Faculty Publications
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Item Influence of laminate thickness and impactor shape on low velocity impact response of jute-epoxy composite: FE study(Elsevier Ltd, 2019) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.This paper aims at numerical and parametric investigation on the outcome of low velocity impact (LVI) response of jute/epoxy (JE) composite of varied thickness subjected to impact at varied velocity of impact within LVI regime using different shaped impactors. The JE composite laminate with varying thickness of 6 mm to 10 mm is subjected to LVI at impact velocity varying from 2 m per second (mps) to 8 mps using impactors of hemispherical (HS), flat (F) and conical (C) shapes. Modelling and simulation of the proposed JE composite laminate is achieved using explicit software available commercially with target as deformable material and the impactor as a rigid body. Simulations are carried out for available possible combination of thickness, impact velocity and impactor shapes. Results reveal that thickness is one of the crucial factors that decide the LVI response of the proposed composite laminate. Laminate impacted with conical shaped impactor results in maximum absorption of energy and the laminate impacted with flat shaped impactor results in bigger and immediate damage. © 2019 Elsevier Ltd.Item Tsunami Resilient Foundation for Breakwater: Centrifuge Model Tests(Springer Science and Business Media Deutschland GmbH, 2021) Chaudhary, B.; Hazarika, H.; Murakami, A.; Fujisawa, K.Many coastal protection structures collapsed due to the past earthquakes and tsunamis. For example, several breakwaters damaged during the 2011 Great East Japan Earthquake and Tsunami in Japan. Due to the failure of the breakwaters, the tsunami waves could not be blocked by the breakwaters. Thus, the tsunami entered in the coastal areas; and imposed deep devastation there. It was found that the breakwaters damaged mainly due to their foundation failures. In order to mitigate such damage of breakwater caused by earthquake and tsunami, new techniques were developed by the authors for breakwater foundation. In the technique, gabions and sheet piles are used in breakwater foundation. Effectiveness of the developed foundations model of breakwater were evaluated by conducting centrifuge model tests. It was observed that the developed models could mitigate damage, and make the breakwater resilient against earthquake and tsunami-induced damage. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Damage level prediction of non-reshaped berm breakwater using ANN, SVM and ANFIS models(Society of Naval Architects of Korea, 2012) Mandal, S.; Rao, S.; Narayana, N.; Lokesha, u.The damage analysis of coastal structure is very important as it involves many design parameters to be considered for the better and safe design of structure. In the present study experimental data for non-reshaped berm breakwater are collected from Marine Structures Laboratory, Department of Applied Mechanics and Hydraulics, NITK, Surathkal, India. Soft computing techniques like Artificial Neural Network (ANN), Support Vector Machine (SVM) and Adaptive Neuro Fuzzy Inference system (ANFIS) models are constructed using experimental data sets to predict the damage level of non-reshaped berm breakwater. The experimental data are used to train ANN, SVM and ANFIS models and results are determined in terms of statistical measures like mean square error, root mean square error, correla-tion coefficient and scatter index. The result shows that soft computing techniques i.e., ANN, SVM and ANFIS can be efficient tools in predicting damage levels of non reshaped berm breakwater. ©SNAK, 2012.Item Seawalls: Performance and their failure analysis along Southern Karnataka, West Coast of India(2012) Rao, S.; Hegde, A.V.; Dwarakish, G.S.; Janardhan, J.; Venkat Reddy, D.Beach erosion is a major problem along the south west coast of India. The beach erosion particularly along the south Karnataka coast is due to, 1) direct attack of waves in an open coast, which might have been intensified in some areas due to wave refraction, 2) erosion at river mouths where one or two rivers together join the sea. The coastal protection works adopted along the South Karnataka coast are mainly the seawalls. However, some portions of these seawalls have been damaged either partially or fully. A critical study shows that these failures are due to the scouring at the toe structure. Scouring causes the failure of the seawall due to loss of support. A calculated risk may be taken to design the seawall without taking scour depth into account but provide for adequate maintenance in case scour occurs and partial failure of the seawall takes place. © 2012 Cafet-Innova Technical Society. All rights reserved.Item Structural Health Monitoring techniques in civil engineering: An overview(CAFET INNOVA Technical Society cafetinnova@gmail.com 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2014) Bhavana Patel, S.S.; Venkataramana, K.; Babu Narayan, K.S.; Parla, B.; Kimura, Y.Structural Health Monitoring (SHM) is an emerging and promising technology for safety and integrity of structures. Vibration Based Monitoring (VBM) has gained more importance in the field of civil engineering as damage parameters are sensitive to vibration. This paper presents brief introduction on SHM and VBM. Traditional and advanced techniques adopted for damage identification, localization and quantification by various authors have been discussed. However it is still a challenging task for the researchers to develop a technique which gives efficient and reliable solution for a particular Structure. © 2014 CAFET-INNOVA TECHNICAL SOCIETY.Item Development of resilient breakwater against earthquake and Tsunami(American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2019) Chaudhary, B.; Hazarika, H.; Murakami, A.; Fujisawa, K.The coastal areas in Japan suffered devastating damage due to the great East Japan earthquake and tsunami in 2011. Breakwaters collapsed mainly because of foundation failures during the earthquake and tsunami. Due to the breakwater failures, the tsunami entered the coastal zones and imposed deep devastation. This study focused on the development of reinforcing countermeasures for a breakwater foundation that can produce a resilient breakwater against earthquakes and tsunamis, such as foundations reinforced with sheet piles and gabions. Physical model tests were carried out for scaled-down breakwater models to examine the performance of the reinforcing countermeasures under an earthquake and tsunami. During the tests, the developed reinforced model was found to be effective in mitigating the damage of the breakwater created by the earthquake and tsunami. Numerical simulations were performed to further clarify the mechanism. © 2018 American Society of Civil Engineers.Item 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 LtdItem 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.Item Development of Sustainable Jute/Epoxy Composite and Assessing the Effect of Rubber Crumb on Low Velocity Impact Response(Taylor and Francis Ltd., 2022) Mahesh, V.; Mahesh, V.; Harursampath, D.; Joladarashi, S.; Kulkarni, S.M.In the current study, the experimental assessment of influence of rubber crumb on the low velocity impact (LVI) behavior of jute epoxy composites are carried out using two types of impactors namely hemispherical and conical. Hand layup technique is used to fabricate the proposed composites. The rubber crumb is incorporated in the epoxy resin with 1.5 wt%, 3 wt%, and 5 wt%. Results revealed that incorporation of 3 wt% of rubber crumb resulted in better LVI response compared to its counterparts. Fractography studies revealed that inclusion of rubber crumb particles enhances the adhesion between resin and fiber, thereby increasing the energy absorption. In addition, they aid in reducing damage area and increasing penetration threshold of proposed composites. The current study’s systematic technique serves as a model for the efficient use and conversion of waste rubber crumb into usable natural fiber reinforced polymer matrix composites for LVI applications. © 2022 Taylor & Francis.Item Internal damage growth in quasi-brittle fibre-reinforced cementitious materials under cyclic compressive loading(Structural Engineering Research Centre, 2023) Vidya Sagar, R.; Basu, D.J.; Suhas Reddy, K.V.; Prathap, Y.; Bhuvaneswari, G.; Sai Keerthi, P.This article reports a comparison between the internal damage growth in cementitious materials without fibres and with fibres subjected to elevated amplitude cyclic compressive loading. The damage progression was assessed using ultrasonic testing method and Acoustic Emission (AE) testing. The intricate fracture mechanism in the test specimens causes rise to a higher harmonic generation, which was used as an indicator to the internal damage. The decrement in wave peak amplitude with higher harmonic generation may be regarded as a ‘internal damge growth’ in the deformable solid. The complexity in the fracture mechanism in fibrous cementitious matrix influenced the heterogeneity of the specimen, which is reflected by the steep decrement in the slope of the line plotted using normalized higher harmonic ratio and load. It was observed that the ‘magnitude of the total damage’ developed in plain concrete at the last loading phase was relatively lower than brass coated steel fibre reinforced concrete. This was supported by the damage parameter based on generated AE, where final failure of the specimens preceded an AE avalanche. Therefore, the utilization of a combination of nondestructive testing techniques such as AE and nonlinear ultrasonic testing can offer a more comprehensive understanding of the progression of damage in quasi-brittle cementitious materials. © 2023, Structural Engineering Research Centre. All rights reserved.