Faculty Publications

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Publications by NITK Faculty

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Author: search.filters.author.Pitchaimani, J.

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    Thermal Buckling of 3D Printed Auxetic Core Sandwich Beams
    (Springer, 2025) Dattam, V.K.; Pitchaimani, J.; Doddamani, M.
    Experimental investigation carried out on the thermal deflection behavior of 3D printed poly lactic acid sandwich beams possessing positive, negative, and zero Poisson’s ratio cellular cores is presented. Using a fused deposition modelling based 3D printer, sandwich beams were fabricated and investigated for thermal buckling under different heating conditions. Influence of Poisson’s ratio of the core and orientation of the beam on thermal buckling were also studied. It is found that Poisson's ratio of the core influences the thermal deflection of the beams remarkably. The sandwich beam having a vertically oriented core with zero Poisson's ratio exhibited superior buckling resistance compared to the other two cases. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.
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    Acoustic response of bi-directional functionally graded beam under axially varying load
    (SAGE Publications Inc., 2023) Somi Naidu, S.N.; Pitchaimani, J.; Mailan Chinnapandi, L.B.
    This paper investigates the effects of bi-directional gradation, length-to-height ratio, and end conditions on the acoustic behaviour of bi-directionally varying functional graded beams. The acoustic responses, including sound-power level (dB), sound-pressure level (dB), and sound-radiation efficiency, are evaluated using Rayleigh’s integral and modal superposition method. The sound power levels are presented up to the selected bandwidth, as well as the octave band center frequency. In contrast, the sound pressure levels are presented as contour plots and in directivity pattern. The buckling load, calculated for quadratically decreasing axial load, is applied in increments from 0 to its highest value. The study reveals that the highest value in the gradation indexes in both directions significantly influences the sound power levels. It is also evident from the study that thin beams have higher sound power levels compared to thick beams. The directivity pattern reveals that bi-directional functionally graded beams predict higher sound pressure levels at the critical buckling load. From the current acoustic study, it is observed that both structural and end stiffness are influential factors in sound power levels (dB) and sound pressure levels (dB). © The Author(s) 2023.
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    Tensile Behaviour of Double-Edge Notched Flax Braided Yarn Woven Fabric Reinforced PLA Composite
    (Korean Fiber Society, 2023) Kanakannavar, S.; Pitchaimani, J.; Goh, K.-L.
    Biodegradable composites were fabricated from poly-lactic acid (PLA) reinforced by flax braided-yarn woven fabric. Composites with different fabric content (corresponding to the 1, 2 and 3 layers of fabric respectively) were obtained by solution casting and compression moulding processes. Tensile fracture properties were evaluated using the double-edge-notch-tension (DENT) test. A scanning electron microscope was used to look at the fractographic features. Reinforcement of braided-yarn fabric resulted in enhanced tensile fracture strength (σf) and toughness of PLA composite. Fracture toughness (KIC) of the composite improved with the fibre contents, namely 64, 79 and 89%, which correspond to 1, 2 and 3 layers of fabric. The improvement in the tensile fracture characteristics of the composites could be contributed by the presence of an effective interfacial bonding of fibre matrix. © 2023, The Author(s), under exclusive licence to the Korean Fiber Society.
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    Free vibration and buckling response of functionally graded triply periodic minimal surface beams considering neutral axis dislocation
    (SAGE Publications Inc., 2023) Kurup, M.; Pitchaimani, J.
    The work pioneers a novel investigation into the free vibration and buckling behavior of triply periodic minimal surface beams, characterized by diverse distribution profiles. Using Euler-Bernoulli theory, under various boundary conditions, the investigation is carried out on four TPMS (Triply Periodic Minimal Surface) patterns, mainly gyroid, primitive, diamond and IWP (I-graph-wrapped package). The neutral axis would not coincide with the geometric center of the functionally graded beams so the neutral shift effect is taken into consideration appropriately. Governing differential equations are derived and the solutions are obtained numerically using the Ritz method. The mode shapes have also been calculated. It can be concluded that the type of pattern and distribution profile, boundary conditions, grade and neutral axis shift effect play a vital role in the prediction of vibration and buckling properties. © The Author(s) 2023.
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    Sound absorption and transmission loss of 3D printed wood fibre reinforced poly lactic acid with functionally graded perforations
    (Taylor and Francis Ltd., 2024) Sailesh, R.; Doddamani, M.; Mailan Chinnapandi, L.B.; Yuvaraj, L.; Pitchaimani, J.
    The effect of wood fibre reinforcement on acoustic properties of 3D printed poly lactic acid samples having varying cross-section perforation and functionally graded spherical perforations is presented. Acoustic characteristics like sound absorption as well as transmission loss are obtained using an impedance tube setup. Results revealed the benefits due to the addition of wood fibres in PLA improved samples’ sound transmission loss characteristics significantly. The sound absorption curve peaks shifted to low-frequency regions which are favourable to living beings. The material can be used in acoustic insulation for structural and transportation applications, especially where eco-friendliness and aesthetics are of major concern. © 2023 Informa UK Limited, trading as Taylor & Francis Group.
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    Driving Cycle-Based Design Optimization and Experimental Verification of a Switched Reluctance Motor for an E-Rickshaw
    (Institute of Electrical and Electronics Engineers Inc., 2024) Bhaktha, B.S.; Jose, N.; Vamshik, M.; Pitchaimani, J.; Gangadharan, K.V.
    This article deals with the design and optimization of a 2 kW switched reluctance motor (SRM) for an electric rickshaw (E-rickshaw). Previously published research on SRM optimization has mostly focused on the optimization of their design and control variables only at the rated conditions. In electric vehicle (EV) applications, the load operating points (LOPs) of a traction motor are dynamic and spread widely across the torque speed envelope. To enhance their overall performance, it is vital to include them in the design optimization process; therefore, in this article, a novel procedure for implementing the multiobjective design optimization (MODO) of an SRM based on a driving cycle has been demonstrated. Higher starting torque and torque density with reduced electromagnetic losses throughout the driving cycle are established as the design objectives, subject to practical restrictions on current density and slot fill factor. The design objectives have been accurately evaluated through transient finite element analysis (FEA) and a computationally efficient SRM drive model (developed in MATLAB/Simulink) with consideration of the excitation control parameters. Kriging models have been constructed to reduce the computation cost of FEA during the optimization process. Then, a nondominated sorting genetic algorithm II (NSGA II) based multiobjective optimization coupled with the constructed Kriging models is conducted to generate a Pareto front. An optimal design that offers the best balance between the design objectives is selected from the Pareto-optimal set, and the dimensions of corresponding design variables are used to build a prototype. Finally, the static and dynamic performance of the SRM prototype are experimentally evaluated and validated with the FEA simulations. © 2024 IEEE.
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    Comparative assessment of a novel 8/18 multi-teeth with conventional 8/10 in-wheel SRM for an E-Scooter
    (Taylor and Francis Ltd., 2024) Bhaktha, S.; Ramnihor, G.R.; Sahu, M.; Jogi, A.; Pitchaimani, J.; Gangadharan, K.V.
    Electric scooters are increasingly gaining popularity in India owing to rising global crude oil prices and rising levels of vehicular pollution. Most of them are currently powered by expensive in-wheel (IW) permanent magnet (PM) brushless DC motors. Owing to their simplicity, and ruggedness while being cost-effective (since they do not employ PMs), switched reluctance motors (SRMs) are a viable alternative. Despite these benefits, SRMs possess drawbacks such as low torque density and inferior efficiency. Recently, a multi-teeth (MT) SRM with an improved performance was reported. However, the design of MTSRM topologies and their electromagnetic performance have not been explored sufficiently. In this paper, a design formula governing the selection of the number of MT and rotor poles for MTSRMs has been proposed. Using this, a novel four-phase 8/18 IW-MTSRM is derived and proposed for an E-scooter. The characteristics of the proposed SRM are numerically compared with a conventional 8/10 SRM based on magnetic characteristics, efficiencies and steady-state operation for the complete torque-speed range. Results indicate that the proposed 8/18 MTSRM has a higher peak torque capacity, torque density, superior drive cycle efficiency and reduced torque ripple. Further, the FEA model is validated experimentally on a downsized 8/18 MTSRM prototype. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
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    Acoustic characterization of natural areca catechu fiber-reinforced flexible polyurethane foam composites
    (John Wiley and Sons Inc, 2024) Mb, S.; Kumar, G.C.M.; Pitchaimani, J.
    The development of acoustic absorbers from natural resources is a novel approach in acoustics. In the current study, the effect of unprocessed raw areca fiber (AF) particle reinforcement on the sound absorption (SA) behavior of polyurethane (PU) foam composites is investigated. Influences of fiber weight percentage and graded distribution of fiber with varying fiber weight percentage on the SA coefficient (SAC) of the composite foams are examined through the impedance tube approach. Morphological studies are carried out with the help of FESEM images to investigate the acoustic energy dissipation mechanism of PU foam and its composites. It is found that the SA capability of the composite foam is enhanced by increased fiber weight percentage, graded distribution of fiber wt%, varying sample thickness, and air cavity length. In general, PU-AF composite specimens show a peak SA value of 0.95 around 450 Hz, which is not the case for other natural fiber results available in the literature. Theoretical results predicted using the JCA (Johnson-Champoux Allard) model agree with the experimental results. © 2023 Wiley Periodicals LLC.
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    Relation between water absorption and mechanical properties of flax 3D braided yarn woven fabric PLA bio-degradable composites
    (SAGE Publications Inc., 2024) Kanakannavar, S.; Pitchaimani, J.
    Natural fibre (flax) plain type of woven fabric is developed by using solid braided yarn and is utilised as filler material and PLA (polylactic acid) as a matrix. Solution casting is then used to create sheets of pure PLA and flax fabric–PLA. Composites are manufactured by sheets sequencing technique using the hot compression moulding method. Water absorption, thickness swelling and flexural tests are performed in loading directions of warp and weft of the composites. Results revealed that the absorption of water and swelling of thickness are enriched with an addition of flax fabric. The weft direction loaded composite displayed greater values of water uptake and thickness swelling. The warp direction loaded composites demonstrated the highest flexural strength (92.3 MPa) and modulus (4.5 GPa) compared to weft direction loaded composites. These values are decreased after water absorption. © The Author(s) 2024.
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    3D Printed Thick Micro-Perforated Panel with Graded Perforation for Practical Wall Sound Absorption Applications
    (Springer, 2024) Shafeer, M.; Pitchaimani, J.; Doddamani, M.
    In recent years, noise pollution has been recognized as a significant environmental issue, and using sustainable materials as sound-absorbing building materials have drawn considerable attention. The influence of graded perforations on the acoustic characteristics of a 3D printed bio-degradable thick micro-perforated panel (MPP) having graded perforation and made of Poly Lactic Acid is presented. Thicker panels are considered owing to the mechanical strength required for practical wall applications. A fused deposition modeling based 3D printer is used to fabricate the MPPs with graded cylindrical perforations and different patterning of perforations. The sound absorption coefficient is measured using the impedance tube technique and compared with theoretical results obtained using an equivalent electro-acoustic model. Results revealed that for normal incidence, the absorption coefficient is only dependent on the overall perforation ratio of the panel, irrespective of the perforation gradation and patterning of perforation. This gives the freedom to distribute the perforation aesthetically for interior wall application. This work also proposes the effective perforation ratio approach to predict the sound absorption coefficient (SAC) of MPPs with graded perforation. For multi-thickness MPPs and MPPs with linearly graded thickness, improved sound absorption characteristics were observed both in terms of bandwidth of absorption and peak value of SAC compared to the conventional constant thickness MPPs. © Australian Acoustical Society 2023.