INVESTIGATION OF DYNAMIC PROPERTIES OF ELASTOMERIC BEARING COMPONENTS VIA MODAL ANALYSIS

2015 ◽  
Vol 76 (8) ◽  
Author(s):  
A. I. Yusuf ◽  
M. A. Norliyati ◽  
M. A. Yunus ◽  
M. N. Abdul Rani
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Seismic Loads ◽  
Ground Structure ◽  
Elastomeric Bearing ◽  
Earthquake Load

Elastomeric bearing is a significant device in structures such as in bridges and buildings. It is used to isolate the ground structure (substructure) and the above ground structure (superstructure) from seismic loads such as earthquake load. Understanding the dynamic behavior of the elastomeric bearing in terms of natural frequencies, mode shapes and damping are increasingly important especially in improving the design and the failure limit of the elastomeric bearing. Modal analysis is one of the methods used to determine the dynamic properties of any materials. Hence, the main objective of this research is to determine the dynamic properties of elastomeric bearing components in terms of natural frequencies, mode shapes, and damping via numerical and experimental modal analysis. This method had been successfully performed in investigating the dynamic behavior of rubber and steel shim plate.

scholarly journals Rayleigh Damping Coefficients of Laminated Rubber Bearing

2019 ◽  
Vol 8 (4) ◽  
pp. 12294-12300
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Ground Structure ◽  
Damping Coefficients ◽  
Rubber Bearing ◽  
Stability And Instability ◽  
Laminated Rubber Bearing

In isolating the ground structure and the above ground structure from seismic loads, a significant device called laminated rubber bearing is usually found in structure. The complexity of the material which is made up from a combination of rubber and steel shim plates in alternate layer, has made it difficult to measure damping value. Damping is a dissipation of energy or energy losses in the vibration of the structure. Measuring the accurate amount of damping is fundamental as damping plays a crucial role in fixing the borderline between stability and instability in structural systems. Therefore, to determine the damping value including dynamic properties in any materials, modal analysis can be used. Hence, the main objective of this research is to determine the Rayleigh’s damping coefficients α and β and to evaluate the performance of the laminated rubber bearing using finite element and experimental modal analysis. Finding shows that, the finite element modal analysis with the addition of Rayleigh’s damping coefficients α and β, shows a good agreement with the experimental modal analysis in term of natural frequencies and mode shapes. Findings show that, the values of natural frequencies reduced when precise Rayleigh’s damping coefficient added in the finite element modal analysis. It can be concluded that both finite element and experimental modal analysis method can be used to estimate the accurate values of damping ratio and to determine the Rayleigh’s damping coefficients α and β as well.

Effect of Weight on the Experimental Modal Analysis of Slender Cantilever Beams

2009 ◽  
Author(s):  
Lawrence Virgin ◽  
David Holland
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Vertical Direction ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Lateral Stiffness ◽  
Axial Loads ◽  
Horizontal Orientation ◽  
Beam System ◽  
Tensile Forces

It is relatively well known that axial loads tend to influence lateral stiffness and hence natural frequencies of slender structural components. Tensile forces tend to increase the lateral stiffness and compressive forces tend to reduce lateral stiffness, bringing with it the possibility of buckling. In many practical situations this is a negligible effect. But for very slender structures it can be important, including the effect of self-weight. This paper will focus attention on a form of double cantilever beam system, i.e., two cantilevers sharing a common hub. A differential axial load can be applied to this system via orientation in a gravitational field. We shall neglect the effect of gravity when the beams are in their horizontal orientation from a limited theoretical standpoint. It is of course present in the experiments but the cantilevers are much stiffer in one direction than the other, and the beams are clamped with their stiffer resistance in the vertical direction. The focus of the current paper is on the natural frequencies and mode shapes of a two-beam system from an experimental modal analysis perspective.

Dynamic Properties of a Heliostat Structure Determined by Numerical and Experimental Modal Analysis

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
J. Felipe Vásquez-Arango ◽  
Reiner Buck ◽  
Robert Pitz-Paal
Keyword(s):  
Modal Analysis ◽  
Vortex Shedding ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Simple Approach ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Fe Model ◽  
Damping Coefficients ◽  
Operating Points

An experimental and numerical modal analysis was performed on an 8 m2 T-shaped heliostat structure at different elevation angles. The experimental results were used to validate a finite element (FE) model by comparing natural frequencies and mode shapes. The agreement between experiments and simulations is good in all operating points investigated. In addition, damping coefficients were determined experimentally for each mode, in order to provide all necessary information for the development of a dynamic model. Furthermore, potentially critical operating conditions caused by vortex shedding were identified using a simple approach.

scholarly journals Identification of Historical Veziragasi Aqueduct Using the Operational Modal Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
E. Ercan ◽  
A. Nuhoglu
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Model Updating ◽  
Dynamic Properties ◽  
Dynamic Test ◽  
Element Model ◽  
Operational Modal Analysis ◽  
Modal Identification ◽  
Ambient Vibration ◽  
Mode Shapes

This paper describes the results of a model updating study conducted on a historical aqueduct, called Veziragasi, in Turkey. The output-only modal identification results obtained from ambient vibration measurements of the structure were used to update a finite element model of the structure. For the purposes of developing a solid model of the structure, the dimensions of the structure, defects, and material degradations in the structure were determined in detail by making a measurement survey. For evaluation of the material properties of the structure, nondestructive and destructive testing methods were applied. The modal analysis of the structure was calculated by FEM. Then, a nondestructive dynamic test as well as operational modal analysis was carried out and dynamic properties were extracted. The natural frequencies and corresponding mode shapes were determined from both theoretical and experimental modal analyses and compared with each other. A good harmony was attained between mode shapes, but there were some differences between natural frequencies. The sources of the differences were introduced and the FEM model was updated by changing material parameters and boundary conditions. Finally, the real analytical model of the aqueduct was put forward and the results were discussed.

Structural Modification of a Pipe Under Harmonic Excitation Using an Hybrid Numerical/Experimental Method

2011 ◽  
Author(s):  
Charles Bodel
Keyword(s):  
Modal Analysis ◽  
Nuclear Power ◽  
Natural Frequencies ◽  
Harmonic Excitation ◽  
Experimental Modal Analysis ◽  
Point Of View ◽  
Mode Shapes ◽  
Design Stage ◽  
Centrifugal Pumps ◽  
Structural Dynamic

Vibrations generated by centrifugal pumps are difficult to predict at the design stage, for it is hardly possible to accurately determine the natural frequencies of pipes and to avoid coincidences with the blade pass frequency of the pump and its harmonics. One is often led to modify the existing structure, by adding stiffness, mass or damping. This paper illustrates this point on a pipe connected to a pump in a nuclear power plant operated by EDF (E´lectricite´ de France). In October 2010, abnormal vibrations were measured on a thin pipe at the outlet of a pump in a powerplant in France. The French nuclear regulatory commission asked EDF to perform a diagnosis and to define solutions within a few months. EDF/R&D division has used an original method developed in 2004 based on hybrid data, and called LMME-SDM (for Local Model Mode-shapes Expansion Structural Dynamic Modification). The main objective is to define a structure modification able to remove all natural frequencies close to the harmonic excitation. For the purpose of the study, we need a numerical model, which should be fairly correct from a static point of view, but which is not necessarily updated from a dynamic point of view, and an experimental modal analysis carried out under real conditions on the pipe. During the experimental modal analysis, a test of added mass has been carried out so that the method can be validated by comparing the predicted and the observed frequency. This method has already been used in industrial cases in former studies [3], however the study presented here has reached a higher level in complexity. Even if this method is able to give reasonable results compared to measurements, it is close to its limits.

Vibrational Analysis of a Dual-Motive Locomotive and Evaluation by Experimental Methods and Modal Analysis

2012 ◽  
Author(s):  
Jesús Otero Yugat ◽  
Gorka Agirre Castellanos ◽  
Igor Alonso Portillo
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Dynamic Properties ◽  
Vibrational Excitation ◽  
Vibrational Analysis ◽  
Experimental Methods ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Hydraulic Actuator ◽  
Diesel Locomotive

This paper presents a theoretical and experimental study done on an electro-diesel locomotive in order to evaluate the dynamic behavior of the vehicle in terms of safety, running performance and wheel-track interaction. The vibration analysis has been made by means of different experimental methodologies. The first one consists on the acquisition of accelerations at points located at the wheelset, the truck frame and the coach, using piezorresistive accelerometers. The registered signals allow to validate the locomotive in terms of safety against derailment and running behavior, according the UIC 518 leaflet. The second method is based on the modal analysis theory and includes the dynamic properties estimation under vibrational excitation. This procedure takes into account the determination of modal parameters such as natural frequencies, modal damping ratios and mode shapes, by means of a control hydraulic actuator. The third methodology consists on the operational modal analysis done with the experimental measurements acquired on track tests, in order to validate the results obtained by modal analysis and evaluate the dynamic behavior under different speed ranges and cant deficiencies. Several tests have been done by means of the described methods in an electro-diesel locomotive composed by a primary suspension with dampers and a secondary suspension with rigid stiffness. In addition, two types of dampers have been evaluated with the purpose of optimizing the damping properties of the vehicle’s primary suspension. Through these experimental methods, a useful tool for the prediction and analysis of the dynamic behavior is provided. Additionally, the results obtained by means of these methodologies permit examining the influence of different running conditions and vehicle properties on the modal parameters.

Spray Car Workbench Racks of Modal Analysis

2015 ◽  
Vol 1094 ◽  
pp. 469-474
Author(s):  
Yu Jing He ◽  
Jiang Feng Shen ◽  
Xiang Fu Li
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Dynamic Structure ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Support Frame

The author designed a intelligential spray car of fruit tree, this support frame of worktable support the whole spraying arm in the course, its dynamic properties is important to determine the product quality and life. On the basis of three-dimensional modeling, The modal of dynamic that support frame was analysis and the first ten modal parameters (natural frequencies and mode shapes) was calculated by using ANSYS finite element of analysis software. Compared with Modal parameters by method and experimental modal analysis obtained, summarizes the higher modes of dynamic structure, and proposed modifications for the structure.

scholarly journals Experimental Modal Analysis of Business Jet Fuselage Tail Section Sub-Assemblies

2020 ◽  
Author(s):  
Ian A. Donaldson ◽  
Chris K. Mechefske
Keyword(s):  
Modal Analysis ◽  
Computational Models ◽  
Natural Frequencies ◽  
Model Updating ◽  
Experimental Modal Analysis ◽  
Experimental Results ◽  
Modal Testing ◽  
Experimental Methodology ◽  
Mode Shapes ◽  
Business Jet

Abstract Experimental modal testing is a technique through which the dynamic response of a system can be found. Parameters such as the natural frequencies and mode shapes of a system can be extracted through experimentation, and these results can be used to confirm computational models and guide structural improvements. This paper provides an overview of experimental modal analysis performed on two aircraft fuselage half scale subassemblies, with the use of shaker excitation. The experimental methodology including the construction of each structure, data acquisition parameters, and validity checks, is presented in detail. Linearity and repeatability checks were used to validate the testing methodology and increase the level of confidence in the experimental results. The experimental natural frequencies were correlated with the computational results, and recommendations were made. The experimental results presented in this work provide a basis for computational model updating work to be considered in future work.

Experimental and numerical investigation on dynamic parameters of broaching machine

2015 ◽  
Vol 231 (10) ◽  
pp. 1907-1920
Author(s):  
Shenshun Ying ◽  
Shiming Ji ◽  
Yangyu Wang ◽  
Zhixin Li ◽  
Lvgao Lin ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Damping Ratio ◽  
Experimental Results ◽  
Mode Shapes ◽  
Fe Model ◽  
Dynamic Parameters ◽  
Machine Structure

Dynamic properties of the whole broaching machine structure greatly contribute to the broaching quality and efficiency. However, it is hard to measure the dynamic parameters because they will change during operation compared with the static results from classic experimental modal analysis. This study is to examine the dynamic parameters of broaching machine LG7120KT using both the numerical finite element (FE) method and the experimental operational modal analysis (OMA). Firstly, FE analysis model of the broaching machine with the real dimension is constructed and calculated. Second, experimental results are obtained from OMA in practical broaching process, which can be used to identify steady-state modes. Modal parameters including mode shapes, damping ratio, and natural frequencies are examined, using both LMS SCADAS III-305 system and PolyMAX method in OMA. The numerical and experimental results show high agreement in their calculated natural frequencies. From the modal analysis results, it is also found the vibration normal to cutting direction can be greatly reduced by adjusting broaching speed. From the topology optimization result based on the already correlated FE model, we redesigned a lightweight machine structure with a better dynamic performance, due to its lower displacement of broaching machine at force point and its higher first-order natural frequency. The experimental and numerical results in this paper help to design the structural parameters of broaching machine and propose a better broaching process.

Experimental and Numerical Investigation of Residual Stress Stiffening Influence on Dynamic Response of Welded Structures

2019 ◽  
Author(s):  
AmirHossein MajidiRad ◽  
Yimesker S. Yihun
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Model Updating ◽  
Experimental Modal Analysis ◽  
Experimental Results ◽  
Welding Residual Stress ◽  
Dynamic Responses ◽  
Mode Shapes

Abstract This paper presents the study of welding residual stress-stiffening effect on the dynamic responses and vibrational parameters of welded aluminum parts through an experimental modal analysis and Center Hole Drilling (CHD) residual stress measurement methods. Having a great corrosion resistance, AA5056 was utilized in this research that has been used in aircraft and ship structures; making the welding assesment of crucial. Natural frequencies and damping factors of several specimens are compared before and after the welding along with verification of experimental modal analysis integrity using Euler-Bernoulli relations. Finite element modeling of welding, cutting and modal/stress analysis of samples are also done to compare the experimental results. The results obtained from the precise modal analysis of all samples show that welding made the structure harder leading to 2% increase in natural frequencies and changing damping factors of different mode shapes. Cutting also reduced the level of residual stresses up to 34%. A good agreement is shown between the modal analysis and the experimental results. The technique used in the experiment and finite element simulation along with modeling assumptions are beneficial to other applications where model updating is required or a prediction of residual stress stiffening influence on modal responses is important.

Sign in / Sign up

Export Citation Format

Share Document