Faculty Publications
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Item Investigation of static and dynamic properties of cenosphere reinforced polymer matrix composite beams(American Institute of Physics Inc. subs@aip.org, 2019) Bharath, J.; Joladarashi, S.; Nagiredla, S.; Kumar, H.Polymer Matrix Composites (PMC) plays a conspicuous role in engineering application. Cenosphere reinforced polymer matrix composite has higher strength, stiffness, lesser density and also saving in cost. These particulate composites are manufactured to meet several structural requirements. Thus there is a need to study their static and dynamic properties. In this work polymer epoxy polymer composites reinforced with cenosphere are fabricated and their static and dynamic properties are analyzed. Experimental investigation involves fabrication of specimen of polymer matrix reinforced with cenosphere by varying volume fractions of 25%, 30%, 35%, and 40%. Tensile and compressive properties are tested on UTM as per ASTM standard. Microstructures of composites are assessed with SEM and also Model analysis of cantilever beam is performed as per ASTM standard in Engineering Data Management System (EDM 7.0) of Crystal Instruments to study variation of natural frequency in each case. The natural frequency results are compared with the commercially available ANSYS FE software by assigning the material propertied obtained by static analysis. Thus effects of volume fraction of cenosphere on static and dynamic characteristics of particulate composites are studied. © 2018 Author(s).Item Experimental investigation of frequency and damping characteristics of magneto-rheological fluid core sandwich beams(American Institute of Physics Inc. subs@aip.org, 2020) Nagiredla, S.; Joladarashi, S.; Kumar, H.In dynamic systems mechanical vibration amplitudes may range from a few nanometres to meters. When the vibration amplitudes are high the system may lead to failure or lost it function. Structures often tend to failure because of the high vibration amplitudes. These vibrations can be reduced by changing the stiffness or damping of the structure. One of the approaches is semi-active damping achieved by using Magneto-rheological fluid (MRF) as core material in a sandwiched beam. Magneto-rheological(MR) fluids change from fluid state to quasi-solid state when it is activated by a magnetic field. Adding MR fluids to mechanical systems may significantly improve their dynamic response. This study aims to analyse the free vibration response of the cantilever sandwich beam filled with the MR fluid as core material with Magnetic field intensity. A sandwich cantilever beam with Composite material as face layer and Magneto-rheological fluid as core was fabricated. Free Vibration test is performed on a sandwich beam filled with MR fluid under the external magnetic field generated by permanent magnets. Magnitude of Viscoelastic moduli of the MR fluid increases with magnetic field intensity as the fluid becomes semi-solid. The aim of the work is to analyse the influence of Magneto-rheological effect on the beam response with respect to externally applied magnetic field. Vibrations of the beam are registered with magnetic field and without magnetic field strength. Obtained data is utilized to analyse the dependency of magnetic field strength on the beams natural frequency and damping. © 2020 Author(s).Item Vibration Analysis of Composite Viscoelastic Core Sandwich Beam Using Active Control Techniques(Springer Science and Business Media Deutschland GmbH, 2024) Raghavendra, P.; Gatty, A.S.; Rajesh, H.; Deepak, T.N.; Rawal, Y.; Nagiredla, S.; Joladarashi, S.Vibration control is swiftly advancing in research, with diverse techniques being investigated to minimize detrimental vibration levels. Compared to metallic alloys, composite materials offer superior material properties while being lightweight. The main objective of this study is to develop active control techniques on Carbon/Glass Epoxy-reinforced composite sandwich beams with viscoelastic core using Proportional Integral Derivative (PID), Linear Quadratic Regulator (LQR), and Linear Quadratic Gaussian (LQG) Controllers. The approach involves conducting an experiment to obtain the Transient Response of the beams subjected to free vibration, which is then utilized to obtain the Transfer Function and State Space variables. MATLAB-Simulink obtained transfer function is used for implementing controllers to actively attenuate vibrational amplitudes and settling time. The outcomes reveal a significant reduction in settling time and vibrational peak amplitudes. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.Item Passive and Active Vibration Control of Hybrid Composite Sandwich Beam(Springer Science and Business Media Deutschland GmbH, 2024) Nagiredla, S.; Joladarashi, S.; Kumar, H.Vibration control is a rapidly developing field and research is being carried out on different methods to attenuate the harmful vibration levels. Composite materials carry the advantage of providing enhanced material properties compared to that of conventional materials. This work mainly focuses on conducting the transient analysis on hybrid composite sandwich beams with viscoelastic core and to implement the linear quadratic regulator (LQR) and Proportional, Integrate and derivative (PID) controllers. The transient response of the hybrid composite sandwich beam with the viscoelastic core is presented and the active vibration control study was implemented on the sandwich beam’s transfer function which is obtained by using system identification technique. It was found that there is a substantial change in settling time as well as vibrational amplitude. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.Item Rheological Properties of the In-house Prepared Magneto-rheological Fluid in the Pre-yield Region(Materials and Energy Research Center, 2022) Nagiredla, S.; Joladarashi, S.; Kumar, H.The essence of the present work is to study the rheological properties of the in-house prepared magnetorheological (MR) fluids in the pre-yield region since the rheological properties play a vital role in better understanding of vibration damping capabilities of MR fluids. In the present work, two different compositions of MR fluid samples were prepared with 24 and 30 volume percentages of carbonyl iron (CI) particles. Prepared MR fluid samples contain CI particles as a dispersive medium, silicone oil as a carrier fluid and white lithium grease as an anti-settling agent. The oscillating driving frequency and amplitude strain sweep tests are performed to investigate the rheological properties within the pre-yield region. The influences of driving frequency, strain amplitude, magnetic field and CI particles volume percentage on the rheological properties of the prepared MR fluids were assessed. The linear viscoelastic region of the prepared MR fluid sample was identified and the yield strain obtained was around 0.371%. It is observed that the volume percentage of CI particles in the MR fluid strongly influenced the rheological properties. © 2022 Materials and Energy Research Center. All rights reserved.Item Characterization of an in-house prepared magnetorheological fluid and vibrational behavior of composite sandwich beam with magnetorheological fluid core(Sharif University of Technology, 2023) Nagiredla, S.; Joladarashi, S.; Kumar, H.In this research work, two different compositions of MR fluid samples with 24 and 30 percentage (%) volume fraction of carbonyl iron (CI) particles are prepared. Prepared MR fluid (MRF) samples contain carbonyl iron particles as a dispersive medium, silicone oil as a carrier fluid, and white lithium grease as an anti-settling agent. Influence of oscillating driving frequency, strain amplitude, magnetic field, and the percentage of CI particle on the rheological properties of the MR fluid samples are presented. Storage modulus and loss factor equations are estimated from the rheometry results using a linear regression method. The properties of MR fluid samples are taken to design and model the sandwich beams using ANSYS ACP software, where carbon epoxy composite material is used as the face layer and MR fluid as the core material. Modal, harmonic, and transient analysis studies have been conducted on all the modelled sandwich beams. Influence of MR fluid core material thickness, face layer thickness, CI particle volume percentage in the prepared MR fluid sample, and magnetic field on the vibrational response of the sandwich beams have been presented. Carbon-epoxy composites with an in-house made MRF sandwich beam has shown some significant results in the vibrational response. © 2023 Sharif University of Technology. All rights reserved.Item Combined Damping Effect of the Composite Material and Magnetorheological Fluid on Static and Dynamic Behavior of the Sandwich Beam(Springer, 2023) Nagiredla, S.; Joladarashi, S.; Kumar, H.Purpose: In the present study, the influence of combined damping due to composite facings and magnetorheological (MR) fluid on the static and dynamic response of the graphite/epoxy composite sandwich beam is investigated because the combined damping effect plays a crucial role in suppressing the high amplitudes of vibration for the structural applications. Methods: The sandwich beam element with 12 degrees of freedom is considered for the finite element (FE) formulation and the Lagrange’s approach is employed to obtain the equations of motion (EOM). The FE code is developed and validated with the available literature to examine the static, free and forced vibration response of the MR composite sandwich beam. Results: The influence of laminate angle, magnetic field, and thickness ratio on the static deflection, loss factor, natural frequency and forced vibration response are presented. Further, the influence of the applied magnetic field on the percentage of reduction in static deflection and the deviation in the first fundamental natural frequency and loss factor are evaluated. Conclusion: It is observed that the central static deflection of the sandwich beam is more for the composite facings at higher laminate angles. The percentage of deviation in the first fundamental natural frequency and loss factor significantly improved with the applied magnetic field. The damping considered in both the composite facings and MR fluid displayed a good attenuation in vibration amplitude. © 2022, Krishtel eMaging Solutions Private Limited.Item Influence of Material and Geometrical Properties on Static and Dynamic Behavior of MR Fluid Sandwich Beam: Finite Element Approach(Institute for Ionics, 2023) Nagiredla, S.; Joladarashi, S.; Kumar, H.Magnetorheological (MR) fluid can transform its rheological properties when it is exposed to a magnetic field. This nature of the MR fluid provides an additional stiffness and damping for the sandwich beam applications. The Lagrange’s method is used to derive the equations of motion for the current finite element formulation. The influence of an applied magnetic field, thickness ratio and the length parameter on the static deflection, loss factor and natural frequency for different boundary conditions are presented. Further, the study is extended to plot the real and imaginary mode shapes corresponding to the fundamental frequencies. The geometrical and material properties considered in the present study showed a significant influence on static deflection and vibration amplitude of the sandwich beam. There is a maximum of 22.74% decrease in static deflection obtained for the simply supported condition. © 2023, The Author(s), under exclusive licence to Shiraz University.Item Modelling and predicting the dynamic response of an axially graded viscoelastic core sandwich beam(KeAi Communications Co., 2023) Nagiredla, S.; Joladarashi, S.; Kumar, H.The present study explored the influence of axial gradation of viscoelastic materials on the dynamic response of the sandwich beam for structural applications. The finite element (FE) formulations are used to model and investigate dynamic response of the sandwich beam. The classical beam theory is used to develop the FE formulations and Lagrange's approach is considered to obtain the equations of motion (EOM). FE code is developed and validated with the existing literature and also conducted the convergence study for the developed FE method. Further, the influence of different viscoelastic materials and boundary conditions on the dynamic response of the sandwich beam is investigated. Four different axial gradation configurations of viscoelastic materials are considered for the present work to explore the influence on natural frequency, loss factor and frequency response of the sandwich beam. The modeled axial gradation of viscoelastic material has displayed a considerable impact on the peak vibrational amplitude response of the sandwich beam for all the boundary conditions and these configurations improved the damping capabilities at different configurations for the structural applications. © 2023 China Ordnance SocietyItem Influence of magneto-rheological fluid pocket configuration on the dynamic response of the composite sandwich beam(Taylor and Francis Ltd., 2024) Nagiredla, S.; Joladarashi, S.; Kumar, H.The present study investigated the influence of magnetorheological (MR) fluid pocket configuration and magnetic field intensity on the dynamic response of the composite sandwich beam under various boundary conditions. The classical beam theory is used to develop the finite element (FE) formulations for the composite sandwich beam element and it is validated with the available literature. Four MR fluid pocket configuration types are considered. The configuration types include 1/4th, 1/2th, 3/4th and the full length of the MR fluid pockets at different locations. Further, a detailed study of the influence of each MR fluid pocket configuration type on the natural frequency, loss factor, and frequency response are presented. The maximum 32.27% of deviation in the first fundamental frequency is observed for the simply-supported boundary condition. From the results obtained, it is concluded that the length and location of the MR fluid pocket have a considerable impact on the dynamic response and also observed that the effect of the configuration depends on the type of boundary condition used. © 2022 Taylor & Francis Group, LLC.