Faculty Publications

Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736

Publications by NITK Faculty

Browse

Subject: search.filters.subject.Composite beam

Search Results

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    Nonuniform Heat Effects on Buckling of Laminated Composite Beam: Experimental Investigations
    (World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2018) George, N.; Jeyaraj, P.
    The influence of nonuniform heating on the critical buckling temperature of laminated glass-epoxy composite beam has been investigated experimentally with the help of a novel experimental setup. The beam is numerically investigated using nonlinear finite element analysis. An initial geometric imperfection is introduced to the modeled geometry in numerical technique to have an experimental-numerical comparison of temperature-deflection plot. The results indicate that the critical buckling temperature of a uniformly heated beam has a significant difference in comparison to the nonuniformly heated beam and it depends on the heating source location and the resulting temperature distribution along the length direction of the beam. © 2018 World Scientific Publishing Company.
  • No Thumbnail Available
    Item
    Investigations on the thermal actuation of carbon black reinforced pdms composite uni-layer and bi-layer cantilever beams
    (ModTech Publishing House office@hotelfloramamaia.ro, 2020) Hiremath, H.; Desai, S.; Kulkarni, S.M.; Karanth P, N.; Desai, V.
    Actuators are the essential components of robots, switches, relays, and many other automatic systems. There are various actuator types based on material, geometry, and stimulus. Nowadays, polymer composite based actuators are gaining importance due to their flexibility, ease of processing, low cost, and easy way of tailoring the properties. Among the polymers, Polydimethylsiloxane (PDMS) is one of the promising polymers for the actuator. In the present study, unilayer and bilayer cantilever beams of PDMS based composite subjected to a thermal stimulus are investigated. The Finite Element (FE) and the analytical models are developed for unilayer and bilayer polymer composite beams and simulated for actuator response. The deflection behavior of these beams is investigated for a temperature input range of 308K to 368K. The beams are analyzed for varying Carbon Black(CB) content from 5 to 25 Vol% in PDMS polymer and beam thickness from 1mm to 5mm. It is observed that with an increasing percentage of filler content, the increment in deflection of the bilayer beam is appreciably higher when compared to the unilayer beam. For 25 Vol% of CB, the bilayer beam shows 11.48 times improvement in deflection value. Also, it is noticed that the thickness of the beams influences deflection more compared to the percentage of the CB content. The deflection of the unilayer and bilayer beam is observed to increase linearly with temperature input. At 368K, the bilayer beam deflection is 6.87 times greater than the unilayer. Hence this analysis is the baseline for predicting the actuator performance of the unilayer and bilayer polymer composite beams considering the set of variables. © International Journal of Modern Manufacturing Technologies.
  • No Thumbnail Available
    Item
    Static stability and free vibration characteristics of a micro laminated beam under varying axial load using modified couple stress theory and Ritz method
    (Elsevier Ltd, 2022) Priyanka, R.; Jeyaraj, J.
    This paper explores the buckling and free vibration behaviors of micro laminated composite beams (MLCBs) exposed to varying axial loads using the modified couple stress theory (MCST), with arbitrary boundary conditions and layups. The size effect is captured in MCST by taking into account the material length scale parameters. In the axial direction, the applied load has either constant, linear, or parabolic variations. The equilibrium equations are derived and solved using Hamilton's principle and Ritz method respectively. The size effect is observed to be more pronounced when the thickness of the beam is similar to the material length scale parameter, and it nearly vanishes as the beam thickness increases. The small size effect variation is different for different boundary conditions. For parabolically increasing loading case, the rate of reduction of the fundamental frequency with an increase in applied load intensity is greater compared to other loadings. © 2021 Elsevier Ltd
  • No Thumbnail Available
    Item
    Nonlinear thermo-elastic stability of variable stiffness curvilinear fibres based layered composite beams by shear deformable trigonometric beam model coupled with modified constitutive equations
    (Elsevier Ltd, 2023) Manickam, G.; Haboussi, M.; D'Ottavio, M.; Kulkarni, V.; Chettiar, A.; Gunasekaran, V.
    Nonlinear thermo-elastic buckling characteristics of composite variable stiffness beam with layers making use of curvilinear fibres under thermal environment is attempted here. The model is based on a shear deformable theory introducing trigonometric function, and considering von Kármán's assumptions based geometrical nonlinear effect. The beam constitutive equation is modified according to the stress-free situation in the width direction of beam-Poisson's effect in the formulation for predicting the behaviour of general lay-up composite beams. By the principle of minimum total potential energy, the governing equations in terms of incremental stiffness matrices are formed introducing general beam finite element. The global equilibrium equations formulated are solved for envisaging the post-buckling path through eigenvalue analysis iteratively, thus establishing the relationship of thermal temperature against moderate amplitude level of beam deflection. A systematic parametric analysis considering different lamina properties such as curvilinear fibre path angles and including lay-up sequences, thermal expansion coefficient, mixed laminate combining straight and curvilinear fibres-based layers is carried out on thermo-structural stability of curvilinear fibre-based beams. Also, the influence of geometric factors, flexible beam end support, and variation in thermal profile, etc. over the stability behaviour of beam is examined. © 2022
  • No Thumbnail Available
    Item
    Post-buckling of variable stiffness curvilinear fibre-reinforced general lay-up composite beams by sinusoidal shear flexible theory
    (SAGE Publications Ltd, 2024) Manickam, G.; Polit, O.; Haboussi, M.; Chettiar, A.; Kulkarni, V.; Gunasekaran, V.
    The mechanical post-buckling behaviour of variable stiffness layered composite beams reinforced by curvilinear fibres subjected to compressive loads is investigated here using a sine function-based shear flexible beam model. The neutral axis stretching force stemming from the axial movement restraints is accounted for through von Karman’s assumption based geometrical nonlinearity. Furthermore, the modified beam constitutive equation arising from the consideration of the Poisson’s effect is introduced in the formulation for the laminated beam analysis with general lay-up or ply sequences. The governing equations incorporating the incremental stiffness matrices are formed through the minimization of total potential energy principle and are solved by numerical method. The solutions for the developed governing equations are evaluated iteratively based on eigenvalue analysis and the characteristics of post-buckling of laminated beams can be inferred through the relationship between the beam deflection level and post-buckling axial load. An in-depth analysis selecting many design parameters for instance lamina’s curvilinear fibre angles, beam slenderness ratio, lay-up and edge conditions, load type and so on is dealt with in bringing out the behaviour of variable stiffness laminated beam in linear and post-buckling regions. Also, the influence of flexible end supports by restraining elastically against ends rotation is studied on the beam elastic stability behaviour. © The Author(s) 2023.
  • No Thumbnail Available
    Item
    Thermoelastic buckling and vibration analysis of shear and normal deformable three-phase bio-inspired composite beams under axially varying temperature fields
    (Springer, 2025) Patil, H.H.; Pitchaimani, J.
    The thermoelastic buckling and free vibration behaviors of a Three-Phase Composite (TPC) beam subjected to axially varying Non-Uniform Temperature (NUFT) fields is investigated by incorporating Temperature-Dependent (TD) elastic properties of both Carbon Nanotubes (CNTs) and the matrix. The Shear and Normal Deformable Beam Theory (SNDBT) is used to model the kinematics, and the governing equations are formulated through Hamilton’s principle and solved using the Ritz method. TD elastic properties of CNTs are accounted in terms of TD Hill’s constants. Dispersion issue of CNT is accounted in terms of partial and complete agglomeration effects for more realistic material modeling. The results indicate that the area beneath the NUFT distribution profiles serves as a meaningful parameter for interpreting both the critical buckling temperature (?Tcr) and the induced axial membrane force (N). NUFT-induced differential thermal expansion generates localized thermal strain variations, and the strain reverses its sign whenever the temperature at a point exceeds the spatially averaged temperature for the given NUFT. Consideration of thickness-stretching deformation (Wz) produces noticeable changes in ?Tcr and the fundamental frequency (?1), particularly for the beams with lower aspect-ratio, emphasizing its necessity in thick-beam modeling. The findings provide practical guidance for the design of lightweight, thermally stable composite structures deployed in aerospace and other thermal-environment-critical engineering systems. © The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature 2025.