Modal-Model Applications for Large Energetic Machines

2007 ◽  
Vol 347 ◽  
pp. 221-226 ◽  
Author(s):  
Piotr Kurowski
Keyword(s):  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Operational Modal Analysis ◽  
Machine Condition ◽  
Research Practice ◽  
Dynamic Characterization ◽  
Applied Method ◽  
Modal Model ◽  
Theoretical Assumptions

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.

Operational Modal Analysis for Dynamic Characterization of a Ro-Lo Ship

2014 ◽  
Vol 58 (04) ◽  
pp. 216-224 ◽  
Author(s):  
Esben Orlowitz ◽  
Anders Brandt
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Operating Conditions ◽  
Operational Modal Analysis ◽  
Mode Shapes ◽  
Dynamic Characterization ◽  
Sea Trial ◽  
Global Modes ◽  
Bending Modes

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.

scholarly journals Vibration Analysis and Dynamic Characterization of Structural Glass Elements with Different Restraints Based on Operational Modal Analysis

Buildings ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 13 ◽  
Author(s):  
Chiara Bedon ◽  
Marco Fasan ◽  
Claudio Amadio
Keyword(s):  
Modal Analysis ◽  
Video Tracking ◽  
Operational Modal Analysis ◽  
Analytical Models ◽  
Design Stage ◽  
Damping Capacity ◽  
Structural Glass ◽  
Dynamic Characterization ◽  
Analysis And Design

Given a series of intrinsic features of structural glass systems (i.e., material properties, type of restraints, operational conditions, etc.), special care should be spent at the design stage, to ensure appropriate fail-safe requirements, but also in the service life of these innovative building components and assemblies. In this paper, the dynamic characterization of simple monolithic glass elements is presented, based on non-destructive laboratory experiments and Operational Modal Analysis (OMA) techniques, including Finite Element (FE) numerical simulations, classical analytical models, and video-tracking approaches. It is shown, in particular, how the actual restraint condition (i.e., flexibility of supports, with respect to ideal boundaries) can affect the vibration parameters of a given glass member (frequency and damping capacity). This turns out in possible variations of its overall structural performance, including stress-strain-related effects, hence suggesting the need for even further dedicated studies and methods for the reliable analysis and design of structural glass assemblies and complex systems under dynamic loads.

Dynamic Characterization of Car Door and Hood Panels Using FEA and EMA

2013 ◽  
Vol 471 ◽  
pp. 89-96 ◽  
Author(s):  
Zahir Hanouf ◽  
Waleed F. Faris ◽  
Mohd Jailani Mohd Nor
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Modal Analysis ◽  
Dynamic Properties ◽  
Experimental Modal Analysis ◽  
Modal Testing ◽  
Dynamic Characterization ◽  
Element Analysis ◽  
Structural Dynamic

The dynamic characterization of vehicle structures is a crucial step in NVH analysis and helps in refining the vibration and noise in new vehicles. This paper investigates the dynamic properties of two parts of the vehicle structure which are door and hood panels. Theoretical modal analysis which is referred to as Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA) or modal testing has been used as investigative tools. The paper investigates the structural dynamic properties of door and hood panels of a local car. ME'scope software was used to analyze the data obtained from Pulse to extract the dynamic properties of the panels. LS-DYNA software was used to analyze the dynamic behavior of the structure. The comparison between the results obtained from both analyses showed some similarity in frequencies and mode shapes. Finally the paper concludes that experimental modal analysis and finite element analysis can both be used to extract dynamic properties of structures.

scholarly journals Operational modal analysis for characterization of mechanical and thermal–hydraulic fluctuations in simulated neutron noise

2021 ◽  
Vol 373 ◽  
pp. 111017
Author(s):  
Luis Alejandro Torres Delgado ◽  
Vasudha Verma ◽  
Cristina Montalvo ◽  
Abdelhamid Dokhane ◽  
Agustín García-Berrocal
Keyword(s):  
Modal Analysis ◽  
Operational Modal Analysis ◽  
Neutron Noise

scholarly journals Analytical evaluation of the lifetime of a three-axle bogie frame using the analytical model validated through experimental modal analysis

2018 ◽  
Vol 211 ◽  
pp. 06004
Author(s):  
Manea Ion ◽  
Sebesan Ioan ◽  
Matache Mihai ◽  
Prenta Gabriel ◽  
Firicel Catalin
Keyword(s):  
Fatigue Strength ◽  
Modal Analysis ◽  
Analytical Model ◽  
Fatigue Tests ◽  
Experimental Modal Analysis ◽  
Bogie Frame ◽  
Fea Model ◽  
Modal Model ◽  
Long Time ◽  
Data Files

The fatigue strength validation by tests of the railway bogie frames requires existence of an expensive laboratory and a long time for testing, of about 6 to 10 months. Considering these aspects, the european norms admit that fatigue tests can be replaced by finite elementes analysis, with condition that analytical model to be correctly realized and validated by tests. Experimental modal analysis provides a powerful tool for validation of the FEA model through experimental data. The article presents an application for analytical assessment of the fatigue strength for a three-axle locomotive bogie frame, before sending it to the laboratory fatigue tests. Using Ansys, it was carried out the structural analysis of the bogie frame, rezulting the modal model characterized by the modal parameters: eigenfrequencies and eigenshapes. The analytical model was validated through an EMA application carried out on the bogie frame and correlation analysis of the EMA and FEA models. The analytical model and data files containing the simulated vertical, transverse and twist loads, applied to the bogie frame according to EN13749/2011, constitutes the input data for nCode program, that evaluates the bogie frame lifetime using appropriate stress curves and a recognized hypothesis of damage accumulation.

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