Faculty Publications

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Subject: search.filters.subject.Finite element analyse

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    Thermal induced motion of functionally graded beams subjected to surface heating
    (Ain Shams University, 2018) Malik, P.; Kadoli, R.
    Thin beam of the functionally graded (FG) type subjected to a step heat input on one surface and insulated or exposed to convective heat loss on the opposite surface is under consideration for the evaluation of thermal induced motion. The dynamic displacement and dynamic thermal moment of the beam are analysed when the temperature gradient is independent of the beam displacement. The power law index dictates the metal–ceramic distribution across thickness of the beam and its effect on the thermal vibration of the beam is examined. The article discusses, in depth, the influence of various factors such as length to thickness ratio of beam, heat transfer boundary conditions, physical boundary conditions, and metal–ceramic combination on the thermal oscillations of FG beam. It is found that attenuation of the amplitude of static thermal deflection and superimposed thermal oscillations is a strong function of the metal–ceramic combination for the FG beam. © 2015 Faculty of Engineering, Ain Shams University
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    Static deflection and thermal stress analysis of non-uniformly heated tapered composite laminate plates with ply drop-off
    (Elsevier Ltd, 2018) Ashok, S.; Jeyaraj, P.
    The effective design of tapered laminated composite structures subject to non-uniform temperature fields requires a thorough understanding of their static behaviour. In this study, a finite element analysis of tapered laminated composite plates with ply drop-off has been carried out to study the static deflection and normal stress patterns developed under non-uniform heating. The study revealed that the nature of the taper configuration, the nature of the applied temperature field and the structural boundary conditions influence the static deflection behaviour and the normal stresses developed in the tapered composite plates. It is found that the static deflection pattern of a tapered plate subject to a particular temperature profile is not sensitive to the nature of the taper configuration. It is also observed that the static deflection pattern of a tapered plate is significantly influenced by the nature of temperature field. Normal stress variation of tapered plates subject to various temperature fields reflects the nature of the temperature profile. Maximum normal stress occurs at locations where the highest temperature exists for that particular temperature field. The stresses are also influenced by the nature of the taper - Taper D plates experience low stresses while Taper B and Taper C plates experience similar values. It was also found that large variations in stresses are observed at resin pockets. © 2018
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    Assessment of Cohesive Parameters Using High Dimensional Model Representation for Mixed Mode Cohesive Zone Model
    (Elsevier Ltd, 2019) Rao, B.; Balu, A.S.
    Simulation of the mechanical behavior of bonded joints using a cohesive zone model (CZM) is the most common technique to characterize the delamination process. It is usually dependent on the calculation of cohesive parameters of the traction-separation law, and the parameters are iteratively obtained with the help of simulation and experimental results. The non-availability of standard methods to obtain the parameters necessitates the iterative adjustments of simulation results to the experimental results. However, the calculations based on all individuals for the simulation are not effective as it demands high computational effort. To overcome this issue, this paper proposes a computationally efficient method using high dimensional model representation (HDMR). The cohesive parameters are determined by adopting an efficient sampling scheme within the limits of the parameters. Single leg bending (SLB) joint is tested under the influence of dominant conditions such as mode-I and mode-II to determine the equivalent parameters. The errors resulted from the comparison between the simulation, and experimental values are minimized in order to determine the optimal values. The mixed mode (MM) CZM is then established by pure mode cohesive parameters, and the same is implemented to the SLB joint under various mode mixities for analyzing the fracture process. Comparison between the numerical analysis and the experimental study proves that the proposed HDMR based approach estimates the failure mechanism exactly. © 2019 Institution of Structural Engineers
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    Densification mechanics of polymeric syntactic foams
    (Elsevier Ltd, 2022) Prabhakar, P.; Feng, H.; P Subramaniyan, S.; Doddamani, M.
    In this paper, a fundamental understanding of the densification mechanics of polymeric syntactic foams under compressive loading is established. These syntactic foams are closed cell composite foams with thin-walled microballoons dispersed in a matrix (resin) whose closed cell structure provides excellent mechanical properties, like high strength and low density. There are several parameters that can contribute towards their mechanical properties, including, microballoon volume fraction, microballoon wall thickness, bonding between the microballoons and the matrix, and the crushing strength of microballoons. Conducting purely experimental testing by varying these parameters can be very time sensitive and expensive. Also, identification of densification mechanics is challenging using experiments only. Higher densification stress and energy are favorable properties under foam compression or crushing. Hence, the influence of key structural and material parameters associated with syntactic foams that dictate the mechanics of densification is studied here by implementing micromechanics based computational models and multiple linear regression analysis. Specifically, specific densification stresses and energy, which are densification stresses and energy normalized by weight, are evaluated which are more relevant for a wide variety of weight saving applications. Microballoon crushing strength and volume fraction are identified as the parameters that have the higher influence on densification stress and energy, and their specific counterparts, whereas the interfacial bonding has the least impact. In addition, designing aspects of syntactic foams with specified overall density are discussed by mapping microballoon volume fraction and wall thickness. The regression model allows for establishing wall thicknesses and corresponding volume fractions that result in higher densification properties for a specified overall foam density. © 2022 Elsevier Ltd
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    Influence of Temperature and Moisture on Free Vibration Behavior of Skew Laminated Composite Sandwich Panels with CNTRC Core
    (World Scientific, 2022) Kallannavar, V.; Kattimani, S.; Ramesh, H.
    This paper presents the influence of temperature and moisture on the free vibration characteristics of skew laminated composite sandwich (SLCS) panels. The face sheets of the panels are made of graphite-epoxy composite, while the core consists of carbon nanotube-reinforced composite. The coupled hygro-elastic and thermo-elastic relations for the SLCS shells/panels are formulated using first-order shear deformation theory. The nonmechanical stiffness matrices are represented by the initial stress stiffness matrix developed using nonlinear strain-displacement relations. The temperature and moisture-dependent material properties are considered to analyze the laminated composite sandwich spherical, hyperbolic, ellipsoid, cylindrical Shells, and flat plates. Several numerical examples are comprehensively studied to establish the influence of temperature, moisture, the volume fraction of carbon nanotubes in the core material, functional gradation types, skew angle, and edge constraints on the vibration responses of SLCS shells. Further exploration is devoted to studying the combined effect of moisture, temperature, and the geometrical parameters such as length to width ratio, length to thickness ratio, radius-to-length ratio, and the core thickness to face sheet thickness ratios on the natural frequency of the skew laminated composite sandwich panels. © 2022 World Scientific Publishing Company.
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    Parametric Study on Frequency Characteristics of Cylindrical Liquid Tanks
    (Springer, 2022) Nimisha, P.; Jayalekshmi, B.R.; Venkataramana, K.
    The response of liquid-storage tanks under seismic loading is a key research area. The study of free vibration characteristics is a prerequisite for understanding the dynamic behaviour of liquid tanks under seismic loading. Hence, the present study focuses on the analysis of different parameters that may influence the frequency characteristics of cylindrical liquid tanks. For this, a database of 560 three-dimensional cylindrical liquid tank models was developed by carrying out modal analysis using ANSYS Mechanical APDL software. The database was analysed with the aid of artificial neural networks and nonlinear regression analysis. Average deviations of 30% and 32% were observed for the impulsive frequency values estimated based on IS1893 (Part2):2014 and Eurocode-8, respectively, compared to the finite element results. Hence, modification coefficients were suggested with aspect ratio as the demarcating parameter and obtained a Pearson correlation coefficient of rXY > 0.9, between the predicted values of frequency and actual values. The predicted formulae reduced the deviations observed between the frequency estimated based on the codal expressions and those obtained from finite element analysis to 13% and 15%, corresponding to IS1893 (Part2):2014 and Eurocode-8, respectively. © 2022, The Institution of Engineers (India).
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    Influence of material heterogeneity on the mechanical response of articulated cartilages in a knee joint
    (SAGE Publications Ltd, 2022) Raju, V.; Koorata, P.K.
    Structurally, the articular cartilages are heterogeneous owing to nonuniform distribution and orientation of its constituents. The oversimplification of this soft tissue as a homogeneous material is generally considered in the simulation domain to estimate contact pressure along with other physical responses. Hence, there is a need for investigating knee cartilages for their actual response to external stimuli. In this article, impact of material and geometrical heterogeneity of the cartilage is resolved using well known material models. The findings are compared with conventional homogeneous models. The results indicate vital differences in contact pressure distribution and tissue deformation. Further, this study paves way for standardizing material models to extract maximum information possible for investigating knee mechanics with variable geometry and case specific parameters. © IMechE 2022.
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    Hybrid Plasmonic Waveguide Based Platform for Refractive Index and Temperature Sensing
    (Institute of Electrical and Electronics Engineers Inc., 2022) Sahu, S.K.; Reddy, S.K.; Singh, M.; Avrutin, E.
    A nanoscale 3D hybrid plasmonic waveguide (HPWG) refractive index-cum-temperature sensor has been proposed and simulated in this work. The aqueous analyte (benzene C6H6) sensing is possible over the wavelength range from 1.18∼μ m to 2.2∼μ m. A well-known refractive index (RI) sensing method (or wavelength interrogation) is considered for the proposed Si-TiO2-SiO2-Au nanostructure. The sensor design includes, titanium dioxide (TiO2) layer deposited over the silicon dioxide to enhance the overall sensitivity of the HPWG sensor. The finite element method (FEM) based 3D-numerical simulations are performed for an IR band signal, predicting 1022.75 nm/RIU device sensitivity and 2.95 nm/°C temperature sensitivity. The proposed sensor is suitable for next-generation on-chip biochemical sensing applications with nanoscale dimensions, low cost, and high sensitivity. © 1989-2012 IEEE.
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    Design and optimization of an external-rotor switched reluctance motor for an electric scooter
    (Elsevier Ltd, 2023) Bhaktha, S.B.; Jogi, A.; Jeyaraj, J.; Gangadharan, K.V.
    In order to reduce the global carbon foot print, the need of the hour is to provide pollution free and economically viable electric vehicles (EVs) as potential alternatives to the conventional ones. Amongst the different traction motors employed in EVs, switched reluctance motors (SRMs) being magnet-free, rugged in construction and fault-tolerant is a potential forerunner for automotive applications in the near future. Therefore, in this work, an external-rotor (ER) SRM has been designed for an electric scooter application. The proposed 4-phase SRM configuration comprises of 8 and 10 poles on the stator and rotor respectively. To achieve a well-balanced design with due consideration to the various performance indicators, a multi-objective design optimization (MOO) has been performed using particle swarm optimization (PSO). The optimization was based on the results obtained from the two-dimensional (2D) electromagnetic static finite element analysis (FEA) which aimed to maximize average torque, efficiency and minimize torque ripple respectively. In comparison to the preliminary design, the optimized ER-SRM demonstrated an increased average torque and decreased copper loss by 3% and 14% respectively. The large scale of simulations performed and the results thereby obtained confirmed that the proposed SRM design met the performance demands of the electric scooter application. The average torque at the rated and the maximum speed exceeded the desired torque requirements demanded by the electric scooter by 13.1% and 42.2% respectively. © 2023
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    Design and Performance Analysis of a Switched Reluctance Motor Using Finite Element Analysis and Magnetic Equivalent Circuit Model
    (Defense Scientific Information and Documentation Centre, 2023) Bhaktha, S.B.; Kumawat, S.; Jeyaraj, J.; Gangadharan, K.V.
    By being magnet-free, and mechanically robust with a longer constant power range, switched reluctance motor (SRM) is gathering much attention as a potential choice to propel electric vehicles (EVs) and hybrid electric vehicles (HEVs). This paper comprehensively investigates the performance sensitivity to geometric design variables such as rotor diameter, pole arc angles, and yoke thicknesses for an SRM using static two-dimensional (2D) electromagnetic Finite-Element Analysis (FEA). The reason for the change in static characteristics due to variation in reluctance between SRM designs has not been detailed previously. This is addressed by the magnetic equivalent circuit (MEC) model that simplifies the design analysis. Results indicate that stator pole reluctance needs to be given due importance while studying the influence of rotor diameter. Also, it is imperative to set an adequate thickness of the stator and rotor yokes to minimize the effect of saturation on the performance. Rotor diameter and stator pole arc angle have a pronounced influence on the performance while the influence of rotor pole arc angle and yoke thicknesses was relatively less. © 2023, DESIDOC.