scholarly journals Similarity Analysis between Scale Model and Prototype of Large Vibrating Screen

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Zerong Zhang ◽  
Yongyan Wang ◽  
Zhimin Fan
Keyword(s):  
Frequency Response ◽  
Natural Frequencies ◽  
Similarity Theory ◽  
Similarity Criteria ◽  
Scale Model ◽  
Mode Shapes ◽  
Dynamic Stresses ◽  
Operating Condition ◽  
Vibrating Screen ◽  
Scale Down

In order to predict the physical characteristics of the large vibrating screen from its scale-down model, the similarity ratios of the frequency response functions, mode shapes, and dynamic stresses between the prototype and the scale model screen are built according to the similarity theory. The natural frequencies and modal shapes are extracted from the frequency response function by means of modal tests, in which the relative error of the natural frequencies is less than 9% and the modal shapes are consistent between the prototype and the model. The operating condition parameters including dynamic stress, displacement, velocity, and acceleration were also measured and conform to the similarity criteria. The results show that the inherent and operating condition parameters of the large vibrating screen can be obtained from the scale-down model conveniently, which provides an effective method for structural optimization and substructure coupling analysis of the large vibrating screen.

Experimental Modal Analysis of a Half-Scale Model Twin-Engine Aircraft Rear Fuselage Engine Mount Support Frame

2017 ◽  
Author(s):  
Diego A. Chamberlain ◽  
Chris K. Mechefske
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Testing Procedure ◽  
Modal Testing ◽  
Scale Model ◽  
Mode Shapes ◽  
Component Testing ◽  
Fitting Procedures ◽  
Engine Mount ◽  
Set Up

Experimental modal testing using an impact hammer is a commonly used method for obtaining the modal parameters of any structure for which the vibrational behavior is of interest. Natural frequencies and associated mode shapes of the structure can be extracted directly from measured FRFs (Frequency Response Functions) through various curve fitting procedures. This paper provides an overview of the modal testing conducted on an aerospace component. Testing set-up, experimental equipment and the methodology employed are all described in detail. Further validation of the testing procedure was done by ensuring that the experimental results satisfy the requirements of repeatability, reciprocity and linearity. The relevant ISO standard has been referenced and important concepts to modal analysis are expanded upon. Recorded natural frequencies, coherence and a description of the observed mode shapes are presented along with notable trends.

scholarly journals Finite Element Modeling of the Dynamic Properties of Composite Steel–Polymer Concrete Beams

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1630
Author(s):  
Paweł Dunaj ◽  
Stefan Berczyński ◽  
Marcin Chodźko ◽  
Beata Niesterowicz
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Natural Frequencies ◽  
Concrete Beams ◽  
Dynamic Properties ◽  
Mode Shapes ◽  
Polymer Concrete ◽  
Response Functions ◽  
Full Agreement ◽  
High Agreement

This paper presents a method for modeling the dynamic properties of steel–polymer concrete beams, the basic structural components of machine tools, assembly lines, vibratory machines, and other structures subjected to time-varying loads during operation. The presented method of modeling steel–polymer concrete beams was developed using the finite element method. Three models of beams differing in cross-sectional dimensions showed high agreement with experimental data: relative error in the case of natural frequencies did not exceed 5% (2.2% on average), the models were characterized by the full agreement of mode shapes and high agreement of frequency response functions with the results of experimental tests. Additionally, the developed beam models supported the reliable description of complex structures, as demonstrated on a spatial frame, obtaining a relative error for natural frequencies of less than 3% (on average 1.7%). Full agreement with the mode shapes and high agreement with the frequency response functions were achieved in the analyzed frequency range.

scholarly journals On Solving One-Dimensional Partial Differential Equations With Spatially Dependent Variables Using the Wavelet-Galerkin Method

2013 ◽  
Vol 80 (6) ◽  
Author(s):  
Simon Jones ◽  
Mathias Legrand
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Galerkin Method ◽  
Frequency Response ◽  
Natural Frequencies ◽  
Basis Functions ◽  
Mode Shapes ◽  
Response Functions ◽  
Partial Differential ◽  
Frequency Response Functions

The discrete orthogonal wavelet-Galerkin method is illustrated as an effective method for solving partial differential equations (PDE's) with spatially varying parameters on a bounded interval. Daubechies scaling functions provide a concise but adaptable set of basis functions and allow for implementation of varied loading and boundary conditions. These basis functions can also effectively describe C0 continuous parameter spatial dependence on bounded domains. Doing so allows the PDE to be discretized as a set of linear equations composed of known inner products which can be stored for efficient parametric analyses. Solution schemes for both free and forced PDE's are developed; natural frequencies, mode shapes, and frequency response functions for an Euler–Bernoulli beam with piecewise varying thickness are calculated. The wavelet-Galerkin approach is shown to converge to the first four natural frequencies at a rate greater than that of the linear finite element approach; mode shapes and frequency response functions converge similarly.

Experiments on the Determination of Immersed Shell Structure Mobilities via Scale Modeling

1983 ◽  
Vol 105 (3) ◽  
pp. 207-215
Author(s):  
S. S. Sattinger
Keyword(s):  
Frequency Response ◽  
Shell Structure ◽  
Peak Frequency ◽  
Scale Model ◽  
Mode Shapes ◽  
Force Frequency ◽  
Scale Modeling ◽  
Modal Damping ◽  
Acceleration Force ◽  
Force Frequency Response

Experiments were conducted to confirm scaling relations for structural frequency response functions as applied to immersed shell structures using same-material, same-liquid scale models. Accelerance (acceleration/force) frequency response magnitude data were acquired for full-scale and half-scale versions of a fixed-free open cylinder mounted in a rigid vessel. The data confirmed that corresponding frequencies in the model and prototype were in proportion to the inverse of the geometric scale. The peak accelerance magnitudes were normalized by damping to form quantities which should scale despite differences in the corresponding modal damping values. Discrepancies in some of these normalized magnitudes coincided with angular mismatches in mode shapes attributed to minor manufacturing differences in the specimens. Thus, peak frequency responses for a prototype immersed shell structure can be estimated from scale model measurements if typical prototype damping values are known, but the locations of corresponding responses may differ between the model and the prototype in some cases.

The Finite Element Analysis of Vibrating Screen

2011 ◽  
Vol 141 ◽  
pp. 134-138
Author(s):  
Chuan Guang Ding ◽  
Fang Zhen Song ◽  
Bo Song ◽  
Xiu Hua Men
Keyword(s):  
Large Scale ◽  
Natural Frequencies ◽  
Modular Design ◽  
Mode Shapes ◽  
Response Analysis ◽  
Element Analysis ◽  
Harmonic Response ◽  
Vibrating Screen ◽  
The Finite Element Analysis ◽  
Harmonic Response Analysis

The large-scale and modular design of vibrating screen brings about the trend that the screen separate from screen frame. The separation of the screen frame and the screen changes their dynamic characteristics. By making modal analysis and harmonic response analysis in ANSYS, the dynamic data of the screen and the screen frame was obtained, such as the natural frequencies, mode shapes, stress distribution and strain distribution. The results show that the stiffness of screen frame is higher than stiffness of the screen and the side plats and beams of screen are the weak parts.

Dynamic Characteristics Analysis and Topology Optimization of Column Based on Finite Element Method

2013 ◽  
Vol 721 ◽  
pp. 541-544
Author(s):  
Jing Chen ◽  
Ze Long Yang ◽  
Xian Xuan Li
Keyword(s):  
Finite Element ◽  
Topology Optimization ◽  
Frequency Response ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Response Analysis ◽  
Response Curves ◽  
Element Analysis ◽  
Column Structure

Aiming to improve the dynamic and static characteristics of a type of machining center column, the finite element modal analysis and harmonic response analysis of the column are performed, and this paper analyzes the dynamic characteristics of the column based on the first five mode shapes and natural frequencies of the column and the displacement - frequency response curves of the column. Topology optimization analysis of the column is performed with ANSYS, and the finite element analysis is performed on the column again after the column structure is improved based on the optimal distribution of material of the column structure and the design experience of column. The result shows that the first five natural frequencies of the column increase, the peak of the displacement - frequency response of the column decrease, and the dynamic characteristics are improved significantly.

Identification of Modal Parameters in a Scale Model for a Railway Bridge

2016 ◽  
Vol 16 (09) ◽  
pp. 1550059 ◽  
Author(s):  
Ladislao R. Ticona Melo ◽  
Ramon S. Y. R. C. Silva ◽  
Tulio N. Bittencourt ◽  
Luciano M. Bezerra
Keyword(s):  
Natural Frequencies ◽  
Numerical Study ◽  
Modal Identification ◽  
Scale Model ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Subspace Identification ◽  
Dynamic Parameters ◽  
Railway Bridge ◽  
Stochastic Subspace Identification

Obtaining the dynamic parameters of a bridge is essential to validation of the model used in the dynamic analysis of the bridge. In order to implement methodologies for damage detection, many experimental modal identification tests are performed for estimating the modal parameters of structures, including the natural frequencies and mode shapes. This paper presents an experimental and numerical study for finding the modal parameters of an aluminum model built to scale of a real railway bridge. Although, so far no test has been performed on the real railway bridge for comparison with the scale model, this paper seeks to apply the scale model experimental and numerical techniques for obtaining the dynamic parameters of the bridge. The software SAP2000 was used for the numerical analyses and for the experimental aspect, the circle fit and the stochastic subspace identification methods are used. Numerical and experimental results showed good correlation.

Design Method of Dynamic Similarity of the Rotor-Bearing System

2013 ◽  
Vol 300-301 ◽  
pp. 1148-1151 ◽  
Author(s):  
Zhong Luo ◽  
Jian Zhang Li ◽  
Yu Long Yan ◽  
Qing Kai Han
Keyword(s):  
Scaling Laws ◽  
Similarity Theory ◽  
Design Method ◽  
Similarity Criteria ◽  
Scale Model ◽  
The Finite Element Method ◽  
Dynamic Similarity ◽  
Equation Analysis ◽  
Rotor Bearing ◽  
Bearing System

To predict the vibration characteristics of the rotor-bearing system by using the scale model and the associated scaling laws may significantly reduce the time and money required by the experiments. To this end, the dynamic similarity criteria are investigated inferring from the model behavior of rotor-bearing system to the vibration response of the prototype. The similar relationship was established by combining method of dimensional analysis and equation analysis based on similarity theory, and the effectiveness was verified through the finite element method. The result provide the theoretical rational for further study of the similarity design of the rotor-bearing system.

On the Deduction and the Application of Dynamic Similarity Criteria of Steel Structure under Large Deformation Condition

2012 ◽  
Vol 512-515 ◽  
pp. 1957-1960 ◽  
Author(s):  
Yuan Li
Keyword(s):  
Large Deformation ◽  
Model Test ◽  
Similarity Theory ◽  
Steel Structure ◽  
Similarity Criteria ◽  
Matrix Analysis ◽  
Scale Model ◽  
Deformation Condition ◽  
Dynamic Similarity ◽  
Similarity Relations

Dynamic similarity criteria for large deformation of huge steel structure were derived according to Dimensional Matrix Analysis of the Buckingham Pi theorem and the similarity relations that must be satisfied by the physical quantities of model and prototype in huge steel structure model test are obtained. The 1/50 scale model of TC power is designed and made based on the similarity theory and the dynamic experiment is done. The calculation data with similarity theory are in agreement with that of experiment. So the model test can substitute for prototype test when they satisfy the similarity relations. A new way to solve dynamic analysis problem of huge steel structure is explored.

scholarly journals Full-Scale Experimental Investigation of the Static and Dynamic Stiffness of Prestressed Concrete Girders

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Yongjun Zhou ◽  
Yu Zhao ◽  
Hengying Yao ◽  
Yuan Jing
Keyword(s):  
Prestressed Concrete ◽  
Flexural Rigidity ◽  
Dynamic Stiffness ◽  
Full Scale ◽  
Scale Model ◽  
Mode Shapes ◽  
Load Case ◽  
Concrete Girders ◽  
Scale Down ◽  
Prestressed Concrete Girders

Cracking damage influences the stiffness of the girders. Many articles in the literatures have studied the development of stiffness of the scale-down model; however, full-scale model testing cannot be completely replaced by scale-down testing because of material component characteristics and boundary effects. This paper deals with the effects of cracking damage on the structural static and dynamic stiffness based on three prestressed concrete (PC) girders which were removed from an old bridge. First, the equivalent flexural rigidity of cracked prestressed concrete girder was assessed using the measured load-deflection response under cycles of loading and unloading. Then, after unloading, the frequencies were measured on the PC girders supported by the elastomeric bearings. Next, the development of frequency under different damage was studied, and finally, the dynamic stiffness of PC girders with cracks was assessed. The results indicate that the first frequency is more sensitive to the cracking of concrete compared with the second frequency and that the mode shapes are not sensitive to girder damage. The test girders cannot be simplified as an ideal simply supported beam for the purpose of identifying frequencies. In addition, the “final” (the end of the ultimate load case) equivalent flexural rigidity of the girders is 30% of the “initial” (the beginning of the first load case) equivalent flexural rigidity, compared with 50% in the scale-down test; and the final dynamic stiffness is approximately 84% of the initial dynamic stiffness, whereas the scale-down test is 72%.

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