Generally, agricultural tires have high and large cross-switch lugs to achieve optimal motion without slipping in a rice field. Therefore, when the agricultural machines run on normal roads, the ...vibration and noise caused by interaction between the tire lugs and the road surface are inevitable. In this study, a test equipment is manufactured to determine the motion of a rolling agricultural tire with ground contact and the characteristics of motion for rotational speed are investigated. Next, natural frequencies and natural modes of the tire are obtained by carrying out experimental modal analysis. By using the obtained results, the influence of vibration characteristics on the dynamic behavior of rolling tires are investigated.
A modal parameter identification software named as N-Broband is developed in VC++ platform. The software is suitable for EMA and OMA with broband identification feature. Meanwhile it also includes ...narrow band and selected band modal parameter identification methods. Correlation analysis between experiment and FEA can be performed in N-Broband. The validation of N-Broband is carried out by Test.Lab modal analysis software. The result coincides with Test.Lab very well, which indicates that the developed software can be used in modal analysis of real structure.
The singular value decomposition of the measured frequency response function matrix, as a very effective tool of experimental modal analysis is used over the last twenty-five years. The complex mode ...indication function has become a common numerical tool in processing experimental data. There are many references on the development of complex mode indication function including the enhanced mode indication function and its use together with the enhanced frequency response function to form spatial domain modal parameter estimation methods. Another amendment of the enhanced mode indicator function method is the extension of the single degree-of-freedom aspects of the complex mode indication function method to include a limited number of modes. In the paper, methods for estimation of damped eigen frequencies, modal damping and mode shapes are presented that are based on singular value decomposition of frequency response function matrix. It is shown how to obtain phase information for the complex mode indication function, in order to use the standard single degree-of-freedom modal parameter estimation methods. New aggregated frequency response function is introduced. A leastsquares approximation will be presented for eliminating the error caused by frequency discretization. Analytical models and examples taken from vehicle industry are also used to demonstrate applications of the aggregated frequency response function method and estimation of modal damping. Keywords: complex mode indication function; damping estimate; experimental modal analysis; frequency response function matrix; singular values decomposition Dekompozicija singularnih vrijednosti izmjerene matrice funkcije frekventnog odziva se, kao vrlo ucinkovit alat eksperimentalne modalne analize, koristi zadnjih dvadeset i pet godina. Funkcija indikacije kompleksnog moda postala je uobicajeni numericki alat u obradi eksperimentalnih podataka. Veliki je broj referenci o razvoju funkcije indikacije kompleksnog moda ukljucujuci poboljsanu funkciju indikacije moda i njenu primjenu skupa s poboljsanom funkcijom frekventnog odgovora u razvoju metoda procjene modalnog parametra prostornog podrucja. Jos jednu nadopunu poboljsanoj metodi funkcije indikatora moda predstavlja prosirenje aspekata jednog stupnja slobode metode indikacije funkcije kompleksnog moda na ograniceni broj modova. U radu su predstavljene metode za procjenu prigusenih eigen frekvencija, modalnog prigusenja i oblika modova, zasnovane na dekompoziciji singularne vrijednosti matrice funkcije frekventnog odgovora. Pokazano je kako dobiti faznu informaciju za funkciju indikacije kompleksnog moda u svrhu primjene standardnih metoda procjene modalnim parametrom s jednim stupnjem slobode. Uvedena je novo dobivena funkcija frekventnog odziva. Pokazat ce se aproksimacija najmanjih kvadrata za eliminiranje greske izazvane diskretizacijom frekvencije. Koristeni su tako?er analiticki modeli i primjeri iz industrije vozila u svrhu demonstracije primjene dobivene metode funkcije frekventnog odziva i procjene modalnog prigusenja. Kljucne rijeci: dekompozicija singularnih vrijednosti; eksperimentalna modalna analiza; funkcija indikacije kompleksnog moda; matrica funkcije frekventnog odziva; procjena prigusenja
Purpose
– The purpose of this paper is to analyse the eigenforms and eigenfrequencies of stator core stack by experimental and numerical investigation. The influence of material parameters on the ...structural vibrations is carried out in order to describe the laminated structure of stator core stack with a homogeneous material model.
Design/methodology/approach
– The finite element method is applied for a numerical modal analysis. Therefore, a homogeneous transversally isotropic material model is introduced and the influence of each material parameter on the dynamical behavior is investigated. These material parameters are stepwise adjusted to the results from the experimental modal analysis. The investigation includes results from different stator core stacks.
Findings
– The influence of material on the modal parameters is shown. Furthermore, material parameters are carried out for stator core stacks, which describe the measured dynamical behaviour.
Originality/value
– The presented investigations show a useable material model and corresponding parameters to the description of the laminated structure of stator core stacks.
Natural modes and frequencies of gas turbine engine hollow fan blades were experimentally investigated. The blades were produced with the method of super-plastic molding and pressure welding ...combination. Two independent experimental methods were used: three-component scanning laser vibrometry and impact modal analysis. Natural frequencies and vibration modes of a hollow fan blade and stress fields corresponding to the natural modes were got. The finite element modal analysis was carried out. The hollow fan blade was stated to have particular natural vibration modes. The investigation results can be used to detune the resonance vibrations and to verify calculation models.
Failures of turbine blades are one of the most critical problems in power generating industry. Among the different failure mechanisms, resonant vibration of blades has a major role and therefore is ...the subject of many recent research works. Therefore, in this paper, modal analysis of a first stage blade in ALSTOM gas turbine is investigated and natural frequencies and vibration modes of blade are found in various conditions. For this purpose, a cloud-point model of a gas turbine blade has been created using 3D Laser Digitizer. Then the numerical calculation by finite element method using ANSYS software based on experimental test conditions is utilized and Experimental natural frequencies have been obtained. The results show acceptable agreement between the experimental and FEM results.
In order to know the vibration characteristics of the vehicle body in white, the experimental modal analysis was performed by using LMS modal equipment. The basic principle of experimental modal ...analysis was introduced. Then, the first ten order modes were obtained within 100 Hz. The front several main modes were analyzed. The test results fully show that the car body in white has excellent first order torsional, bending and overall vibrational characteristics.
Modal Analysis of a Container Filled with Water Mukhopadhyay, Alok Kumar; Chandravanshi, M.L.
Applied Mechanics and Materials,
07/2014, Letnik:
592-594, Številka:
Dynamics of Machines and Mechanisms, Industrial Research
Journal Article
Recenzirano
Modal analysis plays an important role at design stage which helps in diagnosing problems related to structural vibration. This paper delineates about the experimental work to investigate the modal ...parameters, such as mode shapes and natural frequencies of a metallic container. The modal parameters have been experimentally determined for the empty container, the container filled with one liter of water and the container filled with two liters of water. Theoretical analysis is also carried out through finite element analysis using ANSYS workbench 14 for finding out modal parameters of the empty container only. The boundary conditions of the container in the experimental and FEM analysis have been kept same. The values of modal parameters obtained by the two methods then compared for their proximity
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