Design and development of a multi configuration beam vibration test setup
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1) A multi-configuration beam vibration test setup was developed that can test beams in different configurations like cantilever, overhang, and simply supported with spans from 0.5 to 1.125 meters. 2) Experimental modal analysis was performed on cantilever beam specimens made of mild steel, aluminum, and polymer using an FFT analyzer. The first three natural frequencies were measured and agreed well with theoretical and FEA results. 3) The setup was developed at 50% lower cost than commercial options, and provides additional capabilities like variable shaft diameters for torsional testing.
![International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME
26
Recently, the experimental modal analysis (abbreviated as EMA) or simply modal testing has gained
admiration. It has become an effective means for identifying, understanding and simulating dynamic
behaviour and responses of structures [1]. EMA is a non-destructive testing technique based on
vibration responses of the structures. One of the frequently used technique in EMA is impacting the
structure by using a wooden mallet or impact hammer to excite its natural frequencies. The
frequency response functions (FRFs) are captured using the Fast Fourier Transform technique (FFT)
using a suitable transducer and FFT analyser. Figure 1 shows the typical schematic diagram of the
EMA technique. For successful implementation of the EMA for analysing the various key
parameters of the different beam configurations, a multi-functional setup for the experimentation
with provisions for all such configuration is required to set a benchmark in the data acquired.
Moreover, it facilitates same boundary conditions to be incorporated in experimentation for all the
specimens for assessment. In short, there must be repeatability in producing the same clamping
forces to incorporate same boundary conditions for different specimens so as to minimise the errors.
To achieve this, the work of setup development is undertaken to facilitate further studies on it.
Fig.1schematic diagram of the setup [2]
2. DEVELOPMENT OF THE SETUP
As mentioned, a setup with all the possible provisions for the study of beam vibrations with
different configurations is developed. Mild steel is selected as the material for the parts of setup as it
has higher density, high energy absorbing capacity and economical availability, and also provides
rigidity to the structure. The approximate weight of the setup is 180 kg. Due care has been taken
towards the geometrical tolerances and aesthetics while designing and manufacturing the setup.
Figure 2 shows the part details of the setup and figure 3 shows the CAD model of setup developed.
Fig.2 part details of the setup developed](https://image.slidesharecdn.com/designanddevelopmentofamulti-configurationbeamvibrationtestsetup-150820094358-lva1-app6891/85/Design-and-development-of-a-multi-configuration-beam-vibration-test-setup-2-320.jpg)
![International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME
27
Fig.3 CAD model of setup developed
2.1. Features
The setup can house different beam configurations like cantilever, overhang, simply
supported with a span length from 0.5 meters up to 1.125 meters. The beam specimens of width up to
50mm can be mounted on the setup with an additional provision up to 75mm width. Also a torsional
vibration module (free and forced) is developed along with the beam vibration module. An additional
provision of varying the shaft diameter from 1 mm up to 10mm is made in the setup which is not
available with the commercially available setups.
The main feature of the setup along with the features provided in it is its economic costing. It
is manufactured, developed and installed at about 50% cost of commercially available setups. It is
provided with the features that are not available in existing commercial versions. Due care has been
given to aesthetics while modelling and manufacturing the setup.
3. THEORETICAL BACKGROUND OF BEAM VIBRATIONS
The frequency of a simple uniform cantilever beam with rectangular cross section can be
obtained from the following equation:
= (1)
Where,
A is the area of cross section of beam, L is the length of the beam, ρ is the density of
material, EI is the equivalent bending stiffness and is the constant relative to the vibration bound
condition [3][4].Using the formula, we can derive the fundamental mode shape frequencies of the
beam specimens of different materials.](https://image.slidesharecdn.com/designanddevelopmentofamulti-configurationbeamvibrationtestsetup-150820094358-lva1-app6891/85/Design-and-development-of-a-multi-configuration-beam-vibration-test-setup-3-320.jpg)
Design and development of a multi configuration beam vibration test setup
- 1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME 25 DESIGN AND DEVELOPMENT OF A MULTI- CONFIGURATION BEAM VIBRATION TEST SETUP Indrajeet J. Shinde1 , D. B. Jadhav2 , Dr. S. S. Kadam3 , Prasad Ranbhare4 1 Research Scholar, 2 Asst. Professor, 3 Asso. Professor and Head, 4 Research Scholar 1,2,3,4 Department of Mechanical Engineering, Bharati Vidyapeeth University College of Engineering, Satara Road, Pune, Maharashtra, India ABSTRACT Over last few decades, significant work in the area of beam vibrations is reported. Uses of classical beam theories have been implemented to study the modal characteristics viz. mode shapes, frequency and damping. The change of modal characteristics provides an indication of structural condition based on changes in frequencies and mode shapes of vibration. This needs to be checked theoretically and validated experimentally with the specimens. In the present work, a setup for the beam vibrations with different configurations is developed economically. The setup can check many key parameters of beam vibrations. Further a case study is presented, whereby cantilever beam specimens with different materials are checked using FFT analyser on the setup developed and the results are validated using ANSYS package. Key words: ANSYS, Cantilever Beam, FFT Analysis, Modal Analysis, Vibration Analysis. 1. INTRODUCTION Vibration analysis is very significant from the design point of view. It gives an idea about the dynamic behaviour of the structural elements in the actual harsh working environments. The information collected from the vibration data helps the designer to make the necessary changes in the design to avoid the resonance condition of extreme amplitude of vibration, thereby increasing the reliability of the system. So it is imperative to design the system prior to installation to avoid its vibration born failures. Beam structures find widespread applications. They are found in various configurations like fixed-fixed, fixed-free, overhang, continuous etc. as per the application. The parameters for all such configurations differ from application to application. Thus it is needed to check and examine the key parameters with direct bearing on the dynamic behaviour of the system. INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 6, Issue 5, May (2015), pp. 25-33 © IAEME: www.iaeme.com/IJMET.asp Journal Impact Factor (2015): 8.8293 (Calculated by GISI) www.jifactor.com IJMET © I A E M E
- 2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME 26 Recently, the experimental modal analysis (abbreviated as EMA) or simply modal testing has gained admiration. It has become an effective means for identifying, understanding and simulating dynamic behaviour and responses of structures [1]. EMA is a non-destructive testing technique based on vibration responses of the structures. One of the frequently used technique in EMA is impacting the structure by using a wooden mallet or impact hammer to excite its natural frequencies. The frequency response functions (FRFs) are captured using the Fast Fourier Transform technique (FFT) using a suitable transducer and FFT analyser. Figure 1 shows the typical schematic diagram of the EMA technique. For successful implementation of the EMA for analysing the various key parameters of the different beam configurations, a multi-functional setup for the experimentation with provisions for all such configuration is required to set a benchmark in the data acquired. Moreover, it facilitates same boundary conditions to be incorporated in experimentation for all the specimens for assessment. In short, there must be repeatability in producing the same clamping forces to incorporate same boundary conditions for different specimens so as to minimise the errors. To achieve this, the work of setup development is undertaken to facilitate further studies on it. Fig.1schematic diagram of the setup [2] 2. DEVELOPMENT OF THE SETUP As mentioned, a setup with all the possible provisions for the study of beam vibrations with different configurations is developed. Mild steel is selected as the material for the parts of setup as it has higher density, high energy absorbing capacity and economical availability, and also provides rigidity to the structure. The approximate weight of the setup is 180 kg. Due care has been taken towards the geometrical tolerances and aesthetics while designing and manufacturing the setup. Figure 2 shows the part details of the setup and figure 3 shows the CAD model of setup developed. Fig.2 part details of the setup developed
- 3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME 27 Fig.3 CAD model of setup developed 2.1. Features The setup can house different beam configurations like cantilever, overhang, simply supported with a span length from 0.5 meters up to 1.125 meters. The beam specimens of width up to 50mm can be mounted on the setup with an additional provision up to 75mm width. Also a torsional vibration module (free and forced) is developed along with the beam vibration module. An additional provision of varying the shaft diameter from 1 mm up to 10mm is made in the setup which is not available with the commercially available setups. The main feature of the setup along with the features provided in it is its economic costing. It is manufactured, developed and installed at about 50% cost of commercially available setups. It is provided with the features that are not available in existing commercial versions. Due care has been given to aesthetics while modelling and manufacturing the setup. 3. THEORETICAL BACKGROUND OF BEAM VIBRATIONS The frequency of a simple uniform cantilever beam with rectangular cross section can be obtained from the following equation: = (1) Where, A is the area of cross section of beam, L is the length of the beam, ρ is the density of material, EI is the equivalent bending stiffness and is the constant relative to the vibration bound condition [3][4].Using the formula, we can derive the fundamental mode shape frequencies of the beam specimens of different materials.
- 4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME 28 4. EXPERIMENTAL INVESTIGATION The cantilever beam configuration is selected on the setup developed with varying the material of specimens. Specimens used are of mild steel, aluminium and isotropic polymer. Fig.4 actual testing arrangement with cantilever specimen The instruments used in this study are the OROS made 4-channel FFT analyser, and an accelerometer with magnetic base. 4.1Specifications of FFT Analyser • Made- OROS OR34 • Channels- 4 channel per plug-in for online and post analysis. • Range- 512 mHz to 25.6 kHz • Max FFT lines- 6401 • Sampling- 102.4 kS/s to 3200 S/s with 24 bit sigma-delta ADC. • Coupling- AC, DC, ICP, AC & DC float, GND • Sensitivity- User defined in mV/unit.
- 5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME 29 Fig.5 FFT analyser with front and back panel Fig.6 accelerometer 4.2Accelerometer Specifications • Made and model- DYTRAN 3056B2. • Acceleration- -50 to 50 g. • Frequency Range- 1-10000 Hz. • Accuracy- 2.0 +/- % FS • Measurement Axes- Single • Reference sensitivity- 103.7 mV/g. A wooden mallet is used to impact the beam at free end. Necessary input settings and analyser settings are made on the OROS analyser in order to obtain good frequency response functions (FRFs). The hardware is connected to the computer using the NV Gate software provided with the FFT. A typical response of the FFT is as shown in the figure 7. Fig.7 typical FFT response with NV Gate and FFT analyser Fig.8 test specimens used
- 6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME 30 Beam specifications used for the work undertaken are tabulated in TABLE 1: Table 1: Material specification FRFs for all the specimens are taken using the analyser and compared with the theoretical values obtained using equation (1) and the one obtained with ANSYS 14.5 Workbench module. 5. MODAL ANALYSIS USING ANSYS For performing the modal analysis, the beam specimen is first modelled as per the dimensions using the Pro-E Wild Fire 5.0 modeller. The IGES file of the geometry is then imported in the ANSYS 14.5 Workbench. One of the end of beam is constrained as fixed end and other is kept free. A mesh with 200 elements and 1628 nodes is applied and Solid185 element is used. The block lanczos mode extraction method is implemented and total of first ten number of modes are extracted and expanded in the Workbench. Following figures shows the results obtained from the simulation for the first three modes of the cantilever mild steel, aluminium and polymer specimens. (a) (b) (c) Fig.9 modes of vibration for steel beam (a) 1st mode (b) 2nd mode (c) 3rd mode Material Length mm Width mm Thickness mm Density kg/m3 Young’s Modulus GPa Mild steel 450 50 05 7850 210 Aluminium 450 50 05 2700 75 Polymer 450 50 05 900 1.223
- 7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME 31 (a) (b) (c) Fig.10 modes of vibration of aluminium beam (a) 1st mode (b) 2nd mode (c) 3rd mode (a) (b) (c) Fig.11 modes of vibration of polymer beam (a) 1st mode (b) 2nd mode (c) 3rd mode
- 8. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME 32 6. RESULTS AND DISCUSSION Thus the study of the free vibration of the cantilever beams of different materials viz. mild steel, aluminium and isotropic polymer is carried out satisfactorily on the setup developed. Theoretical, numerical and experimental approach is used to calculate the modal frequencies of the specimens. Results are found to be in good agreement with each other. The discrepancies in the results may be due to the material in-homogeneity, loading effects, numerical error built in the software etc. Following table shows the results obtained. The data is compared and tabulated for the first three modes of vibration. Graph shows the comparison of the FEA results for first ten modes of vibration of three specimens. Table 2: Theoretical, numerical and experimental results Fig. 12: mode shapes for specimens (mode shape vs. frequency) 7. CONCLUSION Thus a multi-configuration beam vibration setup is established at around 50% cost of commercially available versions and with additional features. Also a Non-Destructive method for cantilever beam vibration study with three different materials is successfully carried out on the setup and the results obtained are in good agreement with the theoretical and numerical (FEA) results. Theoretical Classical Theory FEA Experimental 1st Mode 2nd Mode 3rd Mode 1st Mode 2nd Mode 3rd Mode 1st Mode 2nd Mode 3rd Mode M.S 20.62 129.28 362.02 20.69 130.73 204.83 22.5 125 212.5 Aluminium 21.01 131.73 368.9 21.27 133.21 208.72 18.5 112.5 185.5 Polymer 4.64 29.13 81.59 4.704 29.464 46.164 6.5 33 57.5
- 9. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 6, Issue 5, May (2015), pp. 25-33© IAEME 33 REFERENCES 1. D. Ravi Prasad and D. R. Seshu, ‘A study on dynamic characteristics of structural materials using modal analysis’, Asian journal of civil Engineering (Building and housing) Vol. 9, No. 2 (2008), pg. 141-152. 2. Ertugrul Cam, Sadettin Orhan, Murat Luy, ‘An analysis of cracked beam structure using impact echo method’, NDT&E International 38 (2005), pg. 368-373. 3. Mohammad Vaziri, Ali Vaziri, Prof. S. S. Kadam, ‘Vibration analysis of a cantilever beam by using FFT analyser’, International Journal of Advanced Engineering Technology/Vol. IV/Issue II/April-June 2013/pg. 112-115. 4. J. P. Chopade, R.B. Barjibhe, ‘Free vibration analysis of fixed free beam with theoretical and numerical approach method’, International Journal of Innovations in Engineering and Technology, Vol. II/Issue I/February 2013, pg. 352-356. 5. Isam Jasim Jaber and Ajeet Kumar Rai, “Design and Analysis of I.C. Engine Piston And Piston-Ring Using Catia and Ansys Software” International Journal of Mechanical Engineering & Technology (IJMET), Volume 5, Issue 2, 2012, pp. 64 - 73, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 6. Dr.Yadavalli Basavaraj and Pavan Kumar B K, “Modeling And Analysis of Base Plate For Brake Spider Fixture by Fem Using Ansys Software” International Journal of Mechanical Engineering & Technology (IJMET), Volume 4, Issue 5, 2012, pp. 26 - 30, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359. 7. Prabhat Kumar Sinha, Rajneesh Pandey and Vijay Kumar Yadav, “Analysis and Modeling Of Single Point Cutting(Hss Material) Tool with Help of Ansys For Optimization of (Transient) Vibration Parameters” International Journal of Mechanical Engineering & Technology (IJMET), Volume 5, Issue 6, 2014, pp. 14 - 27, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.