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.
In a lightweight planar parallel robot, unwanted linkage vibrations are induced during high-speed motion. The transfer functions from motor inputs to linkage vibrations are dependent on the robot ...configuration. In this work, we experimentally identify linkage vibrations by performing experimental modal analysis using lead zirconate titanate transducers. Then, the contributions of linkage modes are separated from configuration-dependent transfer functions. Through redefinition of vibration inputs, the flexible linkage dynamics is approximated by a linear dynamic model with variations of natural frequencies. Based on this simplification, a modal controller is designed to control two linkage modes. Experimental control results, yielding more than 50% reduction of vibration amplitudes of these two modes, validate the effectiveness of the proposed control strategy.
Modal Analysis of a Container Filled with Water Chandravanshi, M L; Mukhopadhyay, Alok Kumar
Applied Mechanics and Materials,
07/2014, Volume:
592-594, Issue:
Dynamics of Machines and Mechanisms, Industrial Research
Journal Article
Peer reviewed
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
The impulse response method is often used to measure firmness of spherical fruits. In this method the fruit is excited using an impact hammer and the response signal is captured using a microphone. ...This vibration response signal is subsequently analysed and related to the firmness of the fruit. In our work the effect of the shape of pears on their resonant frequencies is investigated using finite element (FE) modal analysis. Fifty differently shaped 3D FE meshes of ‘Conference’ pears were generated using a geometrical modelling system. The FE model was validated, and found to be sufficiently accurate. The length/maximal diameter (
L/
D) ratio and the Fourier descriptors were used as shape descriptors. A strong linear relationship (
r
2>0.84) was found between the third normalised Fourier descriptor (F3) and the resonant frequencies. A weak linear relation was detected using the
L/
D and the other normalised Fourier descriptors. A simulation of firmness measurements based on the calculated resonant frequency values was carried out to estimate the Young's (
E) modulus of the pear as a measure of its firmness. The estimated error with these simulations was found to be 31.44,
8.02 and 3.82% if the bending, the compression and the oblate–prolate modes were measured and the
L/
D was used as a shape descriptor. If F3 was used, the following error values were found: 6.0% for the bending, 3.39% for compression and 3.38% for the oblate–prolate modes. The results of this study may help in the development of a non-destructive firmness sensor for non-spherical fruits.
Dynamic tests are performed on similarly structured crankcase covers and boxes made of AZ91D magnesium and A380 aluminum alloys. The real vibration and noise control effect of an AZ91D magnesium ...alloy is evaluated, based on the behavior of the integral frequency response function, which is derived from the measured surface vibrations of the crankcase cover under operating conditions. The results indicate that crankcase covers and boxes made of AZ91D magnesium and A380 aluminum alloys with the same geometry possess similar normal characteristics. Both materials are interchangeable. However, the stiffness of AZ91D crankcase covers and boxes is poor. It is also difficult to obtain good engineering vibration and noise effects in the real structure due to an AZ91D high damping capacity. At the same excitation and frequency response at different structure characteristics, the measurement analysis of time-domain response indicates that methods to strengthen the crankcase box stiffness, such as embedding a main bearing steel sleeve, is favorable for improving the dynamic characteristics of an AZ91D crankcase box.
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