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Relevant bibliographies by topics / Operational and Experimental Modal Analysis

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Academic literature on the topic 'Operational and Experimental Modal Analysis'

Author: Grafiati

Published: 20 February 2023

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Journal articles on the topic "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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Dissertations / Theses on the topic "Operational and Experimental Modal Analysis"

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Grundström, Ulrika. "Operational Modal Analysis of the Stockholm Waterfront Congress Centre." Thesis, KTH, Bro- och stålbyggnad, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-36361.

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Nilsson, Oscar. "Experimental Procedures for Operational Modal Analysis of a Power Pack on a Drill Rig." Thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-143046.

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All structures have modal properties such as natural frequencies and damping. In engineeringit is often of interest to estimate these modal properties for certain structures, to be used whenmodelling for example fatigue. This is done by computing them from finite element models, by using experimental measurements or both. In the case of doing both, a finite elementmodel is usually established first and adjusted to fit measurements from experiments. Atlas Copco Rock Drills AB is the company where this thesis has been performed and the subject is experimental procedures related to estimating modal properties of the so calledpower pack, which essentially is a modularised engine and hydraulic power source of an Atlas Copco drill rig. Their current method for estimating these properties is a classical procedure which makes use of an impact hammer that an operator strikes the power pack with to induce excitation. Due to concealment of behind other parts the power pack when mounted inside the drill rig, the number of places where the operator is able to strike the power pack in is limited. Another problem with the current procedure is that it can be difficult to strike the power pack with a strong enough impulse to generate reliable results. In this thesis a new experimental procedure for Atlas Copco to use is suggested. It is based on operational modal analysis (OMA), which uses the machinery's excitation from its operational conditions to compute modal estimates. A comparison between different experimental procedures have been done and the suggested procedure is the following: excitation by engine sweep; modal identifcation by the PolyMAX method and mode shape scaling by the harmonic scaling method. An experiment was performed to compare two OMA procedures.The suggested procedure is the one that generated the better results of the two.

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Song, Baiyi. "Evaluate Operational Modal Analysis and Compare the Result to Visualized Mode Shapes." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-15599.

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The prototypes vibration test carried out for obtaining reliable information concerning machine’s dynamic properties in development process. Analysis results should be able to correlate with FE model to determine if some underlying assumptions (material properties & boundary conditions) were correct. EMA used for extracting structure modal parameter under laboratory condition. However, EMA can generally not provide all required information concerning machine dynamic property. To simulate vibration in operating, it commonly requires the model based on dynamic properties of the machine under operating. Thus, vibration tests need carried out under operational condition. OMA is a useful tool for extracting information concerning dynamic properties of operating machine. This report concerns vibration test of part of mining machine under operating condition. Modal parameters extracted by two kinds of OMA methods. Results from OMA was compared with corresponding EMA results, illustrates reader the advantages of OMA.

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Sharma, Balaji R. "Feasibility of use of four-post road simulators for automotive modal applications." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1277133229.

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Mejri, Seifeddine. "Identification et modélisation du comportement dynamique des robots d'usinage." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22688/document.

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La robotisation des procédés d’usinage suscite l’intérêt des industriels en raison du grand espace de travail et le faible coût des robots par rapport aux machines-outils conventionnelles et la possibilité d’usiner des pièces de formes complexes. Cependant, la faible rigidité de la structure robotique favorise le déclenchement de phénomènes dynamiques liés à l’usinage sollicitant le robot en bout de l’outil qui dégradent la qualité de surface de la pièce usinée. L’objectif de ces travaux de thèse est de caractériser le comportement dynamique des robots en usinage. Ces travaux ont suivi une démarche en trois étapes : La modélisation d’un premier modèle considéré de référence où le robot est au repos. Ensuite l’identification du comportement dynamique du robot en service. Enfin, l’exploitation des modèles dynamiques du robot en vue de prédire la stabilité de coupe. L’originalité de ces travaux porte sur le développement des méthodes d’identification modale opérationnelles. Elles permettent d’intégrer les conditions réelles d’usinage et d’élaborer des modèles plus précis que le premier modèle de connaissance sans être biaisés par l’effet des harmoniques de rotation de l’outil. Enfin, des préconisations sur le choix de configurations du robot et sur la direction des forces d’excitation sont proposées pour assurer la stabilité de la coupe lors de l’usinage robotisé
Machining robots have major advantages over cartesian machine tools because of their flexibility, their ability to reach inaccessible areas on a complex part, and their important workspace. However, their lack of rigidity and precision is still a limit for precision tasks. The stresses generated by the cutting forces and inertia are important and cause static and dynamic deformations of the structure which result in problems of workpiece surface. The aim of the thesis work is to characterize the dynamic behavior of robots during machining operation. This work followed a three-step approach : Modeling a first model considered as a reference where the robot is at rest. Then the identification of the dynamic behavior in service. Finally, the prediction of the cutting stability using the robot dynamic model. The originality of this work is the development of new operational modal identification methods. They integrate the machining conditions and result into a more accurate model than the first model of reference without being biased by harmonics. Finally, guidlines of robot’s configurations and excitation forces’ direction are proposed to ensure the robotic machining stability

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Blecha, Martin. "Laboratorní demonstrátor pro vibrační diagnostiku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400643.

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This thesis deals with a vibration diagnostics of objects, structures and machines. The theoretical part is divided into three chapters according to type of the measurement. The first part called Modal Analysis discusses the basis of vibration, methods of measurement, relevant technical equipment and principle of experimental modal analysis. The second and third chapters of the thesis are focused on the diagnosis of defects. Each chapter mentioned above describes diagnosed defects, used methods and procedure for the diagnosis. Another part of the thesis summarizes practical issues and results gained in the laboratory experiments. It begins with discovering parameters of the measured object using technical diagnostics – experimental modal analysis. In the next step the hardware concept design was created, including custom measuring application programmed in LabVIEW. One part of the design is the laboratory model which includes a structure for free mounting and a possibility of excitation by an electrodynamic exciter. The application is also modified to enable measurements with shaker excitation. Finally, applications cooperating with professional software ModalVIEW and BK Connect were developed in order to simplify the operation and increase the comfort.

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Maamar, Asia. "Identification modale opérationnelle des robots d'usinage en service." Thesis, Université Clermont Auvergne‎ (2017-2020), 2019. http://www.theses.fr/2019CLFAC013/document.

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L’identification des paramètres modaux des machines-outils et des robots d’usinage, en service, constitue un levier d’optimisation des performances de coupe. En effet, la connaissance en continue du comportement dynamique d’une machine permet une prédiction fine des conditions de stabilité, bases d’un pilotage intelligent des paramètres du procédé. Cependant, la présence de fortes excitations harmoniques, dues à la rotation de la broche et de l’outil coupant, rend les techniques classiques d’Analyse Modale Opérationnelle (AMO) inapplicables. Le premier objectif de cette thèse consiste à déterminer une méthode d’AMO adéquate pour une application en présence des harmoniques. Une étude comparative des méthodes existantes est conduite, à savoir : la méthode de décomposition dans le domaine fréquentiel (EFDD), la méthode d’identification dans le sous-espace stochastique (SSI), la méthode PolyMAX et la méthode basée sur la fonction de transmissibilité (TFB). La méthode TFB est choisie afin de réaliser une identification modale opérationnelle des robots d’usinage. Cette technique est tout d’abord investiguée sur une machine-outil cartésienne. Cette étape est justifiée par le fait qu’une machine-outil est une structure plus rigide qui présente moins de variations des propriétés dynamiques par rapport à un robot d’usinage. Les résultats montrent la pertinence de la méthode TFB pour identifier les paramètres modaux de la machine-outil en usinage, même en présence des composantes harmoniques fortement dominantes. Ensuite, l’identification modale opérationnelle du robot d’usinage ABB IRB 6660, qui présente une structure moins rigide par rapport à une machine-outil, est menée sur une trajectoire d’usinage. Les résultats obtenus permettent d’établir une base modale du robot montrant l’évolution de son comportement modal en service. L’originalité des travaux présentés réside dans le développement d’une procédure robuste d’identification modale opérationnelle qui permet de suivre l’évolution du comportement modal du robot en cours d’usinage dans son espace de travail
The identification of the modal parameters of machining robots in service has a significant adverse influence on machining stability, which will, therefore, decrease the quality of the workpiece and reduce the tool life. However, in presence of strong harmonic excitation, the application of Operational Modal Analysis (OMA) is not straightforward. Firstly, the issue of choosing the most appropiate OMA method for an application in presence of harmonic components, is handled. For a comparison purpose, the modified Enhanced Frequency Domain Decomposition (EFDD) method, the Stochastic Subspace Identification (SSI) method, the PolyMAX method and the Transmissibility Function Based (TFB) method are investigated. The obtained results lead to the adoption of the Transmissibility Function Based (TFB) method for an OMA of machining robots. For an accurate modal identification procedure, the OMA of a machine tool is, initially, conducted. It is a preparation step in order to verify the performance of the chosen method under machining conditions as well as a machine tool is a rigid structure, thus, it has less variation in its dynamic behavior compared to a machining robot. Results demonstrate the efficiency of the TFB method to identify the machine tool modal parameters even in the presence of preponderant harmonic components. Finally, the OMA of the machining robot ABB IRB 6660, which has a flexible structure compared to a machine tool, is carried out for a machining trajectory. The obtained results allow the identification of a modal basis of the machining robot illustrating the evolution of its modal behavior, in service. The main novelty of this thesis lies in the development of a robust procedure for an operational modal identification of machining robots, in service, which makes it possible to continuously follow the variations in the modal parameters of machining robots

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Nicoletti, Vanni. "Experimental Evaluation of Infill Masonry Walls Stiffness for the Modelling of Non-Structural Components in R.C. Frame Buildings." Doctoral thesis, Università Politecnica delle Marche, 2018. http://hdl.handle.net/11566/253124.

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Solitamente le tamponature vengono trascurate nella modellazione delle strutture a telaio in cemento armato e solamente il loro contributo in termini di massa viene preso in considerazione, assumendo che la resistenza e la rigidezza delle stesse non influiscano sulla risposta strutturale. Questa pratica è supportata dal fatto che (i) generalmente allo stato limite ultimo le tamponature si considerano completamente danneggiate e, quindi, il loro contributo in termini di rigidezza è trascurabile, mentre (ii) allo stato limite di danno il valore dello spostamento di interpiano, ottenuto trascurando il contributo di rigidezza delle tamponature, può essere considerato a favore di sicurezza. Tuttavia, per edifici di importanza strategica, quali scuole, ospedali, caserme delle forze dell’ordine e dei Vigili del Fuoco, è cruciale preservare le tamponature da qualsiasi danno, anche per terremoti di entità severa, in modo da garantire il normale utilizzo dell’edificio durante la gestione dell’emergenza. Inoltre, questi edifici a volte sono sismicamente protetti con sistemi e dispositivi (smorzatori, isolatori, ecc…) il cui progetto richiede che sia tenuto in considerazione il reale comportamento dinamico della struttura (in termini di frequenze e/o spostamenti e/o velocità). Per questo diventa cruciale modellare accuratamente l’intera struttura, includendo le tamponature, e validare questo modello così ottenuto sulla base dell’evidenza sperimentale. La tipologia delle pareti e le loro procedure costruttive sono fonte di incertezze nella modellazione delle interazioni tra la struttura e gli elementi non strutturali. Quindi, una valutazione sperimentale delle proprietà di rigidezza dei pannelli di tamponatura potrebbe essere molto utile per valutare, all’interno del modello strutturale adottato per il progetto, il contributo in termini di rigidezza fornito alla struttura in c.a. da questi elementi non strutturali. In questa tesi viene presentata una procedura per realizzare modelli globali agli elementi finiti accurati di edifici a telaio in c.a. tamponati, basandosi su risultati ottenuti da analisi modali sperimentali e operative sviluppate rispettivamente su elementi non strutturali e sull’intero edificio. In particolare, sono stati eseguiti test di impatto con martello strumentato su pareti omogenee per identificarne i parametri modali (frequenze e forme modali) e per stimarne le proprietà meccaniche. Dopo di che, le tamponature sono state inserite nel modello strutturale globale agli elementi finiti, i cui parametri modali vengono confrontati con quelli derivanti da analisi modali operative basate su misurazioni di vibrazioni ambientali per valutarne l’accuratezza. In seguito, è stata condotta una campagna sperimentale su tre provini di tamponatura costruiti all’interno del Laboratorio di Prove di Materiali e Strutture della Facoltà di Ingegneria dell’Università Politecnica delle Marche. Questi provini sono stati realizzati con l’intento di riprodurre le caratteristiche di alcune delle tamponature testate in sito e su di essi vengono svolte prove sia dinamiche che statiche. Innanzi tutto, sono stati effettuati test ad impatto con martello strumentato per investigarne il comportamento dinamico fuori dal piano; successivamente sono state svolte prove di spinta laterale per investigare il comportamento statico nel piano dei pannelli soggetti a bassi livelli di forze orizzontali. I risultati sperimentali ottenuti sono stati utilizzati per calibrare modelli agli elementi finiti dei provini al fine di valutare l’esattezza delle proprietà meccaniche delle tamponature stimate in precedenza e secondo diversi approcci.
Infill walls are commonly disregarded in the modelling of reinforced concrete (r.c.) frame structures and only their contribution in terms of mass is taken into account assuming that resistance and stiffness do not affect the structural response. This practice is supported by the fact that (i) at ultimate limit state infill walls are usually considered to be completely damaged, so that their contribution is negligible in terms of stiffness, while (ii) at the damage limitation limit state the value of the interstorey drift, obtained by neglecting the infill walls stiffness contribution, is commonly considered to be conservative. However, for strategic buildings, such as schools, hospitals, police and fire stations, it is crucial to preserve the infill walls from any damage, even for severe earthquake, in order to guarantee the building occupancy during the emergency management. Furthermore, these buildings are sometimes seismically protected with system and devices (dampers, isolators, etc…) whose design requires the real dynamic behaviour of the structure (in terms of frequencies and/or displacements and/or velocities) to be considered. To this purpose, it becomes crucial to accurately model the entire structure, including infill walls, and to validate this model on the basis of experimental evidences. The wall typology and the construction procedures are source of uncertainties in modelling interactions between structural and non-structural components. Thus, an experimental evaluation of the stiffness properties of the wall infill panel could be very useful to assess the stiffening contribution added by the infill masonry walls to the concrete frame in the structural model adopted for the design. In this thesis is presented a procedure for developing accurate global finite element (f.e.) models of infilled r.c. frame buildings based on results of experimental an operational modal analysis of non-structural components and of the whole buildings. In particular, impact load tests with an instrumented hammer are performed on homogeneous wall panels to identify the modal parameters (frequency and mode shapes) and to estimate the mechanical properties of the masonry walls. Afterwards, the infill walls are included in the f.e. structural model, whose modal parameters are compared with those derived with operational modal analysis based on ambient vibration measurements. Furthermore, an experimental campaign on three specimens of infill masonry walls built in the Laboratory of Materials and Structures of the Faculty of Engineering at the Università Politecnica delle Marche is conducted. These specimens are built with the target to reproduce the features of some of the in situ investigated infill walls and are tested both dynamically and statically. First of all, impact load tests with an instrumented hammer are performed to investigate the out of plane dynamic behaviour of these walls; then, lateral load tests are carried out to investigate the in plane static behaviour of the panel under low level of lateral forces. The experimental results obtained are used to calibrate f.e. models of the specimens with the aim to evaluate the reliability of the masonry mechanical properties estimated through different approaches.

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Martell, Raymond F. "Investigation of Operational Modal Analysis Damping Estimates." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1291147391.

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SPERANZA, ELISA. "The Importance of Calibration and Modelling Non-Structural Elements in the Evaluation of Seismic Vulnerability Index of Strategic Buildings Before and After Retrofitting." Doctoral thesis, Università Politecnica delle Marche, 2020. http://hdl.handle.net/11566/274486.

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Questa tesi si propone di indagare sulla modellazione degli elementi non strutturali relativi alle pareti di tamponamento interne ed esterne, cercando di quantificare la differenza indotta dalle diverse strategie di modellazione sul valore dell'indice di vulnerabilità sismica con riferimento a edifici strategici. A tale scopo vengono analizzati due casi studio: il liceo Benedetto Croce di Avezzano e il liceo Varano di Camerino, entrambi edifici a telaio in c.a. oggetto di adeguamento sismico tramite torri dissipative esterne dotate di dissipatori viscosi alla base. Per entrambi i casi di studio, sono stati implementati tre modelli sia prima che dopo l'adeguamento, caratterizzati da un livello crescente di dettaglio: modello A con solo le componenti strutturali, modello B con tamponature esterne modellate come puntoni equivalenti secondo letteratura e modello C con pareti di tamponamento esterne ed interne calibrate attraverso i risultati dei test dinamici in situ. Per quanto riguarda la fase di pre-retrofitting, il calcolo dell'indice di vulnerabilità sismica è stato effettuato mediante analisi statica non lineare (pushover). Per quanto riguarda la fase post-retrofitting, il calcolo dell'indice di vulnerabilità sismica è stato effettuato mediante analisi dinamica non lineare (I.D.A). I risultati sono mostrati in termini di confronto tra le curve di capacità ottenute con analisi push over (pre-retrofitting) e con analisi dinamiche incrementali, per i diversi modelli implementati. Inoltre, i risultati sono mostrati anche in termini di livello di intensità dell'azione sismica necessaria per raggiungere uno stato limite predeterminato per il modello A, il modello B e il modello C.
This thesis aims to investigate on the modelling of the non-structural elements related to internal and external infill walls, trying to quantify the difference induced by different modelling strategies on the value of the seismic vulnerability index with reference to strategic buildings. On this purpose, two case studies are analysed: the Benedetto Croce high school in Avezzano and the Varano high school in Camerino, r.c. frame buildings retrofitted with external steel towers equipped with viscous dampers at the basis. For both case studies, three models are implemented, before and after the retrofitting, which are characterized by an increasing level of detail: model A with only structural components, model B with external infill panels modelled as equivalent connecting struts according to literature, and model C with external and internal infill walls calibrated through the results of in-situ dynamic tests. As regards the pre-retrofitting phase, the calculation of the seismic vulnerability index was carried out by means of nonlinear static analysis (pushover). As for the post-retrofitting phase, the calculation of the seismic vulnerability index was carried out by means of non-linear dynamic analysis (I.D.A). The results are shown in terms of comparison between the capacity curves obtained with push over analyses (pre-retrofitting) and with incremental dynamic analyses for the different model. In addition, the outcomes are shown also in terms of intensity level of the seismic action necessary to reach a predetermined limit state for model A, model B and model C.

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Books on the topic "Operational and Experimental Modal Analysis"

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Au, Siu-Kui. Operational Modal Analysis. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-4118-1.

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Brincker, Rune, and Carlos E. Ventura. Introduction to Operational Modal Analysis. Chichester, UK: John Wiley & Sons, Ltd, 2015. http://dx.doi.org/10.1002/9781118535141.

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Brincker, Rune. Introduction to operational modal analysis. Chichester, West Sussex: John Wiley and Sons, Inc., 2015.

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Rainieri, Carlo, and Giovanni Fabbrocino. Operational Modal Analysis of Civil Engineering Structures. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-0767-0.

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Brandt, Anders. Noise and vibration analysis: Signal analysis and experimental procedures. Chichester: Wiley, 2011.

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Brincker, Rune, and Carlos Ventura. Introduction to Operational Modal Analysis. Wiley & Sons, Incorporated, John, 2015.

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Brincker, Rune. Introduction to Operational Modal Analysis. Wiley & Sons, Limited, John, 2015.

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Brincker, Rune, and Carlos Ventura. Introduction to Operational Modal Analysis. Wiley & Sons, Incorporated, John, 2015.

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Brincker, Rune, and Carlos Ventura. Introduction to Operational Modal Analysis. Wiley & Sons, Incorporated, John, 2015.

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Au, Siu-Kui. Operational Modal Analysis: Modeling, Bayesian Inference, Uncertainty Laws. Springer, 2017.

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Book chapters on the topic "Operational and Experimental Modal Analysis"

1

Thibault, Louis, Timothy Marinone, Peter Avitabile, and Charles Van Karsen. "Comparison of Modal Parameters Estimated from Operational and Experimental Modal Analysis Approaches." In Topics in Modal Analysis I, Volume 5, 77–88. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-2425-3_9.

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Orlowitz, Esben, and Anders Brandt. "Producing Simulated Time Data for Operational Modal Analysis." In Conference Proceedings of the Society for Experimental Mechanics Series, 339–50. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15248-6_36.

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Frøseth, Gunnstein T., Anders Rönnquist, and Ole Øiseth. "Operational Modal Analysis and Model Updating of Riveted Steel Bridge." In Conference Proceedings of the Society for Experimental Mechanics Series, 229–35. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-29751-4_23.

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Busca, Giorgio, Alessio Datteo, Murathan Paksoy, Chiara Pozzuoli, Carlo Segato, and Marcello Vanali. "Experimental vs Operational Modal Analysis: A Flyover Test Case." In Conference Proceedings of the Society for Experimental Mechanics Series, 365–77. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15248-6_39.

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Christensen, Silas S., and Anders Brandt. "Parameter Study of Statistics of Modal Parameter Estimates Using Automated Operational Modal Analysis." In Conference Proceedings of the Society for Experimental Mechanics Series, 243–54. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-12115-0_34.

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Bajrić, Anela, Christos T. Georgakis, and Rune Brincker. "Evaluation of Damping Using Frequency Domain Operational Modal Analysis Techniques." In Conference Proceedings of the Society for Experimental Mechanics Series, 351–55. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15248-6_37.

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Boorsma, Anne, and E. Peter Carden. "Use of Operational Modal Analysis in Solving Ship Vibration Issues." In Conference Proceedings of the Society for Experimental Mechanics Series, 281–88. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-9299-4_24.

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Gille, Max, Johannes Maierhofer, and Daniel J. Rixen. "A Low-Cost Excitation System for Operational Modal Analysis (OMA)." In Special Topics in Structural Dynamics & Experimental Techniques, Volume 5, 145–52. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-47709-7_13.

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Avci, Onur, Khalid Alkhamis, Osama Abdeljaber, and Mohammed Hussein. "Operational Modal Analysis and Finite Element Model Updating of a 53-Story Building." In Conference Proceedings of the Society for Experimental Mechanics Series, 83–91. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77143-0_9.

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Motte, Kenny, Wout Weijtjens, Christof Devriendt, and Patrick Guillaume. "Operational Modal Analysis in the Presence of Harmonic Excitations: A Review." In Conference Proceedings of the Society for Experimental Mechanics Series, 379–95. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15248-6_40.

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Conference papers on the topic "Operational and Experimental Modal Analysis"

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Zhou, Suxia, Yunye Xie, Jilong Xie, and Fang Li. "Operational modal analysis of vehicle system based on SSI under operational conditions." In Fourth International Conference on Experimental Mechanics, edited by Chenggen Quan, Kemao Qian, Anand K. Asundi, and Fook S. Chau. SPIE, 2009. http://dx.doi.org/10.1117/12.851704.

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Cauberghe, Bart, Patrick Guillaume, Peter Verboven, Eli Parloo, and Steve Vanlanduit. "Combined Deterministic-Stochastic Frequency-Domain Subspace Identification for Experimental and Operational Modal Analysis." In ASME 7th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2004. http://dx.doi.org/10.1115/esda2004-58542.

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Until recently frequency-domain subspace algorithms were limited to identify deterministic models from input/output measurements. In this paper, a combined deterministic-stochastic frequency-domain subspace algorithm is presented to estimate models from input/output spectra, frequency response functions or power spectra for application as experimental and operational modal analysis. The relation with time-domain subspace identification is elaborated. It is shown by both simulations and real-life test examples that the presented method outperforms traditional frequency-domain subspace methods.

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Poncelet, F., G. Kerschen, J. C. Golinval, and F. Marin. "Second-Order Blind Identification for Operational Modal Analysis." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34480.

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For modal analysis of large structures, it is unpractical and expensive to use artificial excitation (e.g., shakers). However, engineering structures are most often subject to ambient loads (e.g., traffic and wind) that can be exploited for modal parameter estimation. One difficulty is that the actual loading conditions cannot generally be measured, and output-only measurements are available. This paper proposes to explore the utility of blind source separation (BSS) techniques for operational modal analysis. The basic idea of BSS is to recover unobserved source signals from their observed mixtures. The feasibility and practicality of the proposed method are demonstrated using an experimental application.

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Saito, Keisuke, Shigeyuki Naruta, Hiroaki Eto, Osamu Saijo, and Kiyotaka Ohki. "Operational Modal Analysis of Existing Floating Structure." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79829.

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The oceanic architectural buildings were designed in consideration of structural safety based on various structural calculations. However, there is not conclusive proof such as constructed buildings satisfy strength according to the expectation or the buildings built in 1970’s still satisfies specified concrete strength. Therefore, in this study, vibration characteristics of existing floating structure were measured by mode analysis. Generally mode analysis is performed by giving a measurement object a shock with the impulse hammer. But it is hard to be allowed to strike the existing oceanic architectural buildings with a big impulse hammer for a vibration experiment. Therefore, operational modal analysis (OMA) which does not give a shock to measurement object was adopted in this study. In the OMA, natural frequency, mode shape and damping ratio are calculated from the measurement results of ordinary vibration by ground vibration, winds and waves. OMA is used in a field of mechanical engineering. However, it is not easy to apply a vibration experiment by OMA to floating structure. It is because the mode peaks of rigid motions such as heaving and pitching motion in low frequency domain is prominent, and the mode peaks of elastic vibration are difficult to be confirmed. Firstly, we carried out a water tank experiment with floating elastic plate model. Concretely, elastic plate model in floating condition on the water was analyzed by OMA. Because mode peak of the elastic vibration in floating condition was detected by examining frequency response function carefully, it was confirmed that we could apply OMA to the vibration experiment of existing floating structure. Secondly, vibration characteristic of the floating lounge named “WATERLINE” in Tokyo Bay was investigated by OMA. Ordinary vibrations of the base and the building of “WATERLINE” were measured, and natural frequency, mode shape and damping ratio were calculated. And it was reported about vibration characteristic that is given by measurement of existing floating structure by OMA.

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Iyer, Ganesh, Sakthivel Mohan, Naveen Rao, and Sarat Unnithan. "Evaluation of Dynamic Characteristics of an Automotive Exhaust System using Operational Modal Analysis (OMA) and Experimental Modal Analysis (EMA)." In 8th SAEINDIA International Mobility Conference & Exposition and Commercial Vehicle Engineering Congress 2013 (SIMCOMVEC). 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2013. http://dx.doi.org/10.4271/2013-01-2903.

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Carden, Eoin Peter, and Stefano Morosi. "Operational Modal Analysis of Lateral Rotordynamic Modes of Rotating Machinery." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26308.

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The lateral rotordynamic response of turbomachinery is typically speed dependent due to hydrodynamic lubricated bearings, seals, gyroscopic and centrifugal effects, etc. Rotordynamic tools are used to predict the behavior of the machine during operation, however validating these results is challenging. Traditional experimental modal testing techniques rely on controlled and measured excitation together with measured responses. However, during operation this is unpractical, as the actual excitation force is rarely known. Operational modal analysis (OMA) can identify the modal parameters of a system over its entire operational range from measurement of response due to some (unknown) excitation. OMA has proven successful on non-rotating structures, but has seldom been applied to rotating machinery. Three case studies are presented demonstrating the use of OMA in identifying lateral rotors modes based on measurements from existing radial proximity probes during normal production undertaken as part of commissioning campaigns. Challenges encountered in using and interpreting OMA results are discussed. The results show that proximity probe data acquired during normal operation may be used as input to OMA for the assessment of stability margins of rotating machinery, to produce experimentally derived Campbell diagrams and to identify backwards as well as forwards whirling modes.

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Vigsø, Michael, and Christos Georgakis. "Estimating Loads From Breaking Waves Using Operational Modal Analysis." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19170.

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Abstract Load effects from breaking waves on offshore structures may be a driving point for the design. It is hence important to assess the likelihood of occurrence along the magnitude of the loads in the event of an impact. Traditionally, loads are predicted using wave theory combined with a load model such as the Morison. This paper features an alternative approach in determining the loads from wave breaking. It is demonstrated how the structural response can be used for (indirectly) estimating the magnitude of the loads caused by wave breaking. The theory is applied to an experimental setup in a wave flume, where a flexible model is subjected to loads from breaking waves. The dynamic properties are mapped using operational modal analysis and it is consequently shown that the loads can be identified using the vibration measurements.

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Carden, Eoin Peter, and Mattias Lindblad. "Operational Modal Analysis of Torsional Modes in Rotating Machinery." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26305.

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Traditional experimental modal testing techniques rely on controlled and measured excitation together with measured responses in order to identify the mode shape, natural frequency and damping factor of each mode. Applying a controlled and measured excitation to a rotor train when in operation is logistically difficult and especially challenging in the field. Operational modal analysis (OMA) identifies the modal parameters of a system from measurement of response due to some (unknown) excitation. OMA has proven successful over the past several decades on non-rotating structures but has relatively rarely been applied to rotating machinery. Case studies are presented demonstrating the use of OMA in identifying torsional modes on an electric motor driven reciprocating compressor, on a diesel engine driven fire water pump and on a marine propulsion system. In contrast to lateral modes, torsional modes of rotor trains are typically not speed dependent. However phenomena exist whereby the torsional modes may be different at stand still, off-load and at different loads. The case studies provide examples of such phenomena and also of significant differences between predicted and measured behaviour which suggests that improvements in industrial practice would be beneficial. Such improvements should be based on reconciliation of measured and predicted behaviour and OMA offers a valuable tool to facilitate this. OMA provides a significant benefit in investigating and understanding torsional behaviour in operation.

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Kushnir, Emmanuil. "Application of Operational Modal Analysis to a Machine Tool Testing." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59572.

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Modal analysis testing of a mechanical structure is performed usually by artificial excitation of a structure and measuring input forces and output responses of a mechanical system. The excitation is either transient (impact hammer testing), random, burst-random or sinusoidal (shaker testing). The modern signal processing tools enable to determine properties of a mechanical structure such as resonance frequencies, damping ratios, and mode patterns by measuring the response of the structure without using an artificial excitation. The advantage of this technique is that modal parameters of a structure may be evaluated while the structure is under actual operating conditions. That will allow developing a model within true boundary conditions and actual force and vibration levels. The machine tool structure characteristics that effect productivity and quality have to be evaluated by testing. These characteristics include natural frequencies, modes of vibration, and external sources of high level vibration. Not all modes of machine tool structure effect machine quality. As a result only the modes that are excited during cutting have to be taken in the account. This approach narrowed the frequency range, which has to be considered in test. The machine tool during cutting and/or idling is loaded by a set of external and internal exciting forces. Spectrum, frequency range and application points of these forces are unknown in many cases. Under these exciting forces the vibration between the tool and workpiece, and vibration of machine tool components are sums of many independent vibrations and may be considered as stationary random processes. This assumption allows applying the theory of stationary random processes to machine tool dynamic testing during cutting. Several characteristics of random processes are used to separate harmonic vibration from narrow-band random vibration at natural frequencies. The spectral analysis of machined surface profiles and its correlation with observed vibration allows choosing modes that have to be developed. The analysis of these modes provides a basis for machine tool structure improvement. The proposed experimental approach was verified by experiments at different machine tools. Results of these tests are presented in the paper.

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Kléperon, Alexis Klauber Chaia, Robson Demétrius Araújo Abreu, Rômulo Morais Bitencourt, and Francis José Marochi Almeida. "Brake Moan Noise Study through Experimental and Operational Modal Analysis Techniques in a Passenger Car." In SAE Brasil International Noise and Vibration Colloquium 2014. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2014. http://dx.doi.org/10.4271/2014-36-0768.

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Reports on the topic "Operational and Experimental Modal Analysis"

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Candy, J. V., L. M. Stoops, S. N. Franco, and M. C. Emmons. MODAL FREQUENCY TRACKING: Performance Analysis on Noisy Experimental Ground Test Data. Office of Scientific and Technical Information (OSTI), January 2018. http://dx.doi.org/10.2172/1438608.

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Allemang, Randall J., and David L. Brown. Experimental Modal Analysis and Dynamic Component Synthesis. Volume 5. Universal File Formats. Fort Belvoir, VA: Defense Technical Information Center, December 1987. http://dx.doi.org/10.21236/ada197032.

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Allemang, Randall J., and David L. Brown. Experimental Modal Analysis and Dynamic Component Synthesis. Volume 1. Summary of Technical Work. Fort Belvoir, VA: Defense Technical Information Center, December 1987. http://dx.doi.org/10.21236/ada207270.

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Ratcliffe, Colin P. Experimental Modal Analysis of a Sandwich Construction, Glass Reinforced Plastic Composite Deck Panel. Fort Belvoir, VA: Defense Technical Information Center, July 1996. http://dx.doi.org/10.21236/ada359147.

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Alt, Jonathan, Willie Brown, George Gallarno, John Richards, Jennifer Olszewski, and Titus Rice. Risk-based prioritization of operational condition assessments : methodology and case study results. Engineer Research and Development Center (U.S.), November 2022. http://dx.doi.org/10.21079/11681/46123.

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USACE operates, maintains, and manages more than $232 billion of the Nation’s water resource infrastructure. USACE uses the Operational Condition Assessment (OCA) to allocate limited resources to assess condition of this infrastructure in efforts to minimize risks associated with performance degradation. The analysis of risk associated with flood risk management (FRM) assets includes consideration of how each asset contributes to its associated FRM watershed system, understanding the consequences of the asset’s performance degradation, and a determination of the likelihood that the asset will perform as expected given the current OCA condition ratings of critical components. This research demonstrates a proof-of-concept application of a scalable methodology to model the probability of a dam performing as expected given the state of its gates and their components. The team combines this likelihood of degradation with consequences generated by the application of designed simulation experiments with hydrological models to develop a risk measure. The resulting risk scores serve as an input for a mixed-integer optimization program that outputs the optimal set of components to conduct OCAs on to minimize risk in the watershed. This report documents the results of the application of this methodology to two case studies.

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Alt, Jonathan, Willie Brown, George Gallarno, John Richards, and Titus Rice. Risk-based prioritization of operational condition assessments : Jennings Randolph case study. Engineer Research and Development Center (U.S.), April 2022. http://dx.doi.org/10.21079/11681/43862.

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The US Army Corps of Engineers (USACE) operates, maintains, and manages over $232 billion worth of the Nation’s water resource infrastructure. Using Operational Condition Assessments (OCA), the USACE allocates limited resources to assess asset condition in efforts to minimize risks associated with asset performance degradation, but decision makers require a greater understanding of those risks. The analysis of risk associated with Flood Risk Management assets in the context of its associated watershed system includes understanding the consequences of the asset’s failure and a determination of the likelihood that the asset will perform as expected given the current OCA ratings of critical components. This research demonstrates an application of a scalable methodology to model the probability of a dam performing as expected given the state of its subordinate gates and their components. The research team combines this likelihood with consequences generated by the application of designed simulation experiments with hydrological models to develop a measure of risk. The resulting risk scores serve as an input for an optimization program that outputs the optimal set of components to conduct OCAs on to minimize risk in the watershed. Proof-of-concept results for an initial case study on the Jennings Randolph Dam are provided.

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Tanny, Josef, Gabriel Katul, Shabtai Cohen, and Meir Teitel. Micrometeorological methods for inferring whole canopy evapotranspiration in large agricultural structures: measurements and modeling. United States Department of Agriculture, October 2015. http://dx.doi.org/10.32747/2015.7594402.bard.

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Original objectives and revisions The original objectives as stated in the approved proposal were: (1) To establish guidelines for the use of micrometeorological techniques as accurate, reliable and low-cost tools for continuous monitoring of whole canopy ET of common crops grown in large agricultural structures. (2) To adapt existing methods for protected cultivation environments. (3) To combine previously derived theoretical models of air flow and scalar fluxes in large agricultural structures (an outcome of our previous BARD project) with ET data derived from application of turbulent transport techniques for different crops and structure types. All the objectives have been successfully addressed. The study was focused on both screenhouses and naturally ventilated greenhouses, and all proposed methods were examined. Background to the topic Our previous BARD project established that the eddy covariance (EC) technique is suitable for whole canopy evapotranspiration measurements in large agricultural screenhouses. Nevertheless, the eddy covariance technique remains difficult to apply in the farm due to costs, operational complexity, and post-processing of data – thereby inviting alternative techniques to be developed. The subject of this project was: 1) the evaluation of four turbulent transport (TT) techniques, namely, Surface Renewal (SR), Flux-Variance (FV), Half-order Time Derivative (HTD) and Bowen Ratio (BR), whose instrumentation needs and operational demands are not as elaborate as the EC, to estimate evapotranspiration within large agricultural structures; and 2) the development of mathematical models able to predict water savings and account for the external environmental conditions, physiological properties of the plant, and structure properties as well as to evaluate the necessary micrometeorological conditions for utilizing the above turbulent transfer methods in such protected environments. Major conclusions and achievements The major conclusions are: (i) the SR and FV techniques were suitable for reliable estimates of ET in shading and insect-proof screenhouses; (ii) The BR technique was reliable in shading screenhouses; (iii) HTD provided reasonable results in the shading and insect proof screenhouses; (iv) Quality control analysis of the EC method showed that conditions in the shading and insect proof screenhouses were reasonable for flux measurements. However, in the plastic covered greenhouse energy balance closure was poor. Therefore, the alternative methods could not be analyzed in the greenhouse; (v) A multi-layered flux footprint model was developed for a ‘generic’ crop canopy situated within a protected environment such as a large screenhouse. The new model accounts for the vertically distributed sources and sinks within the canopy volume as well as for modifications introduced by the screen on the flow field and microenvironment. The effect of the screen on fetch as a function of its relative height above the canopy is then studied for the first time and compared to the case where the screen is absent. The model calculations agreed with field experiments based on EC measurements from two screenhouse experiments. Implications, both scientific and agricultural The study established for the first time, both experimentally and theoretically, the use of four simple TT techniques for ET estimates within large agricultural screenhouses. Such measurements, along with reliable theoretical models, will enable the future development of lowcost ET monitoring system which will be attainable for day-to-day use by growers in improving irrigation management.

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Cytryn, Eddie, Mark R. Liles, and Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598174.bard.

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Control of agro-associated pathogens is becoming increasingly difficult due to increased resistance and mounting restrictions on chemical pesticides and antibiotics. Likewise, in veterinary and human environments, there is increasing resistance of pathogens to currently available antibiotics requiring discovery of novel antibiotic compounds. These drawbacks necessitate discovery and application of microorganisms that can be used as biocontrol agents (BCAs) and the isolation of novel biologically-active compounds. This highly-synergistic one year project implemented an innovative pipeline aimed at detecting BCAs and associated biologically-active compounds, which included: (A) isolation of multidrug-resistant desert soil bacteria and root-associated bacteria from medicinal plants; (B) invitro screening of bacterial isolates against known plant, animal and human pathogens; (C) nextgeneration sequencing of isolates that displayed antagonistic activity against at least one of the model pathogens and (D) in-planta screening of promising BCAs in a model bean-Sclerotiumrolfsii system. The BCA genome data were examined for presence of: i) secondary metabolite encoding genes potentially linked to the anti-pathogenic activity of the isolates; and ii) rhizosphere competence-associated genes, associated with the capacity of microorganisms to successfully inhabit plant roots, and a prerequisite for the success of a soil amended BCA. Altogether, 56 phylogenetically-diverse isolates with bioactivity against bacterial, oomycete and fungal plant pathogens were identified. These strains were sent to Auburn University where bioassays against a panel of animal and human pathogens (including multi-drug resistant pathogenic strains such as A. baumannii 3806) were conducted. Nineteen isolates that showed substantial antagonistic activity against at least one of the screened pathogens were sequenced, assembled and subjected to bioinformatics analyses aimed at identifying secondary metabolite-encoding and rhizosphere competence-associated genes. The genome size of the bacteria ranged from 3.77 to 9.85 Mbp. All of the genomes were characterized by a plethora of secondary metabolite encoding genes including non-ribosomal peptide synthase, polyketidesynthases, lantipeptides, bacteriocins, terpenes and siderophores. While some of these genes were highly similar to documented genes, many were unique and therefore may encode for novel antagonistic compounds. Comparative genomic analysis of root-associated isolates with similar strains not isolated from root environments revealed genes encoding for several rhizospherecompetence- associated traits including urea utilization, chitin degradation, plant cell polymerdegradation, biofilm formation, mechanisms for iron, phosphorus and sulfur acquisition and antibiotic resistance. Our labs are currently writing a continuation of this feasibility study that proposes a unique pipeline for the detection of BCAs and biopesticides that can be used against phytopathogens. It will combine i) metabolomic screening of strains from our collection that contain unique secondary metabolite-encoding genes, in order to isolate novel antimicrobial compounds; ii) model plant-based experiments to assess the antagonistic capacities of selected BCAs toward selected phytopathogens; and iii) an innovative next-generation-sequencing based method to monitor the relative abundance and distribution of selected BCAs in field experiments in order to assess their persistence in natural agro-environments. We believe that this integrated approach will enable development of novel strains and compounds that can be used in large-scale operations.

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Wu, Yingjie, Selim Gunay, and Khalid Mosalam. Hybrid Simulations for the Seismic Evaluation of Resilient Highway Bridge Systems. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, November 2020. http://dx.doi.org/10.55461/ytgv8834.

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Bridges often serve as key links in local and national transportation networks. Bridge closures can result in severe costs, not only in the form of repair or replacement, but also in the form of economic losses related to medium- and long-term interruption of businesses and disruption to surrounding communities. In addition, continuous functionality of bridges is very important after any seismic event for emergency response and recovery purposes. Considering the importance of these structures, the associated structural design philosophy is shifting from collapse prevention to maintaining functionality in the aftermath of moderate to strong earthquakes, referred to as “resiliency” in earthquake engineering research. Moreover, the associated construction philosophy is being modernized with the utilization of accelerated bridge construction (ABC) techniques, which strive to reduce the impact of construction on traffic, society, economy and on-site safety. This report presents two bridge systems that target the aforementioned issues. A study that combined numerical and experimental research was undertaken to characterize the seismic performance of these bridge systems. The first part of the study focuses on the structural system-level response of highway bridges that incorporate a class of innovative connecting devices called the “V-connector,”, which can be used to connect two components in a structural system, e.g., the column and the bridge deck, or the column and its foundation. This device, designed by ACII, Inc., results in an isolation surface at the connection plane via a connector rod placed in a V-shaped tube that is embedded into the concrete. Energy dissipation is provided by friction between a special washer located around the V-shaped tube and a top plate. Because of the period elongation due to the isolation layer and the limited amount of force transferred by the relatively flexible connector rod, bridge columns are protected from experiencing damage, thus leading to improved seismic behavior. The V-connector system also facilitates the ABC by allowing on-site assembly of prefabricated structural parts including those of the V-connector. A single-column, two-span highway bridge located in Northern California was used for the proof-of-concept of the proposed V-connector protective system. The V-connector was designed to result in an elastic bridge response based on nonlinear dynamic analyses of the bridge model with the V-connector. Accordingly, a one-third scale V-connector was fabricated based on a set of selected design parameters. A quasi-static cyclic test was first conducted to characterize the force-displacement relationship of the V-connector, followed by a hybrid simulation (HS) test in the longitudinal direction of the bridge to verify the intended linear elastic response of the bridge system. In the HS test, all bridge components were analytically modeled except for the V-connector, which was simulated as the experimental substructure in a specially designed and constructed test setup. Linear elastic bridge response was confirmed according to the HS results. The response of the bridge with the V-connector was compared against that of the as-built bridge without the V-connector, which experienced significant column damage. These results justified the effectiveness of this innovative device. The second part of the study presents the HS test conducted on a one-third scale two-column bridge bent with self-centering columns (broadly defined as “resilient columns” in this study) to reduce (or ultimately eliminate) any residual drifts. The comparison of the HS test with a previously conducted shaking table test on an identical bridge bent is one of the highlights of this study. The concept of resiliency was incorporated in the design of the bridge bent columns characterized by a well-balanced combination of self-centering, rocking, and energy-dissipating mechanisms. This combination is expected to lead to minimum damage and low levels of residual drifts. The ABC is achieved by utilizing precast columns and end members (cap beam and foundation) through an innovative socket connection. In order to conduct the HS test, a new hybrid simulation system (HSS) was developed, utilizing commonly available software and hardware components in most structural laboratories including: a computational platform using Matlab/Simulink [MathWorks 2015], an interface hardware/software platform dSPACE [2017], and MTS controllers and data acquisition (DAQ) system for the utilized actuators and sensors. Proper operation of the HSS was verified using a trial run without the test specimen before the actual HS test. In the conducted HS test, the two-column bridge bent was simulated as the experimental substructure while modeling the horizontal and vertical inertia masses and corresponding mass proportional damping in the computer. The same ground motions from the shaking table test, consisting of one horizontal component and the vertical component, were applied as input excitations to the equations of motion in the HS. Good matching was obtained between the shaking table and the HS test results, demonstrating the appropriateness of the defined governing equations of motion and the employed damping model, in addition to the reliability of the developed HSS with minimum simulation errors. The small residual drifts and the minimum level of structural damage at large peak drift levels demonstrated the superior seismic response of the innovative design of the bridge bent with self-centering columns. The reliability of the developed HS approach motivated performing a follow-up HS study focusing on the transverse direction of the bridge, where the entire two-span bridge deck and its abutments represented the computational substructure, while the two-column bridge bent was the physical substructure. This investigation was effective in shedding light on the system-level performance of the entire bridge system that incorporated innovative bridge bent design beyond what can be achieved via shaking table tests, which are usually limited by large-scale bridge system testing capacities.

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Tire Experimental Characterization Using Contactless Measurement Methods. SAE International, August 2021. http://dx.doi.org/10.4271/2021-01-1114.

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In the frame of automotive Noise Vibration and Harshness (NVH) evaluation, inner cabin noise is among the most important indicators. The main noise contributors can be identified in engine, suspensions, tires, powertrain, brake system, etc. With the advent of E-vehicles and the consequent absence of the Internal Combustion Engine (ICE), tire/road noise has gained more importance, particularly at mid-speed driving and in the spectrum up to 300 Hz. At the state of the art, the identification and characterization of Noise and Vibration sources rely on pointwise sensors (microphones, accelerometers, strain gauges). Optical methods such as Digital Image Correlation (DIC) and Laser Doppler Vibrometer (LDV) have recently received special attention in the NVH field because they can be used to obtain full-field measurements. Moreover, these same techniques could also allow to characterize the tire behavior in operating conditions, which would be practically impossible to derive with standard techniques. In this paper we will demonstrate how non-contact full-field measurement techniques can be used to reliably and robustly characterize the tire behavior up to 300 Hz, focusing on static conditions. Experimental modal analysis will extract the modal characteristic of the tire in both free-free and statically preloaded boundary conditions, using both DIC and LDV. The extracted natural frequencies, damping ratios and full-field mode shapes will be used on one side to improve the accuracy of tire models (either by deriving FRF based models or updating FE ones) but also as a reference for future investigation on the tire behavior characterization in rotating conditions.

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