Journal articles: 'Operational and Experimental Modal Analysis'

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KUWABARA, Hiroki, Takahiko ITO, Yuichi TANABE, Mitsuo IWAHARA, Akio NAGAMATSU, and Masayuki TAKAHASHI. "21315 Experimental modal analysis and operational modal analysis which use strain gauge." Proceedings of Conference of Kanto Branch 2007.13 (2007): 469–70. http://dx.doi.org/10.1299/jsmekanto.2007.13.469.

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Chen, Gongfa, Zhihua Wu, Chunjian Gong, Jiqiao Zhang, and Xiaoli Sun. "DIC-Based Operational Modal Analysis of Bridges." Advances in Civil Engineering 2021 (February 4, 2021): 1–13. http://dx.doi.org/10.1155/2021/6694790.

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A new method has been proposed to identify the natural frequencies and mode shapes of a bridge model, in which the digital image correlation (DIC) technique is used to track the dynamic displacement. A key issue in vibration-based damage detection for a bridge is to determine its modal parameters. It is difficult to use traditional acceleration sensors to obtain the accurate mode shapes of bridges as the sensors are only deployed on a few measurement points of the bridges. In this article, the DIC technique is used to capture the movement of the entire experimental bridge model. A steel truss is used as a bridge model and stimulated by a hammer; its dynamic displacement is recorded by using a digital video camera. The correlation analysis is used to track the displacement of the points of interest, and their displacement time histories are inputted into a modal analysis system; the natural frequencies and mode shapes of the bridge model were obtained by both operational modal analysis (OMA) and traditional experimental modal analysis (EMA) methods. (1) The DIC results are compared with those obtained by a traditional acceleration sensor-based method; the natural frequencies obtained by the two measurement methods are very close. (2) The DIC results are sensitive to the amplitude of the measured displacement and the shooting distance; small displacement amplitudes and long shooting distance may result in the low quality of the measured time-history curves, and low-frequency noise signals might be observed in their power spectral density (PSD) curves, while they can be easily solved by the filtering method in this article. (3) In addition, the first frequencies obtained by EMA and OMA are very close, which validates the applicability of the DIC measurement under ambient excitation. The research has illustrated the feasibility of the DIC method for obtaining the modal parameters of the bridges.

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Huňady, Róbert, František Trebuňa, Martin Hagara, and Martin Schrötter. "The Use of Modan 3D in Experimental Modal Analysis." Applied Mechanics and Materials 486 (December 2013): 36–41. http://dx.doi.org/10.4028/www.scientific.net/amm.486.36.

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Experimental modal analysis is a relatively young part of dynamics, which deals with the vibration modes identification of machines or their parts. Its development has started since the beginning of the eighties, when the computers hardware equipment has improved and the fast Fourier transform (FFT) could be used for the results determination. Nowadays it provides an uncountable set of vibration analysis possibilities starting with conventional contact transducers of acceleration and ending with modern noncontact optical methods. In this contribution we mention the use of high-speed digital image correlation by experimental determination of mode shapes and modal frequencies. The aim of our work is to create a program application called Modan 3D enabling the performing of experimental modal analysis and operational modal analysis. In this paper the experimental modal analysis of a thin steel sample performed with Q-450 Dantec Dynamics is described. In Modan 3D the experiment data were processed and the vibration modes were determined. The reached results were verified by PULSE modulus specialized for mechanical vibration analysis.

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Zhao, Ming Ming, Yi Ming Wang, Xiang Dong Shi, and Jian Guo Li. "Vibration of Press Based on Operational Modal Analysis." Applied Mechanics and Materials 312 (February 2013): 273–76. http://dx.doi.org/10.4028/www.scientific.net/amm.312.273.

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Press vibration characteristic is the basic of press fault diagnosis and static optimization. We get press vibration characteristics with Operational Modal Analysis .Comparing theoretical analysis of the finite element method for press with operation modal analysis of test method for press in the actual condition. We get vibration modal orders and vibration modes of press wallboard under natural excitation. The experimental results show that the test modal frequency identification value of Operational Modal Analysis for the press components is highly accurate.

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Cara, Javier. "Computing the modal mass from the state space model in combined experimental–operational modal analysis." Journal of Sound and Vibration 370 (May 2016): 94–110. http://dx.doi.org/10.1016/j.jsv.2016.01.043.

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Xu, Jun Chen, Ming Hong, and Hong Yu Cui. "The Contrast Experimental Study on Operational Modal Analysis of Ship Structural Model." Applied Mechanics and Materials 226-228 (November 2012): 241–46. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.241.

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A ship is a large and multifunctional marine structure operating on the sea. In practice, the environmental noise on a ship has many complicated components and they influence the vibration of the ship structure. Besides the stochastic excitations such as waves and winds, there are also propeller- and host-induced harmonic excitations. In this paper, NExT/ERA algorithm program and a ship model have been made to realize the modal parameters identification of ship structure in the presence of both white noise and harmonic excitations. Moreover, whether the signal filtering technology has a great effect on the results of modal analysis is discussed. In order to study and analyze the influence of the harmonic excitations, experiments under different signal-to-noise ratio (SNR) conditions have been carried out. This has a guiding significance to the engineering practice.

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Kortiš, Ján, Ľuboš Daniel, Matúš Farbák, Lukáš Maliar, and Milan Škarupa. "Operational Modal Analysis of the Cablestayed Footbridge." Civil and Environmental Engineering 13, no. 2 (December 20, 2017): 92–98. http://dx.doi.org/10.1515/cee-2017-0012.

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Abstract Modern architecture leads to design subtle bridge structures that are more sensitive to increased dynamic loading than the massive ones. This phenomenon can be especially observed on lightweight steel structures such as suspended footbridges. As a result, it is necessary to know precisely its dynamic characteristics, such as natural frequencies, natural shapes and damping of construction. This information can be used for further analysis such as damage detection, system identification, health monitoring, etc. or also for the design of new types of construction. For this purpose, classical modal analysis using trigger load or harmonic vibration exciter in combination with acceleration sensors is used in practice. However, there are many situations where it is not possible to stop the traffic or operation of the bridge. The article presents an experimental measurement of the dynamic parameters of the structure at the operating load using the operational modal analysis.

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Guillaume, Patrick, Peter Verboven, Bart Cauberghe, Steve Vanlanduit, Eli Parloo, and Gert De Sitter. "Frequency-Domain System Identification Techniques for Experimental and Operational Modal Analysis." IFAC Proceedings Volumes 36, no. 16 (September 2003): 1609–14. http://dx.doi.org/10.1016/s1474-6670(17)34990-x.

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Dziedziech, Kajetan, Krzysztof Mendrok, Piotr Kurowski, and Tomasz Barszcz. "Multi-Variant Modal Analysis Approach for Large Industrial Machine." Energies 15, no. 5 (March 3, 2022): 1871. http://dx.doi.org/10.3390/en15051871.

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Power generation technologies are essential for modern economies. Modal Analysis (MA) is advanced but well-established method for monitoring of structural integrity of critical assets, including power ones. Apart from classical MA, the Operational Modal Analysis approach is widely used in the study of dynamic properties of technical objects. The principal reasons are its advantages over the classical approach, such as the lack of necessity to apply the excitation force to the object and isolate it from other excitation sources. However, for industrial facilities, the operational excitation rarely takes the form of white noise. Especially in the case of rotating machines, the presence of rotational speed harmonics in the response signals causes problems with the correct identification of the modal model. The article presents a hybrid approach where combination of results of two Operational Modal Analyses and Experimental Modal Analysis is performed to improve the models’ quality. The proposed approach was tested on data obtained from a 215 MW turbogenerator operating in one of Polish power plants. With the proposed approach it was possible to diagnose the machine’s excessive vibration level correctly.

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Ercan, E., and A. Nuhoglu. "Identification of Historical Veziragasi Aqueduct Using the Operational Modal Analysis." Scientific World Journal 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/518608.

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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.

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Rosu, Paul-Virgil, Mihai Mihaila, Radu Canarache, and Eddy Dascotte. "Correlation between Numerical and Experimental Analysis Using Model Updating Techniques." Key Engineering Materials 601 (March 2014): 137–40. http://dx.doi.org/10.4028/www.scientific.net/kem.601.137.

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With the increasing complexity of the products, engineers face a higher level of uncertainty in both simulation and test. Correlation between numerical and experimental analysis using model updating techniques helps engineers to asses uncertainty. Present research efforts focus to combine finite element analysis and testing in one common framework. Experimental and operational modal analysis and simulation make benefit from common databases. Some applications presented emphasize the advantages of these techniques.

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Frankovský, Peter, Ingrid Delyová, Peter Sivák, Jozef Bocko, Jozef Živčák, and Michal Kicko. "Modal Analysis Using Digital Image Correlation Technique." Materials 15, no. 16 (August 17, 2022): 5658. http://dx.doi.org/10.3390/ma15165658.

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The present paper discusses a new approach for the experimental determination of modal parameters (resonant frequencies, modal shapes and damping coefficients) based on measured displacement values, using the non-contact optical method of digital image correlation (DIC). The output is a newly developed application module that, based on a three-dimensional displacement matrix from the experimental measurement results, can construct a frequency response function (FRF) for the purpose of experimental and operational modal analysis. From this frequency response function, the modal parameters of interest are able to be determined. The application module has been designed for practical use in Scilab 6.1.0, and its code interfaces directly with the ISTRA4D high-speed camera software. The module was built on measurements of a steel plate excited by an impact hammer to simulate experimental modal analysis. Verification of the correctness of the computational algorithm or the obtained modal parameters of the excited sheet metal plate was performed by simulation in the numerical software Abaqus, whose modal shapes and resonant frequencies showed high agreement with the results of the newly developed application.

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Volkmar, Robin, Keith Soal, Yves Govers, and Marc Böswald. "Experimental and operational modal analysis: Automated system identification for safety-critical applications." Mechanical Systems and Signal Processing 183 (January 2023): 109658. http://dx.doi.org/10.1016/j.ymssp.2022.109658.

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Orlowitz, Esben, and Anders Brandt. "Comparison of experimental and operational modal analysis on a laboratory test plate." Measurement 102 (May 2017): 121–30. http://dx.doi.org/10.1016/j.measurement.2017.02.001.

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Kurowski, Piotr. "Modal-Model Applications for Large Energetic Machines." Key Engineering Materials 347 (September 2007): 221–26. http://dx.doi.org/10.4028/www.scientific.net/kem.347.221.

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Modal models are commonly encountered forms of dynamic characterization of mechanical structures. They are applied in machine-condition diagnosing as well as in monitoring processes. In research practice the most frequently applied method is Experimental Modal Analysis, and in exploitation - Operational Modal Analysis. Difficulties associated with the EMA and OMA have contributed to the increase of OMAX model applications, especially in case of energetic machines. Theoretical assumptions related with modal analysis are very strong. In reality when big and heavy structures are considered often those assumptions are not fulfilled. In the paper such situations are considered and practical solutions are showed.

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Fadhil Shazmir, M., N. Ayuni Safari, M. Azhan Anuar, A. A.Mat Isa, and Zamri A.R. "Operational Modal Analysis on a 3D Scaled Model of a 3-Storey Aluminium Structure." International Journal of Engineering & Technology 7, no. 4.27 (November 30, 2018): 78. http://dx.doi.org/10.14419/ijet.v7i4.27.22485.

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Obtaining a good experimental modal data is essential in modal analysis in order to ensure accurate extraction of modal parameters. The parameters are compared with other extraction methods to ascertain its consistency and validity. This paper demonstrates the extraction of modal parameters using various identification algorithms in Operational Modal Analysis (OMA) on a 3D scaled model of a 3-storey aluminium structure. Algorithms such as Frequency Domain Decomposition (FDD), Enhanced Frequency Domain Decomposition (EFDD) and Stochastic Subspace Identification (SSI) are applied in this study to obtain modal parameters. The model test structure is fabricated of aluminium and assembled using bolts and nuts. Accelerometers were used to collect the responses and the commercial post processing software was used to obtain the modal parameters. The resulting natural frequencies and mode shapes using FDD method are then compared with other OMA parametric technique such as EFDD and SSI algorithm by comparing the natural frequencies and Modal Assurance Criterion (MAC). Comparison of these techniques will be shown to justify the validity of each technique used and hence confirming the accuracy of the measurement taken.

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Devriendt, Christof, Tim De Troyer, Gert De Sitter, and Patrick Guillaume. "Transmissibilty-Based Operational Modal Analysis for Flight Flutter Testing Using Exogenous Inputs." Shock and Vibration 19, no. 5 (2012): 1071–83. http://dx.doi.org/10.1155/2012/938039.

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During the recent years several new tools have been introduced by the Vrije Universiteit Brussel in the field of Operational Modal Analysis (OMA) such as the transmissibility based approach and the the frequency-domain OMAX concept. One advantage of the transmissibility based approach is that the ambient forces may be coloured (non-white), if they are fully correlated. The main advantage of the OMAX concept is the fact that it combines the advantages of Operational and Experimental Modal Analysis: ambient (unknown) forces as well as artificial (known) forces are processed simultaneously resulting in improved modal parameters. In this paper, the transmissibility based output-only approach is combined with the input/output OMAX concept. This results in a new methodology in the field of operational modal analysis allowing the estimation of (scaled) modal parameters in the presence of arbitrary ambient (unknown) forces and artificial (known) forces.

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Luczak, M. M., E. Mucchi, and J. Telega. "Experimental and operational modal analysis of a laboratory scale model of a tripod support structure." Journal of Physics: Conference Series 753 (September 2016): 072008. http://dx.doi.org/10.1088/1742-6596/753/7/072008.

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Atmaca, Barbaros, Şevket Ateş, and Murat Günaydın. "Analytical, numerical, and experimental determination of dynamic characteristics of prestressed concrete girders." Journal of Structural Engineering & Applied Mechanics 5, no. 1 (March 31, 2022): 1–12. http://dx.doi.org/10.31462/jseam.2022.01001012.

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To determine the dynamic characteristics of bridges with prestressed girders, their natural frequencies and mode shapes used to construct the superstructure must be known. However, there is no agreement among scientists on how prestress force affects the dynamic characteristics of a precast prestressed girder. The purpose of this paper is to obtain the dynamic characteristics of prestressed concrete girders through analytically, numerically, and operational modal testing. For this purpose, one of a typical precast I-girder with 1.2 m height and 27.45 m effective span length is selected as a numerical application. The three-dimensional (3D) finite element model (FEM) of the girder is modeled by SAP2000. Experimental measurements of the girder were conducted at the construction site by the operational modal testing method. For experimental measurements, ten uniaxial seismic accelerometers were mounted at the top flange of the PSC girder in the x- and z-direction. The vibrations that occur from the movement of trucks and cranes at the construction site and the impact of the hammer were measured by these accelerometers as acceleration. The measured signal was collected at the data bank and then sent to the computer equipped with Operational Modal Analysis software which used Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification techniques. The dynamic behaviors of girder were derived from analysis performed by this software. At the end of the study, the dynamic characteristic was obtained by the analytical prediction, numerical and experimental were compared with each other. It is seen that natural frequencies and mode shapes obtained from theoretical prediction, numerical and operational modal testing are not too far apart.

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Reynders, Edwin, and Guido De Roeck. "Reference-based combined deterministic–stochastic subspace identification for experimental and operational modal analysis." Mechanical Systems and Signal Processing 22, no. 3 (April 2008): 617–37. http://dx.doi.org/10.1016/j.ymssp.2007.09.004.

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Bezručová, Kristína, Radim Nečas, and Jan Koláček. "Operation Modal Analysis of Pedestrian Bridge in Kroměříž." Solid State Phenomena 309 (August 2020): 281–87. http://dx.doi.org/10.4028/www.scientific.net/ssp.309.281.

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The publication outlines the issue of the experimental determination of modal parameters of structures using a method called operational modal analysis. The principle of the method and possible approaches of calculation of modal parameters are presented. An example of the method’s application is the determination of mode shapes and frequencies of the repaired footbridge in Kroměříž where the dynamic test was performed twice – before and after reinforcement of the structure. The results of both dynamic tests and their comparisons with the results of the calculation model performed in the ANSYS environment are presented in this article. Additionally, and integral to this article is a description of the completed footbridge reconstruction.

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Priyatmoko, Ricky, and Yoyong Arfiadi. "PREDICTION OF DYNAMIC PARAMETERS OF STRUCTURES BASED ON MODAL ANALYSIS USING FDD." Jurnal Teknik Sipil 15, no. 2 (October 1, 2020): 99–104. http://dx.doi.org/10.24002/jts.v15i2.3718.

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Dynamic behavior and system identification are important topic in monitoring and maintaining existing infrastructures. System identification using Frequency Domain Decomposition (FDD) is an operational modal analysis (OMA) in frequency domain used on experiment of shear frame model with random vibration method is validated by comparing output of FDD data using acceleration input from simulated model with output of FDD using acceleration result of experimental model. The result of acceleration data is recorded using USB accelerometer X16-1D then calibrated and analyzed using Matlab programs, data_procces.m and solve FDD_eksperiment.m to estimate the modal parameter of model structure. Compared with parameter modal of simulation model, FDD method with input simulated acceleration resulted in difference of 1.757% in first frequency and 0.462% in second frequency. Meanwhile for FDD method using acceleration of experimental model, resulted in difference of 6.3126% in first frequency and 7.7327% in second frequency. FFD method is fairly accurate in predicting the frequency of structure, but for difference of mode shapes in experimental is very big compared to simulated model therefore it can be concluded that, this modal parameter is cannot be detected in experimental model.

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Soria, L., B. Peeters, J. Anthonis, and H. Van der Auweraer. "Operational Modal Analysis and the Performance Assessment of Vehicle Suspension Systems." Shock and Vibration 19, no. 5 (2012): 1099–113. http://dx.doi.org/10.1155/2012/127316.

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Comfort, road holding and safety of passenger cars are mainly influenced by an appropriate design of suspension systems. Improvements of the dynamic behaviour can be achieved by implementing semi-active or active suspension systems. In these cases, the correct design of a well-performing suspension control strategy is of fundamental importance to obtain satisfying results. Operational Modal Analysis allows the experimental structural identification in those that are the real operating conditions: Moving from output-only data, leading to modal models linearised around the more interesting working points and, in the case of controlled systems, providing the needed information for the optimal design and verification of the controller performance. All these characters are needed for the experimental assessment of vehicle suspension systems. In the paper two suspension architectures are considered equipping the same car type. The former is a semi-active commercial system, the latter a novel prototypic active system. For the assessment of suspension performance, two different kinds of tests have been considered, proving ground tests on different road profiles and laboratory four poster rig tests. By OMA-processing the signals acquired in the different testing conditions and by comparing the results, it is shown how this tool can be effectively utilised to verify the operation and the performance of those systems, by only carrying out a simple, cost-effective road test.

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Li, Xinhui, Jerome Antoni, Michael J. Brennan, Tiejun Yang, and Zhigang Liu. "A frequency domain blind identification method for operational modal analysis using a limited number of sensors." Journal of Vibration and Control 26, no. 17-18 (January 14, 2020): 1383–98. http://dx.doi.org/10.1177/1077546319897218.

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Operational modal analysis is an experimental modal analysis approach, which uses vibration data collected when the structure is under operating conditions. Amongst the methods for operational modal analysis, blind source separation–based methods have been shown to be efficient and powerful. The existing blind source separation modal identification methods, however, require the number of sensors to be at least equal to the number of modes in the frequency range of interest to avoid spatial aliasing. In this article, a frequency domain algorithm that overcomes this problem is proposed, which is based on the joint diagonalization of a set of weighted covariance matrices. In the proposed approach, the frequency range of interest is partitioned into several frequency ranges in which the number of active modes in each band is less than the number of sensors. Numerical simulations and an experimental example demonstrate the efficacy of the method.

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Li, Ya Jun, Li Zhang, Yan Miao Ma, and Bin Liu. "The Dynamic Research of Industrial Sewing Machines Based on the Modal and Operational Deformation Analysis." Applied Mechanics and Materials 432 (September 2013): 269–74. http://dx.doi.org/10.4028/www.scientific.net/amm.432.269.

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The vibration of the operational sewing machine is caused mostly by the fundamental frequency of the motor and its harmonic frequencies. The experimental modal analysis was conducted on a certain industrial sewing machine to identify its modal parameters. The operational deformation analysis was carried out and the actual deformation in the first six harmonic frequencies of the main speed frequency was obtained. Finally, the dynamic characteristic was identified by analyzing how each mode influences the harmonic vibration. This paper provides a valuable reference for noise reduction of the sewing machine.

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Tarpø, Marius, Bruna Nabuco, Christos Georgakis, and Rune Brincker. "Expansion of experimental mode shape from operational modal analysis and virtual sensing for fatigue analysis using the modal expansion method." International Journal of Fatigue 130 (January 2020): 105280. http://dx.doi.org/10.1016/j.ijfatigue.2019.105280.

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ABBES, MOHAMED SLIM, MARIEM MILADI CHAABANE, ALI AKROUT, TAHAR FAKHFAKH, and MOHAMED HADDAR. "VIBRATORY BEHAVIOR OF A DOUBLE PANEL SYSTEM BY THE OPERATIONAL MODAL ANALYSIS." International Journal of Modeling, Simulation, and Scientific Computing 02, no. 04 (December 2011): 459–79. http://dx.doi.org/10.1142/s1793962311000578.

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The present study tackles the vibratory behavior of a double panel system by operational modal analysis (OMA) using one of the major techniques of blind source separation (BSS), which is the independent component analysis (ICA). For this purpose, the OMA method and the ICA concept are presented and exploited in order to identify the eigenmodes of a double panel system. Then, results obtained by the OMA technique are presented and compared with those achieved by the modal recombination method. Since a good argument is observed, this approach can be used in conjunction with experimental works.

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Antoni, Jérôme, Luigi Garibaldi, Stefano Marchesiello, and Menad Sidhamed. "New Separation Techniques for Output-Only Modal Analysis." Shock and Vibration 11, no. 3-4 (2004): 227–42. http://dx.doi.org/10.1155/2004/560576.

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The paper is devoted to the problem of discriminating between operational and natural modes of structures excited by generic inputs. This case often occurs when the system under analysis holds rotating parts and is contemporary excited by ambient noise; in this case the output-only techniques may fail being easily trapped in a misinterpretation of the system eigenvalues. A survey of the methods available in literature is given, together with the explanation of their failures. To solve this problem, two new techniques are introduced and their capabilities are checked with numerical and experimental data from a paper machine.

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Mironov, Aleksey, Pavel Doronkin, Aleksander Priklonsky, and Igor Kabashkin. "Condition Monitoring Of Operating Pipelines With Operational Modal Analysis Application." Transport and Telecommunication Journal 16, no. 4 (December 1, 2015): 305–19. http://dx.doi.org/10.1515/ttj-2015-0028.

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Abstract In the petroleum, natural gas and petrochemical industries, great attention is being paid to safety, reliability and maintainability of equipment. There are a number of technologies to monitor, control, and maintain gas, oil, water, and sewer pipelines. The paper focuses on operational modal analysis (OMA) application for condition monitoring of operating pipelines. Special focus is on the topicality of OMA for definition of the dynamic features of the pipeline (frequencies and mode shapes) in operation. The research was conducted using two operating laboratory models imitated a part of the operating pipeline. The results of finite-element modeling, identification of pipe natural modes and its modification under the influence of virtual failure are discussed. The work considers the results of experimental research of dynamic behavior of the operating pipe models using one of OMA techniques and comparing dynamic properties with the modeled data. The study results demonstrate sensitivity of modal shape parameters to modification of operating pipeline technical state. Two strategies of pipeline repair – with continuously condition-based monitoring with proposed technology and without such monitoring, was discussed. Markov chain reliability models for each strategy were analyzed and reliability improvement factor for proposed technology of monitoring in compare with traditional one was evaluated. It is resumed about ability of operating pipeline condition monitoring by measuring dynamic deformations of the operating pipe and OMA techniques application for dynamic properties extraction.

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Do, Van Dong, Thien Phu Le, and Alexis Beakou. "Operational modal analysis of mechanical systems using transmissibility functions in the presence of harmonics." Journal of Science and Technology in Civil Engineering (STCE) - NUCE 13, no. 3 (August 31, 2019): 1–14. http://dx.doi.org/10.31814/stce.nuce2019-13(3)-01.

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Ambient vibration testing is a preferred technique for heath monitoring of civil engineering structures because of several advantages such as simple equipment, low cost, continuous use and real boundary conditions. However, the excitation not controlled and not measured, is always assumed as Gaussian white noise in the processing of ambient responses called operational modal analysis. In presence of harmonics due to rotating parts of machines or equipment inside the structures, e.g., fans or air-conditioners…, the white noise assumption is not verified and the response analysis becomes difficult and it can even lead to biased results. Recently, transmissibility function has been proposed for the operational modal analysis. Known as independent of excitation nature in the neighborhood of a system's pole, the transmissibility function is thus applicable in presence of harmonics. This study proposes therefore to apply the transmissibility functions for modal identification of ambient vibration testing and investigates its performance in presence of harmonics. Numerical examples and an experimental test are used for illustration and validation. Keywords: operational modal analysis; transmissibility function; harmonic component; ambient vibration testing.

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Tomaszewska, Agnieszka, Milena Drozdowska, and Marek Szafrański. "Material Parameters Identification of Historic Lighthouse Based on Operational Modal Analysis." Materials 13, no. 17 (August 28, 2020): 3814. http://dx.doi.org/10.3390/ma13173814.

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In the present paper, the identification of the material parameters of a masonry lighthouse is discussed. A fully non-invasive method was selected, in which the material properties were determined via numerical model validation applied to the first pair of natural frequencies and their related mode shapes, determined experimentally. The exact structural model was built by means of the finite element method. To obtain experimental data for the inverse analysis, operational modal analysis was applied to the structure. Three methods were considered: peak picking (PP), eigensystem realization algorithm (ERA) and natural excitation technique with ERA (NExT-ERA). The acceleration’s responses to environmental excitations, enhanced in some periods of time by sheet piling hammering or by sudden interruptions like wind stroke, were assumed within the analysis input. Different combinations of the input were considered in the PP and NExT-ERA analysis to find the most reasonable modal forms. A number of time periods of a free-decay character were considered in the ERA technique to finally calculate the averaged modal forms. Finally, the elastic modulus, Poisson’s ratio and material density of brick, sandstone and granite masonry were determined. The obtained values supplement the state of the art database concerning historic building materials. In addition, the numerical model obtained in the analysis may be used in further cases of structural analysis.

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Jiang, Xuchu, Hu Zhang, Ying Li, Wei Jiang, Xinyong Mao, Hai Lin, and Biao Zhang. "Vibration stability analysis of cantilever structure based on symbolic regression algorithm and modal analysis method." Advances in Mechanical Engineering 13, no. 5 (May 2021): 168781402110212. http://dx.doi.org/10.1177/16878140211021242.

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The vibration stability of cantilever mechanism under high-speed rotation directly affects the positioning accuracy. Modal analysis method is usually used to study the vibration stability. However, the traditional experimental modal analysis (EMA) method needs to measure the impulse excitation, while the operational modal analysis (OMA) method needs to satisfy the assumption of white noise. Therefore, the existing modal analysis methods cannot be applied to the study of vibration stability of high-frequency cantilever mechanism. In this paper, the symbolic regression (SR) algorithm is combined with the EMA method, and the robustness analysis and feasibility verification are carried out under the condition of adding noise. The validation of the new method is divided into two parts. In the first part, a three degree of freedom (DOF) linear model is constructed, and the modal parameters identified by SR method and state space method are compared. In the second part, the method is applied to identify the modal parameters of stepped bar. The results are compared with the results of LMS (Siemens’ Testlab). Based on the time-domain response signal only, the modal parameters are extracted by SR, and the main vibration frequency is extracted from the response signal. The system simulation and experimental results show the method provides a possibility to analyze the vibration stability of cantilever structure.

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Tuhta, Sertaç, Obaidullah Abrar, and Furkan Günday. "Experimental Study on Behavior of Bench-Scale Steel Structure Retrofitted with CFRP Composites under Ambient Vibration." European Journal of Engineering Research and Science 4, no. 5 (May 23, 2019): 109–14. http://dx.doi.org/10.24018/ejers.2019.4.5.1335.

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Usage of FRP composites for the retrofitting purpose of the structures against the harmful effect of dynamic loads are gaining popularity, it is used in a wide variety of disciplines including civil engineering. Thus, there is a great need to study the behavior of FRP composites for strengthening purposes of structures using empirical methods. In this study, a bench-scale steel structure model was strengthened with CFRP composite and tested using operational modal analysis. To conduct operational modal analysis a bench-scale earthquake simulator and ambient vibration emulator were used. Same steel structure model was tested without strengthening procedure. Obtained dynamic responses (maximum-minimum displacements and accelerations before and after application of CFRP) of steel structure model have compared to each other. This study shows that floor displacements of the model have been decreased along the height of the structure up to 41.43 %. Therefore, the results of the experiment confirm the effectiveness CFRP composites for the strengthening of steel structures.

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Tuhta, Sertaç, Obaidullah Abrar, and Furkan Günday. "Experimental Study on Behavior of Bench-Scale Steel Structure Retrofitted with CFRP Composites under Ambient Vibration." European Journal of Engineering and Technology Research 4, no. 5 (May 23, 2019): 109–14. http://dx.doi.org/10.24018/ejeng.2019.4.5.1335.

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Usage of FRP composites for the retrofitting purpose of the structures against the harmful effect of dynamic loads are gaining popularity, it is used in a wide variety of disciplines including civil engineering. Thus, there is a great need to study the behavior of FRP composites for strengthening purposes of structures using empirical methods. In this study, a bench-scale steel structure model was strengthened with CFRP composite and tested using operational modal analysis. To conduct operational modal analysis a bench-scale earthquake simulator and ambient vibration emulator were used. Same steel structure model was tested without strengthening procedure. Obtained dynamic responses (maximum-minimum displacements and accelerations before and after application of CFRP) of steel structure model have compared to each other. This study shows that floor displacements of the model have been decreased along the height of the structure up to 41.43 %. Therefore, the results of the experiment confirm the effectiveness CFRP composites for the strengthening of steel structures.

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Mbarek, Ayoub, Alfonso Fernández Del Rincon, Ahmed Hammami, Miguel Iglesias, Fakher Chaari, Fernando Viadero, and Mohamed Haddar. "Comparison of experimental and operational modal analysis on a back to back planetary gear." Mechanism and Machine Theory 124 (June 2018): 226–47. http://dx.doi.org/10.1016/j.mechmachtheory.2018.03.005.

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Rainieri, C. "Perspectives of Second-Order Blind Identification for Operational Modal Analysis of Civil Structures." Shock and Vibration 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/845106.

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Innovative methods for output-only estimation of the modal properties of civil structures are based on blind source separation techniques. In the present paper attention is focused on the second-order blind identification (SOBI) algorithm and the influence of its analysis parameters on computational time and accuracy of modal parameter estimates. These represent key issues in view of the automation of the algorithm and its integration within vibration-based monitoring systems. The herein reported analyses and results provide useful hints for reduction of computational time and control of accuracy of estimates. The latter topic is of interest in the case of single modal identification tests, too. A criterion for extraction of accurate modal parameter estimates is identified and applied to selected experimental case studies. They are representative of the different levels of complexity that can be encountered during real modal tests. The obtained results point out that SOBI can provide accurate estimates and it can also be automated, confirming that it represents a profitable alternative for output-only modal analysis and vibration-based monitoring of civil structures.

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Wu, Guo Yang, Cheng Rong Jiang, and Yi Jian Liao. "Modal Analysis and Experiment on 2.0 MW Wind Turbine Gearbox." Advanced Materials Research 542-543 (June 2012): 52–56. http://dx.doi.org/10.4028/www.scientific.net/amr.542-543.52.

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By using Solidworks, a three-dimensional solid model of the wind turbine gearbox is established. Use Spring element in ANSYS joins transmission system and case structure system, the whole gearbox coupling dynamic model is built up and the first 20-order bound mode of the gearbox is calculated. Through modal analysis and experimental test show that the structure of wind turbine gearbox is reasonable, and resonance wouldn’t occur during the operational process, ensure the reliability of the unit operation and that for the wind turbine gearbox structure design to provide the theoretical basis.

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Tozkoparan, Ã.-mer AnÄ±l, Osman Taha Sen, and Rajendra Singh. "Case study: Identification of brake squeal source mechanism through experimental and computational approaches." Noise Control Engineering Journal 68, no. 1 (January 20, 2020): 21–37. http://dx.doi.org/10.3397/1/37682.

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In this case study, mechanism leading to squeal noise in an automotive disc brake system is investigated with focus on systematic laboratory experiments and associated computational models. First, experimental modal analyses are conducted on the brake corner assembly components, and the natural frequencies and corresponding mode shapes are obtained. Second, finite element models of same components are developed, updated and validated by comparing predicted modal characteristics with those measured. Third, a controlled laboratory experiment is designed, constructed and operated in a semi-anechoic room. Experiments are conducted at many operational disc speeds and brake line pressures, and acceleration on the caliper and sound pressure are measured. Squeal events at distinct frequencies are successfully identified in the experiments. Fourth, a comprehensive computational model of the brake corner assembly is constructed using validated component models, and squeal investigation is then conducted through complex eigenvalue analyses while mimicking the operational conditions of experiments. The system model yields unstable frequencies at several operational conditions. It is observed that experimentally detected squeal frequencies match well with predicted unstable frequencies. Finally, operational deflection shape measurements on the caliper are also carried out during squeal events, and the predictions are found to be similar to those measured. In conclusion, the squeal generation mechanism of the brake system is understood from the perspective of frictioninduced modal coupling, and an experimentally validated computational model of the brake system is successfully developed that may be used to find solutions to mitigate squeal.

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Alpaslan, Emre, Burcu Dinç, Kemal Hacıefendioğlu, Gökhan Demir, and Olgun Köksal. "Modal identification of a reduced-scale masonry arch bridge with experimental measurements and finite element method." Challenge Journal of Structural Mechanics 3, no. 3 (September 18, 2017): 108. http://dx.doi.org/10.20528/cjsmec.2017.06.012.

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This study aims to investigate modal parameters such as mode shapes, natural frequencies and damping ratios of a reduced scale one-span historical masonry arch bridge constructed in laboratory conditions by performing numerical and experimental analysis. Sarp Dere historical masonry bridge, in Ordu, Ulubey, has 15.5m in length and 4.75m in width was chosen as a prototype model. The reduced-scale bridge model and structural details were carried out in the scale of 1:12.5. Operational Modal Analysis (OMA) technique was used for experimental study. The experimental modal parameters of the bridge model were figured out by using Enhanced Frequency Domain Decomposition (EFDD). ANSYS software was used to create 3D finite element (FE) model and to expose the analytical modal parameters of the reduced-scaled bridge model. Moreover, FE model of the reduced-scale bridge model was calibrated based on the experimental results by using the Response Surface based FE model calibration technique to obtain more accurate results. The analysis results of experimental, initial and calibrated FE model were compared. It is noted that there are significant differences between the modal parameters obtained from experimental and initial FE model. Model calibration techniques are beneficial to get a more reasonable FE model.

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Molchanov, Dmitrii S., Heinz Palkowski, Sergey Chernyakin, and Panagiotis G. Karagiannidis. "Investigation of Metal-based Composites Vibration Properties Using Modal Analysis in Combination with Wavelet Transforms Under Imitation of Operational Loads." Materials and Geoenvironment 67, no. 2 (September 22, 2020): 45–63. http://dx.doi.org/10.2478/rmzmag-2020-0010.

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AbstractThe present article is dedicated to the study of the vibration properties of metal-based composite materials and the application of the non-destructive testing method. The main modal parameters of the metal-based composites were investigated. For experimental determination of natural frequencies and modes of oscillations, the method of scanning laser Doppler vibrometry was used. For the numerical modal analysis, the finite element method was used. The material model was a layered composite with isotropic linearly elastic layers and metal layers. The task of identifying the material model was considered as the problem of minimising the discrepancy between the calculated natural frequencies and the experimental ones. The developed method can be recommended for the determination of parameters of material models for calculating the modal characteristics of polymer–metal sandwich sheets and metallic mono-materials composite products. Methodology for identifying models of elastic behaviour of polymer–metal composite materials, based on the results of the experimental modal analysis, is presented. Wavelet-based damage detection is also presented as an appropriate approach for the identification of integral conditions of the metal–polymer–metal composite materials. Results of wavelet transform convolutions are presented.

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Çelik, M. "Experimental Structural Analysis of Pedestal Mounted Stinger System Turret." Applied Mechanics and Materials 7-8 (August 2007): 107–15. http://dx.doi.org/10.4028/www.scientific.net/amm.7-8.107.

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An experimental approach for the solution of the turret stress state and dynamic behavior has been presented using strain gages and accelerometers on Pedestal Mounted Stinger System. The critical stress locations were determined by finite element analysis outputs where rosettes are bonded in order to perform the life profile simulation tests. The fatigue state is determined by cycle counting methods used in data processing of the turret launcher connection zone. The lowest disturbing frequency of the turret determined from the operational tests is further investigated by the experimental modal analysis. Consequently, the servo drive system is operated efficiently after design modifications applied to the turret.

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Mironov, Aleksey, Pavel Doronkin, Aleksander Priklonsky, and Andris Chate. "EFFECTIVENESS OF APPLICATION OF MODAL ANALYSIS FOR THE MONITORING OF STRESSED OR OPERATED STRUCTURES." Aviation 19, no. 3 (November 13, 2015): 112–22. http://dx.doi.org/10.3846/16487788.2015.1104860.

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This paper presents a brief summary of the research results of the application of experimental and operational modal analysis (EMA and OMA) effectiveness for the assessment of the change in the condition of operating structures by modifying their dynamic characteristics. Special focus is given to the topicality of the operational modal analysis for the definition of the dynamic features of the structures (frequencies, modes and deformation) under near-natural conditions. The research was conducted using two operating laboratory models, when the first one imitated a part of a fuel/gas pipeline and the second – a helicopter blade. The results of finite-element model simulation, identification of natural mode and the influence of the two types of virtual defects on the changes in the dynamic properties are provided. The work describes the results of experimental research of the dynamic behaviour of the pipe model, using the methods of OMA and comparing them with the modelling results. The research results demonstrate how the modification of the condition of the large-scaled models impacts pipe and blade models when the defects of local and global nature are introduced.

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Zhang, Peng, Zhengjie He, Chunyi Cui, Liang Ren, and Ruqing Yao. "Operational Modal Analysis of Offshore Wind Turbine Tower under Ambient Excitation." Journal of Marine Science and Engineering 10, no. 12 (December 9, 2022): 1963. http://dx.doi.org/10.3390/jmse10121963.

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The condition of an offshore wind turbine (OWT) should be monitored to assure its reliability against various environmental loads and affections. The modal parameters of the OWT can be used as an indicator of its condition. This paper combines the Kalman filter, the random decrement technique (RDT), and the stochastic subspace identification (SSI) methods and proposes an RDT-SSI method to estimate the operational frequency of an OWT subjected to ambient excitation. This method imposes no requirement on the input/loads; therefore, it is relatively easy for field application. An experimental study with a small-scale OWT was conducted to verify the accuracy of the proposed RDT-SSI method. The test results implied that the frequency estimated by the RDT-SSI method is close to that estimated by an impact hammer test. Moreover, the small-scale OWT was buried at different embedment depths to simulate the influence of the scouring phenomenon, and the frequency of the OWT decreased with decreasing embedment depth. Additionally, the bolts at the root of the turbine blades were also loosened to investigate their influence on the frequency. As more blades were loosened, the identified frequency of the OWT also decreased, indicating that the proposed RDT-SSI method can be employed for the health monitoring of an OWT.

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Foti, Dora, Nicola Ivan Giannoccaro, Vitantonio Vacca, and Michela Lerna. "Structural Operativity Evaluation of Strategic Buildings through Finite Element (FE) Models Validated by Operational Modal Analysis (OMA)." Sensors 20, no. 11 (June 7, 2020): 3252. http://dx.doi.org/10.3390/s20113252.

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In this paper, a non-destructive technique based on the monitoring of the environmental vibrations of two strategic buildings by positioning accelerometers in well-defined points was used for fixing their dynamic behavior. The accelerometers measurements were elaborated through Operational Modal Analysis (OMA) techniques, in order to identify natural frequencies, damping coefficients, and modal shapes of the structure. Once these parameters have been determined, a numerical model calibrated on the identified frequencies and verified on the corresponding mode shapes was created for each building. The structural operational efficiency index of the buildings was determined by using the Seismic Model Ambient Vibration (SMAV) methodology, which allows us to evaluate their seismic vulnerability. The results obtained from the experimental analysis (on three different tests for each analyzed building) concern the frequencies and the modal shapes of the structure. They have been compared to the results of the finite element model, with a very small error, indicating a good quality of the analysis and also the possibility of using directly well-tuned models for verifying the structural operating indices.

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Chen, Dong Di, Luo Wu, and Jia Wei Xiang. "The Comparison Investigation of OMA Methods on Time Domain." Advanced Materials Research 422 (December 2011): 443–47. http://dx.doi.org/10.4028/www.scientific.net/amr.422.443.

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Operational modal analysis (OMA) is an effective method to identify structural modal parameters from response signal under operational condition. Aiming at the evaluation of different time domain OMA methods in structural modal parameters identification, both numerical simulation and experimental investigation of cantilever beam have been applied to different methods, such as Sparse Time Domain (STD) method, Least Square Complex Exponential (LSCE) method and Eigensystem Realization Algorithm (ERA), etc. The comparison results indicated that ERA is the best one, LSCE method follows and STD method is worst.

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Mitchell, M. R., R. E. Link, Abdurrahman Şahin, and Alemdar Bayraktar. "ModalCAD—Interactive Dynamic Characteristic Identification Software for Experimental and Operational Modal Analysis of Engineering Structures." Journal of Testing and Evaluation 38, no. 6 (2010): 102816. http://dx.doi.org/10.1520/jte102816.

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Marwitz, S., and V. Zabel. "An Experimental Evaluation of Two Potential Improvements for 3D Laser Vibrometer Based Operational Modal Analysis." Experimental Mechanics 57, no. 8 (July 6, 2017): 1311–25. http://dx.doi.org/10.1007/s11340-017-0307-x.

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Kromulski, J., and E. Hojan. "AN APPLICATION OF TWO EXPERIMENTAL MODAL ANALYSIS METHODS FOR THE DETERMINATION OF OPERATIONAL DEFLECTION SHAPES." Journal of Sound and Vibration 196, no. 4 (October 1996): 429–38. http://dx.doi.org/10.1006/jsvi.1996.0493.

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Zhang, P. Q., X. L. Tang, B. X. Shan, J. A. Brandon, and A. S. K. Kwan. "ANALYTICAL AND EXPERIMENTAL MODAL ANALYSIS FOR OPERATIONAL VALIDATION AND CALIBRATION OF A MINIATURE SILICON SENSOR." Journal of Sound and Vibration 214, no. 5 (July 1998): 903–13. http://dx.doi.org/10.1006/jsvi.1998.1577.

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Orlowitz, Esben, and Anders Brandt. "Operational Modal Analysis for Dynamic Characterization of a Ro-Lo Ship." Journal of Ship Research 58, no. 04 (December 1, 2014): 216–24. http://dx.doi.org/10.5957/jsr.2014.58.4.216.

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The dynamic characteristics of ship structures are becoming more important as the flexibility of modern ships increases, for example, to predict reliable design life. This requires an accurate dynamic model of the structure, which, because of complex vibration environment and complex boundary conditions, can only be validated by measurements. In the present paper the use of operational modal analysis (OMA) for dynamic characterization of a ship structure based on experimental data, from a full-scale measurement of a 210-m long Ro-Lo ship during sea trial, is presented. The measurements contain three different data sets obtained under different operating conditions of the ship: 10 knots cruising speed, 18 knots cruising speed, and at anchor. Natural frequencies, modal damping ratios, and mode shapes have been successfully estimated for the first 10 global modes. Damping ratios for the current ship were found within the range 0.9%–1.9% and natural frequencies were found to range from 0.8 to 4.1 Hz for the first 10 global modes of the ship at design speed (18 knots). The three different operating conditions showed, in addition, a speed dependency of the natural frequencies and damping ratios. The natural frequencies were found to be lower for the 18-knots condition compared with the two other conditions, most significantly for the vertical bending modes. Also, for the vertical bending modes, the damping ratios increased by 28%–288% when the speed increased from 10 to 18 knots. Other modes were not found to have the same strong speed dependency.

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Journal articles on the topic 'Operational and Experimental Modal Analysis'

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