Enhanced Rayleigh Damping Model for Dynamic Analysis of Inelastic Structures

2020 ◽  
Vol 146 (10) ◽  
pp. 04020216 ◽  
Author(s):  
Mohammad Salehi ◽  
Petros Sideris
Keyword(s):  
Dynamic Analysis ◽  
Rayleigh Damping ◽  
Inelastic Structures ◽  
Damping Model

Modeling the damped dynamic behavior of a flexible pendulum

2019 ◽  
Vol 54 (2) ◽  
pp. 116-129 ◽  
Author(s):  
Roberto Ortega ◽  
Geraldine Farías ◽  
Marcela Cruchaga ◽  
Matías Rivero ◽  
Mariano Vázquez ◽  
...  
Keyword(s):  
High Speed ◽  
Time Integration ◽  
Integration Scheme ◽  
Step Size ◽  
Time Step ◽  
Time Step Size ◽  
Rayleigh Damping ◽  
Integration Schemes ◽  
Time Integration Schemes ◽  
Damping Model

The focus of this work is on the computational modeling of a pendulum made of a hyperelastic material and the corresponding experimental validation with the aim of contributing to the study of a material commonly used in seismic absorber devices. From the proposed dynamics experiment, the motion of the pendulum is recorded using a high-speed camera. The evolution of the pendulum’s positions is recovered using a capturing motion technique by tracking markers. The simulation of the problem is developed in the framework of a parallel multi-physics code. Particular emphasis is placed on the analysis of the Newmark integration scheme and the use of Rayleigh damping model. In particular, the time step size effect is analyzed. A strong time step size dependency is obtained for dissipative time integration schemes, while the Rayleigh damping formulation without time integration dissipation shows time step–independent results when convergence is achieved.

scholarly journals Computation of Rayleigh damping coefficient of a rectangular submerged floating tunnel (SFT)

2020 ◽  
Vol 2 (5) ◽  
Author(s):  
Md. Hafizur Rahman ◽  
Chhavi Gupta
Keyword(s):  
Dynamic Analysis ◽  
Modal Analysis ◽  
Fundamental Frequency ◽  
Significant Role ◽  
Analytical Study ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Damping Coefficients ◽  
Rayleigh Damping ◽  
Submerged Floating Tunnel

Abstract The dynamic behaviors of the submerged floating tunnel, a buoyant structure of high slenderness, are a matter of concern since it is surrounded by the huge hazardous effects called hydrodynamic, seismic and functional action. Modal analysis and Rayleigh damping coefficients play a significant role in dynamic analysis, but it is not sufficiently simple to predict the reasonable damping coefficients named α and β. The present paper outlines the modal analysis and the calculation of Rayleigh damping coefficients that provide the natural frequencies, mode shapes, mode’s motion as well as coefficients α and β. To compute the Rayleigh damping coefficients, 2–10% damping to the critical damping has been assumed for this analytical study. For the analysis, an FEA-based software ANSYS is utilized successfully. It has been seen that the fundamental frequency and Rayleigh damping coefficients (α = 0.946 and β = 0.00022) of the SFT are reasonably high and it is under noticeable damping.

scholarly journals Aerodynamic Damping Prediction for Turbomachinery Based on Fluid-Structure Interaction with Modal Excitation

2019 ◽  
Vol 9 (20) ◽  
pp. 4411
Author(s):  
Jianxiong Li ◽  
Xiaodong Yang ◽  
Anping Hou ◽  
Yingxiu Chen ◽  
Manlu Li
Keyword(s):  
Wave Mode ◽  
Aeroelastic Stability ◽  
Fluid Structure ◽  
Aerodynamic Damping ◽  
Transonic Compressor ◽  
Rayleigh Damping ◽  
Flutter Boundary ◽  
Novel Method ◽  
Bending Modes ◽  
Damping Model

Aerodynamic damping predictions are critical when analyzing aeroelastic stability. A novel method has been developed to predict aerodynamic damping by employing two single time-domain simulations, specifically, one with the blade impulsed naturally in a vacuum and one with the blade impulsed in flow. The focus is on the aerodynamic damping prediction using modal excitation and the logarithmic decrement theory. The method is demonstrated by considering the first two bending modes with an inter-blade phase angle (IBPA) of 0° on a transonic compressor. The results show that the flutter boundary prediction is basically consistent with the experiment. The aerodynamic damping prediction with an IBPA of 180° is also performed, demonstrating that the method is suitable for different traveling wave mode representations. Furthermore, the influence of the amplitude of modal excitation and mechanical damping using the Rayleigh damping model for aerodynamic damping was also investigated by employing fluid-structure coupled simulations.

Improved Large Spring / Stiffness Technique for Dynamic Response Analysis of Structures Subjected to Base Excitations

2011 ◽  
Vol 474-476 ◽  
pp. 1974-1979
Author(s):  
Guo Liang Zhou ◽  
Xiao Jun Li ◽  
Xiao Bo Peng
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Response Analysis ◽  
Spring Stiffness ◽  
Seismic Excitations ◽  
Structural Dynamic ◽  
Theoretical Methods ◽  
Rayleigh Damping ◽  
Stiffness Method ◽  
Improved Technique

Based on the large spring/stiffness method (LSM), this paper develops an improved technique (I-LSM) applicable to structural dynamic analysis with the assumption of Rayleigh damping. To estimate the accuracy of the technique, the dynamic response is analyzed for a 2-DOFs model respectively subjected to uniform/nonuniform seismic excitations. It indicates that the traditional LSM is inapplicable when Rayleigh damping is adopted. And the errors increase monotonously with the aggrandizement of damping. It’s also validated that the I-LSM based on the modification of displacement considering the influences of Rayleigh damping presented in this paper is able to effectively yield results almost identical to those of theoretical methods with errors beneath 4%.

Multi-objective optimisation of a small aircraft turbine engine rotor system with self-updating Rayleigh damping model and frequency-dependent bearing-pedestal model

2019 ◽  
Vol 233 (16) ◽  
pp. 5710-5723 ◽  
Author(s):  
Joseph Shibu K ◽  
K Shankar ◽  
Ch Kanna Babu ◽  
Girish K Degaonkar
Keyword(s):  
Power Unit ◽  
Rotor System ◽  
Frequency Dependent ◽  
Turbine Engine ◽  
Multi Objective ◽  
Auxiliary Power Unit ◽  
Rayleigh Damping ◽  
Auxiliary Power ◽  
Damping Model ◽  
Engine Rotor

A self-updating Rayleigh damping model and frequency-dependent bearing-pedestal model for multi-objective optimisation is presented through this paper and is applied for a small turbine engine rotor system for aircraft application. This engine is used as an auxiliary power unit on aircraft. The Rayleigh damping model and frequency-dependent bearing pedestal model are verified by carrying out experiments on this auxiliary power unit rotor system. The novel self-updating feature calculates the Rayleigh damping coefficients and frequency-dependent bearing-pedestal stiffness for each chromosome and modifies rotor system equation of motion for computing the objectives during multi-objective optimisation for each chromosome. This novel model is used for multi-objective optimisation of auxiliary power unit rotor system. The unbalance response and weight are minimised subjected to critical speed constraint. Controlled elitist genetic algorithm is used for the optimisation resulting in Pareto optimal solutions and the acceptable solution is identified as the solution close to Utopia point. The results are compared with the constant Rayleigh damping model. The new model has produced an accurate optimum solution superior to constant Rayleigh damping model.

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