Dynamic Behavior of Rolling Tires Under Different Operating Conditions

2012 ◽  
Author(s):  
S. Vercammen ◽  
C. González Díaz ◽  
P. Kindt ◽  
C. Thiry ◽  
J. Middelberg ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Modal Analysis ◽  
Dynamic Behavior ◽  
Operating Conditions ◽  
Operational Modal Analysis ◽  
Modal Parameters ◽  
Road Noise ◽  
Vibration Measurements ◽  
Noise And Vibration ◽  
Propagation Behavior

Although tire/road noise and tire vibration phenomena have been studied for decades, there are still some missing links in the process of accurately predicting and controlling the overall tire/road noise and vibration. An important missing link is represented by the effect of rolling on the dynamic behavior of a tire. Consequently, inside the European seventh framework program, an industry-academia partnership project, named TIRE-DYN, has been founded between KU Leuven, Goodyear and LMS International. By means of experimental and numerical analyses, the effects of rolling on the tire dynamic behavior are quantified. This paper presents the results of vibration measurements on a rotating tire with an embedded accelerometer. Modal parameters of the rolling tire are estimated from an operational modal analysis. In addition, the dispersion curves, which give detailed insight in the wave propagation behavior of a structure, are analyzed for the rolling tire. The goal of these analyses is to deepen the understanding on the influence of rolling on the tire dynamic behavior.

scholarly journals Comparison of Mode Shapes of Carbon-Fiber-Reinforced Plastic Material Considering Carbon Fiber Direction

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 311
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Modal Analysis ◽  
Dynamic Behavior ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic

Previous studies have demonstrated the sensitivity of the dynamic behavior of carbon-fiber-reinforced plastic (CFRP) material over the carbon fiber direction by performing uniaxial excitation tests on a simple specimen. However, the variations in modal parameters (damping coefficient and resonance frequency) over the direction of carbon fiber have been partially explained in previous studies because all modal parameters have only been calculated using the representative summed frequency response function without modal analysis. In this study, the dynamic behavior of CFRP specimens was identified from experimental modal analysis and compared five CFRP specimens (carbon fiber direction: 0°, 30°, 45°, 60°, and 90°) and an isotropic SCS13A specimen using the modal assurance criterion. The first four modes were derived from the SCS13A specimen; they were used as reference modes after verifying with the analysis results from a finite element model. Most of the four mode shapes were found in all CFRP specimens, and the similarity increased when the carbon fiber direction was more than 45°. The anisotropic nature was dominant in three cases of carbon fiber, from 0° to 45°, and the most sensitive case was found in Specimen #3.

scholarly journals Identification of modal parameters of machine tools during cutting by operational modal analysis

Procedia CIRP ◽  
2018 ◽  
Vol 77 ◽  
pp. 473-476 ◽  
Author(s):  
Jan Berthold ◽  
Martin Kolouch ◽  
Volker Wittstock ◽  
Matthias Putz
Keyword(s):  
Modal Analysis ◽  
Machine Tools ◽  
Operational Modal Analysis ◽  
Modal Parameters

Evaluation of the effect of operational modal analysis algorithms on identified modal parameters of railway bridges

2021 ◽  
Author(s):  
Mohammadreza Salehi ◽  
Kultigin Demirlioglu ◽  
Emrah Erduran
Keyword(s):  
Modal Analysis ◽  
Health Monitoring ◽  
Iron Ore ◽  
Operational Modal Analysis ◽  
Modal Parameters ◽  
Vibration Source ◽  
Light Weight ◽  
Railway Bridges ◽  
Different Types ◽  
Vibration Responses

<p>The accuracy of modal parameters identified by Operational Modal Analysis (OMA) algorithms is of vital importance in vibration-based health monitoring. This paper reports the effects of using different OMA algorithms on identified modal parameters of railway bridges. For this purpose, comparison and application of three different OMA methods including FDD, ARX, SSI-COV are discussed. The vibration measurements are conducted on two railway bridges in Northern Norway for using five triaxial accelerometers. The first bridge is a single-span bridge with the length of 50 m, while the second is a two-span bridge with a total length of 85m. OMA has been conducted on the free vibration responses after passage of different types of trains including light-weight railway vehicles and heavily loaded iron ore trains to evaluate the variation of the identified modal parameters with the chosen algorithm and the vibration source on the OMA results.</p>

Identification of Modal Parameters of an Elastic Rotor With Oil Film Bearings

1984 ◽  
Vol 106 (1) ◽  
pp. 107-112 ◽  
Author(s):  
Rainer Nordmann
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Design Process ◽  
Mechanical Engineering ◽  
Mechanical Systems ◽  
Rotating Machinery ◽  
Modal Parameters ◽  
Powerful Method ◽  
Oil Film ◽  
Engineering Problems

Investigations of the dynamic behavior of structures have become increasingly important in the design process of mechanical systems. To have a better understanding of the dynamic behavior of a structure, the knowledge of the modal parameters is very important. The powerful method of experimental modal analysis has been used to measure modal parameters in many mechanical engineering problems. But the method was mainly applied to nonrotating structures. This presentation shows improvements of the classical modal analysis for a successful application in rotating machinery with nonconservative effects. An example is given, investigating the modal parameters of an elastic rotor with oil film bearings.

Signal Processing for Operational Modal Analysis of a Jacket-Type Offshore Platform: Sea Test Study

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Xingxian Bao ◽  
Zhihui Liu ◽  
Chen Shi
Keyword(s):  
Noise Reduction ◽  
Modal Analysis ◽  
Measured Data ◽  
Offshore Platform ◽  
Operational Modal Analysis ◽  
Ambient Vibration ◽  
Data Matrix ◽  
Modal Parameters ◽  
Stability Diagrams ◽  
Free Decay

Operational modal analysis (OMA) has been widely used for large structures. However, measured signals are inevitably contaminated with noise and may not be clean enough for identifying the modal parameters with proper accuracy. The traditional methods to estimate modal parameters in noisy situation are usually absorbing the “noise modes” first, and then using the stability diagrams to distinguish the true modes from the “noise modes.” However, it is still difficult to sort out true modes because the “noise modes” will also tend to be stable as the model order increases. This study develops a noise reduction procedure for polyreference complex exponential (PRCE) modal analysis based on ambient vibration responses. In the procedure, natural excitation technique (NExT) is first applied to get free decay responses from measured (noisy) ambient vibration data, and then the noise reduction method based on solving the partially described inverse singular value problem (PDISVP) is implemented to reconstruct a filtered data matrix from the measured data matrix. In our case, the measured data matrix is block Hankel structured, which is constructed based on the free decay responses. The filtered data matrix should maintain the block Hankel structure and be lowered in rank. When the filtered data matrix is obtained, the PRCE method is applied to estimate the modal parameters. The proposed NExT-PDISVP-PRCE scheme is applied to field test of a jacket type offshore platform. Results indicate that the proposed method can improve the accuracy of OMA.

scholarly journals Numerical Study on the Critical Frequency Response of Jet Engine Rotors for Blade-Off Conditions against Bird Strike

2019 ◽  
Vol 9 (24) ◽  
pp. 5568 ◽  
Author(s):  
Saeed Badshah ◽  
Ahsan Naeem ◽  
Amer Farhan Rafique ◽  
Ihsan Ul Haq ◽  
Suheel Abdullah Malik
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Critical Frequency ◽  
Material Model ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Bird Strike ◽  
Critical Mode ◽  
Jet Engine ◽  
Engine Rotor

Vibrations are usually induced in aero engines under their normal operating conditions. Therefore, it is necessary to predict the critical frequencies of the rotating components carefully. Blade deformation of a jet engine under its normal operating conditions due to fatigue or bird strike is a realistic possibility. This puts the deformed blade as one of the major safety concerns in commercially operating civil aviation. A bird strike introduces unbalanced forces and non-linearities into the engine rotor system. Such dynamic behavior is a primary cause of catastrophic failures. The introduction of unbalanced forces due to a deformed blade, as a result of a bird strike, can change the critical frequency behavior of engine rotor systems. Therefore, it is necessary to predict their critical frequencies and dynamic behavior carefully. The simplified approach of the one-dimensional and two-dimensional elements can be used to predict critical frequencies and critical mode shapes in many cases, but the use of three-dimensional elements is the best method to achieve the goals of a modal analysis. This research explores the effect of a bird strike on the critical frequencies of an engine rotor. The changes in critical mode shapes and critical frequencies as a result of a bird strike on an engine blade are studied in this research. Commercially available analysis software ANSYS version 18.2 is used in this study. In order to account for the material nonlinearities, a Johnson Cook material model is used for the fan blades and an isotropic–elastic–plastic–hydrodynamic material model is used for modeling the bird. The bird strike event is analyzed using Eularian and smoothed particle hydrodynamics (SPH) techniques. A difference of 0.1% is noted in the results of both techniques. In the modal analysis simulation of the engine rotor before and after the bird strike event, the critical failure modes remain same. However, a change in the critical frequencies of the modes is observed. An increase in the critical frequencies and excitation RPMs (revolution per minute) of each mode are observed. As the mode order is increased, the higher the rise in critical frequency and excitation RPMs. Also, a change in the whirl direction of the different modes is noted.

Operational modal analysis of a nonlinear oscillation system under a harmonic excitation

2020 ◽  
pp. 095440622097755
Author(s):  
Xuchu Jiang ◽  
Feng Jiang ◽  
Biao Zhang
Keyword(s):  
Modal Analysis ◽  
Nonlinear Oscillation ◽  
Normal Modes ◽  
Nonlinear Normal Modes ◽  
Harmonic Excitation ◽  
Forced Response ◽  
Operational Modal Analysis ◽  
Single Frequency ◽  
Modal Parameters ◽  
Oscillation System

Operational modal analysis (OMA) is a procedure that allows the modal parameters of a structure to be extracted from the measured response to an unknown excitation generated during operation. Nonlinearity is inevitably and frequently encountered in OMA. The problem: The traditional OMA method based on linear modal theory cannot be applied to a nonlinear oscillation system. The solution: This paper aims to propose a nonlinear OMA method for nonlinear oscillation systems. The new OMA method is based on the following: (1) a self-excitation phenomenon is caused by nonlinear components; (2) the nonlinear normal modes (NNMs) of the system appear under a single-frequency harmonic excitation; and (3) using forced response data, the symbolic regression method (SR) can be used to automatically search for the NNMs of the system, whose modal parameters are implicit in the expression structure expressing each NNM. The simulation result of a three-degree-of-freedom (3-DOF) nonlinear system verifies the correctness of the proposed OMA method. Then, a disc-rod rotor model is considered, and the proposed OMA method’s capability is further evaluated.

EFFECTIVENESS OF OPERATIONAL MODAL ANALYSIS (OMA) FOR DAMAGE DETECTION IN FIBERGLASS REINFORCED EPOXY

2015 ◽  
Vol 76 (8) ◽  
Author(s):  
Haizuan Abd Rahman ◽  
Ahmad Azlan Mat Isa ◽  
Abdul Rahim Bahari
Keyword(s):  
Finite Element Method ◽  
Boundary Condition ◽  
Composite Material ◽  
Damage Detection ◽  
Modal Analysis ◽  
Detection Method ◽  
Small Deviation ◽  
Operational Modal Analysis ◽  
Modal Parameters ◽  
Fiber Glass

This study attempts to apply vibration-based damage detection method specifically Operational Modal Analysis (OMA) on fiberglass reinforced epoxy plate. OMA is used on healthy fiber glass reinforced epoxy plate to extract the modal parameters and the procedure is extended to damaged fiberglass reinforced epoxy plate. Both healthy and damaged composite material are tested under different boundary conditions i.e. free-free on 4 edges, 1 edge clamped, 2 edges clamped, 3 edges clamped and 4 edges of free-free boundary condition. The result of frequency from OMA was compared analytically with Finite Element Method (FEM). Nastran software is employed in this study. The FEM using Nastran shows that the result obtained is not accurate enough compared to OMA. Therefore, another method was applied to look at the effectiveness of OMA method using Experimental Modal Analysis (EMA). It was observed that both EMA and OMA methods gave small deviation and good correlation.

Comparing Measured Responses of an Offshore Structure with Operational Modal Analysis assisted Classical Model Approach

2020 ◽  
pp. 1-10
Author(s):  
Bruna Nabuco ◽  
Sandro D. Amador ◽  
Evangelos I. Katsanos ◽  
Ulf T. Tygesen ◽  
Erik Damgaard Christensen ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Element Model ◽  
Operating Conditions ◽  
Operational Modal Analysis ◽  
Mode Shapes ◽  
Wave Forces ◽  
Wave Load ◽  
Offshore Structure

Abstract Aiming to ensure the structural integrity of an offshore structure, wave-induced responses have been measured during normal operating conditions. Operational Modal Analysis is applied to the data obtained from continuously monitoring the structure. Sensors placed only on the topside of an offshore platform are sufficient to provide information to identify the modal properties of the structure, such as natural frequencies, damping ratios, and mode shapes. A finite element model is created and updated in line with the identified dynamic properties for applying a modal expansion technique in the interest of accessing information at any point of the structure. Wave radars are also placed at the platform from which the wave forces are calculated based on basic industrial standard models. In this way, the wave kinematics are estimated according to the linear wave theory associated with Wheeler stretching. Since this study is related to offshore structures composed by slender elements, the wave forces are estimated using Morison formulation. By assigning typical values to the drag and inertia coefficients, wave loads are estimated and applied to the updated finite element model. For the diffraction effect, the wave load has also been evaluated according to MacCamy and Fuchs theory. The responses obtained from this procedure are compared with measured responses. In addition to describing the process, this paper presents a case study to verify the theory using monitoring data from a tripod jacket. Results indicate realistic response estimation that contributes to the knowledge about the state of the structure.

Operational Modal Analysis of Aluminum Beams

2007 ◽  
Vol 50 (1) ◽  
pp. 74-85 ◽  
Author(s):  
S. Rudroju ◽  
A. Gupta ◽  
S. Yandamuri
Keyword(s):  
Modal Analysis ◽  
Impact Test ◽  
Force Measurement ◽  
Operating Conditions ◽  
Impact Testing ◽  
Operational Modal Analysis ◽  
Normal Functioning ◽  
Large Structures ◽  
Output Only ◽  
Ambient Excitation

Natural frequencies obtained by modal analysis are important to engineers interested in predicting the dynamic behavior of structures. Traditional modal analysis involves impact testing or shaker testing, where response signal and input force are measured to obtain the transfer function. However, for large structures, input excitation force measurement may be difficult, if not impossible. Large structures may be subjected to ambient excitation; operational modal analysis (OMA), also known as output-only modal analysis, has been used for extracting modal parameters of these types of structures. The main advantage of operational modal analysis is that no artificial excitation is needed, and the analysis is based on measurements of only the output data of the system. Operational modal analysis tests are performed under the actual operating conditions of the system without any change of boundary conditions; the tests use the ambient loads as input and thus do not interfere with the normal functioning of the system. In this study, six aluminum beams of different configurations (beams with and without cuts of various lengths) were used for conducting experiments. Results based on impact test, shaker test, and operational modal analysis are presented.

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