Faculty Publications
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Item Mechanical properties of MWCNTs and graphene nanoparticles modified glass fibre-reinforced polymer nanocomposite(Springer, 2021) Seshaiah, S.; Reddy, K.V.K.; Sahu, R.K.; Katiyar, J.K.In the present study, the multi-walled carbon nanotubes (MWCNTs) and graphene nanoparticles were used as a reinforcement to fabricate glass fibre polymer composite at different orientations (unidirectional glass fibres 0° and 90°; woven glass fibres 0°/90° and 45°/45°). The composites were developed using hand lay-up-assisted vacuum bagging method at 1 torr pressure. The concentrations of nanoparticles (~diameter 5–20 nm) were varied in the range of 0.1–0.3 wt% in the matrix. The mechanical properties like impact strength, tensile strength and fatigue strength were carried out on Izod and Charpy machine, universal testing machine and computer-controlled machine under sinusoidal wave, respectively. It is observed that the glass fibre/epoxy composite blended with MWCNTs/graphene by 0.2 wt% has shown higher fatigue life by 56%, higher tensile strength by 36% and higher capability of energy absorption by 927.7% in notched type and lower capability of energy absorption by 155.43% in un-notched type, as compared to pure composite. The increment in properties is due to the better bonding between fillers and matrix. However, the increase of MWCNTs and graphene nanoparticles by wt% in composite laminates have shown lower fatigue strength because of the agglomeration of MWCNTs particles in matrix that caused the propagation of fatigue cracks under cyclic loading. Further, the damage behaviour of composite materials was analysed using scanning electron microscopy. It is found that a different damage behaviour in each composite is observed which is attributed to the matrix cracking, fibre rupture, fibre pullout, fibre split and fibre de-bonding. © 2021, Indian Academy of Sciences.Item Fabrication and mechanical properties of braided flax fabric polylactic acid bio-composites(Taylor and Francis Ltd., 2022) Kanakannavar, S.; Jeyaraj, J.This paper primarily describes the development of flax braided yarn fabric reinforced thermoplastic composites. Plain woven fabric is made by interlacing 3D braided yarn produced by solid braiding method. Tensile properties of braided yarn and woven fabric are evaluated. Solution casting is used prior to composite fabrication to prepare polylactic acid (PLA) and (natural fiber braided fabric) NFBF–PLA sheets. Followed by this, composite laminates are prepared using through film stacking and compression molding. Influence of number of layers of fabric and loading along warp and weft directions on mechanical properties such as tensile, flexural and impact properties are presented. It is observed that the reinforcement enhances the tensile, flexural and impact properties of the composite significantly for the warp loading. Results also clearly indicates that braided yarn fabric reinforcement have the potential for significant improvement of mechanical and thermal properties of PLA composites. © 2021 The Textile Institute.Item Structural-Acoustic Response Analysis of Variable Stiffness Laminates with Inherent Material Damping(World Scientific, 2022) Gunasekaran, V.; Gulhane, S.; Gupta, S.; Jeyaraj, J.; Vasudevan, V.; Manickam, G.Sound radiation and transmission loss characteristics of variable stiffness composite plate reinforced with the curvilinear fibers are investigated numerically. The formulation is developed using higher-order shear flexible finite element model combined with Helmholtz wave equation. The governing equations obtained using Hamilton's approach are further solved through the modal super position method to analyze the vibration response under steady state excitation. The inherent material damping of the laminate is accounted through the modal damping calculated using the modal strain energy approach. The acoustic pressure of the variable stiffness laminates is estimated using the Raleigh integral. Subsequently, acoustic response characteristics such as acoustic power level, radiation efficiency, directivity pattern, and transmission loss from the laminates are predicted using the estimated sound pressure for various forcing frequencies. A parametric study covering a wide range of design variables including center and edge fiber angles, lamination scheme, thickness ratio, and boundary conditions on the acoustic sound behavior arising from the vibration of curvilinear fiber composite plate is detailed. This study reveals that the acoustic response of the curvilinear fiber composite plate is significantly influenced by the curvilinear fiber angles at the center/edge fiber angle of the layers. It is hoped that the results obtained here will be useful for designers in developing structures with desired acoustic response characteristics. © 2022 World Scientific Publishing Company.Item Nonlinear flutter of 2D variable stiffness curvilinear fibers composite laminates by a higher-order shear flexible beam theory with Poisson's effect(Elsevier Ltd, 2022) Manickam, G.; Vasudevan, V.; Gunasekaran, V.; Jeyaraj, J.; Mohamed, H.In this work, the nonlinear supersonic panel flutter characteristics of two-dimensional variable stiffness curvilinear fibres based laminated composite panels are studied using a higher-order shear flexible theory represented by sine function coupled with first-order approximation leading to quasi-aerodynamic theory. The structural formation takes care of geometric nonlinearity with von Karman's assumptions. The beam constitutive equation is modified for the laminated beam with general lay-up by accounting for Poisson's effect. The nonlinear dynamic equilibrium equations developed by Lagrangian equations of motion are solved using finite element approach in conjunction with the direct iterative solution procedure. For limit cycle oscillation, critical dynamic pressure is predicted iteratively through eigenvalue analysis, thereby identifying the first coalescence of vibrational modes. Also, the flutter behavior of two-dimensional panel under static differential pressure is investigated considering nonlinear static equilibrium position of panel obtained by Newton-Raphson's iterative approach and then followed by modes coalescence approach. These solution procedures are tested against the results in literature. A thorough numerical investigation is done to show the effect of the curvilinear fiber path orientation, limited cycle amplitude, static differential pressure, panel thickness, panel end condition flexibilities and thermal environment on the nonlinear supersonic panel flutter of two-dimensional variable stiffness laminated panels. © 2022Item A comprehensive damping study of variable stiffness composite rectangular/skew laminates reinforcement with curvilinear fibers by higher-order shear flexible model(Taylor and Francis Ltd., 2023) Mohamed, H.; Gunasekaran, V.; Jeyaraj, J.; Vasudevan, V.; Kotriwar, G.; Manickam, G.In this work, a comprehensive investigation of curvilinear fiber reinforcement on damping of rectangular and skew composite plates is computationally estimated using higher-order shear flexible model. A set of governing equilibrium equations developed here in form of eigenvalue analysis is solved by adopting the Q-R algorithm. The damping factors associated with different vibrational modes are evaluated from the complex eigenvalues. The proposed model is validated against the available analytical and experimental results. The damping capability of laminated rectangular/skew composite plates is thoroughly analyzed by varying the curvilinear fiber path angles in the layers, lay-up orientations, structural boundary conditions, skew angle of the laminate, and nature of the material. Results reveal that the damping pretending to the curvilinear fibers plate is better than the conventional composite laminate; it varies significantly according to the variation in center and edge of the curvilinear fiber angles. It is also noted that the damping increases with the skew angle of the plate. The study conducted here shows the suitability of such variable stiffness composite structure for safe design under dynamic/impact loading situation. © 2022 Taylor & Francis Group, LLC.