
Modal Interaction ◽  
Motion Equations ◽  
Double Frequency ◽  
Modal Reduction ◽  
Direct Integration Method ◽  
Bearing System

A finite element model for a generator-bearing system with asymmetrical stiffness is developed for investigation of the double frequency vibration. The modal reduction method is used for reducing the degrees of freedom system to improve computing efficiency, and the Newmark direct integration method is employed to solve the reduced motion equations. The two-modal interaction vibration is induced when the rotation speed is half a critical speed of the system due to asymmetry and gravity force of the generator. Such a phenomena is observed in the practical test.

scholarly journals Numerical simulations of the microvascular fluid balance with a non-linear model of the lymphatic system

2019 ◽  
Vol 122 ◽  
pp. 101-110 ◽  
Author(s):  
Luca Possenti ◽  
Giustina Casagrande ◽  
Simone Di Gregorio ◽  
Paolo Zunino ◽  
Maria Laura Costantino
Keyword(s):  
Numerical Simulations ◽  
Linear Model ◽  
Fluid Balance ◽  
Lymphatic System ◽  
Non Linear

scholarly journals Extension of modal reduction methods to non-linear coupled structure-acoustic problems

2011 ◽  
Vol 20 (1-4) ◽  
pp. 227-245 ◽  
Author(s):  
Youssef Gerges ◽  
Emeline Sadoulet-Reboul ◽  
Morvan Ouisse ◽  
Noureddine Bouhaddi
Keyword(s):  
Modal Reduction ◽  
Non Linear ◽  
Reduction Methods

Modal Reduction Method for Vibrational Analysis of Structures Partially Filled With Internal Liquids

2005 ◽  
Author(s):  
Jean-Se´bastien Schotte´ ◽  
Roger Ohayon
Keyword(s):  
Degrees Of Freedom ◽  
Reduction Method ◽  
Flexible Structures ◽  
Vibrational Analysis ◽  
Galerkin Projection ◽  
The Finite Element Method ◽  
Aircraft Wings ◽  
System A ◽  
Modal Reduction ◽  
Fluid Sloshing

In the framework of the vibrational analysis of structures, we propose a method to take into account the internal liquids (like fuel) in the structure modelling. Since the “classical” added-mass hydroelastic model cannot be used for slender and flexible structures such as space launchers or civil aircraft wings (because the decoupling assumption of sloshing and hydroelasticity is not valid for such structures), we propose here a revised hydroelastic formulation which takes this coupling into account. Since this model introduces in the system a great number of degrees of freedom for the fluid, we will present a reduction method using the Ritz-Galerkin projection onto the fluid sloshing modal basis. A discretization of the reduced equations by the finite element method will be proposed and the convergence rate of this modal reduction method will be discussed on an application example.

The Extended Modal Reduction Method Applied to Rotor Dynamic Problems

1991 ◽  
Vol 113 (1) ◽  
pp. 79-84 ◽  
Author(s):  
K. Kane ◽  
B. J. Torby
Keyword(s):  
Degrees Of Freedom ◽  
Reduction Method ◽  
Mode Shapes ◽  
Dynamic Problems ◽  
Modal Reduction ◽  
Stiffness Matrices ◽  
Space Formulation ◽  
Gyroscopic Effects ◽  
Stiffness And Damping ◽  
Rotor Dynamic

In this paper, the existing Modal Reduction Method, which was developed to handle symmetric mass and stiffness matrices, is extended utilizing state-space formulation to handle nonsymmetric mass, damping, and stiffness matrices. These type of matrices typically accompany rotor dynamic problems since journal bearings supporting the rotor have nonsymmetric stiffness and damping characteristics. The purpose of modal reduction is to eliminate unimportant modes and degrees of freedom from the analytical model after they are found, so that further numerical analysis can be accelerated. The reduction described here leaves the retained eigenvalues and mode shapes unaltered from their original values. This method is demonstrated for a simple rotor problem having nonsymmetric system matrices including gyroscopic effects.

Development of a Non-Linear Model of a Double Wishbone Suspension for the Characterization of Force Transmission to the Steering Column and Chassis

2004 ◽  
Author(s):  
Vinod Cherian ◽  
Nader Jalili ◽  
Imtiaz Haque
Keyword(s):  
Numerical Simulation ◽  
Linear Model ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Quantitative Measure ◽  
Steering System ◽  
Force Transmission ◽  
Non Linear ◽  
Tire Forces ◽  
Vehicle Chassis

A non-linear model of a double wishbone suspension is developed to investigate the effects of variation of suspension parameters on the transmission and distribution of tire forces acting on the wheel spindle to the steering system and the vehicle chassis. The suspension is idealized as a four degree-of-freedom model, with suspension members considered as rigid links and the bushings idealized as linear spring-damper elements. Degrees-of-freedom representing the longitudinal compliance of the suspension mounting bushings, steering and the rotation of the control arms are considered. The equations of motion are derived using the Lagrange multiplier method, and solved numerically using MATLAB. A system of relative co-ordinates is used to reduce the number of equations due to the large number of geometric and kinematic constraints for an efficient numerical simulation. The equations retain all the non-linearity’s associated with large changes in the geometric configuration of the suspension system. The analytical model can be used to develop a quantitative measure of the importance of the parameters such as mass, inertia of the control arms, suspension bushing stiffness and damping and spatial geometry of installation to the force distribution and force transmissibility to the vehicle chassis and the steering system. The results of numerical simulation are compared with simulation data obtained from ADAMS.

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