Faculty Publications
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Item Effect of lamination schemes on natural frequency and modal damping of fiber reinforced laminated beam using Ritz method(EDP Sciences, 2021) Somi Naidu, S.N.; Jeyaraj, J.; Mailan Chinnapandi, L.B.; Reddi, C.V.S.N.The current study focussed on analysing natural frequency and damping of laminated composite beams (LCBs) by varying fiber angle, aspect ratio, material property and boundary conditions. Ritz method with displacement field based on the shear and normal deformable theory is used and the modal damping is calculated using modal strain energy method. Effects of symmetric angle-ply and cross-ply, anti symmetric cross-ply, balanced and quasi-isotropic lay up schemes on modal damping are presented for the first time. Results revealed that influence of lay-up scheme on natural frequencies is significant for the thin beams while the modal damping of the thin beams are not sensitive to lay-up scheme. However, the lay-up scheme influences the damping significantly for the thick beams. Similarly, high strength fiber reinforced LCBs have higher natural frequency while low strength fiber reinforced LCBs have higher damping due to the better fiber-matrix interaction. © S.N. Balireddy et al., Published by EDP Sciences, 2021.Item Acoustic response of bi-directional functionally graded beam under axially varying load(SAGE Publications Inc., 2023) Somi Naidu, S.N.; Pitchaimani, J.; Mailan Chinnapandi, L.B.This paper investigates the effects of bi-directional gradation, length-to-height ratio, and end conditions on the acoustic behaviour of bi-directionally varying functional graded beams. The acoustic responses, including sound-power level (dB), sound-pressure level (dB), and sound-radiation efficiency, are evaluated using Rayleigh’s integral and modal superposition method. The sound power levels are presented up to the selected bandwidth, as well as the octave band center frequency. In contrast, the sound pressure levels are presented as contour plots and in directivity pattern. The buckling load, calculated for quadratically decreasing axial load, is applied in increments from 0 to its highest value. The study reveals that the highest value in the gradation indexes in both directions significantly influences the sound power levels. It is also evident from the study that thin beams have higher sound power levels compared to thick beams. The directivity pattern reveals that bi-directional functionally graded beams predict higher sound pressure levels at the critical buckling load. From the current acoustic study, it is observed that both structural and end stiffness are influential factors in sound power levels (dB) and sound pressure levels (dB). © The Author(s) 2023.Item Free vibration and inherent material damping characteristics of boron-FRP plate: Influence of non-uniform uniaxial edge loads(EDP Sciences, 2021) Gunasekaran, V.; Jeyaraj, J.; Mailan Chinnapandi, L.B.The current investigation presents the analytical investigation on free vibration and inherent material damping of boron-FRP plate, subjected to non-uniform uniaxial edge loads. Initially critical buckling load (Pcr) is obtained, then followed by free vibration response and inherent material damping values for corresponding modal indices of the FRP plate is calculated for different load fraction of non-uniform uniaxial edge loads. The buckling load and free vibration response are obtained by using strain energy method and Reddy's TSDT respectively. It is observed that the nature of load and aspect ratio influence the bucking, free vibration and inherent material damping behaviour of the fibre reinforced polymer plate significantly. © V. Gunasekaran et al., Published by EDP Sciences, 2021.Item Acoustic behaviour of 3D printed bio-degradable micro-perforated panels with varying perforation cross-sections(Elsevier Ltd, 2021) Sailesh, R.; Yuvaraj, L.; Jeyaraj, J.; Doddamani, M.; Mailan Chinnapandi, L.B.Influence of perforations having arbitrarily varying cross-sections on the acoustic behaviour of 3D printed bio-degradable panels made of Poly Lactic Acid (PLA) is presented. Circular perforations having six different types of cross-sectional variations namely convergent-divergent (CD), divergent-convergent (DC), convergent (C), divergent (D) with two different perforation diameters are realized using Fused Filament Fabrication (FFF) based 3D printing. Sound absorption and transmission loss characteristics of these perforated panels are estimated through impedance tube technique. Results revealed that sound absorption of perforated panels with varying cross-section is better than uniform cross-sectional perforation for the given frequency range. Among, the different cross-sectional variations explored, comparable and lower transmission losses are exhibited by DC and D perforation pattern with respect to constant diameter 1 mm panel. The sound transmission results of all other five specimens were significantly higher than constant diameter 8 mm panel and observed to be increasing with frequency. Geometrical perforation variations are noted to be a very crucial factor in designing soundproof panels as presented in this work. The experimental results are compared with the numerical results and found to be in good agreement. Such numerical analysis paves the guidelines for designing optimum perforation geometries prior to the on-field testing of the functional prototypes. © 2020 Elsevier LtdItem Analytical Solution for Sound Radiation Characteristics of Graphene Nanocomposites Plate: Effect of Porosity and Variable Edge Load(World Scientific, 2021) Gunasekaran, V.; Jeyaraj, J.; Mailan Chinnapandi, L.B.; Kumar, A.The effects of graded dispersion of graphene platelets and porosity on vibro-acoustics of nanocomposite plate exposed to variable edge loads are analytically investigated. Voigt and Halpin-Tsai micromechanics model is used to obtain effective properties of the porous graphene nanocomposites. The strain energy technique is implemented to estimate the buckling load (Pcr). By means of Reddy's third-order shear deformation theorem and Rayleigh Integral, vibration and acoustic responses are obtained. After validating the present analysis with the published results, the nature of edge loads on buckling and vibro-acoustic response is significant. It is noted that an increase in the intensity of non-uniform in-plane loads leads to changes in free vibration modes and resonant amplitude of response. The weight percentage and grading pattern of graphene reinforcement cause the stiffness hardening effect, whereas porosity distribution and coefficients cause the stiffness softening effect on the nanocomposite plate. It is found that the plate with symmetric distribution of graphene platelets with more concentration at the surface and symmetric porosity variation with more porosity at the center radiates less sound power. © 2021 World Scientific Publishing Company.Item Acoustic radiation and transmission loss of FG-Graphene composite plate under nonuniform edge loading(Elsevier Ltd, 2021) Gunasekaran, V.; Jeyaraj, J.; Mailan Chinnapandi, L.B.The influence of nonuniform edge loads on the acoustic response of a functionally graded graphene reinforced composite plate is investigated analytically. The energy method is implemented to calculate the buckling load (Pcr). An analytical method based on Reddy's third-order shear deformation theorem is used to obtain the vibration response, and acoustic response is obtained using Rayleigh Integral. The nature of edge load variation on buckling and vibro-acoustic response is significant. Free vibration mode shape changes with an increase in edge load and consequently affects the resonant amplitude of responses also especially for the plates with a higher aspect ratio. Volume fraction and dispersion pattern of graphene nano-platelets also influences the resonance amplitudes. Plate with FG?GRCC dispersion pattern has improved buckling and vibro-acoustic response behavior. Similarly, change in sound transmission loss level is significant in the stiffness region compared to the damping and mass dominated region. © 2021 Elsevier Masson SASItem Buckling and Free Vibration of Porous Functionally Graded Metal Ceramic Beams under Thermal and Mechanical Loading: A Comparative Study(Springer, 2021) Patil, H.B.; Jeyaraj, J.; Mailan Chinnapandi, L.B.Buckling and free vibration characteristics of functionally graded porous metal ceramic beams subjected to mechanical and thermal loads are presented. Five-noded, beam element with ten degrees of freedom is used to analyse the buckling and vibration behaviour. The effects of porosity, porosity pattern, functional grading of material, elastic foundations, slenderness ratio and different boundary conditions are analysed for critical comparison of behaviour of the beam under thermal and mechanical load. Results revealed that buckling and dynamic behaviour of the beam under thermal load is significantly different compared to the mechanical load. It is also observed that nature of porosity distribution and its volume fraction also influences the buckling strength significantly. Beam with uniform porosity shows better thermal buckling strength likewise beam with graded porosity for mechanical buckling strength. © 2021, The Institution of Engineers (India).Item Acoustic Response of an Isotropic Beam under Axially Variable Loads Using Ritz and Rayleigh Integral Methods(Polska Akademia Nauk, 2022) Somi Naidu, S.N.; Jeyaraj, J.; Mailan Chinnapandi, L.B.; Reddi Chintapalli, V.S.N.R.Vibro-acoustic response of an isotropic beam under the action of variable axial loads (VALs), is presented in the study. Effects of six different types of VALs and three types of end conditions on buckling, free vibration and sound radiation characteristics are investigated. Static buckling and free vibration behaviours using shear and normal deformable theorem and Ritz method. However, the forced vibration response is evaluated using modal superposition method and the acoustic radiation characteristics are obtained using Rayleigh integral. The nature of variation of VALs and end conditions are influencing buckling and free vibration characteristics remarkably. Results indicate that the acoustic response is highly sensitive to the nature of VAL and intensity of the VAL. In general, sound power at resonance decreases when the magnitude of VAL is increased. © © 2022 S.N. Balireddy et al.Item Sound absorption and transmission loss of 3D printed wood fibre reinforced poly lactic acid with functionally graded perforations(Taylor and Francis Ltd., 2024) Sailesh, R.; Doddamani, M.; Mailan Chinnapandi, L.B.; Yuvaraj, L.; Pitchaimani, J.The effect of wood fibre reinforcement on acoustic properties of 3D printed poly lactic acid samples having varying cross-section perforation and functionally graded spherical perforations is presented. Acoustic characteristics like sound absorption as well as transmission loss are obtained using an impedance tube setup. Results revealed the benefits due to the addition of wood fibres in PLA improved samples’ sound transmission loss characteristics significantly. The sound absorption curve peaks shifted to low-frequency regions which are favourable to living beings. The material can be used in acoustic insulation for structural and transportation applications, especially where eco-friendliness and aesthetics are of major concern. © 2023 Informa UK Limited, trading as Taylor & Francis Group.Item Exploring the acoustic potential of 3D printed micro-perforated panels: A comparative analysis(Elsevier Ltd, 2024) Deepak; Pitchaimani, J.; Raghukiran, R.; Mailan Chinnapandi, L.B.In the present study, the sound absorption performance of inhomogeneous Micro-Perforated Panels (MPPs) with multiple cavities is investigated. Two models, a three-cavity system and a four-cavity system, are proposed and a numerical study is performed using MATLAB. The models are validated through experimental analysis in an impedance tube. The study meticulously varies the geometrical parameters, including pore diameter, thickness of the MPP, perforation ratio, and back-cavity length. It is found that MPPs with a greater number of sub-cavities have a better sound absorption coefficient than two-cavity systems. The results suggest that the back air cavity is predominantly responsible for multiple peaks, ensuring wideband sound absorption. It is also found that smaller perforation ratios for sub-cavities with larger pore diameters improve sound absorption performance in the lower frequency region. The study indicates that a pore diameter of less than 0.5 mm should be used for better sound absorption above the range of 800–850 Hz, and back cavity length has greater control than pore diameter between 850 Hz and 2000 Hz to make the curve smooth with less fluctuation. The findings have significant implications for the design of MPPs for real-world applications. © 2024 The Authors