Faculty Publications
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Item The effects of sulphuric acid concentration and the sequential layup of glass fibre reinforcements on the diffusion behaviour of glass epoxy composite laminates were studied. In all, composites of six different resin systems viz., general purpose polyester, bis phenol-A polyester, vinyl ester, LY 556 epoxy, and MY 750 epoxy resins, reinforced with different layup sequencing consisting of chopped strand mat (CSM) and woven roving mat (WR) were exposed to sulphuric acid environments of different concentrations. The results of the study indicated that isophthalic polyester resin exhibited maximum resistance to sulphuric acid while general purpose polyester resin performed relatively inferior. The diffusion phenomenon became anamalous as the concentration of the sulphuric acid increased. Among the layup sequences considered, composite specimens with CSM as the skin layers exhibited higher weight gain than those with WR as the skin layers.(SAGE Publications Ltd, Acid resistance of glass fibre composites with different layup sequencing: Part I-diffusion studies) Pai, R.; Kamath, M.S.; Rao, R.M.V.G.K.1997Item Analytical solutions using a higher order refined computational model with 12 degrees of freedom for the free vibration analysis of antisymmetric angle-ply plates(2008) Swaminathan, K.; Patil, S.S.Analytical formulations and solutions to the natural frequency analysis of simply supported antisymmetric angle-ply composite and sandwich plates hitherto not reported in the literature based on a higher order refined computational model with 12 degrees of freedom already reported in the literature are presented. The theoretical model presented herein incorporates laminate deformations which account for the effects of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane displacements with respect to the thickness coordinate thus modelling the warping of transverse cross sections more accurately and eliminating the need for shear correction coefficients. In addition, another higher order computational model with five degrees of freedom already available in the literature is also considered for comparison. The equations of motion are obtained using Hamilton's principle. Solutions are obtained in closed-form using Navier's technique by solving the eigenvalue equation. Plates with varying slenderness ratios, number of layers, degrees of anisotropy, edge ratios and thickness of core to thickness of face sheet ratios are considered for analysis. Numerical results with real properties using above two computational models are presented and compared for the free vibration analysis of multilayer antisymmetric angle-ply composite and sandwich plates, which will serve as a benchmark for future investigations. © 2007 Elsevier Ltd. All rights reserved.Item MPI-based parallel synchronous vector evaluated particle swarm optimization for multi-objective design optimization of composite structures(2012) Omkar, S.N.; Venkatesh, A.; Mudigere, M.This paper presents a decentralized/peer-to-peer architecture-based parallel version of the vector evaluated particle swarm optimization (VEPSO) algorithm for multi-objective design optimization of laminated composite plates using message passing interface (MPI). The design optimization of laminated composite plates being a combinatorially explosive constrained non-linear optimization problem (CNOP), with many design variables and a vast solution space, warrants the use of non-parametric and heuristic optimization algorithms like PSO. Optimization requires minimizing both the weight and cost of these composite plates, simultaneously, which renders the problem multi-objective. Hence VEPSO, a multi-objective variant of the PSO algorithm, is used. Despite the use of such a heuristic, the application problem, being computationally intensive, suffers from long execution times due to sequential computation. Hence, a parallel version of the PSO algorithm for the problem has been developed to run on several nodes of an IBM P720 cluster. The proposed parallel algorithm, using MPI's collective communication directives, establishes a peer-to-peer relationship between the constituent parallel processes, deviating from the more common master-slave approach, in achieving reduction of computation time by factor of up to 10. Finally we show the effectiveness of the proposed parallel algorithm by comparing it with a serial implementation of VEPSO and a parallel implementation of the vector evaluated genetic algorithm (VEGA) for the same design problem. © 2012 Elsevier Ltd. All rights reserved.Item Mechanical and sliding wear properties of multi-layered laminates from glass fabric/graphite/epoxy composites(Elsevier Ltd, 2013) Shivamurty, B.; Bhat, K.; Anandhan, S.Multi-layered laminates of bi-directionally woven E-glass fabric/epoxy with different loading of graphite particles were made by hand layup followed by compression molding. Tensile and flexural behaviors, impact strength, hardness and density of these laminates were determined. Wear behaviors of these composites were investigated by a pin-on-disc wear test apparatus. Specific wear rates of these composites strongly depend on their filler content and applied normal loads. The hybrid composite containing 3 wt% of graphite exhibits the optimum mechanical and wear performances. A further increase in the graphite content increases the specific wear rate and deteriorates the mechanical behavior. The lowest (? e)-1 factor (the reciprocal of the product of tensile strength and elongation at break) signifies the lowest specific wear rate. The results of the morphology study of the wear test specimens support the results of the wear test. © 2012 Elsevier Ltd.Item Synergy of fiber length and content on free vibration and damping behavior of natural fiber reinforced polyester composite beams(Elsevier Ltd, 2014) Krishnasamy, K.; Siva, I.; Jeyaraj, P.; Winowlin Jappes, J.T.; Amico, S.C.; Nagarajan, N.This work addresses the results of experimental investigation carried out on free vibration characteristics of short sisal fiber (SFPC) and short banana fiber (BFPC) polyester composites. Influence of fiber length and weight percentage on mechanical properties and free vibration characteristics are analyzed. Composite beam specimen is fabricated with random fiber orientations at17. MPa compression using compression molding machine. Natural frequencies and associated modal damping values of the composite laminates were obtained by carrying out the experimental modal analysis. It is found that an increase in fiber content increases the mechanical and damping properties. For SFPC, 3. mm fiber length and 50. wt% fiber content yielded better properties, whereas for BFPC, 4. mm fiber length and 50. wt% fiber content was the best combination. Scanning electron microscopy was performed to study the interfacial mechanism. © 2013 Elsevier Ltd.Item Free vibration analysis of axisymmetric laminated composite circular and annular plates using Chebyshev collocation(SpringerOpen, 2015) Powmya, A.; Narasimhan, M.C.Solutions, based on principle of collocating the equations of motion at Chebyshev zeroes, are presented for the free vibration analysis of laminated, polar orthotropic, circular and annular plates. The analysis is restricted to axisymmetric free vibration of the plates and employs first-order shear deformation theory for the displacement field, in terms of midplane displacements, u, ? and w. The eigenvalue problem is defined in terms of three equations of motion in terms of the radial co-ordinate r, the radial variation of the displacements being represented in polynomial series, with appropriate boundary conditions. Numerical results are presented to show the validity and accuracy of the proposed method. Results of parametric studies for laminated polar orthotropic circular and annular plates with different boundary conditions, orthotropic ratios, lamination sequences, number of layers and shear deformation are also presented. © 2015, The Author(s).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 Sliding wear and mechanical properties of alumina/glass fabric/epoxy composites(Huthig GmbH, 2015) Shivamurty, B.; Anandhan, S.; Bhat, K.U.In this study, laminates of neat glass fabric/ epoxy composite (GEC) and three levels of Al2O3 filled glass fabric/epoxy composites, designated as 3AGEC, 6AGEC and 9AGEC (micro particulates of Al2O3 - by 3, 6 and 9 wt. % of resin respectively) were prepared using hand lay-up method. 3AGEC exhibits higher tensile strength, flexural strength and flexural modulus besides improved hardness compared to GEC, 6AGEC and 9AGEC. 3AGEC exhibits the lowest specific wear rate compared to GEC, 6AGEC and 9AGEC at all the three loads (i.e., 15, 30 and 45 N) and at a constant sliding velocity of 3.5 m· s-1 for a sliding distance of 1.5 km. It was found that beyond filler content of 3 wt. % is deteriorates the mechanical and sliding wear properties of the composites due to agglomeration of the filler. Also, it was found that lowest factor signifies lowest specific wear rate in both neat and all the Al2O3 filled composites.Item Soft computing techniques during drilling of bi-directional carbon fiber reinforced composite(Elsevier Ltd, 2016) Shetty, N.; Herbert, M.A.; Shetty, R.; Shetty, D.S.; Vijay, G.S.Due to the intricacy of machining processes and inconsistency in material properties, analytical models are often unable to describe the mechanics of machining of carbon fiber reinforced polymer (CFRP) composites. Recently, soft computing techniques are used as alternate modeling and analyzing methods, which are usually robust and capable of yielding comprehensive, precise, and unswerving solutions. In this paper, drilling experiments as per the Taguchi L27 experimental layout are carried out on bi-directional carbon fiber reinforced polymer (BD CFRP) composite laminates using three types of drilling tools: high speed steel (HSS), uncoated solid carbide (USC) and titanium nitride coated SC (TiN-SC). The focus of this work is to determine the best drilling tool that produces good quality drilled holes in BD CFRP composite laminates. This paper proposes a novel prediction model 'genetic algorithm optimised multi-layer perceptron neural network' (GA-MLPNN) in which genetic algorithm (GA) is integrated with Multi-Layer Perceptron Neural Network. The performance capability of response surface methodology (RSM) and GA-MLPNN in prediction of thrust force is investigated. RSM is also used to evaluate the influence of process parameters (spindle speed, feed rate, point angle and drill diameter) on thrust force. GA is used to optimize the thrust force and its optimization performance is compared with that of RSM. It is observed that the GA-MLPNN is better predicting tool than the RSM model. The investigation in this paper demonstrates that TiN-SC is the best tool for drilling BD CFRP composite laminates as minimum thrust force is developed during its use. © 2016 Elsevier B.V. All rights reserved.Item The effect of higher order model on the geometric nonlinear analysis of antisymmetric angle ply laminates(Smithers Rapra, 2016) Swaminathan, K.; Sangeetha, D.M.Geometric nonlinear analysis of simply supported antisymmetric angle-ply laminated composite plates are investigated based on first order and higher order displacement models with five degrees of freedom. Analytical formulations and solutions are developed based on Von-Karman nonlinear plate theory and Taylor's series expansion of displacement components. Equations of equilibrium are obtained using Principle of Minimum Potential Energy (PMPE) and closed form solutions using Navier's Solution technique. A four layered square plate is considered for the present study. Parametric studies are performed on both the models to study the behaviour of displacements and stresses in laminated composite plates. Comparative studies are performed on both the models and the effect of geometric nonlinearity is discussed. © 2016 Smithers Information Ltd.