Faculty Publications
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Item Active vibration control of a smart cantilever beam on general purpose operating system(Defense Scientific Information and Documentation Centre, 2013) Parameswaran, A.P.; Pai, A.B.; Tripathi, P.K.; Gangadharan, K.V.All mechanical systems suffer from undesirable vibrations during their operations. Their occurrence is uncontrollable as it depends on various factors. However, for efficient operation of the system, these vibrations have to be controlled within the specified limits. Light weight, rapid and multi-mode control of the vibrating structure is possible by the use of piezoelectric sensors and actuators and feedback control algorithms. In this paper, direct output feedback based active vibration control has been implemented on a cantilever beam using Lead Zirconate-Titanate (PZT) sensors and actuators. Three PZT patches were used, one as the sensor, one as the exciter providing the forced vibrations and the third acting as the actuator that provides an equal but opposite phase vibration/force signal to that of sensed so as to damp out the vibrations. The designed algorithm is implemented on Lab VIEW 2010 on Windows 7 Platform. © 2013, DESIDOC.Item Modeling and design of field programmable gate array based real time robust controller for active control of vibrating smart system(Academic Press, 2015) Parameswaran, A.P.; Ananthakrishnan, B.; Gangadharan, K.V.The current paper focuses on accurate mathematical modeling of a vibrating piezoelectric laminate cantilever beam theoretically as well as experimentally so as to obtain the best replication of the system dynamics on the software platform for simulation studies. The developed models were tested for accuracy in time as well as frequency domain by employing the sweep sine test. The focus of the study is on the flexural modes of vibrations of the cantilever beam. Here, modeling is focused on the first vibratory mode as it has been observed that the effects of felt vibrations would be maximum in terms of system stability and its operational efficiency when the excitation frequency matches with the first natural frequency of the system (fn1). This was validated by appropriate non-parametric modeling of the smart system by subjecting it to the Impact Hammer test. Development of accurate system models play an important role in designing and testing various control algorithms for reliable active vibration control (AVC). In the final stage, a real time active vibration robust controller was designed using a proportional derivative sliding mode control (PDSMC) technique and deployed on a Field Programmable Gate Array (FPGA) platform. The efficiency of the developed real time controller was proved in time as well as frequency domains by subjecting the closed loop system to harmonic excitations at first natural frequency as well as sweep sine test focussing on the first vibratory mode with the conclusion that the developed controller will function satisfactorily at higher modes of vibrations. © 2015 Elsevier Ltd.Item Parametric modeling and FPGA based real time active vibration control of a piezoelectric laminate cantilever beam at resonance(SAGE Publications Inc., 2015) Parameswaran, A.P.; Gangadharan, K.V.The operational efficiency and life of mechanical systems/structures depends to a large extent on their vibration control. Continuously occurring vibrations on the systems can cause fatigue and the effects of these vibrations are particularly severe if they occur at a frequency matching with that of the concerned systems natural frequency - a stage called resonance. This paper focuses on achieving active vibration control of a smart cantilever beam at its first resonant frequency as it is at this stage that maximum damage to the system performance is expected. The smart system is modelled in the parametric domain using finite element modeling techniques and the obtained model is validated through experimental means. The active vibration control is achieved by employing two control algorithms namely - output feedback and error based control through general purpose operating system (LabVIEW on Windows 7) as well as in real time operating system (LabVIEW FPGA coupled with compact reconfigurable input output modules) and the performances are compared thereby justifying the importance of the deterministic and reliable real time control over the usual PC based control in experimental studies. © The Author(s) 2014.Item Modeling of delamination in fiber-reinforced composite using high-dimensional model representation-based cohesive zone model(Springer Verlag service@springer.de, 2019) Rao, B.; Balu, A.S.Prediction of delamination failure is challenging when the researchers try to achieve the task without overburdening the available computational resources. One of the most powerful computational models to predict the crack initiation and propagation is cohesive zone model (CZM), which has become prominent in the crack propagation studies. This paper proposes a novel CZM using high-dimensional model representation (HDMR) to capture the steady-state energy release rate (ERR) of a double-cantilever beam (DCB) under mode I loading. The finite element models are created using HDMR-based load and crack length response functions. Initially, the model is developed for 51-mm crack size DCB specimens, and the developed HDMR-based CZM is then used to predict the ERR variations of 76.2-mm crack size DCB model. Comparisons have been made between the available unidirectional composite (IM7/977-3) experimental data and the numerical results obtained from the 51-mm and 76.2-mm initial crack size DCB specimens. In order to demonstrate the efficiency of the proposed model, the results of the second-order nonlinear regression model using RSM are used for the comparison study. The results show that the proposed method is computationally efficient in capturing the delamination strength. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.Item Semi-active vibration control of MRF core PMC cantilever sandwich beams: Experimental study(SAGE Publications Ltd info@sagepub.co.uk, 2020) Allien, J.V.; Kumar, H.; Desai, V.The semi-active vibration control of sandwich beams made of chopped strand mat glass fiber reinforced polyester resin polymer matrix composite (PMC) and magnetorheological fluid (MRF) core were experimentally investigated in this study. Two-, four- and six-layered glass fiber reinforced polyester resin polymer matrix composites were prepared using the hand-layup technique. The magnetorheological fluid was prepared in-house with 30% volume of carbonyl iron powder and 70% volume of silicone oil. Nine cantilever sandwich beams of varying thicknesses of the top and bottom layers glass fiber reinforced polyester resin polymer matrix composite beams and middle magnetorheological fluid core were prepared. The magnetorheological fluid core was activated with a non-homogeneous magnetic field using permanent magnets. The first three modes, natural frequencies and damping ratios of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams were determined through free vibration analysis using DEWESoft modal analysis software. The amplitude frequency response of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams through forced vibration analysis was determined using LabVIEW. The effect of various parameters such as magnetic flux density, thickness of glass fiber reinforced polyester resin polymer matrix composite layers and magnetorheological fluid core layer on the natural frequencies, damping ratio and vibration amplitude suppressions of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams was investigated. Based on the results obtained, 2 mm thickness top and bottom layers glass fiber reinforced polyester resin polymer matrix composite and 5 mm thickness magnetorheological fluid core sample have achieved a high shift in increased natural frequency, damping ratio and vibration amplitude suppression under the influence of magnetic flux density. © IMechE 2020.Item PDMS–ZnO flexible piezoelectric composites for measurement of muscle activity(Springer, 2020) Jugade, S.S.; Kulkarni, S.M.Measurement of muscle activity is important for muscle health monitoring, biomechanics studies, developing prosthesis, etc. This article describes a flexible piezoelectric composite material as a sensing element for measuring muscle activity. The developed piezoelectric material is a composite of polydimethylsiloxane and zinc oxide, and exists in monolayer and bilayer configurations. To test the piezoelectric properties in bending mode, a composite patch is attached to a cantilever beam setup. Peak sinusoidal voltage generated from the composite material due to the vibrating cantilever is found to be highest (1.5 V) for bilayer configuration with 30 wt% ZnO. For testing in axial mode, the peak output voltage from the material due to an impulse load is maximum (0.9 V) for the monolayer configuration of the composite with 30 wt% ZnO. The sensor consisting of a bilayer composite patch is wrapped around a specific muscle to measure its activity. The change in output voltage from the sensor is measured for increasing load and is then mapped to the corresponding value of elastic modulus of the muscle measured using a durometer. The sensitivity of the muscle activity measurement for biceps brachii and flexor carpi is found to be 3.826 and 1.245 V MPa?1, respectively. © 2020, Indian Academy of Sciences.Item Effect of similar and dissimilar interface layers on delamination in hybrid plain woven glass/carbon epoxy laminated composite double cantilever beam under Mode-I loading(Elsevier B.V., 2021) Suman, M.L.J.; Murigendrappa, S.M.; Kattimani, S.Effect of similar and dissimilar interface layers on delamination in hybrid plain woven glass/carbon epoxy laminated composite double cantilever beam under Mode-I loading has been investigated experimentally and analytically. Glass-glass, glass-carbon interface layers in three different configurations of hybrid plain woven glass/carbon epoxy laminated composites were fabricated. Valvo's mode partition method from the literature is utilised to compute individual modal contributions and total fracture toughness of the hybrid composite laminates. Mode-I fracture toughness contribution is compared with standard data reduction schemes of ASTM D5528-13. The comparison reveals that Valvo's mode partition method considers mode-mixity and provides conservative results. The Valvo's mode partition does not require any correction factors including curve fitting, it provides a straightforward method for evaluating fracture toughness as they are based on the mechanics of composite materials. The comparison of R-curves of hybrid configurations reveal that the insertion of carbon with glass at the interface of symmetric hybrid configuration enhances initial fracture toughness and stabilises whereas, with the change in layer configuration of anyone arm of the double-cantilever beam, the crack growth trend is also affected irrespective of same interface layers. The fractography analysis of delamination surfaces reveals that crack propagation through a resin-rich layer creates a rougher fracture surface resulting in higher energy dissipation as compared to crack propagation through resin-rich pockets. © 2021 Elsevier LtdItem Dynamic characterization of hybrid composite material of rotor-bearing support system(Taylor and Francis Ltd., 2022) Gonsalves, T.H.; Garje Channabasappa, M.K.; Motagondanahalli Rangarasaiah, R.; Joladarashi, S.In this paper, the dynamic characterization of hybrid composite material of carbon-epoxy sandwiched by steel is presented from the rotor-bearing system perspective. The tensile and flexural strengths of the hybrid material are investigated followed by the detailed damping estimation using modal testing in cantilever mode and dynamic mechanical analysis in double cantilever mode. The experimental characterization results obtained in this work have fundamentally ascertained the mechanical and dynamic behavior of hybrid composite material for the intended application. © 2020 Taylor & Francis Group, LLC.Item Vibration control of laminated composite cantilever beam operating in elevated thermal environments using fuzzy logic controller(SAGE Publications Inc., 2022) Akumalla, R.K.; Kallannavar, V.; Kattimani, S.In the present study, vibration control of laminated composite cantilever beam operating in the elevated thermal environment is achieved using combined experimental and numerical techniques. The impact hammer test is performed on the glass-epoxy cantilever beam at different temperatures. Experimentally recorded impact hammer force signals and piezoelectric accelerometer time-domain signals are processed through a system identification toolbox in MATLAB to obtain transfer functions of the plant models. A robust fuzzy logic controller is developed to accomplish the effective vibration control of a cantilever composite beam operating at different temperatures. The fuzzy logic controller with two inputs and one output is designed using the 20 if-then rules. The results are presented in both frequency and time domain, keeping the vibration attenuation of the fundamental frequency as the point of interest. The results indicate the proposed fuzzy logic control strategy can attenuate the vibrations of a cantilever composite beam for a wide temperature range. © The Author(s) 2022.Item Numerical and Experimental Investigations on Robust Output Feedback Control for Active Vibration Attenuation of Flexible Smart System(Institute of Electrical and Electronics Engineers Inc., 2023) Parameswaran, A.P.; Padmasali, A.N.; Gangadharan, K.V.This paper investigates the prototyping and implementation of an output feedback-based robust controller on a Field Programmable Gate Array (FPGA) platform. The Smart System under Test (SSuT) in this submission is a flexible cantilever beam bonded with Piezoelectric (PZT 5H) patches that act as a sensor as well as an actuator (perturbance creation as well as control actuation). For ease of modeling and subsequent controller design in the laboratory studies, the low-frequency dynamics of the smart system are approximated to only a Single Degree of Freedom (SDOF) in terms of flexural vibrations. The SSuT is modeled analytically through finite element modeling and experimentally through sub-space system identification process. The developed models' accuracy is compared with the experimental results of non - parametric modeling. The developed models are then used to conduct the simulation studies with the designed robust output feedback controller in the closed loop. Apart from the simulation studies, the designed controller was also prototyped on an FPGA platform using LabVIEW FPGA with the associated hardware in loop to carry out the experimental validation of its performance. The robustness and efficiency of the prototype controller to control the system vibrations in real-time were proved through extensive tests at single resonant frequencies and a range of frequencies encompassing the dominant resonant regions in the flexural mode. Findings from this study are further used to ensure satisfactory active vibration control of smart cantilever systems in various heavy/aerospace industries by approximating them to suitable benchmark systems in the laboratory. © 2013 IEEE.