Faculty Publications

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    Analytical investigation on free vibration frequencies of polymer nano composite plate: Effect of graphene grading and non-uniform edge loading
    (Elsevier Ltd, 2020) Gunasekaran, V.; Jeyaraj, J.; Mailan Chinnapandi, L.B.M.
    An analytical investigation carried out on free vibration characteristics of functionally graded graphene reinforced nanocomposite (FG-GRC) plate under different non-uniform edge loads is presented. Graphene nano-platelets (GPLs) are homogeneously dispersed and graded by varying weight fraction through the thickness. An analytical method based on strain energy approach is adopted to estimate the buckling load. Natural frequencies of the FG-GRC plate are attained using analytical solutions derived based on Reddy's third-order shear deformation theorem (TDST). Results revealed that buckling and free vibration behavior of the plate is influenced by the GPLs dispersion pattern and weight fraction under non-uniform edge loads. It is also observed that buckling mode and the fundamental vibration mode of the plate under combined tensile-compression load is entirely different from the other non-uniform edge load cases. © 2020 Elsevier Ltd
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    Static stability and vibration behavior of graphene platelets reinforced porous sandwich cylindrical panel under non-uniform edge loads using semi-analytical approach
    (Elsevier Ltd, 2022) Twinkle, C.M.; Jeyaraj, J.
    Buckling and free vibration characteristics of sandwich cylindrical panel with porous functionally graded graphene platelets (FG-GPL) core are investigated using semi-analytical approach. The effective mechanical properties are obtained by using properties of open cell foams and Halpin–Tsai micro mechanical model. The governing equations are obtained using Hamilton's principle, considering a higher order theory to account the transverse shear and solved by Galerkin's method. Effects of nature of in-plane edge load, distribution of porosity and GPL, porosity coefficient, GPL loading, core to total thickness ratio are analyzed in detail. It is shown that for a FG-GPL core sandwich cylindrical panel with high core thickness, even at higher amount of porosity the buckling resistance and free vibration frequency can be improved by properly tailoring both the GPL and porosity distribution. Moreover, a much variation in buckling and free vibration response with the type of in plane loading is observed and evident mode shape changes are observed with increase in aspect ratio. The cylindrical sandwich panel having a core with D-PD porosity variation and I-GPL-P pattern of GPL distribution has the maximum buckling resistance and free vibration frequency value. © 2021 Elsevier Ltd
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    A semi-analytical nonlocal elasticity model for static stability and vibration behaviour of agglomerated CNTs reinforced nano cylindrical panel under non-uniform edge loads
    (Elsevier Inc., 2022) Twinkle, C.M.; Jeyaraj, J.
    A semi analytical nonlocal elasticity model to analyze the effect of non-uniform edge loads on static stability and free vibration characteristics of agglomerated carbon nanotubes (CNTs) reinforced nano cylindrical panels are presented. Effective material properties of the agglomerated CNT reinforced composite are obtained using a two-parameter micro-mechanics model while Eringen's non-local theory is used to account the size effect. Sinusoidal shear deformation theory is adopted to analyze the buckling and vibration parameters using Galerkin's approach. The accuracy of the proposed model is presented first by comparing the results in the literature. Then a comprehensive study is carried out to analyze the influence of various degrees of agglomeration (complete, partial), nature of edge load, and non-local effects on the buckling and free vibration response of CNT reinforced nano cylindrical panel. The results revealed that non-local size effect leads to a reduction in stiffness and thus reduces buckling and dynamic characteristics. Moreover, it is observed that critical buckling load varies with type of in plane load and reduction in natural frequency is different for different in plane loading conditions. © 2021 Elsevier Inc.
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    Vibration and stability characteristics of functionally graded sandwich plates with/without porosity subjected to localized edge loadings
    (Taylor and Francis Ltd., 2023) Swaminathan, K.; Hirannaiah, S.; Rajanna, T.
    This article investigates the influence of porosity and localized edge loads on the vibration and buckling characteristics of functionally graded material (FGM) plates using the finite element (FE) method. The analysis is carried out by choosing a single-layer FGM and two different types of FGM sandwich plates in such a way that there is no material discontinuity along the thickness direction. The porosity imperfections are accounted for in this study as criteria of stiffness reduction and are incorporated using modified power law distribution. The vibration and buckling responses are studied by considering four types of localized edge loads on plates with different porosity distributions. The application of different types of localized edge loads on the plate leads to the development of nonuniform in-plane stresses. Hence, they are computed first by using a dynamic approach before obtaining the buckling loads. The accuracy of the FE formulation is first validated for FGM plates by comparing the natural frequencies and the critical buckling loads obtained in the present investigation with the solutions already available in the literature. After validating the accuracy, detailed parametric studies have been performed on plates with varying volume fraction exponent, porosity distribution, porosity index, side-to-thickness ratio, load width ratio, aspect ratio, and support condition, and the results are presented with appropriate conclusions. A probabilistic sensitivity analysis is carried out to identify the significant parameter affecting the buckling load and natural frequency of porous FGM plates subjected to localized edge loads, which considerably aids in the design of the FGM plates. © 2022 Taylor & Francis Group, LLC.
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    Influence of porosity and nonuniform in-plane edge loads on vibration and buckling response of power law and sigmoid function based FG sandwich plates with geometrical discontinuities
    (Taylor and Francis Ltd., 2023) Swaminathan, K.; Hirannaiah, S.; Rajanna, T.
    Porosity defects can emerge during the manufacturing process of Functionally Graded Sandwich Plates (FGSPs). In practice, FGSPs have geometric discontinuities/cutouts and are exposed to Nonuniform In-plane Edge Loads (NIELs). The presence of porosity, cutout and NIELs causes a significant reduction in the stiffness of the plate affecting its vibration and buckling behavior. Therefore, in this paper vibration and buckling results obtained using the Finite Element (FE) method hitherto not reported in the literature are presented for porous FGSPs with cutouts and subjected to NIELs. Four types of porosity distribution models are explored, and the porosity imperfections are modeled as the criteria of stiffness reduction. Porosity-dependent material properties of FGSPs are evaluated using modified power law and sigmoid function. The current study incorporates two distinct kinds of sandwich configuration in such a way that there is no material mismatch along the thickness direction. The application of different cases of NIELs on the plate with cutouts leads to the development of nonuniform stresses. Hence a novel dynamic approach has been proposed to evaluate buckling loads by implementing two sets of boundary conditions. The first set of boundary conditions calculates pre-buckling stress, while second set calculates critical buckling loads. The generated results from the current FE formulation are compared with existing results in the literature to ensure accuracy. Finally, the effect of porosity distribution, NIELs, cutout ratio and its positions, support conditions, volume fraction exponents and geometric parameters on the vibration and buckling response are studied and discussed to arrive at appropriate conclusion. © 2022 Taylor & Francis Group, LLC.
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    Localised edge load dependent aeroelastic stability of porous plates with GPL reinforcement under the influence of supersonic flow
    (Elsevier Ltd, 2025) Twinkle, T.; Pitchaimani, J.; Lacarbonara, W.
    Buckling and flutter characteristics of porous plates with graphene platelet (GPL) reinforcement subjected to concentrated edge loads are explored for the first time. The plate is considered to be having simultaneous variation of GPL and porosity content through the thickness. For the porous plate with GPL reinforcement, the effective material properties are determined using the Halpin–Tsai micromechanical model. Further, to obtain the solutions the Galerkin method is employed for the governing differential equations derived using Hamilton's principle. The results of the present model are validated for accuracy and reliability by comparing them with the results available in the open literature for buckling, free vibration, and flutter studies. To study the flutter behaviour of plates under the effect of different types of concentrated edge loads, several parametric studies are performed for the first time. Additionally, the influence of GPL weight percentage, amount of porosity, dispersion of porosity, and GPL on the flutter instability is investigated. The results indicate that the type of concentrated edge load has a major impact on the flutter instability of the plate with centrally distributed (case 1) type of loading leading to a higher reduction in flutter pressure. Further, an increase in porosity and GPL content significantly affects the flutter and buckling coefficient values. © 2024 Elsevier Ltd
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    Vibration and Stability Characteristics of Functionally Graded Plates Subjected to Localized Edge Loadings
    (Springer, 2025) Swaminathan, K.; Hirannaiah, S.; Rajanna, T.
    In this article, the influence of various types of localized in-plane edge loadings on vibration and stability characteristics of Functionally Graded Material (FGM) plates have been studied by developing finite element (FE) code in FORTRAN. Due to the complex arrangement of plates and situations arising during the real time application, loads acting on the member are not always uniform, rather nonuniform or localized in nature. For a such loading and boundary condition, the stress distribution within an element is highly non-uniform in nature. Therefore, the buckling loads are evaluated by dynamics approach. Here, in this study FGM plate is modelled using eight-noded isoparametric element with five degrees of freedom at each node. In the FE formulations, the influence of shear deformation and rotary inertia are included. In the FGM plate, the effective materials properties are assumed to vary in the thickness direction according to power-law distribution of volume fraction of the constituents. The analysis is carried out for four types of localized edge loads. Effect of different parameters such as boundary condition, side to thickness ratios, volume fraction exponent, load width ratio and the aspect ratio of the plate is considered to study the buckling characteristics of FGM plate. From the current study, it is mainly understood that the buckling characteristics of FGM plate of various volume fraction exponent is highly influenced by the position and width of localized in-plane edge loads. © The Institution of Engineers (India) 2024.