Browsing by Author "Kulkarni, S.M."

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A comprehensive review on material selection for polymer matrix composites subjected to impact load
(China Ordnance Industry Corporation, 2021) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
Polymer matrix composites (PMC) are extensively been used in many engineering applications. Various natural fibers have emerged as potential replacements to synthetic fibers as reinforcing materials composites owing to their fairly better mechanical properties, low cost, environment friendliness and biodegradability. Selection of appropriate constituents of composites for a particular application is a tedious task for a designer/engineer. Impact loading has emerged as the serious threat for the composites used in structural or secondary structural application and demands the usage of appropriate fiber and matrix combination to enhance the energy absorption and mitigate the failure. The objective of the present review is to explore the composite with various fiber and matrix combination used for impact applications, identify the gap in the literature and suggest the potential naturally available fiber and matrix combination of composites for future work in the field of impact loading. The novelty of the present study lies in exploring the combination of naturally available fiber and matrix combination which can help in better energy absorption and mitigate the failure when subjected to impact loading. In addition, the application of multi attributes decision making (MADM) tools is demonstrated for selection of fiber and matrix materials which can serve as a benchmark study for the researchers in future. © 2020 The Authors
A Development of Micropump Based on Cooling System for Laptops
(Springer Science and Business Media Deutschland GmbH, 2024) Patil, S.S.; Mohith, S.; Karanth P, P.; Kulkarni, S.M.
This paper aims to study a new mechanical diaphragm micropump for a liquid cooling system for laptops. A low weight, high discharge diaphragm pump has been developed successfully to pump the coolant by the crank and extended rocker mechanism using a micro gear dc motor. The bossed diaphragm pump chamber and mechanism are fabricated using high-quality PLA with optimized parameters and the FDM 3D printing method. Both valves and diaphragm are created using silicon rubber. The reciprocating action of the mechanism develops the suction and discharge stages that make the pump work. The pumpâ€™s performance is analyzed using an experimental setup that has been developed and implemented. The diaphragm design, pump chamber, operating voltage, and coolant type all affect the performance of a bossed diaphragm pump driven by a crank and extended rocker mechanism. The measured maximum flow rate of the designed prototype is 94Â mL/min for water and 65Â mL/min for ethylene glycol solution within 5Â V actuation voltage and zero pressure head. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
A Novel Flexible Green Composite with Sisal and Natural Rubber: Investigation under Low-Velocity Impact
(Taylor and Francis Ltd., 2022) Rajkumar, D.; Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
The present work concentrates on assessing the low-velocity impact (LVI) response of sisal-natural rubber (NR)-based flexible green composite in two different stacking sequences, namely, sisal/rubber/sisal (SRS) and sisal/rubber/sisal/rubber/sisal (SRSRS). The influence of the impactor shape on LVI response of the proposed composite was assessed using hemispherical and conical-shaped impactors. Results showed that the proposed composites exhibit better energy absorption and resistance to damage due to inclusion of compliant matrix. The study of damage mechanism of the proposed composites showed that the inclusion of NR as a matrix material in the proposed composites helps to avoid catastrophic failure since rubber undergoes failure by matrix tearing as opposed to matrix cracking as in the case of stiff composites. The proposed composites eliminate two of the major damage mechanisms, namely, matrix cracking and delamination, due to usage of compliant matrix material. The results obtained suggest that the proposed flexible composites can serve as excellent sacrificial structures. The outcome of the present study serves as a benchmark for interested designers/engineers to explore the usage of natural material candidates for developing sustainable impact-resistant composites. © 2022 Taylor & Francis.
A Simple Displacement Function to Determine the Response of a Micro Capacitive Pressure Sensor
(2011) Simha, A.; Kulkarni, S.M.; Meenatchi Sundaram, S.; Bhat, S.
The response of a capacitive pressure sensor is generally represented by a fourth order partial differential equation which is complex to solve and does not possess an exact solution. Several attempts have been made earlier through various techniques such as the Galerkin method, Finite Difference Method etc.... In this paper an attempt has been made to develop a simple approximate analytical approach to determine the response of a micro capacitive pressure sensor whose diaphragm is designed to undergo very small deflections (typically less than 25% of the thickness). The non-uniform gap between the electrodes is mathematically expressed as a combination of the initial gap between the electrodes (in the undeformed state) and a displacement function in (x,y). The proposed displacement function is then utilized in evaluating the capacitance as a function of the applied pressure. The results obtained from the analytical approach are benchmarked against those obtained from COMSOL MultiphysicsÂ®, a popular Finite Element Analysis tool in the MEMS industry. It is observed that the results obtained from COMSOL MultiphysicsÂ® and those from the analytical approach are in good agreement with a maximum deviation of about 8.66%. Â© 2011 American Institute of Physics.
An analytical method to determine the response of a micro capacitive pressure sensor
(2011) Simha, A.; Kulkarni, S.M.; Meenatchi Sundaram, S.
The response of a capacitive pressure sensor is generally represented by a fourth order partial differential equation which is complex to solve and does not possess an exact solution. Several attempts have been made earlier through various techniques such as the Galerkin method, Finite Difference Method etc. In this paper an attempt has been made to develop a simple approximate analytical approach to determine the response of a capacitive pressure sensor whose diaphragm is designed to undergo very small deflections (typically less than 25 % of the thickness). The nonuniform gap between the electrodes is mathematically expressed as a combination of the initial gap between the electrodes (in the undeformed state) and a displacement function in (x, y). The proposed displacement function is then utilized in evaluating the capacitance as a function of the applied pressure. The results obtained from the analytical approach are benchmarked against those obtained from COMSOL Multiphysics®, a popular Finite Element Analysis tool in the MEMS industry. It is observed that the results obtained from COMSOL Multiphysics® and those from the analytical approach are in good agreement with a maximum deviation of about 3.38 %. © 2011 IFSA.
An experimental investigation on low-velocity impact response of novel jute/rubber flexible bio-composite
(Elsevier Ltd, 2019) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
This paper presents an experimental investigation on low velocity impact (LVI) behaviour of flexible biocomposite laminates with different stacking sequence namely jute/rubber/jute (JRJ), jute/rubber/rubber/jute (JRRJ), jute/rubber/jute/rubber/jute (JRJRJ) and subjected to different impact energy levels using a conical shaped impactor. The performances of the proposed flexible composites are evaluated based on their energy absorption, peak force, coefficient of restitution (CoR), energy loss percentage (ELP) and failure behavior. Results indicated that JRJ provides better energy absorption and JRJRJ provides better damage resistance when subjected to LVI. Microscopic analysis revealed that the flexible composites fail mainly due to the tearing mechanism of the matrix as opposed to cracking in case of conventional stiff composites. It was also found that flexible composites are free from delamination. Compared to conventional stiff composites, there is no catastrophic failure observed in the proposed flexible composite. The overall performance evaluation of these proposed flexible composites indicates that these flexible composites can be potential sacrificial materials such as claddings used to protect primary structural components subjected to LVI. The systematic methodology employed in the present study serves as a benchmark for the effective utilization and selection of flexible composites for LVI applications. © 2019 Elsevier Ltd
An experimental study on adhesion, flexibility, interlaminar shear strength, and damage mechanism of jute/rubber-based flexible “green” composite
(SAGE Publications Ltd, 2022) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
Determining the interlaminar shear strength (ILSS) of the composite laminates is vital for deciding their usage in any engineering applications. The matrix used and its curing characteristics are vital in deciding the ILSS of the composite. Present work deals with an experimental study on adhesive behavior, degree of flexibility, ILSS, and damage mechanism of the novel jute/rubber-based flexible “green” composite. The proposed flexible composites were prepared in three different stacking sequences, namely jute/rubber/jute (JRJ), jute/rubber/rubber/jute (JRRJ), and jute/rubber/jute/rubber/jute (JRJRJ), using compression molding technique. After determining the optimal curing characteristics of the proposed rubber-based matrix, the constituents are tested for their adhesive strength with the matrix which showed that rubber matrix system is compatible with jute fabric and natural rubber sheet. Composites are prepared and degree of flexibility for each stacking sequence is found out. Results pertaining to ILSS show that JRJRJ has better ILSS compared to JRJ and JRRJ. Fractographic analysis using scanning electron microscope reveals the mode of failure of the composites and the mechanism governing their failure. Fourier transform infrared spectroscopic study reveals the bonding between the constituents is good enough to be used in composites with flexibility. © The Author(s) 2019.
Analysis of a Chevron Beam Thermal Actuator
(2018) Sanjay, Joshi, A.; Mohammed, H.; Kulkarni, S.M.
Thermal MEMS (Micro-Electro-Mechanical Systems) actuators and sensors have a wide range of applications. The chevron type thermal actuators comparatively show superior performance over other existing electrostatic and thermal actuators. This paper describes the design and analysis of chevron type thermal actuator. Here standard design of Chevron type thermal actuator is considered which comprises of proof mass at center and array of six beams of a uniform cross section of 3 3 microns and an initial angle of 5�. The thermal actuator was designed and analyzed using analytical and finite element method and the results were compared. The model was also analyzed for initial angles of 2.5� and 7.5�, and the results were compared with FEA model. The cross section of the beam was varied and the finite element analysis of all three models was compared to suggest the best suitable thermal actuator structure. � Published under licence by IOP Publishing Ltd.
Analysis of a Chevron Beam Thermal Actuator
(Institute of Physics Publishing helen.craven@iop.org, 2018) Sanjay Joshi, A.; Mohammed, H.; Kulkarni, S.M.
Thermal MEMS (Micro-Electro-Mechanical Systems) actuators and sensors have a wide range of applications. The chevron type thermal actuators comparatively show superior performance over other existing electrostatic and thermal actuators. This paper describes the design and analysis of chevron type thermal actuator. Here standard design of Chevron type thermal actuator is considered which comprises of proof mass at center and array of six beams of a uniform cross section of 3 3 microns and an initial angle of 5Â°. The thermal actuator was designed and analyzed using analytical and finite element method and the results were compared. The model was also analyzed for initial angles of 2.5Â° and 7.5Â°, and the results were compared with FEA model. The cross section of the beam was varied and the finite element analysis of all three models was compared to suggest the best suitable thermal actuator structure. Â© Published under licence by IOP Publishing Ltd.
Analysis of annularly excited bossed diaphragm for performance enhancement of mechanical micropump
(Elsevier B.V., 2022) Mohith, M.; Karanth P, N.K.; Kulkarni, S.M.
Piezo actuated mechanical micropumps find extensive application in microfluidic devices for precise delivery of the fluids. The deflection of the diaphragm dramatically influences the performance of the mechanical micropump. The present work emphasises a novel method of annular excitation of the diaphragm to enhance the volumetric performance of the micropump. The proposed work incorporates a bossed diaphragm excited through a novel approach of annular excitation. The amplified piezoelectric actuator is used as a primary source of actuation. In the present work, theoretical and finite element methods are considered to analyse the deflection behaviour of the bossed diaphragm under central and annular excitation. Experimental characterisation is carried out to validate the results obtained from finite element analysis. The annular excitation of the bossed diaphragm delivers a higher range of deflection when compared with the conventional central excitation. The maximum simulated deflection of about 1998.4 µm is achieved with an annularly excited bossed diaphragm at 150 V, 45.5 Hz, which is far superior to the deflection range achieved with a conventional centrally excited bossed diaphragm with the deflection of 725.91 µm at 150 V, 9.96 Hz. The corresponding experimental deflection of annularly excited and centrally excited bossed diaphragm is about 1953.4 ± 8.00 µm at 50 V, 43.5 Hz and 717.99 ± 4.00 µm at 150 V, 9.5 Hz. © 2022 Elsevier B.V.
Analysis of coefficient of thermal expansion in carbon black filled PDMS composite
(2020) Shivashankar, H.; Sangamesh, R.; Kulkarni, S.M.
Polymer composites are gaining attention due to their superior thermal properties. Especially carbon black /carbon nanotubes/ graphene filled polymer composites are used in energy harvesting, thermal actuators and MEMS. The coefficient of thermal expansion (CTE) is one of the most important properties in the polymer composite. In the present study, thermal expansion of polydimethylsiloxane (PDMS) matrix is filled with carbon black particle of varied volume fraction is modeled. Two-dimensional finite element (FE) model is computed in order to explain the thermal expansion behavior of the polymer composite and same is carried out for ambient to 70 K temperature. A 2D regular arrangement of circular particle packing model is set up and simulated. The FE model predicts that filler geometry has a little effect on the thermal expansion than the percentage of filler in the composite. Thermal expansion of composite is compared with the theoretical model. It shows that the CTE of composite reduces as the filler percentage increase, also gives good agreement in the both models. Hence, it is found that the addition of carbon black to the polymer composite could make it perform significantly better in thermal expansion. � 2020 Trans Tech Publications Ltd, Switzerland.
Analysis of coefficient of thermal expansion in carbon black filled PDMS composite
(Trans Tech Publications Ltd ttp@transtec.ch, 2020) Hiremath, H.; Sangamesh, R.; Kulkarni, S.M.
Polymer composites are gaining attention due to their superior thermal properties. Especially carbon black /carbon nanotubes/ graphene filled polymer composites are used in energy harvesting, thermal actuators and MEMS. The coefficient of thermal expansion (CTE) is one of the most important properties in the polymer composite. In the present study, thermal expansion of polydimethylsiloxane (PDMS) matrix is filled with carbon black particle of varied volume fraction is modeled. Two-dimensional finite element (FE) model is computed in order to explain the thermal expansion behavior of the polymer composite and same is carried out for ambient to 70 K temperature. A 2D regular arrangement of circular particle packing model is set up and simulated. The FE model predicts that filler geometry has a little effect on the thermal expansion than the percentage of filler in the composite. Thermal expansion of composite is compared with the theoretical model. It shows that the CTE of composite reduces as the filler percentage increase, also gives good agreement in the both models. Hence, it is found that the addition of carbon black to the polymer composite could make it perform significantly better in thermal expansion. Â© 2020 Trans Tech Publications Ltd, Switzerland.
Analysis of impact behaviour of sisal-epoxy composites under low velocity regime
(International Information and Engineering Technology Association, 2021) Mahesh, V.; Nilabh, A.; Joladarashi, S.; Kulkarni, S.M.
The present study concentrates on development of conceptual proof for sisal reinforced polymer matrix composite for structural applications subjected to low velocity impact using a finite element (FE) approach. The proposed sisal-epoxy composite of various thicknesses of 3.2 mm, 4 mm and 4.8 mm is subjected to different impact velocities of 1 m/s, 2 m/s and 3 m/s ranging in the low velocity impact regime to study the energy absorbed and damage mitigation behaviour of the proposed composite. The consequence of velocity of impact and thickness of laminate on the sisal epoxy composite's impact behaviour is assessed statistically using Taguchi's experimental design. Outcome of the present study discloses that the energy absorption increases with increased impact velocity and laminate thickness. However, the statistical study shows that impact velocity is predominant factor affecting the impact response of sisal epoxy composite laminate compared to laminate thickness. The role of matrix and fiber in damage initiation is studied using Hashin criteria and it is found that matrix failure is predominant over the fiber failure. © 2021 Lavoisier. All rights reserved.
Analysis of light weight natural fiber composites against ballistic impact: A review
(KeAi Publishing Communications Ltd., 2023) Doddamani, S.; Kulkarni, S.M.; Joladarashi, S.; Mohan Kumar, M.K.; Gurjar, A.K.
The main factors in the ballistic impact mechanism, an incredibly complicated mechanical process, are the target material's thickness, toughness, strength, ductility, density, and projectile parameters. Creating resilient, high-strength, and high-modulus fibers has made it possible to use natural fibers and their composite laminates for various impact-related applications today. Kinetic energy absorption, penetration depth, and residual velocity were the parameters affecting the performance of natural fiber composites used in the armor systems. This review aims to comprehend the several influencing factors that significantly impact the target's ballistic impact performance. In addition to experimental study efforts, many analytical, numerical modeling, and empirical technique-based research approaches have also been considered while analyzing the various components. The paper also examines several factors that determine how well natural fiber composite functions, including internal factors like material composition, characteristics of matrix and reinforcement, the kind and choice of fiber/matrix, failure modes, impact energy absorption, and external factors such as residual velocity, and various projectile nose angles. It also emphasizes the ways to improve composites for high performance and ballistic efficiency, as well as the economic cost analysis of switching out synthetic fibers for natural ones in a ballistic composite. © 2023 The Authors
Analysis of Miniaturized Acoustic Transducer for Cell-Lysis
(2018) Matey, Y.; Sri, Charan, A.; Kulkarni, S.M.
A model of sonar emitter used in underwater navigation is considered. The model is miniaturized and the effect of the operation on total acoustic pressure and directivity index is analysed using COMSOL Multiphysics�. Effect of two different acoustic head geometries is studied. AC voltage is applied to piezoelectric actuator present in the model. Effect of changing frequency is studied. Depending on the results obtained, it was concluded that the miniaturized sonar emitter model is more suitable for cell disruption for cell organelle extraction rather than in cancer cell ablation. And also, the model with tapered acoustic head geometry showed better results. � 2018 IEEE.
Analysis of Miniaturized Acoustic Transducer for Cell-Lysis
(Institute of Electrical and Electronics Engineers Inc., 2018) Matey, Y.; Sri Charan, A.; Kulkarni, S.M.
A model of sonar emitter used in underwater navigation is considered. The model is miniaturized and the effect of the operation on total acoustic pressure and directivity index is analysed using COMSOL MultiphysicsÂ®. Effect of two different acoustic head geometries is studied. AC voltage is applied to piezoelectric actuator present in the model. Effect of changing frequency is studied. Depending on the results obtained, it was concluded that the miniaturized sonar emitter model is more suitable for cell disruption for cell organelle extraction rather than in cancer cell ablation. And also, the model with tapered acoustic head geometry showed better results. Â© 2018 IEEE.
Axial capacity of rectangular concrete-filled steel tube columns - DOE approach
(2010) Chitawadagi, M.V.; Narasimhan, M.C.; Kulkarni, S.M.
This paper presents the effect of change in wall thickness of the steel tube (t), strength of in-filled concrete (fcu), cross-sectional area of the steel tube (A) and length of the tube (L) on ultimate axial load and axial shortening at ultimate point of rectangular concrete-filled steel tubes (CFT). Taguchi's approach with an L9 orthogonal array is used to reduce the number of experiments. With the help of initial experiments, linear regression models are developed to predict the ultimate axial load and the axial shortening at ultimate point. A total of 243 rectangular CFT samples are tested to verify the accuracy of these models at three factors with three levels. The experimental results are analyzed using Analysis Of Variance to investigate the most influencing factor on strength and axial shortening of CFT samples. Comparisons are made with predicted column strengths using the existing design codes, AISC-LRFD-1994 and EC4-1994. © 2009 Elsevier Ltd. All rights reserved.
Axial strength of circular concrete-filled steel tube columns - DOE approach
(Elsevier Ltd, 2010) Chitawadagi, M.V.; Narasimhan, M.C.; Kulkarni, S.M.
This paper presents the effect of changes in diameter of the steel tube (D), wall thickness of the steel tube (t ), strength of in-fill concrete (f cu), and length of the tube (L) on ultimate axial load (P ue) and axial shortening at the ultimate point (?ue ) of circular Concrete Filled steel Tubes (CFT). Taguchi's approach with an L9 orthogonal array is used to reduce the number of experiments. With the help of initial experiments, linear regression models are developed to predict the axial load and the axial shortening at the ultimate point. A total of 243 circular CFT samples are tested to verify the accuracy of these models at three factors with three levels. The experimental results are analyzed using Analysis Of Variance to investigate the most influencing factor on strength and axial shortening of CFT samples. Comparisons are made with predicted column strengths using the existing design codes, AISC-LRFD-2005 and EC4-1994. © 2010 Elsevier Ltd. All rights reserved.
Ballistic impact analysis of multilayered armour system using finite element analysis
(Elsevier, 2024) Doddamani, S.; Kulkarni, S.M.; Joladarashi, S.; Mohan Kumar, T.S.; Gurjar, A.K.
The application of finite element analysis (FEA) to the ballistic impact analysis of polymer composites used in armor is covered in this chapter. This study aims to assess polymer composite armor materials' performance and establish their resistance to high-velocity projectile impacts. The use of FEA enables accurate simulations of the impact process that take into consideration the properties of the materials, the geometry of the projectile and the armor panel, and the impact conditions. The investigation' findings shed important light on how the polymer composite armor responds to impacts and its capacity to absorb and dissipate impact energy. For the development of cutting-edge armor materials and the multiscale modeling method of armor design, this information is essential. The chapter ends with recommendations for further research as well as a discussion of the difficulties and restrictions of employing FEA for ballistic impact analysis. © 2024 Elsevier Ltd. All rights are reserved including those for text and data mining AI training and similar technologies.
Ballistic Impact Study on Jute-Epoxy and Natural Rubber Sandwich Composites
(2018) Sangamesh; Ravishankar, K.S.; Kulkarni, S.M.
Since ages, human beings have used different methods to protect themselves and their armors from the impact of bullets/projectiles by using structures made up of wood, metals, glass and sand bags etc. These protective structures are heavy and incur cost and inconvenience to transport. Of late, they are replaced by structures of polymers and their composites, because of their light weight and good corrosion resistance. Ballistic impact analysis of composite materials is necessary in order to establish their use in military, aerospace and automotive applications either through experimental studies or using modeling techniques. The aim of the present investigation is to model and analyze the behavior of composites for ballistic impact. Residual velocity, energy absorption and ballistic limit for three different materials Jute-Epoxy (JE), Rubber (Ru), Jute-Epoxy-Rubber sandwich (JRE) for three thicknesses (5, 10, 15mm) and at three velocities (150, 250, 350 m/s) is studied. The study exhibits a significant amount of energy absorption in rubber, almost 10 times as compared to JE plate. Also damage observed was ductile in the case of rubber, while brittle in JE. Sandwich composites (JRE) displayed energy absorption and ballistic limit on par with rubber plates. Thus the applicability of these sandwiches in ballistic impact is established as better energy absorbing protective target structures. � 2017 Elsevier Ltd.