Vibration Analysis of Viscoelastic Sandwich Beam

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1 Vibration Analysis of Viscoelastic Sandwich Beam Prashant Ashok Patil, Sachin Shashikant Patil, Chaudhari Hemant D. TMES s J. T. Mahajan College of Engineering, Faizpur (M.S.) paprashant1991@gmail.com, sachinptl93@gmail.com Abstract: Beam is a key member of any structure. Viscoelastic and fiber reinforced composites are finding increasing application in aerospace, marine, transportation, electrical, chemical, construction and consumer goods industries. In some of these applications these materials subjected to dynamic loads. We are going to make the vibration analysis of a viscoelastic sandwich beam. A finite element model will developed for the three layer viscoelastic sandwich beam. Different specimens will be model by varying the core layers and face layers and will be study under the fixed-fixed boundary condition for modal analysis. The Natural frequencies will be obtained for various models using different core and boundary conditions. The results obtained will be comparing with the software analysis. The models are consisting of viscoelastic material (Rubber & Neoprene) as core layer. An attempt is to be made to reduce the vibration by analyzing different sandwich plates. Key words: Sandwich beam, Viscoelastic, Damping, Finite Element Method. level provided by the designer to completely comprehend their mechanical behavior. In viscoelastic material the mechanical energy is released through normal deformation and cyclic shear. Vibration: Any Motion which repeats itself after an interval of the time is called vibration or oscillation. Causes of Vibrations: The main reasons of vibration are as follows 1) Unbalanced centrifugal force in the system which is caused because of non-uniform material distribution in a rotating machine elements. 2) Elastic nature of the system. 3) External excitation applied on the system. 4) Winds may cause vibrations of certain systems such as electricity lines, telephone lines. I. INTRODUCTION Vibration mainly influences the life of engineering structures and their performance and invariably, damping in structures influences its behavior. Many types of damping mechanisms have been developed over time to control the undesired vibration of structures. Basically damping refers to the extraction of mechanical energy from a vibrating system, mainly by converting the mechanical energy into heat energy by means of some dissipation mechanism. Mostly all materials exhibit some amount of internal structural damping. Most of the time it is not substantially effective to minimize the vibration around resonant frequencies. Hence, by bringing these materials in contact with the highly damped and dynamically stiffed material it is possible to control the vibration. Viscoelastic materials are one such that they are capable of storing strain energy when they are deformed; these types of materials exhibit the material characteristics of both viscous fluid and elastic solid. Viscoelastic damping property was exhibited by the large variety of polymeric materials ranging from synthetic/natural rubbers to various Thermoset/thermostat materials used in different industries. Here polymers display rheological behavior intermediate between a simple fluid and crystalline solids, due to having tangled molecules and large molecular order. This type of viscoelastic materials offers a wide range of possibilities for developing a desire damping Figure 1 Sandwich beam model In the present study the constrained layer damping treatment has been used for the study of vibration behavior in sandwich beams. The viscoelastic material has been bonded between the top and bottom elastic layers to form the sandwich beam model. BEAM SPECIFICATION Top layer: Elastic material (Steel, Aluminum) Core layer: viscoelastic material (Rubber) Bottom layer: Elastic material (Steel, Aluminum) Specifications: 1) Length of plate: 45 mm 2) Width of plate: 5 mm 3) Thickness of plate: 4.5 mm SOFTWARE ANALYSIS BY USING ANSYS The simulation of plates can be done in ANSYS 12. (Student License) software. The software is compatible with 6, nodes and having 6 degree of freedom (D.O.F.). ANSYS Modeling and Result for sandwich beam (4.5 mm Thickness) For 115

2 Al-Ru-Al sandwich beam Al-Ne-Al sandwich beam Figure 2 Mode Shapes of Al-Ru-Al Beam in Figure 3 Mode Shapes of Al-Ru-Al Beam in 116

3 St-Ru-St sandwich beam St-Ne-St sandwich beam Figure 4 Mode Shapes of St-Ru-St Beam in Simply Supported Condition Figure 5 Mode Shapes of St-Ne-St Beam in 117

4 Y/t Chart Y/t Chart Y/t Chart Y/t Chart Prashant Ashok Patil et. al. / International Journal of New Technologies in Science and Engineering EXPERIMENAL ANALYSIS Plan of Instrumentation The complete experimental setup for vibration analysis is shown in figure 6 In order to obtain natural frequencies of plates. The values of natural frequencies obtained by exciting the handle bar using Impact Hammer shown in figure 7 and measuring the response by an Accelerometer shown in figure: 5.3 which was connected to FFT Analyzer (Bruel & Kjaer, Type 35-B-4, 4-ch. Input module 5k). Results of Experimental Work For Impact Hammer Test For Al-Ru-Al sandwich beam(4.5 mm thickness) Relative Amplitude (db) Figure 8 Frequency Response Curve for Al-Ru-Al Beam in Al-Ne-Al sandwich beam (4.5 mm thickness) Relative Amplitude (db) Figure 9 Frequency Response Curve for Al-Ne-Al Beam in Figure 6 Schematic Diagram of Experimental Setup Impact hammer The model hammer exits the structure with a constant force over a frequency range of interest. Three interchange tips are provided which determine the width of the input pulse and thus the band width the hammer structure is acceleration compensated to avoid glitches in the spectrum due to hammer structure resonance. Relative Amplitude (db) Relative Amplitude (db) St-Ru-St sandwich beam (4.5 mm thickness) Figure 1 Frequency Response Curve for St-Ru-St Beam in St-Ne-St sandwich beam (4.5 mm thickness) Figure 7 Impact Hammer FFT Analyser FFT Analyser is used to measure the frequency ranges to which the foundation various machines are subjected to when the machine is running with no load and full load. This will help us in designing the foundations of various machines on such a way that they are able to resist the vibration caused in them Figure 11 Frequency Response Curve for St-Ne-St Beam in 118

Result Table for Sandwich beam under Simply Supported Condition Comparison Gr

Won et al, Three-layered damped beam element for forced vibration analysis of symmetric sandwich structures with a viscoelastic core, Finite Elements in Analysis and Design 68 (213) 39 51 [2] Fei Lin

Rao, Vibroacoustical Analysis of Multiple-Layered Structures with Viscoelastic Damping Cores, ISRN Mechanical Engineering, Volume 213, Article ID 645232, 1-13 [3] Farough Mohammadi, Ramin Sedaghati,

5 Result Table for Sandwich beam under Simply Supported Condition Comparison Graph of Natural frequencies Al-Ru-Al & Al-Ne-Al Sandwich beam of 4.5 mm thickness REFERENCES [1] S.G. Won et al, Three-layered damped beam element for forced vibration analysis of symmetric sandwich structures with a viscoelastic core, Finite Elements in Analysis and Design 68 (213) [2] Fei Lin and Mohan D. Rao, Vibroacoustical Analysis of Multiple-Layered Structures with Viscoelastic Damping Cores, ISRN Mechanical Engineering, Volume 213, Article ID , 1-13 [3] Farough Mohammadi, Ramin Sedaghati, Vibration analysis and design optimization of viscoelastic sandwich cylindrical shell, Journal of Sound and Vibration 331 (212) [4] Y.A. Zhuk, I.A. Guz, C.M. Sands, Monoharmonic approximation in the vibration analysis of a sandwich beam containing piezoelectric layers under mechanical or electrical loading, Journal of Sound and Vibration 33 (211 ) [5] S.M.R. Khalili, Free vibration analysis of sandwich beam carrying sprung masses, International Journal of Mechanical Sciences 52 (21) Comparison Graph of Natural frequencies St-Ru-St & St -Ne- St Sandwich beam of 4.5 mm thickness CONCLUSION From above experimental and software work and its results clears that damping characteristics for neoprene viscoelastic material has significant effect when compared with the rubber viscoelastic material. Finally the frequency responses of the modeled sandwich beams have been plotted for the simply supported boundary conditions. Results show that the viscoelastic constrained layer damping treatment has a great significance in controlling the vibration of structures like beams, plates, etc. About Author Author 1: Prashat Ashok Patil B.E.(Mechanical) TMES s J. T. Mahajan College of Engineering, Faizpur (M.S.) Experience:2.3 Years paprashant1991@gmail.com Author 2: Sachin Shashikant Patil B.E.(Mechanical) ME(appear) TMES s J. T. Mahajan College of Engineering, Faizpur (M.S.) Experience:2 Years sachinptl93@gmail.com Author 3: Hemant Dnyandev Chaudhari B.E.(Mechanical) ME.(CAD/CAM) TMES s J. T. Mahajan College of Engineering, Faizpur (M.S.) Experience:12 Years 119

STUDY ON VIBRATION ANALYSIS OF SANDWICH CANTILEVER BEAM USING FINITE ELEMENT ANSYS SOFTWARE

STUDY ON VIBRATION ANALYSIS OF SANDWICH CANTILEVER BEAM USING FINITE ELEMENT ANSYS SOFTWARE Rahul E.Dhoble 1, Dr. R. B. Barjibhe 2 1. P.G.Student, Department of Mechanical Engineering, S.S.G.B.C.O.E. &