R. K. Misra

Some Experimental and Theoretical Investigations on Fire Retardant Coir/Epoxy Micro-Composites

This article reports some experimental and theoretical investigations on fire retardant coir/epoxy micro-composites. The coir fiber is treated with saturated bromine water for increasing the electrical properties and then mixed with stannous chloride solution for improving the fire retardant properties. Only 5% (approximately) of fire retardant filler reduces the smoke density by 25% and the LOI value increases to 24%. The mechanical properties of the coir/epoxy micro-composites are not affected much after incorporation of filler. Flexural strength and flexural modulus of the NET increases tremendously compared to NEU and NE. Multiquadric radial basis function (MQRBF) method is applied for static and dynamic analysis of coir/epoxy micro-composite plate under uniformly distributed load. Damping behavior and natural frequencies are observed in NE, NEU, and NET. MQRBF is applied for spatial discretization and Newmark implicit scheme is used for temporal discretization. The discretization of the differential equations generates greater number of algebraic equations than the unknown coefficients. The multiple linear regression analysis, which is based on the least square error norm, is employed to obtain the coefficients. Simple supported and clamped boundary conditions are considered for verification of present results and they are compared with other existing analytical methods.

Finite-Element Analysis of Jute- and Coir-Fiber-Reinforced Hybrid Composite Multipanel Plates

Natural-fiber-reinforced polymer composite materials are rapidly gaining interest worldwide both in terms of research and industrial applications. The present work includes the characterization and modeling of jute- and coir-fiber-reinforced hybrid composite materials. The mechanical behavior of a two-panel plate and a sixpanel box structure is analyzed under various loading regimes by using the finite-element software ABAQUS®. Exhaustive parametric studies are also performed to obtain a clear insight into the relationships between various parameters and deflections of the panels and stress distributions in them. Deflections of both the structures are compared and found to be in good agreement with published results. To determine the mechanical behavior of natural-fiber-reinforced composite panels, a finite-element analysis is performed.

The Influence of Fiber Treatment on the Mechanical Behavior of Jute-Coir Reinforced Epoxy Resin Hybrid Composite Plate

A novel surface modification of coir fiber was done by oxidation followed by furfuryl alcohol treatment. The surface modified coir fiber showed better interfacial adhesion with epoxidized phenolic novolac (EPN) thermoset resin compared to unmodified coir fiber reinforced composites. Experimentally, tensile and flexural properties are evaluated at a different percentage of the coir fibers. Stiffness and damping behavior of the composite plates are evaluated theoretically, using a meshless multiquadric radial basis function method. Numerical results are compared with those obtained by other analytical methods. The aim of the study is to observe the behavior of a chemically treated and untreated coir fiber-reinforced composite plate at a different percentage of the coir fibers.

Analysis of Laminates using Multiquadric Radial Basis Function

Multiquadric radial basis function (MQRBF) is developed for static and dynamic analysis and to estimate natural frequency of laminated plate at various boundary conditions. MQRBF is applied for spatial discretization and Newmark implicit scheme is used for temporal discretization. The spatial discretization of the differential equations generates a greater number of algebraic equations than the unknown coefficients. The multiple linear regression analysis, which is based on the least square error norm, is employed to obtain the coefficients. Numerical results are compared with those obtained by other analytical methods.

Finite element modeling of effective thermomechanical properties of Al–B4C metal matrix composites

The present work aims to investigate the influences of thermal residual stresses and material properties on the thermomechanical deformation behavior of Al–B4C composites. Boron carbide-reinforced aluminum matrix composites having 4, 8, and 12 vol% boron carbide were fabricated using squeeze liquid stir casting method for experimental characterization of their microstructure, effective elastic moduli and effective CTEs at room temperature as well as elevated temperatures. Next, the thermomechanical behavior of fabricated composites was investigated using finite element modeling. The effects of thermal residual stresses on the effective material properties were examined by simulating the cooling process of MMCs from processing temperature to room temperature. The effective elastic moduli and the effective CTEs were predicted considering linear elastic as well as elastoplastic deformation of aluminum matrix, and the results obtained were compared with the experimental values. The effects of voids on effective material behavior are studied by simulating the void growth and nucleation using Gurson–Tvergaard–Needleman model.

Solving Singularly Perturbed Problems Using Multi-quadric/Inverse Multi-quadric Radial Basis Function Method

This work focuses on the implementation of a multi-quadric/inverse multi-quadric (MQ/IMQ) radial basis function method on Singularly Perturbed Problems (SPP). Elliptic equation and convection–diffusion differential equation are solved using MQ/IMQ RBF methods and results are compared with analytical results. Numerical results are computed using stationary approximation and non-stationary approximation for SPP problems. Condition number of the system matrix in both cases is tuned with shape parameters. Maximum error is reduced for small shape parameter although it is depending on the perturbation parameter. Accuracy and CPU time are computed with increasing the number of distinct centres with a given shape parameter also. Better accuracy is obtained in the case of elliptic SPP as compared to convective–diffusion SPP for a very small perturbation parameter.

Investigation of the Thermomechanical Behavior of a 2 × 2 TWILL Weave Fabric Advanced Textile Composite

The thermomechanical performance of a 2 × 2 twill weave fabric advanced textile composite was evaluated. The tensile, compressive, and flexural properties of flat beam specimens of the composite were tested at room temperature, in water (24.9 to 96.7°C), and in liquid nitrogen (−96.9 to 99.4°C) by using a high-precision instrument called the dynamic mechanical analyzer (DMA). The storage modulus and tanδ of the carbonfiber-reinforced plastic (CFRP) specimens at various temperatures were evaluated. The scanning electron micrograph (SEMs) of deformed composite specimens revealed their failure mode (fiber pull-out, debonding, crack propagation, delamination, matrix cracking, and kinking of fibers).

Mechanical Behavior of Polyethylene Fibers Reinforced Resol/VAC-EHA

Polyethylene fibers reinforced Resol/VAC-EHA composites have been prepared in the laboratory at different volume fraction of fibers for the evaluation of mechanical properties. Resol solution was blended with vinyl acetate-2-ethylhexyl acrylate (VAc-EHA) resin in an aqueous medium with varying volume fraction of polyethylene fibers. It has also been observed that reinforcement of the polyethylene fiber in Resol/VAC-EHA matrix shows improvement in ductility, tensile strength and Youngs modulus. But damping property decreases as soon as percentage of the polyethylene fiber increases. In order to study the static and dynamic response of polyethylene fiber reinforced Resol/VAC-EHA composite plate at uniformly distributed load and fluctuating uniformly distributed load, a multi-quadric radial basis function (MQRBF) method is developed. MQRBF is applied for spatial discretization and a Newmark implicit scheme is used for temporal discretization. The discretization of the differential equations generates a greater number of algebraic equations than the unknown coefficients. To overcome this ill-conditioning, the multiple linear regression analysis, based on the least square error norm, is employed to obtain the coefficients. Simple supported and clamped boundary conditions are considered. Numerical results are compared with those obtained by other analytical methods.

Numerical Dispersion in Small Varying Meandering Channel Using Multiquadric Radial Basis Function(MQRBF) Method

The multiquadric radial basis function (MQRBF) scheme is adapted to estimate the concentration of a solute with slow varying curvature at different cross sections of a meandering channel. The concentration profile is estimated for different wave numbers and for different Peclet numbers. The velocity profile and flow rate depend on wave number, Peclet numbers and shape parameters. Concentration is decreasing with increasing wave number at a fixed cross section. The scheme works well for Peclet numbers to the order of 102. As the Peclet number is very high, the model becomes numerically unstable and requires some adaptation in the scheme. This is prelude study for a complete numerical model for varying curvature and the concentration distribution may evaluate for wider ranges of parameters involved.

Evaluation of Vibration of a Crankshaft and a Driveshaft Using FEM

The present paper is based on comparative studies of modal analysis of a four-cylinder crankshaft and a driveshaft of different materials which includes metals, alloys as well as composites. The five materials chosen for this investigation are steel, gray cast iron, titanium alloy, E-glass/epoxy unidirectional composite and carbon/epoxy unidirectional composite. Modal analysis was carried out on the crankshaft and the driveshaft using commercially available software ANSYS, which solves problems based on linear and nonlinear behavior for obtaining natural frequency and deformation at different modes with different materials. In order to achieve accurate results, the loading and boundary conditions were taken as in the case of real-life situations. Maximum total deformation was achieved by the composites, followed by alloys and finally the metals, with the minimum deformation. The results were then compared by conducting a parametric study, and an alternative material has been proposed from the investigation.