Faculty Publications
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Item Compressive properties of 3D braided flax fiber textile fabric reinforced PLA composites(IOP Publishing Ltd, 2021) Kanakannavar, S.; Jeyaraj, J.In this study, fabric woven using 3D braided flax yarn is used to reinforce Poly Lactic Acid (PLA) composites. Solid braiding technique is used to convert the typical yarns into braided yarn and further these yarns are used to prepare woven fabric. Finally, composites are fabricated through layer stacking method using hot-press hydraulic compression moulding machine. Compression and shrinkage tests are performed on the braided composites. The braided flax fiber composite results are compared with the as received PLA polymer results. Results showed significant enhancement in the compression properties of PLA composites due to the braided fabric reinforcement. These properties are further increased with the increase in filler content respectively. Thermal shrinkage of the braided flax fiber composites is lower than the PLA polymer. This is due to the higher thermal sustainability property associated with the braided flax fiber. © Published under licence by IOP Publishing Ltd.Item Mechanical behavior of 3D printed syntactic foam composites(Elsevier Ltd, 2020) Bharath, H.S.; Sawardekar, A.; Waddar, S.; Jeyaraj, J.; Doddamani, M.A three-dimensional printed (3DP), polymer based syntactic foams are developed using hollow glass micro balloons (GMB) dispersed in high density polyethylene (HDPE). This work presents the buckling and vibration response of 3D printed foams subjected to axial compression. The buckling load is estimated using Modified Budiansky Criteria (MBC) and Double Tangent Method (DTM) through the load–deflection plots. The first three natural frequencies and their mode shapes are computed as a function of axial compressive load. It is noted that the natural frequency reduces with an increase in axial compressive load. It is also observed that with an increase in GMB %, the natural frequencies and critical buckling load increases. In mode-1, the natural frequency decreases in pre-buckling regimes and increases exponentially in post-critical loading conditions. Analytical solutions obtained from the Euler-Bernoulli-beam theory are compared with experimental results. It is noted that the fundamental frequency approaches zero when the axial load is equal to the critical load. The critical buckling load is estimated through the vibration correlation technique and compared with the results obtained using DTM and MBC methods. The property map is plotted for buckling load against the density of various composites. © 2020 Elsevier LtdItem 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 Vibration analysis of a tapered laminated thick composite plate with ply drop-offs(Springer Verlag service@springer.de, 2015) Edwin Sudhagar, P.; Arumugam, A.; Vasudevan, R.; Jeyaraj, J.In this study, vibration characteristics of a tapered laminated thick composite plate have been investigated using finite element method by including the shear deformation and rotary inertia effects. The governing differential equations of motion of a tapered laminated thick composite plate are presented in the finite element formulation based on first-order shear deformation theory for three types of taper configurations. The effectiveness of the developed finite element formulation in identifying the various dynamic properties of a tapered laminated thick composite plate is demonstrated by comparing natural frequencies evaluated using the present FEM with those obtained from the experimental measurements and presented in the available literature. Various parametric studies are also performed to investigate the effect of taper configurations, aspect ratio, taper angle, angle ply orientation and boundary conditions on free and forced vibration responses of the structures. The comparison of the transverse free vibration mode shapes of the uniform and tapered composite plates under various boundary conditions is also presented. The forced vibration response of a composite plate is investigated to study the dynamic response of tapered composite plate under the harmonic force excitation in various tapered configurations. It is concluded that the dynamic properties of laminated thick composite plates could be tailored by dropping off the plies to yield various tapered composite plate. © 2015, Springer-Verlag Berlin Heidelberg.Item Sound radiation and transmission loss characteristics of a honeycomb sandwich panel with composite facings: Effect of inherent material damping(Academic Press, 2016) Arunkumar, M.P.; Jagadeesh, M.; Jeyaraj, J.; Gangadharan, K.V.; Mailan Chinnapandi, M.C.L.This paper presents the results of numerical studies carried out on vibro-acoustic and sound transmission loss behaviour of aluminium honeycomb core sandwich panel with fibre reinforced plastic (FRP) facings. Layered structural shell element with equivalent orthotropic elastic properties of core and orthotropic properties of FRP facing layer is used to predict the free and forced vibration characteristics. Followed by this, acoustic response and transmission loss characteristics are obtained using Rayleigh integral. Vibration and acoustic characteristics of FRP sandwich panels are compared with aluminium sandwich panels. The result reveals that FRP panel has better vibro-acoustic and transmission loss characteristics due to high stiffness and inherent material damping associated with them. Resonant amplitudes of the response are fully controlled by modal damping factors calculated based on modal strain energy. It is also demonstrated that FRP panel can be used to replace the aluminium panel without losing acoustic comfort with nearly 40 percent weight reduction. © 2016 Elsevier LtdItem Buckling and dynamic characteristics of a laminated cylindrical panel under non-uniform thermal load(Techno Press technop2@chollian.net, 2016) Bhagat, V.; Jeyaraj, J.; Murigendrappa, S.M.Buckling and free vibration behavior of a laminated cylindrical panel exposed to non-uniform thermal load is addressed in the present study. The approach comprises of three portions, in the first portion, heat transfer analysis is carried out to compute the non-uniform temperature fields, whereas second portion consists of static analysis wherein stress fields due to thermal load is obtained, and the last portion consists of buckling and prestressed modal analyzes to capture the critical buckling temperature as well as first five natural frequencies and associated mode shapes. Finite element is used to perform the numerical investigation. The detailed parametric study is carried out to analyze the effect of nature of temperature variation across the panel, laminate sequence and structural boundary constraints on the buckling and free vibration behavior. The relation between the buckling temperature of the panel under uniform temperature field and non-uniform temperature field is established using magnification factor. Among four cases considered in this study for position of heat sources, highest magnification factor is observed at the forefront curved edge of the panel where heat source is placed. It is also observed that thermal buckling strength and buckling mode shapes are highly sensitive to nature of temperature field and the effect is significant for the above-mentioned temperature field. Furthermore, it is also observed that the panel with antisymmetric laminate has better buckling strength. Free vibration frequencies and the associated mode shapes are significantly influenced by the non-uniform temperature variations. © 2016 Techno-Press, Ltd.Item Sound transmission loss characteristics of sandwich aircraft panels: Influence of nature of core(SAGE Publications Ltd info@sagepub.co.uk, 2017) Arunkumar, M.P.; Jeyaraj, J.; Gangadharan, K.V.; Mailan Chinnapandi, M.C.Sandwich panel which has a design involving acoustic comfort is always denser and larger in size than the design involving mechanical strength. The respective short come can be solved by exploring the impact of core geometry on sound transmission characteristics of sandwich panels. In this aspect, the present work focuses on the study of influence of core geometry on sound transmission characteristics of sandwich panels which are commonly used as aircraft structures. Numerical investigation has been carried out based on a 2D model with equivalent elastic properties. The present study has found that, for a honeycomb core sandwich panel in due consideration to space constraint, better sound transmission characteristics can be achieved with lower core height. It is observed that, for a honeycomb core sandwich panel, one can select cell size as the parameter to reduce the weight with out affecting the sound transmission loss. Triangular core sandwich panel can be used for low frequency application due to its increased transmission loss. In foam core sandwich panel, it is noticed that the effect of face sheet material on sound transmission loss is significant and this can be controlled by varying the density of foam. © 2016, © The Author(s) 2016.Item Mechanical Properties of Natural Fiber Braided Yarn Woven Composite: Comparison with Conventional Yarn Woven Composite(Science Press bcanji@mail.sioc.ac.cn, 2017) RAJESH, M.; Jeyaraj, J.The effect of reinforcing natural fiber in the form of braided yarn woven fabric on mechanical properties of polymer composite was investigated. The results of braided yarn fabric composites were compared with the conventional yarn fabric composite and random oriented intimately mixed short fiber composites for the same percentage of fiber weight. The effect of intra-ply hybridization, by keeping two different natural fiber yarns along two different directions of a woven fabric, on mechanical properties of the woven fabric composite was also analyzed. Natural fiber braided yarn fabric reinforcement significantly increased the mechanical properties of the composites compared with that of the conventional woven fabric and short fiber reinforcements. Intra-ply hybridization of two different natural fibers improved the mechanical properties of the conventional woven fabric composite while it could not enhance the properties of the braided fabric composite. The improvement in impact property is very high compared to tensile and flexural properties due to the braided yarn fabric reinforcement. © 2017 Jilin UniversityItem Structural optimization of rotating tapered laminated thick composite plates with ply drop-offs(Springer Netherlands, 2017) Edwin Sudhagar, P.; Arumugam, A.; Vasudevan, V.; Jeyaraj, J.In this study, structural optimization of rotating tapered thick laminated composite plates with ply drop-offs has been investigated numerically. The governing differential equations of motion of the tapered composite plate have been presented including the energy associated with the inertia force, coriolis force, displacement dependent centrifugal force and initial stress resultants due to steady state rotation. Four noded quadrilateral finite element has been formulated based on the first order shear deformation theory. Finite element analysis results are validated with experimental results for natural frequencies of the tapered plate with various configurations. Various cases of optimization problems are formulated with different objective functions in terms of maximization of natural frequencies and damping factors (individually and combined) and solved using genetic algorithm in order to obtain optimal ply sequence and ply orientation. It is shown that the optimization problem with maximization of fundamental modal damping factor without rotating condition yields the optimal layout as 90° for all the layers in the plate. It is also observed that maximization of the fundamental modal damping factor yields identical optimal orientation for uniform and all the configurations of a tapered composite plate. © 2015, Springer Science+Business Media Dordrecht.Item Experimental investigation on buckling and free vibration behavior of woven natural fiber fabric composite under axial compression(Elsevier Ltd, 2017) RAJESH, M.; Jeyaraj, J.Influence of axial compression load on buckling and free vibration characteristics of natural fiber fabric polymer composite beam is analyzed experimentally. Critical buckling strength, free vibration frequencies and modal loss factors are obtained and analyzed. It is found that buckling strength increases with number of layers of fabric in composite. It is also observed that weaving pattern of the fabric influences buckling strength of the composite and basket type woven fabric enhances the buckling strength compared to plain and herringbone woven fabric composites. Sandwich composites with glass fiber fabric facing layer and natural fiber fabric as core layer having higher buckling strength. Free vibration frequency reduces with increase in axial compression load while modal damping factor increases in the pre-buckling region. However, this behavior reverses in the post-buckling region. The load-deflection obtained experimentally is compared with finite element result obtained considering the geometric non-linearity. © 2016 Elsevier Ltd