Faculty Publications
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Item Strength behaviour of geogrid reinforced shedi soil subgrade and aggregate system(2006) Ravi Shankar, A.U.R.; Suresha, S.N.Shedi soil (Lithomargic clay), a yellowish-white silty soil underlying lateritic soil, is densely deposited along Konkan belt of India. The strength behaviour of Shedi soil under varying moisture content is major problem for road construction projects in this region. In the present investigation, the subgrade is stabilized with geogrid, keeping the geogrid at different positions from top of subgrade, to locate its optimum position. The plate load tests were also conducted at soaked and unsoaked conditions for unreinforeced, reinforced (with Geogrid) subgrade with aggregate base course. An equation has been established based on load-deflection values recorded for subgrade of un-reinforced and reinforced with geogrid at different levels. The deflection values obtained from equation and from the laboratory investigation were compared. In the case of reinforced subgrade with aggregate base course, the theoretical deflection values were computed based on Burmister's theory and compared with laboratory deflection values.Item Static analysis of functionally graded beams using higher order shear deformation theory(2008) Kadoli, R.; Akhtar, K.; Ganesan, N.Displacement field based on higher order shear deformation theory is implemented to study the static behavior of functionally graded metal-ceramic (FGM) beams under ambient temperature. FGM beams with variation of volume fraction of metal or ceramic based on power law exponent are considered. Using the principle of stationary potential energy, the finite element form of static equilibrium equation for FGM beam is presented. Two stiffness matrices are thus derived so that one among them will reflect the influence of rotation of the normal and the other shear rotation. Numerical results on the transverse deflection, axial and shear stresses in a moderately thick FGM beam under uniform distributed load for clamped-clamped and simply supported boundary conditions are discussed in depth. The effect of power law exponent for various combination of metal-ceramic FGM beam on the deflection and stresses are also commented. The studies reveal that, depending on whether the loading is on the ceramic rich face or metal rich face of the beam, the static deflection and the static stresses in the beam do not remain the same. © 2007 Elsevier Inc. All rights reserved.Item Slim – Gal for shape optimization of structures(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Babu Narayan, K.S.; Devraj, M.; Arun Prabha, K.S.Structural Optimization has been & continues to be an active area of research offering scope and need to handle a wide & varied range of problems. Genetic Algorithms (GA) recently have been, with great success employed to solve structural engineering problems either in conjunction with traditional methods or as alternatives. Sizing, shape and topology design of trusses is an interesting exercise that has attracted the attention of researchers. However design problems have not been kept free of conceptual designs, defeating the possibility of evolution of more efficient & innovative designs, the reason being the complexity of the problem on hand. This paper presents GA based methodology of arriving at the best configuration & member sizing employing simultaneous mode of failure approach for problem formulation of the multi-objective type to yield a structure that satisfies functional & structural requirements optimally. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Analysis of berthing structures for wave induced forces(2011) Shanthala, B.; Rao, S.; Venkataramana, K.; Narayana, H.Countries surrounded by ocean can easily achieve tremendous progress in trade and industry provided proper planning of ports and harbours is made for transportation of goods and materials through sea transport. Berthing structures are to be designed for different load combinations. The deck of berthing structure is generally supported by vertical piles. Marine and offshore structures are subjected to wave and current forces and the loads acting on the member are cyclic and will induce time varying forces and moments. Due to this nature of wave forces and moments, the stress in the structure material fluctuates with respect to time, leading to progressive growth of cracks and they ultimately lead to fracture. This fatigue changes depends upon the wave action. To reduce wave and berthing forces, it is important to fix the alignment in such a way that incoming forces are minimum. Berthing structures are the facilities constructed in ports for berthing and mooring of vessels, for loading and unloading of cargo and for embarkment and disembarkment of passengers or vehicles. The berthing structures are designed for dead load, live load, berthing force, mooring force, earthquake load and other environmental loading due to winds, waves, currents etc,. In the present study layout of jetty for berthing 5000 DWT ship at NMPT is modeled using the ship dimensions from IS code and analyzed for the available environmental data from NMPT using StruCAD 3D software. The detailed analysis of the berthing structure for the significant wave height of 3.2m is carried out for a full cycle of wave and the Variation of deflection, forces and moments for perpendicular wave directions and different pile diameters is done by Static and Dynamic analysis. Dynamic Amplification Factor is calculated by comparing static and dynamic analysis results. Time history analysis is also done for the wave loading and deflection, forces and moments of the structure is calculated. From the results it is observed that the forces and moments are large as the diameter of pile increases and the deflection is reduced. From the time history analysis it is observed that as the pile diameter increases the maximum deflection occurs at the larger time period. It was found that at time period of 8.611sec peak response occurs. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item 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. © 2018Item Progression and characterization of polydimethylsiloxane-carbon black nanocomposites for photothermal actuator applications(Elsevier B.V., 2021) Hiremath, S.; H, S.M.; Kulkarni, S.M.The new development of polymer-based actuators triggers the progress of nanocomposites. Polymer materials are currently used in sensors, microfluidic devices, electrical and thermal actuators, and energy harvesting applications due to ease of availability, excellent tolerable properties, and customizable properties. The polymer-based nanocomposite can be driven by various stimuli, which is the actuator's emerging field. Thus, photothermal actuation is a thurst area of research transforming light energy into mechanical energy through the polymer material. The photo-responsive material can be prepared and tested for photo-actuation by incorporating the nanoparticles into the polymer. The present work focuses on developing polydimethylsiloxane (PDMS) and carbon black (CB) nanocomposite. The objective here is to investigate the photothermal actuator's performance by illuminating the infrared (IR) light source and studying its most influential characteristics, such as absorbance, thermal conductivity, and the thermal expansion coefficient. The PDMS / CB nanocomposite absorbs the IR light and then increases temperature, which is finally transformed into a beam deflection. Responses are measured as a result of time deflection using the Laser displacement sensor. It is noted that the deflection of the nanocomposite beam is linearly increased during illumination with light while it is exponentially decreasing when the light is turned off. The proposed polymer nanocomposite is approximately deflected by 9 mm in the duration of 16 s duration. Furthermore, the experimental deflection of the photothermal actuator is very close to theoretical results. The nanocomposite PDMS / CB reveals that there is an increase in absorbance by increasing the filler content. The nanocomposite conductivity is 35.2 % higher than the base material. As well, the thermal expansion coefficient decreases with an increase in carbon black content. The photothermal actuator's development is an ongoing process in which the material parameter, actuator geometry, and many more are modified. As a result, the photothermal bending performed can provide a means for various light-driven applications. © 2020 Elsevier B.V.Item Thermal buckling of braided flax woven polylactic acid composites(SAGE Publications Ltd, 2021) Kanakannavar, S.; Jeyaraj, J.This study presents influence of thermal environment on buckling behaviour of natural fibre braided yarn fabric reinforced polylactic acid composite beams. The thermal buckling study is carried out using an in-house built experimental set up for beam like composites exposed to different types of in-plane temperature variations. Influences of temperature variations, direction of loading and volume fraction of fibre are studied in detail. Results indicate that deflection behaviour of natural fibre braided fabric/polylactic acid beam is entirely different from the polylactic acid beam. Enhancement of natural fibre braided fabric reinforcement on thermal deflection is observed only at higher temperature as less deflection is observed for polylactic acid beams at lower temperature range (25°C to 45°C). According to the nature of heating, maximum deflection in the range of 0.503 cm to 1.082 cm corresponding to the temperature range of 63.443°C to 67.917°C is observed for polylactic acid beams. For natural fibre braided fabric/polylactic acid beams, the maximum deflection range is 0.826 cm to 0.105 cm corresponding to the temperature range of 57.031°C to 44.742°C according to the heating condition. Thermal deflection of natural fibre braided fabric beam is sensitive to testing orientation of the beam and maximum deflection for warp loading is 29% to 54% lower than the weft loading. © The Author(s) 2020.Item Performance comparison of piezo actuated valveless micropump with central excitation and annular excitation for biomedical applications(IOP Publishing Ltd, 2021) Mohith, S.; Karanth P, N.; Kulkarni, S.M.; Desai, V.; Patil, S.S.In recent years, microfluidic devices, particularly micropumps, are extensively utilized in biomedical applications. The micropump used in biomedical applications needs to possess precise delivery of fluids at requires rate and pressure. The present work proposes a valveless mechanical micropump with a disposable chamber integrated with a novel concept of annular excitation of the diaphragm to fulfil the need for precise delivery of fluids in biomedical applications. The proposed design of the micropump involves a reusable configuration of the amplified piezoelectric actuator (APA) for micropump actuation and a disposable pump chamber. The pumping of the fluids occurs through the oscillation of the silicone rubber bossed diaphragm. The performance of a mechanical micropump depends on the oscillation amplitude of the diaphragm. Thus, the conventional approach of central excitation of the bossed diaphragm is replaced by a novel approach of annular excitation intended to enhance the deflection range, thus the volumetric performance of the micropump. An experimental comparative study is carried out to assess the deflection characteristics of central excitation and annular excitation of the bossed diaphragm. The maximum deflection measured with the annularly excited configuration of the bossed diaphragm is about 1953.4 ± 8.00 µm at 150 V, 43.5 Hz, which is superior to the maximum deflection of centrally excited configuration delivering 717.99 ± 4.00 µm at 150 V, 9.5 Hz. Further, the experimental studies aimed to fabricate and characterize the micropump with central and annular excitation approaches. The proposed micropump with central excitation delivered the maximum water flow rate of about 7.192 ± 0.147 ml min-1 and backpressure of 0.294 kPa at 150 V, 5 Hz. However, the enhancement of the deflection characteristics of the bossed diaphragm under annular excitation leads to performance enhancement of the micropump with the flow rate of 95.10 ± 0.444 ml min-1 and backpressure of 1.472 kPa at 150, 30 Hz. © 2021 IOP Publishing Ltd.Item 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.Item Elasticity solution of fixed beams under linear temperature variation: An experimental and numerical study(Taylor and Francis Ltd., 2025) Raju, B.; Kaliveeran, V.This article presents the Airy stress function method for predicting the structural response of a fixed beam subjected to a linear temperature distribution, using the superposition principle. In this approach, the fixed-end beam is decomposed into three simply supported beams with unknown reactions and a linear temperature variation. For each loading condition, the suitable Airy’s stress functions were formulated to satisfy the stress equilibrium and strain compatibility equations. The results obtained using this method are subsequently contrasted with those derived from finite element modeling. To validate the analytical and experimental results, two finite element modeling approaches, namely two-dimensional and three-dimensional modeling, are implemented using the ANSYS finite element software. This numerical modeling approach utilizes a sequentially coupled steady-state thermal and static structural analysis. In addition to employing Airy’s stress function method and finite element analysis, experiments were conducted on SS304 rectangular specimens under proper insulation to investigate their thermal bowing response. Samples were tested in a simple thermal bending experimental setup under fixed support conditions, and subjected to conduction-type heating to achieve linear temperature changes along their depth. The analytical method predicts that the beam will not deflect under linear temperature variation in a fixed-beam situation. The numerical analysis results confirm this, showing a minimal deflection, that aligns well with the Airy’s stress function method. However, the deflection measured in the experimental program is significantly larger than the predictions from the analytical method. This method eliminates the complexity involved in applying boundary conditions along with thermal loading on a fixed beam. © 2025 Taylor & Francis Group, LLC.