Journal Articles

Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884

Browse

Author: search.filters.author.Kulkarni, S.M.Subject: search.filters.subject.Rubber

Search Results

Now showing 1 - 10 of 26
  • No Thumbnail Available
    Item
    Behavior of sandwich beams with functionally graded rubber core in three point bending
    (2011) Doddamani, M.R.; Kulkarni, S.M.; Kishore
    The three-point bending behavior of sandwich beams made up of jute epoxy skins and piecewise linear functionally graded (FG) rubber core reinforced with fly ash filler is investigated. This work studies the influence of the parameters such as weight fraction of fly ash, core to thickness ratio, and orientation of jute on specific bending modulus and strength. The load displacement response of the sandwich is traced to evaluate the specific modulus and strength. FG core samples are prepared by using conventional casting technique and sandwich by hand layup. Presence of gradation is quantified experimentally. Results of bending test indicate that specific modulus and strength are primarily governed by filler content and core to sandwich thickness ratio. FG sandwiches with different gradation configurations (uniform, linear, and piecewise linear) are modeled using finite element analysis (ANSYS 5.4) to evaluate specific strength which is subsequently compared with the experimental results and the best gradation configuration is presented. © 2011 Society of Plastics Engineers.
  • No Thumbnail Available
    Item
    Response of fly ash-reinforced functionally graded rubber composites subjected to mechanical loading
    (2012) Doddamani, M.R.; Kulkarni, S.M.
    A novel approach to estimate the Young's modulus of a functionally graded rubber composite (FGRC) from the damping ratio is demonstrated with the examples of unreinforced and fly ash-reinforced materials. FGRC coupons were prepared using the conventional casting technique. The occurrence of gradation in the specimens was attributed to the variable density of particles present in the fly ash, settling at different depths. The technique of free vibrations was used for experimentation. The damping response of the FGRC specimens was studied. The results obtained from the experiments showed that, with growing filler weight fraction, the Young's modulus of the composite increased. The empirical model developed to predict the magnitude of the modulus turned out to be in good agreement with experimental data. © 2012 Springer Science+Business Media, Inc.
  • No Thumbnail Available
    Item
    Experimental investigation on slurry erosive behaviour of biodegradable flexible composite and optimization of parameters using Taguchi's approach
    (Lavoisier, 2018) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
    In the present study, the emphasis is on analysing the slurry erosive behaviour of novel green flexible composite made from jute fiber and natural rubber of ribbed smoke sheet (RSS) grade. The bonding gum made of natural rubber is used to bind the fiber and RSS rubber. Three different stacking sequences namely jute-rubber-jute (JRJ), jute-rubber-rubberjute (JRRJ) and jute-rubber-jute-rubber-jute (JRJRJ) are considered. Erosive studies are carried out on the prepared composites under three different rotation speeds (500, 1000 and 1500 rpm) and three different sand concentration (50, 75 and 100 gms) with silica sand as the abrasive medium dispersed in tap water. Design of experiments (DOE) is carried out using Taguchi's L9 orthogonal array on slurry erosion test to find out the effect of the stacking sequence, rotation speed and sand concentration on the weight loss of the composite. Through ANOVA, it was concluded that sand concentration is the main factor affecting the weight loss of composite. Regression model is developed and it was found that the developed model is adequate and feasible to predict the weight loss due to slurry erosion within the range of experimental conditions. © 2018 Lavoisier. All rights reserved.
  • No Thumbnail Available
    Item
    Investigation on the eect of using rubber as core material in sandwich composite plate subjected to low-velocity normal and oblique impact loadings
    (Sharif University of Technology, 2019) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
    In this article, the structural performance of composite plate under low-velocity impact is studied. Two forms of layup sequence, namely, Jute-Epoxy laminate (JE) and Jute-Epoxy-Rubber sandwich (JE-R-JE), were considered for evaluation. Special emphasis was on evaluating the inuence of normal and oblique loadings. Various dynamic parameters, such as energy, peak load, and deformation, were analysed in detail to study the eect of impact angle on both laminate and sandwich structures. Stress analysis of both laminate and sandwich structures was carried out to discuss the eect of introducing rubber as a core material. The results revealed that using rubber as a core material had a signicant eect on energy absorption. In addition, it was noticed that increasing the angle of impact would yield better performance of the composite plate. The results presented here may serve as benchmark for eective utilization of composite plates in low-velocity impact applications. © 2019 Sharif University of Technology. All rights reserved.
  • No Thumbnail Available
    Item
    Physio-mechanical and wear properties of novel jute reinforced natural rubber based flexible composite
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
    This paper deals with the design, fabrication, physio-mechanical and wear characterization of the composites prepared from naturally available jute fiber and rubber matrix materials. Jute and natural rubber are cost effective, abundant and environmental friendly materials which can be used as fiber and matrix respectively. The flexible composite with different stacking sequence are manufactured using compression moulding machine and void percentage, water absorption percentage, tensile properties, tear strength, impact strength and shore hardness of the prepared composites are found along with the wear. The void content and water absorption are found to increase with increased number of plies in the composite with fibers contributing more compared to rubber. Tensile, tear, specific wear rate and hardness are found to better with a composite having minimum number of plies, which is JRJ. Charpy impact test revealed that the variation in specific impact strength of the three configuration of composites are negligible and no failure of composites were absorbed owing to their flexibility indicating all the three composites have additional capability to absorb much higher energy and suitable as sacrificial components for structural applications subjected to low velocity impact. The fractography analysis of tensile and tear test shows that the flexible composites are free from matrix cracking, but matrix tearing plays a vital role in failure. The mechanism of wear involved in the proposed composites when different constituents of the composite are exposed to abrasive medium is studied through surface morphology. © 2019 IOP Publishing Ltd.
  • No Thumbnail Available
    Item
    Influences of dielectric and conductive fillers on dielectric and mechanical properties of solid silicone rubber composites
    (Springer London, 2019) Manohar Shankar, B.S.; Kulkarni, S.M.
    Dielectric elastomers are materials being used for electromechanical transduction applications. Their electromechanical response depends on permittivity, Young’s modulus and electric breakdown strength. A factor that limits its application is high operating voltages that can be reduced through improvement in permittivity. One of the methods is by incorporating high permittivity fillers into polymer matrix to obtain dielectric–dielectric composites (DDC).These composites show high permittivity at the cost of reduced flexibility. An alternative solution is development of composites by incorporating organic or inorganic conductive fillers into polymer matrix. These composites show high permittivity with high dielectric loss and low breakdown strength. To overcome both the above limitations both dielectric and conductive fillers are incorporated into dielectric polymer matrix to obtain conductor–dielectric composites (CDC). In this study, high temperature vulcanized solid silicone rubber as matrix has been used to prepare DDC composites with barium titanate (BT) filler and CDC composites with both BT as dielectric and ketjenblack as conductive fillers, using Taguchi design of experiments. The effect of factors such as amount of fillers and curing agent, mixing time in roll mill and curing temperature on the dielectric and mechanical properties are reported. Lichtenecker model predicts the permittivity of the DDC composite more accurately. For the CDC composites permittivity increased by 390%, effective resistivity decreased by 80%, Young’s modulus increased by 368% and Shore A hardness increased by 90% as compared to those of reference matrix. Important interaction effects are observed among both the fillers that are uniformly dispersed without any aggregation. © 2019, Iran Polymer and Petrochemical Institute.
  • No Thumbnail Available
    Item
    Influence of conductive and dielectric fillers on the relaxation of solid silicone rubber composites
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Manohar Shankar, B.S.; Hiremath, S.; Kulkarni, S.M.
    Flexible dielectrics possessing high permittivity and low loss are desirable for many electromechanical transduction applications. Solid silicone rubber composites are promising materials for electromechanical applications. These composites are fabricated using high-temperature vulcanization process, with various amounts of conductive, dielectric and conductor-dielectric filler and processing parameters. Dielectric and conductivity relaxations of these composites are investigated using dielectric spectroscopy in the 20 Hz-2 MHz frequency range at room temperature. Dielectric relaxations of dielectric filler composites show different behaviour compared to conductive and conductive - dielectric filler composites even with the same filler loading. All composites show increased permittivity at lower frequencies. The maximum permittivity of 46, 5.8 and 46 at 20 Hz was attained for the conductive, dielectric and conductive-dielectric composites respectively at similar filler loadings. The composites follow the AC universality law with exponents in the range of 0.82 to 1.02. The conductive filler is more reinforcing than dielectric filler as seen from the variation of Young's modulus with filler type. Uniform dispersion of fillers is observed for all the three composites. © 2019 IOP Publishing Ltd.
  • No Thumbnail Available
    Item
    Comparative study of damage behavior of synthetic and natural ber-reinforced brittle composite and natural ber-reinforced exible composite subjected to low-velocity impact
    (Sharif University of Technology, 2020) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
    In the present study, a comparative study of the damage behavior of Glass-Epoxy (GE), Jute-Epoxy (JE) laminates with [0=90]s orientation, and Jute-Rubber-Jute (JRJ) sandwich is carried out by ABAQUS/CAE nite element software. The GE, JE laminate, and JRJ sandwich with a thickness rate of 2 mm are impacted by a hemispherical-shaped impactor at a velocity of 2.5 m/s. The mechanisms by which the brittle laminate gets damaged are analyzed in accordance with Hashin's 2D failure criterion, and exible composites are analyzed by the ductile damage mechanism. The absorbed energy and the incipient point of each laminate were compared. According to the results, there was no evidence of delamination in JRJ as opposed to GE and JE. The compliant nature of a rubber plays a role in absorbing more energy, which is slightly higher than the energy absorbed in GE. Moreover, it was observed that there was no incipient point in JRJ sandwich, meaning that there was no cracking of matrix since the rubber was elastic material. Thus, the JRJ material can be a better substitute for GE laminate in low-velocity applications. The procedure proposed for the analysis in the present study can serve as a benchmark method for modeling the impact behavior of composite structures in further investigations. © 2020 Sharif University of Technology. All rights reserved.
  • No Thumbnail Available
    Item
    Evaluation of tensile strength and slurry erosive behaviour of jute reinforced natural rubber based flexible composite
    (International Information and Engineering Technology Association info@iieta.org, 2020) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
    Polymer based natural fiber reinforced composites are finding their applications in almost all fields of engineering. Flexible composites are different class of composite materials finding their usage in secondary structural application such as sacrificial structures like claddings. Mechanical and tribological characterization of the newly developed composites becomes important prior to using them in any engineering application. The present study concentrates on evaluating the tensile and slurry erosive behaviour of flexible composite manufactured by reinforcing naturally available jute fiber in the form of woven fabric in the naturally available sun dried rubber sheets (NR) using compression moulding technique. ASTM D412 standard is used to evaluate the tensile properties of the proposed flexible composite and the NR sheets. The slurry erosive behaviour is assessed using Ducom slurry erosion testing machine. The results reveal that reinforcing jute with natural rubber enhances the tensile strength compared to natural rubber sheet and the wear of the proposed flexible composite is minimal due to inclusion of natural rubber which is elastic in nature. © 2020 Lavoisier. All rights reserved.
  • No Thumbnail Available
    Item
    Performance analysis of valveless micropump with disposable chamber actuated through Amplified Piezo Actuator (APA) for biomedical application
    (Elsevier Ltd, 2020) Mohith, M.; Karanth P, N.; Kulkarni, S.M.
    The precise manipulation of fluid through pumping systems has been the technological challenge in microfluidic applications. The biomedical applications call for precise and accurate delivery of fluid through miniaturized pumping systems. This paper presents a novel valveless micropump for biomedical applications operated by the Amplified Piezo Actuator. Integrating the disposable chamber and reusable actuator with the proposed micropump allows the actuator to be reused and eliminates the possibility of infection or contagion. The micropump was fabricated using low-cost polymeric materials like Polymethylmethacrylate (PMMA), Silicone rubber through CNC milling, Laser Cutting, conventional moulding operation. The micropump chamber, nozzle/diffusers, and a bossed diaphragm constituted disposable part and Amplified Piezo Actuator with structural support formed the reusable part of the micropump. The bossed diaphragm of the pump chamber consists of a central cylindrical protrusion to reduce the force of adhesion on the diaphragm and transmit force required for micropump actuation. A theoretical analysis was performed to assess the effect of diaphragm thickness and the bossed region on the effective stiffness of the diaphragm, which in turn influences the deflection achieved. Besides, an analytical approach has been presented to address the effect of adhesive force on the diaphragm surface due to the residual fluid and chamber depth. The experimental characterization of the micropump was carried out to determine the optimal performance parameters with water, fluids mimicking blood plasma, and whole blood. Based on the experimental results, the pumping rate and head developed by the micropump have been significantly affected by factors such as bossed ratio, diaphragm thickness, depth of the micropump chamber, and viscosity of the fluid. The optimum configuration of the micropump cosidered silicone rubber diaphragm with thickness of 0.20 mm having a bossed ratio of 0.33 and a chamber depth of 1.25 mm. With the optimal operating parameters of 150 V sinusoidal input of frequency 5 Hz, the proposed micropump was capable of delivering 7.192 ml/min, 6.108 ml/min, and 5.013 ml/min of water and blood plasma, whole blood mimicking fluid with the maximum backpressure of 294.00 Pa, 226.243 Pa, and 204.048 Pa respectively. The corresponding resolution, i.e., pumping volume/stroke of the micropump was about 23.972 µl, 20.358 µl, and 16.708 µl, respectively. © 2020 Elsevier Ltd