Examinando por Materia "Modal analysis"

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    Base shear determination using response-spectrum modal analysis of multi-degree-of-freedom systems with soil–structure interaction
    (Springer Netherlands, 2019-01-01) Arias H.; Jaramillo J.D.; Mecánica Aplicada
    Building codes and design guidelines, e.g. FEMA (NEHRP recommended seismic provisions for new buildings and other structures, FEMA P-1050, Washington, 2015) and ASCE (Minimum design loads for buildings and other structures ASCE/SEI 7-10/2010, Reston, 2010), describe the problem of multi-degree-of-freedom systems with soil-structure interaction (SSI). These systems are modeled like those having a fundamental degree of freedom on a foundation with lateral and rotational interactions and the other vibration modes isolated and supported on a fixed foundation. This model oversimplifies the problem, neglecting the effects of having all modes coupled in the foundation with SSI. A simple, easily programmable, SSI model in which all vibration modes are coupled an attached to an infinitely rigid shallow foundation subjected to soil excitation is introduced here. Initially, the total response of the coupled system is calculated. Then, using traditional procedures to combine modal responses, a simplified alternative methodology to find the total response of this coupled system is proposed. The new methodology is verified against a robust numerical technique, i.e. boundary elements method, using a wide variety of cases that combine several types of soils, building heights and two structural typologies: bending frames and shear walls. Finally, it is clear from the parametric study that current methodologies, based only on the interaction of the fundamental mode of vibration of the structure, in some cases has a significant influence on the total base shear of buildings, particularly in tall buildings founded in soft soils. © 2019, Springer Nature B.V.
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    Determination of the technical state of suspension elements based on the OMA-LSCE method
    (Collegio Ingegneri Ferroviari Italiani, 2012-01-01) Castañeda, L.; Martinod, R.; Betancur, G.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Estudios en Mantenimiento (GEMI)
    A study is established regarding the behavior of the vehicle under the influence of the damping elements, proposing a methodology for the validation of the technical state of the dampers through the registration of dynamic variables under commercial operating conditions of the vehicle, by applying the Operational Modal Analysis COMA) technique via Least-Square Complex Exponential (LSCE) method to experimental tests and numeric simulations to a multi-body system (MBS) model. The OMA-LSCE method is applied to the signals acquired during a test performed on a passenger of a three- car unit in typical commercial travel operation. From the signals in time domain of each section of the segment, the respective discrete function PSD is calculated. Once the model is defined, a set of numeric simulation is executed according to the design of the experiment. The results of the numeric simulations show that the natural frequency generates a lineal regressive model with correlation coefficient values.
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    Determinazione dello stato tecnico degli elementi delle sospensioni sulla base del metodo OMA-LSCE
    (Collegio Ingegneri Ferroviari Italiani, 2012-01-01) Castañeda, L.; Martinod, R.; Betancur, G.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Estudios en Mantenimiento (GEMI)
    A study is established regarding the behavior of the vehicle under the influence of the damping elements, proposing a methodology for the validation of the technical state of the dampers through the registration of dynamic variables under commercial operating conditions of the vehicle, by applying the Operational Modal Analysis COMA) technique via Least-Square Complex Exponential (LSCE) method to experimental tests and numeric simulations to a multi-body system (MBS) model. The OMA-LSCE method is applied to the signals acquired during a test performed on a passenger of a three- car unit in typical commercial travel operation. From the signals in time domain of each section of the segment, the respective discrete function PSD is calculated. Once the model is defined, a set of numeric simulation is executed according to the design of the experiment. The results of the numeric simulations show that the natural frequency generates a lineal regressive model with correlation coefficient values.
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    Ítem
    Identification of the technical state of suspension elements in railway systems
    (TAYLOR & FRANCIS LTD, 2012-01-01) Mauricio Martinod, Ronald; Rene Betancur, German; Castaneda Heredia, Leonel Francisco; Universidad EAFIT. Departamento de Ingeniería Mecánica; Estudios en Mantenimiento (GEMI)
    The running safety and passenger comfort levels in a vehicle are tightly related to the technical state of the suspension elements. The technical state of the suspension depends of the service life time as its components become old and wear out. In this paper, a study on the dynamic behaviour of a railway vehicle is established in relation to the damping elements in one of its suspension stages. An experimental measurement model is developed, obtaining a set of useful signals for the identification of the dynamic parameters of the vehicle and developing a test through the application of the operational modal analysis technique, using least-squares complex exponential method as a basis to validate the numerical model of the multi-body system. Then, the study focuses on developing numerical simulations for the identification of the technical state of the dampers by the registration of dynamic variables under commercial service conditions and on estimating the state of the suspension elements. © 2012 Taylor & Francis.
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    Multi-modal interface for a real-time CFD solver
    (2007-01-01) Kasakevich, M.; Boulanger, P.; Bischof, W.F.; Garcia, M.; Kasakevich, M.; Boulanger, P.; Bischof, W.F.; Garcia, M.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Mecánica Aplicada
    Advances in computer processing power and networking over the past few years have brought significant changes to the modeling and simulation of complex phenomena. Problems that formerly could only be tackled in batch mode, with their results visualized afterwards, can now be monitored whilst in progress using graphical means. In certain cases, it is even possible to alter parameters of the computation whilst it is running, depending on what the scientist perceives in the current visual output. This ability to monitor and change parameters of the computational process at any time and from anywhere is called computational steering. Combining this capability with advanced multi-modal tools to explore the data produced by these systems are key to our approach. In this paper, we present an advanced multi-modal interface where sonification and 3D visualization are used in a computational steering environment specialized to solve real-time Computational Fluid Dynamics (CFD) problems. More specifically, this paper describes how sonification of CFD data can be used to augment 3D visualization. © 2006 IEEE.
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    Quality identification methodology applied to wall-elements based on modal analysis
    (Emerald Group Publishing Ltd., 2015-01-01) Zóltowski, M.; Martinod, R.M.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Estudios en Mantenimiento (GEMI)
    Purpose - The recommendation of structural standards, e.g. PN-B-03002, shows a need to control the production quality of wall-elements; the quality control demands suitable guidelines to fit the requirements of the current mass-production of the wall-elements, then, the structural standard recognizes the need of improving the methods to identify the real elements quality. The paper aims to discuss these issues. Design/methodology/approach - The proposed inspection methodology corresponds to assessment models that combine the numerical and symptomatic models to evaluate the critical levels of wall-elements, based on non-intrusive tests through the measurement of a set of signals, using the Experimental Modal Analysis (EMA)-based techniques. Findings - The presented work is developed with an approach that applies advanced calculating techniques used for the structural analysis in civil engineering focused on the technical state assessment. Originality/value - The paper proposes a diagnostic methodology that can be added to the current regulations and standards based on EMA techniques. © Emerald Group Publishing Limited.