Faculty Publications
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Publications by NITK Faculty
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Item Finite element magnetostatic analysis of magnetostrictive (Tb 0.3Dy0.7Fe1.95) actuator with different housing materials(Defense Scientific Information and Documentation Centre, 2013) Joshi, R.; Subba Rao, M.; Kadoli, R.Permeability of a housing material is one of the significant factors affecting the performance of Tb0.3Dy0.7Fe1.95 based magnetostrictive actuator. According to Lenz's law the rate of flux transfer depends on permeability of housing material surrounding the terfenol-D. In this paper the co-axial coils in a free air are analysed under direct current excitation and the results are found to agree well with both analytical and Maxwell simulation. Also, the comparison of flux density distribution in co-axial coils placed inside different housing materials of magnetostrictive actuator is found by solving magnetostatic equations using Ansoft Maxwell 2D solver. The axial distribution of magnetic flux density, radial distribution of magnetic flux density and flux distribution in the actuator assembly with different housing materials namely mild steel, cast iron and aluminium with and without Terfenol-D are discussed. © 2013, DESIDOC.Item Dielectric and piezoelectric properties of PVDF/PZT composites: A review(John Wiley and Sons Inc, 2015) Jain, A.; Prashanth, K.J.; Sharma, A.K.; Jain, A.; P.n, R.Smart materials, which exhibit piezoelectricity, find an eclectic range of applications in the industry. The direct piezoelectric effect has been widely used in sensor design, and the inverse piezoelectric effect has been applied in actuator design. Ever since 1954, PZT and BaTiO3 were widely used for sensor and actuator applications despite their toxicity, brittleness, inflexibility, etc. With the discovery of PVDF in 1969, followed by development of copolymers, a flexible, easy to process, nontoxic, high density alternate with high piezoelectric voltage coefficient was available. In the past 20 years, heterostructural materials like polymer ceramic composites, have received lot of attention, since these materials combine the excellent pyroelectric and piezoelectric properties of ceramics with the flexibility, processing facility, and strength of the polymers resulting in relatively high dielectric permittivity and breakdown strength, which are not attainable in a single phase piezoelectric material. The current review article is an attempt to provide a compendium of all the work carried out with reference to PVDF-PZT composites. The review article evaluates the effect of grain size, content and other factors under the purview of dielectric and piezoelectric properties while evaluating the sensitivity of the material for sensor application.Item Displacement characteristics of a piezoactuator-based prototype microactuator with a hydraulic displacement amplification system(Korean Society of Mechanical Engineers, 2015) Rao, M.; Rao, R.In this study, a new piezoactuator-based prototype microactuator is proposed with a hydraulic displacement amplification system. A piezoactuator is used to deflect a diaphragm which displaces a certain volume of hydraulic fluid into a smaller-diameter piston chamber, thereby amplifying the displacement at the other end of the piston. An electro-mechanical model is implemented to estimate the displacement of a multilayer piezoelectric actuator for the applied input voltage considering the hysteresis behavior. The displacement characteristics of the proposed microactuator are studied for triangular actuation voltage signal. Results of the experiments and simulation of the displacement behavior of the stacked piezoactuator and the amplified displacement of the prototype actuator were compared. Experimental results suggest that the mathematical model developed for the new piezoactuator-based prototype actuator is capable of estimating its displacement behavior accurately, within an error of 1.2%. © 2015, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.Item Aileron endurance test rig design based on high fidelity mathematical modeling(Springer-Verlag Wien michaela.bolli@springer.at, 2017) Prasad, M.; Gangadharan, K.V.This paper presents a model-based approach to design aileron endurance test rig (ETR). ETR is a dynamic load simulator which simulates aerodynamic load on-ground for verifying and validating the design, performance and stability of aileron actuator. Aileron actuator is a servo-controlled linear hydraulic actuator used to control the movement of ailerons in aircraft. Aileron is one of the primary flight control surfaces which controls roll of the aircraft. In ETR, Aileron actuator acts as unit under test (UUT) while a double-acting linear hydraulic actuator produces a dynamic load with the help of high pressure fluid source and electro-hydraulic servo valve (EHSV). The design of the test rig depends on load and velocity requirements which vary widely over the whole flight envelop and depends on deflection of surface, angle of attack, aircraft speed and altitude. One of the critical factor in designing ETR is to accurately model the interaction between the UUT and load system. This paper presents a simple yet powerful approach of free body diagram to account the power flow between the two systems. Model-based approach allowed to simulate the complete test rig behavior identifying the values of the critical parameters prior to building it. A high fidelity, non-linear mathematical model of aileron ETR is developed, simulated and verified. An appropriate load actuator and its electro-hydraulic servo valve are chosen to meet load and velocity requirements. The minimum rig structure stiffness is determined to ensure the stability of the load control system. A velocity feed-forward-based load controller along with proportional-integral control is implemented and tuned to meet the load control performance satisfactorily. Finally, the developed model is validated against the experimental data from actual test rig. © 2017, Deutsches Zentrum für Luft- und Raumfahrt e.V.Item Experimental investigation on performance of disposable micropump with retrofit piezo stack actuator for biomedical application(Springer Verlag service@springer.de, 2019) Mohith, S.; Karanth P, P.N.; Kulkarni, S.M.Extensive researches are being conducted to develop miniaturized pumping systems to fulfill the need for accurate delivery of fluids at required rates, particularly in the biomedical field. This paper presents the design, fabrication, and testing of novel valveless micropump actuated through an amplified piezo actuator. The proposed model of the micropump pump has the unique feature of a disposable chamber and employs low-cost polymeric materials, conventional molding and machining operations for fabrication. The disposable part of the pump consists of a laser-cut pump chamber with nozzle/diffuser made of Polymethyl methacrylate (PMMA) and conventionally molded silicone rubber diaphragm. The retrofit part includes the amplified piezo actuator and support structures build from PMMA. Systematic characterization of the pump was carried with water and blood mimicking fluid to understand the effect of operating parameters such as driving frequency and actuation voltage on flow rate and back pressure of the micropump. Experimental results show that the proposed design was capable of pumping 3.3–3.4 ml/min of dye solution and 1.7–1.75 ml/min of blood mimicking fluid at a driving frequency of 5 Hz and actuation voltage of 150 V. The corresponding computed volume resolution/stroke of the pump was found to about 5.75 µl and 11.25 µl of blood mimicking fluid and dye solution, respectively. The proposed pump was found to work effectively against a maximum back pressure of 156 Pa with blood mimicking fluid and 250 Pa with the dye solution as the working fluid under the same operating condition of 5 Hz and 150 V. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.Item Performance analysis of valveless micropump with disposable chamber actuated through Amplified Piezo Actuator (APA) for biomedical application(Elsevier Ltd, 2020) Mohith, M.; Karanth P, N.; Kulkarni, S.M.The precise manipulation of fluid through pumping systems has been the technological challenge in microfluidic applications. The biomedical applications call for precise and accurate delivery of fluid through miniaturized pumping systems. This paper presents a novel valveless micropump for biomedical applications operated by the Amplified Piezo Actuator. Integrating the disposable chamber and reusable actuator with the proposed micropump allows the actuator to be reused and eliminates the possibility of infection or contagion. The micropump was fabricated using low-cost polymeric materials like Polymethylmethacrylate (PMMA), Silicone rubber through CNC milling, Laser Cutting, conventional moulding operation. The micropump chamber, nozzle/diffusers, and a bossed diaphragm constituted disposable part and Amplified Piezo Actuator with structural support formed the reusable part of the micropump. The bossed diaphragm of the pump chamber consists of a central cylindrical protrusion to reduce the force of adhesion on the diaphragm and transmit force required for micropump actuation. A theoretical analysis was performed to assess the effect of diaphragm thickness and the bossed region on the effective stiffness of the diaphragm, which in turn influences the deflection achieved. Besides, an analytical approach has been presented to address the effect of adhesive force on the diaphragm surface due to the residual fluid and chamber depth. The experimental characterization of the micropump was carried out to determine the optimal performance parameters with water, fluids mimicking blood plasma, and whole blood. Based on the experimental results, the pumping rate and head developed by the micropump have been significantly affected by factors such as bossed ratio, diaphragm thickness, depth of the micropump chamber, and viscosity of the fluid. The optimum configuration of the micropump cosidered silicone rubber diaphragm with thickness of 0.20 mm having a bossed ratio of 0.33 and a chamber depth of 1.25 mm. With the optimal operating parameters of 150 V sinusoidal input of frequency 5 Hz, the proposed micropump was capable of delivering 7.192 ml/min, 6.108 ml/min, and 5.013 ml/min of water and blood plasma, whole blood mimicking fluid with the maximum backpressure of 294.00 Pa, 226.243 Pa, and 204.048 Pa respectively. The corresponding resolution, i.e., pumping volume/stroke of the micropump was about 23.972 µl, 20.358 µl, and 16.708 µl, respectively. © 2020 Elsevier LtdItem Numerical analysis of polymer composites for actuation(International Information and Engineering Technology Association, 2020) Hiremath, S.; Sangappa, V.; Rajole, S.; Kulkarni, S.M.The design of a polymer composite actuator is essential for micro and nano applications. Thus, the composite material may deform or deflects as specific stimuli are applied, such as heat, electrical, light source, etc. The deformation of the composite material is caused by the type of stimulus applied. Hence, while it is heated, the expansion takes place quickly, and the heating is shut down, the material shrinks very slowly. In the present investigation, this phenomenon is mainly studied in the actuation of composite beams. Numerical analysis of carbon black filled polymer composite beam expansion, and contraction is being analyzed in this research. The structure of the beam has been created, and the composite properties are incorporated into the beam, and the uniform heat source is applied on to the surface of the beam. The heating and cooling of the composite material predict the increase and decrease in the temperature of the beam. The numerical analysis of the temperature-dependent expansion and contraction of the composite beam has been carried out successfully. An increase in temperature is observed to signify the slight expansion in the composite beam, whereas the contraction of the composite beam takes a longer time to reach room temperature. Also, the increase in the content of the filler leads to a decrease in the expansion of the composite beam. The numerical simulation of the polymer composite thus provides a solid platform for the experimental study of thermal actuators. © 2020 Lavoisier. All rights reserved.Item Progression and characterization of polydimethylsiloxane-carbon black nanocomposites for photothermal actuator applications(Elsevier B.V., 2021) Hiremath, S.; H, S.M.; Kulkarni, S.M.The new development of polymer-based actuators triggers the progress of nanocomposites. Polymer materials are currently used in sensors, microfluidic devices, electrical and thermal actuators, and energy harvesting applications due to ease of availability, excellent tolerable properties, and customizable properties. The polymer-based nanocomposite can be driven by various stimuli, which is the actuator's emerging field. Thus, photothermal actuation is a thurst area of research transforming light energy into mechanical energy through the polymer material. The photo-responsive material can be prepared and tested for photo-actuation by incorporating the nanoparticles into the polymer. The present work focuses on developing polydimethylsiloxane (PDMS) and carbon black (CB) nanocomposite. The objective here is to investigate the photothermal actuator's performance by illuminating the infrared (IR) light source and studying its most influential characteristics, such as absorbance, thermal conductivity, and the thermal expansion coefficient. The PDMS / CB nanocomposite absorbs the IR light and then increases temperature, which is finally transformed into a beam deflection. Responses are measured as a result of time deflection using the Laser displacement sensor. It is noted that the deflection of the nanocomposite beam is linearly increased during illumination with light while it is exponentially decreasing when the light is turned off. The proposed polymer nanocomposite is approximately deflected by 9 mm in the duration of 16 s duration. Furthermore, the experimental deflection of the photothermal actuator is very close to theoretical results. The nanocomposite PDMS / CB reveals that there is an increase in absorbance by increasing the filler content. The nanocomposite conductivity is 35.2 % higher than the base material. As well, the thermal expansion coefficient decreases with an increase in carbon black content. The photothermal actuator's development is an ongoing process in which the material parameter, actuator geometry, and many more are modified. As a result, the photothermal bending performed can provide a means for various light-driven applications. © 2020 Elsevier B.V.