Available online at www.sciencedirect.com ScienceDirect Procedia Materials Science 10 (2015 ) 638 643 2nd International Conference on Nanomaterials and Technologies (CNT 2014) Frequency Response of Sandwich Beam Embedded With Shape Memory Alloy Wires D. J. More a, S. A. Chavan b a D. J. More PG Student, Department of Mechanical Engineering, R.I.T Rajaramnagar, Sangli, Maharashtra, India b S. A. Chavan Assistant Professor, Department of Automobile Engineering, I.O.K C.O.E Pimple Jagtap, Pune, Maharashtra, India.. Abstract Experimental investigation of the dynamic behavior of sandwich beam and an embedded with shape memory alloy (SMA) wires are deliberated. In this study wires composition of Ni 56.2% remaining Ti were used for vibration control. These wires were inserted in sandwich beam with its neutral axis. The wires are embedded along a length of beam and beam is sandwiched between two copper plates. The beam is tested for free boundary condition and observed natural frequency when the stiffness of beam is changed by actuating the wire with electric current. This paper depicts the frequency response of beam due to embedded SMA wires. Effect of SMA wires on natural frequency and damping factor are examined. The maximum frequency is obtained at 1.5 amps after that frequency continuously decreases because of increase in temperature of the beam. 2015 The Authors. Published by Elsevier by Elsevier Ltd. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the of International the International Conference Conference Nanomaterials on Nanomaterials and Technologies and Technologies (CNT 2014) (CNT 2014). Keywords: Shape memory alloy; Sandwich Beam; Actuation; Silicon Rubber; Electric Current. Introduction The development of smart sandwich beam and structures has become an attractive research topic in an area of materials science and engineering and in structural control. Shape memory alloy wires (SMA) having high specific modulus, high specific strength, and the capability to be designed and fabricated with greater flexibility. SMA wires have advantages over traditional materials. The SMA technology into smart material structures has to receive considerable attention at the contemporary. There are many different ways to design SMA embedded composite structures, in this work the sandwich beams were prepared with inserted SMA wires, beam are placed between two copper plates with fully bonded with another material. This can be achieved by using a technique of mixing the required SMA elements with silicon rubber. After that silicone rubber and SMA elements are fabricated into an elastomer beam which comprises copper plates. The SMA wires are changing its physical property as well as its stiffness by actuating current. 2211-8128 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the International Conference on Nanomaterials and Technologies (CNT 2014) doi:10.1016/j.mspro.2015.06.056
D.J. More and S.A. Chavan / Procedia Materials Science 10 ( 2015 ) 638 643 639 Nomenclature M s M f As A f Martensite start temperature Martensite finishe temperature Austenite start temperature Austenite finish temperature 2. Beam With SMA Components Shape memory components are in the form of wires embedded to elements of structures enable active control of their static and dynamic characteristics. This is possible due to the fact that certain mechanical properties of shape memory alloys can be very precisely controlled and changed in a required manner according to the particular implementation. Certain dynamic characteristics of structural elements such as the maximum deflection, natural frequencies, and modes of vibrations and amplitudes of forced vibrations or damping properties can be controlled by the use of shape memory alloy components. The properties of shape memory alloy as given, in Table 1. Table 1 Properties of SMA alloy Ms ( 0 C 9 As ( 0 C) 30 Mf ( 0 C) 18 Af ( 0 C) 45 Ni 55.4%-56.2% C 0.07 H 0.01 N 0.05 Ti Reminder 3. Preparation of SMA Composite Beam In this work the specimen prepared with geometry for beam embedded with six wires. The elastomer core of beam is sandwiched between two thin copper plates as shown in fig 1. Where, L is length of sandwich beam, h1, h2 distance between two SMA wires, h3 distance between neutral axis and SMA wire is width of beam. Six SMA wires are embedded in rectangular elastomer core. Wires are placed horizontally along the length, 15 mm apart from each other at either side of the neutral axis.
640 D.J. More and S.A. Chavan / Procedia Materials Science 10 ( 2015 ) 638 643 D. J. More a, S. A. Chavan b / Procedia Materials Science 00 (2015) 000 000 3 4. Mould Preparation Fig. 1 Elastomer of sandwich beam when six wire embedded For preparation of mould the materials with specific properties given in table 2 are used for sandwich beam, Sylartivi 11 is a room temperature vulcanizing silicon rubber. When mixed with the catalyst Metroark 27 supplied and allowed to standard temperature, the product becomes a rubbery solid in 24 hours. The dimensions of beam specimen are 250mm x 60mm x 20mm. The thin copper plates, having thickness 3mm are used to sandwich elastomer core. For the molding of SMA wire and silicon rubber, Syrartivi 11 is mixed with 27 catalysts just before using in the proportion of 2.3 parts catalyst to 100 parts of Sylartivi 11 by weight. The catalyst is packed in dropper bottles from which 60 drops make 1 cc which used to dropping while stirring of rubber. Table 2 Properties of Silicon Rubeer Properties 24 hrs 7 Days Hardness 45-50 50-60 Elongation, Percent (%) 110 110 Brittle point, degree 0F Shrink, Linear percent 0.2 0.4 Water absorption, percent Colour Red Red Thermal conductivity, Cal per (cm) degrees C) (Sec) 0.525 x 10 3 Volume coefficient of thermal expansion from 0 to 1000C 7.5 x 10 4 5. Experimentation The free boundary condition is achieved for experimentation as shown in fig 2. The instruments are used for experiments include Dela-Tron IEPE accelerometer, B&K FFT analyzer with 4 Channel Input module, Data acquisition and analysis software (B&K PULSE 14.1.1) and Impact hammer is used for measurement of frequency response functions using impact excitation techniques. The detail experimental procedure is an accelerometer is mounted on sandwich beam to receive vibration. Current range of 0 to 1.5 Amp per wire is applied to the beam. The FFT of analog signals and vibration spectrum in frequency domain is obtained with the help of PULSE 14.1.1 analysis software. In this case sandwich beam is mounted according to boundary condition i.e. free-free condition. Six wires are clamped at 10 mm from neutral axis at either side then activated with current.this varies with 0 to 9 Amps. Each wire activated with current 1.5 Amps which is 1/6 of actual current. Experimental set up is as shown in Fig 2,
D.J. More and S.A. Chavan / Procedia Materials Science 10 ( 2015 ) 638 643 641 Fig. 2 Experimental set up 6. Result and Discussion In this experimentation the beam with six wires free boundary condition is tested for natural frequency. Six wires are activated with electric current at range 0 to 9 Amps. Each wire activated with current 1.5 amps which is 1/6 of actual current. Fig 3 Frequency Vs current
642 D.J. More and S.A. Chavan / Procedia Materials Science 10 ( 2015 ) 638 643 There is a significant effect of actuation mode on the natural frequency of sandwich beam. From results, it is observed that actuation of current is directly proportional to the percentage natural frequency of beam. While increasing actuation current, percentage natural frequency of beam also goes on increasing. No change in natural frequency is observed up to 0.5 Amp. Following fig. shows the results for frequency with respect to current. 7. Calculation of damping factor The damping factor is calculated by half power bandwidth method. To calculate damping factor equation (ζ) is used. The results of damping factor with respect to current are shown in fig. 4. Damping factor (ζ) = Fig. 4 Damping Factor Vs Current Conclusion In this paper, the frequency response of sandwich beam driven by embedded SMA actuators is investigated through an experimental study and significant factors are examined experimentally. This work supports the following conclusions, a) When the SMA wires are actuated, the stiffness of beam changes proportionally and this leads to shift in natural frequency of the beam.
D.J. More and S.A. Chavan / Procedia Materials Science 10 ( 2015 ) 638 643 643 b) There is a significant effect of actuation mode on the natural frequency of the sandwich beam. As an actuation current increases, the stiffness of beam increases. c) In this case wherein six pre-strained wires are placed symmetrically about neutral axis of the beam, on actuation of wires by 1.5 Amp per wire current. d) The damping factor of the beam changes at up to 1.5 Amp. Current after that it may get constant with changing current. References 1] Blonky B. J., Lagoudaszx D. C., Actuation of elastomeric rods with embedded two-way shape memory alloy actuators, Smart Mater. Struct., 7 (1998) 771 783. 2] Wei K., Meng G., Zhang W., Zhu S., Experimental investigation on vibration characteristics of sandwich beams with magnetorheological elastomers cores, J. Cent South Univ. Technol., (2008) 239-242. 3] Lau K., Zhou L., Tao X., Control of natural frequencies of aclamped claped composite beam with embedded shape memory alloy wires, Journal of composite structures, (2002) 39-47. 4] Kanas K., Lekakou C., Vrellos N., FEA and Experimental Studies of Adaptive Composite Materials with SMA wire, Proceedings of the World Congress on Engineering 2007 Vol. IIWCE 2007, July 2-4-2007, London, U.K. 5] Su X., parametric vibration of composite Beams with integrated shape memory Alloy elements, 2009. 6] Terner T. L., Dynamic response tuning of composite beams by embedded shape memory alloy actuators, NASA Langley Research Center, MS 463. 7] Takeda N., Minkuchi S., Okabe Y., Smart composite structure for future are scope application, Damage detection and suppression, Journal of solid mechanics and materials engineering vol.1 (2007). 8] Baz A., Imam K., Mccoy J., Active Vibration Control Of Flexible Beams Using Shape Memory Actuators, Journal of Sound and Vibration (1990) 437-456. 9] Barzegari M., Dardel M., fathi A., Effect of Shape Memory Alloy Wires on Natural Frequency of Plates, Journal of Mechanical Engineering and Automation (2012), 2(1) 23-28. 10] Diodati G., Ameduri S., Concilio A., Adaptive Vibration Control through a SMA Embedded Panel, Journal of Theoretical and Applied Mechanics 45-4 (2007) 919-930, Warsaw. 11] Rao S.S., Mechanical Vibration, Fourth Edition, (2003), 813-814, Pearson Education. 12] Gowda T., Jagdeesha T., Girish D. V., Mechanical Vibration, Tata McGraw Hill Education Private Limited (2012).