Browsing by Author "Singh, R.K."

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An experimental evaluation of the microstructure, mechanical and functional fatigue properties of the boron-doped Cu-Al-Be SMA wires
(Elsevier Ltd, 2021) Singh, R.K.; Biswas, P.; Murigendrappa, S.M.; Kattimani, S.
An experimental evaluation of the microstructure, mechanical and functional fatigue properties of the Cu-11.70Al-0.45Be doped with Bx (x = 0.05, 0.10, 0.12, and 0.14 wt%) SMA wires has been carried out. The experiments were performed to investigate microstructure, phase/precipitates, and transformation temperatures for both as-cast and wire samples. Furthermore, tensile properties, shape recovery ratio, and functional fatigue evaluation have also been carried out for the wire samples. The investigation shows that the addition of the minor amount of boron and secondary processes involved during the specimen preparation induced excellent grain refinement. The addition of boron decreased transformation temperatures; however, there was not a considerable change observed due to the secondary process. It was observed that tensile properties increases with the boron addition, and complete shape recovery was observed for all the selected alloys. Finally, functional fatigue tests were conducted under constant stress condition and observed that the number of cycles until the failure has increased and more distance recovery was achieved with an increase in boron doping. © 2021
Comparison of Stress Distribution of Graphene-Based Bioactive Material for Zirconia and Titanium by Applying Orthotropic Properties: A Finite Element Analysis
(Springer Science and Business Media Deutschland GmbH, 2024) Singh, R.K.; Verma, K.; Kumar, G.C.
This study employs finite element analysis to examine stress distribution at the boneâ€“implant interface in graphene-based dental implants. Four implant models, encompassing titanium and zirconia with and without graphene coating, are assessed under axial and oblique loading. Considering their anisotropic nature, bone tissues are simulated as orthotropic, while implants are treated as homogeneous and isotropic. The study utilizes one-way ANOVA and Kruskalâ€“Wallis tests for statistical analysis to compare stress distribution among implant groups. Results indicate superior von Mises stress distribution in graphene-based implants (A2 and A4) compared to the pure material group. The incorporation of graphene coating significantly reduces implant stresses under axial and oblique loads compared to titanium and zirconia. In conclusion, the study underscores the potential benefits of graphene-based implant models in optimizing stress distribution at the boneâ€“implant interface, emphasizing the importance of suitable implant models and biomaterial selection for enhanced dental implant performance. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Conversion of waste polypropylene to liquid fuel using acid-activated kaolin
(SAGE Publications Ltd, 2014) Panda, A.K.; Singh, R.K.
Waste polypropylene was subjected to thermal degradation in the presence of kaolin and acid-treated kaolin, with different catalyst-to-plastics ratios, in a semi-batch reactor at a temperature range of 400-550°C to obtain optimized process conditions for the production of liquid fuels. The effects of process temperature, catalyst and feed composition on yield and quality of the oil were determined. For a thermal decomposition reaction at up to 450°C, the major product is volatile oil; and the major products at a higher temperature (475-550°C) are either viscous liquid or wax. The highest yield of condensed fraction in the thermal reaction is 82.85% by weight at 500°C. Use of kaolin and acid-treated kaolin as a catalyst decreased the reaction time and increased the yield of liquid fraction. The major product of catalysed degradation at all temperatures is highly volatile liquid oil. The maximum oil yield using kaolin and acidtreated kaolin is 87.5% and 92%, respectively, at 500°C. The oil obtained was characterized using GC-MS for its composition and different fuel properties by IS methods. © The Author(s) 2014.
Enhancing the Flow-Accelerated Corrosion Resistance of X70 API Steel Through Laser Surface Melting in Synthetic Oilfield Water
(John Wiley and Sons Inc, 2025) Ajmal, T.S.; Singh, R.K.; Arya, S.B.; Kumar D, S.
Hydrodynamic flow conditions play a critical role in piping failure due to sharp variations of the Reynolds number in process and petrochemical industries. The current study aims to enhance flow-accelerated corrosion (FAC) resistance using metallurgy of the surface by utilizing the laser surface melting (LSM) technique. The FAC behavior of API X70 steel in simulated Indian synthetic oilfield water was studied by utilizing a closed-loop corrosion apparatus to simulate the pipeline flow. Electrochemical corrosion experiments (AC and DC methods) were conducted at a constant fluid velocity of 3 m/s in untreated and LSM-treated samples (at 2.5 and 3.0 kW) placed at a 90° pipe elbow. Experimental results showed that LSM-treated samples displayed enhanced resistance to FAC, attributed to changes in surface metallurgy. Additionally, it was observed that the corrosion rate varied within the pipe elbow for the different samples at different locations. © 2024 Wiley-VCH GmbH.
Enhancing X70 steel durability: Tribo-corrosion resistance through protective laser cladding
(Elsevier Ltd, 2025) Singh, R.K.; Bhole, K.B.; Arya, S.B.; Nayak, J.
This study investigates the effects of laser surface cladding (L-DED technique) on the tribo-corrosion behavior of API X70 steel in the simulated Indian oilfield water. Using optimized parameters, 500 W laser power, 720 mm/min scan speed, and 4.2 g/min powder feed rate, 316 L SS was successfully clad onto X70 steel without any significant defects. The results showed a significant improvement in corrosion resistance, with the SS clad exhibiting a corrosion rate of 131.3 ?m/year at 20 N, compared to 287.9 ?m/year for the X70 substrate. SEM and 3D profilometer analyses revealed a more stable tribo-layer on the SS clad, with less damage and debris accumulation. These findings highlight the potential of laser cladding to enhance the durability and lifespan of steel components. © 2025 Elsevier Ltd
Experimental investigation on free vibration of composite beams implanted Ni-Ti shape memory alloy wires
(2019) Singh, R.K.; Murigendrappa, S.M.; Kattimani, Subhas Chandra
The paper presents free vibration of shape memory alloy hybrid composite beams by experimentally. The hybrid composite beams are fabricated using glass fiber with epoxy resin matrix implanted with the Ni-Ti SMA wires with diameter 0.47mm. The rectangular cross-section of beams with sizes, thickness, 3mm, width, 20mm and length 250mm are considered in the investigation. Free vibration test has been performed for the cantilever beams to investigate the effect on the fundamental natural frequency shift by changing the current as well as increasing the number of SMA wires. The fundamental natural frequency of the beam has shifted on higher side, 12.82% for single wire and 35.48% for two wires implant under the influence of current in comparison with no current state. Further, as supplied current increases in the SMA wire the natural frequency of beam increases helps in improving the stiffness and encourages to avoid resonance state. � 2018 Author(s).
Experimental investigation on free vibration of composite beams implanted Ni-Ti shape memory alloy wires
(American Institute of Physics Inc. subs@aip.org, 2019) Singh, R.K.; Murigendrappa, S.M.; Kattimani, S.
The paper presents free vibration of shape memory alloy hybrid composite beams by experimentally. The hybrid composite beams are fabricated using glass fiber with epoxy resin matrix implanted with the Ni-Ti SMA wires with diameter 0.47mm. The rectangular cross-section of beams with sizes, thickness, 3mm, width, 20mm and length 250mm are considered in the investigation. Free vibration test has been performed for the cantilever beams to investigate the effect on the fundamental natural frequency shift by changing the current as well as increasing the number of SMA wires. The fundamental natural frequency of the beam has shifted on higher side, 12.82% for single wire and 35.48% for two wires implant under the influence of current in comparison with no current state. Further, as supplied current increases in the SMA wire the natural frequency of beam increases helps in improving the stiffness and encourages to avoid resonance state. Â© 2018 Author(s).
Investigation on Properties of Shape Memory Alloy Wire of Cu-Al-Be Doped with Zirconium
(Springer, 2020) Singh, R.K.; Murigendrappa, S.M.; Kattimani, S.
Abstract: In this paper, the effect of wire drawing on the microstructures, mechanical properties, and shape memory effect of compositions Cu87.85-Al11.70-Be0.45 (CAB) and Cu87.73-Al11.70-Be0.45-Zr0.12 (CABZ) has been experimentally investigated. The wires with a diameter of 1.33 mm are manufactured from the casted round bars through the rolling and drawing (secondary) process. Investigations are performed on microstructure and phase for both as-cast and wire-drawn SMAs. Further, wire-drawn SMAs are investigated for phase transformation temperatures, hardness, ductility, and shape memory effect. The results show that the average grain size decreased with 73.06% by adding Zr to the CAB alloy. Further, the grain size of CABZ alloy wire decreased with 67.38% in the longitudinal direction and 67.07% in the transverse direction as compared to CAB alloy wire after the secondary process. Improvement of the grain structure in CABZ alloy wire resulted in an enhancement in the hardness of 13.86% in longitudinal and 12.43% in the transverse direction, and tensile strength of 134.58% and ductility of 177.06%. The phase transformation temperatures reduced by the addition of Zr, and better shape recovery is observed in CABZ alloy wire. Graphic Abstract: [Figure not available: see fulltext.] © 2020, ASM International.
Meltpool characteristics, microstructure, and corrosion performance of laser-directed energy deposition cladded 316L SS/X70 steel for oilfield applications
(Elsevier Ltd, 2025) Singh, R.K.; Arya, S.B.; Nayak, J.
In oilfield pipeline transmission, complex geometries such as elbows, reducers, tees, and orifices face significant corrosion risks, especially in aggressive environments where multiphase turbulent flow and chloride ions cause sharp variations in hydrodynamic parameters. This study explores a laser cladding approach to mitigate internal corrosion in these complex geometries. The Laser-Directed Energy Deposition (L-DED) technique, known for its precision and efficiency, is employed to apply corrosion-resistant 316 L stainless steel (SS) over API X70 steel. Key parameters, including laser power and scan speed, were varied across nine combinations to evaluate their effects on melt pool characteristics, microstructure, and corrosion properties of the clads. Results showed that as laser energy increased (higher power and lower scan speed), melt pool dimensions and heat-affected zone (HAZ) thickness also increased, with clad thickness and HAZ ranging from 172 to 504 µm and 159–272 µm, respectively. Cellular and columnar sub-grain structures were present across all process combinations, with sub-grain size increasing at higher laser energy. A notable variation in chromium content was detected, with the clad produced at 500 W and 720 mm/min exhibiting superior pitting and corrosion resistance. This high-energy clad featured 16.3 % chromium and larger sub-grain sizes, facilitating stable passive film formation during corrosion. The optimized clad demonstrated approximately two orders better corrosion performance than the base X70 steel. © 2025
Optimizing dental implant design parameters through orthotropic properties of bone: a DOE-based approach
(Springer-Verlag Italia s.r.l., 2025) Singh, R.K.; Verma, K.; Kumar, G.C.; Doddamani, S.
Dental implant research has provided insights into the effects of thread design and occlusal loading rate on stress distribution within implants and adjacent bone structures. However, ongoing advancements in materials necessitate further investigation to optimize implant performance through a thorough understanding of design parameters. This study developed a comprehensive three-dimensional CAD model of dental implants, incorporating cortical and cancellous bone, crown, and various thread types (V type, buttress, and trapezoidal threads). Multiple thread design parameters (pitch, length, angle, and depth) were varied to analyze their impact on stress distribution. Taguchi's design of experiments, combined with finite element analysis, was employed to explore stress distribution around dental implants. The implant material used was Ti6Al7Nb alloy, comprising 90% titanium, 6% aluminium, and 7% niobium. Von Mises stresses were compared to identify the optimal design. Taguchi's analysis revealed that raising all parameters except pitch reduced implant stress. However, for trapezoidal and buttress designs, increasing pitch resulted in higher stress levels. A confirmation experiment, utilizing the developed regression equation, validated these findings. Comparative analysis between simulation and statistical results showed a close match across all cases; with an error rate of less than 10%. These findings underscore the reliability and accuracy of the research outcomes, emphasizing the significance of identified thread types and their impacts on implant stress. Further research in this area could lead to advancements in dental implant design, enhancing patient outcomes and implant longevity. © The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature 2025.
Potential of Graphene-Functionalized Polymer Surfaces for Dental Applications: A Systematic review
(Taylor and Francis Ltd., 2025) Singh, R.K.; Verma, K.; Kumar, G.C.M.; Jalageri, M.B.
Graphene, a two-dimensional carbon nanomaterial, has garnered widespread attention across various fields due to its outstanding properties. In dental implantology, researchers are exploring the use of graphene-functionalized polymer surfaces to enhance both the osseointegration process and the long-term success of dental implants. This review consolidates evidence from in-vivo and in-vitro studies, highlighting grapheneâ€™s capacity to improve bone-to-implant contact, exhibit antibacterial properties, and enhance mechanical strength. This research investigates the effects of incorporating graphene derivatives into polymer materials on tissue response and compatibility. Among 123 search results, 14 articles meeting the predefined criteria were analyzed. The study primarily focuses on assessing the impact of GO and rGO on cellular function and stability in implants. Results indicate promising improvements in cellular function and stability with the use of GO-coated or composited implants. However, it is noted that interactions between Graphene derivatives and polymers may alter the inherent properties of the materials. Therefore, further rigorous research is deemed imperative to fully elucidate their potential in human applications. Such comprehensive understanding is essential for unlocking the extensive benefits associated with the utilization of Graphene derivatives in biomedical contexts. Â© 2024 Informa UK Limited, trading as Taylor & Francis Group.
Potential of Graphene-Functionalized Polymer Surfaces for Dental Applications: A Systematic review
(Taylor and Francis Ltd., 2025) Singh, R.K.; Verma, K.; Kumar, G.C.; Jalageri, M.B.
Graphene, a two-dimensional carbon nanomaterial, has garnered widespread attention across various fields due to its outstanding properties. In dental implantology, researchers are exploring the use of graphene-functionalized polymer surfaces to enhance both the osseointegration process and the long-term success of dental implants. This review consolidates evidence from in-vivo and in-vitro studies, highlighting graphene’s capacity to improve bone-to-implant contact, exhibit antibacterial properties, and enhance mechanical strength. This research investigates the effects of incorporating graphene derivatives into polymer materials on tissue response and compatibility. Among 123 search results, 14 articles meeting the predefined criteria were analyzed. The study primarily focuses on assessing the impact of GO and rGO on cellular function and stability in implants. Results indicate promising improvements in cellular function and stability with the use of GO-coated or composited implants. However, it is noted that interactions between Graphene derivatives and polymers may alter the inherent properties of the materials. Therefore, further rigorous research is deemed imperative to fully elucidate their potential in human applications. Such comprehensive understanding is essential for unlocking the extensive benefits associated with the utilization of Graphene derivatives in biomedical contexts. © 2024 Informa UK Limited, trading as Taylor & Francis Group.
Predictive modeling of PMMA-based polymer composites reinforced with hydroxyapatite: a machine learning and FEM approach
(Gruppo Italiano Frattura, 2025) Singh, R.K.; Verma, K.; Kumar, G.C.
This research examines the mechanical characteristics of polymer composites (PMMA) that are reinforced with Hydroxyapatite (HAp), with a particular emphasis on the Elastic Modulus and Compressive Strength. The investigation employs a multifaceted approach that integrates experimental methods, micromechanical analysis, and machine learning techniques. Experimental assessments of Elastic Modulus and Compressive Strength were conducted at various HAp concentrations (5%, 15%, and 30%) and were compared with theoretical predictions derived from Representative Volume Element (RVE) and micromechanical frameworks, including Voigt and Reuss bounds. Various machine learning algorithms, such as Feedforward Neural Network (FFNN), Radial Basis Neural Network (RBNN), and Support Vector Machine (SVM), were used to predict the mechanical properties. The RBNN exhibited high accuracy (R² = 0.92; MAE = 0.05) for intermediate HAp levels (20-30%) but displayed instability at the extremes % of reinforcements values . The FFNN consistently provided lower estimates of the properties, whereas the SVM yielded robust and stable predictions that closely matched both experimental and theoretical results with the error of (2-5) % (Result value). This research highlights the effectiveness of integrating micromechanical modeling with machine learning to improve the prediction and comprehension of composite behavior, thereby offering valuable insights for the design and application of advanced materials. © 2025, Fracture Structural Integr. All rights reserved.
Secure web based Single Sign-On (SSO) framework using identity based encryption system
(2009) Singh, R.K.; Pais, A.R.
Due to the vulnerability caused by poor password selection it is very important to have a secure authentication and authorization infrastructure for web based applications. In the current scenario it is very difficult to remember different passwords for different web based applications. We propose centralized password based multiuser and multi-application Single Sign-On (SSO) framework for such applications. Unlike traditional Single Sign-On architectures we are using Identity Based Encryption System (IBES) instead of Public key infrastructure (PKI). Our proposed design provides better security for the users and the system is efficient. This framework is deployed as a web service and can be deployed on a web server. � 2009 IEEE.
Secure web based Single Sign-On (SSO) framework using identity based encryption system
(2009) Singh, R.K.; Pais, A.R.
Due to the vulnerability caused by poor password selection it is very important to have a secure authentication and authorization infrastructure for web based applications. In the current scenario it is very difficult to remember different passwords for different web based applications. We propose centralized password based multiuser and multi-application Single Sign-On (SSO) framework for such applications. Unlike traditional Single Sign-On architectures we are using Identity Based Encryption System (IBES) instead of Public key infrastructure (PKI). Our proposed design provides better security for the users and the system is efficient. This framework is deployed as a web service and can be deployed on a web server. Â© 2009 IEEE.
Thermo-catalytic degradation of low density polyethylene to liquid fuel over kaolin catalyst
(Inderscience Publishers, 2014) Panda, A.K.; Singh, R.K.
Waste low-density polyethylene samples were subjected to thermo-catalytic degradation using kaolin as catalyst in a batch reactor at temperature range of 400 to 500°C and atmospheric pressure. The quality and yield of the condensable product has been studied as a function of temperature and amount of catalyst. Both in thermal and catalytic degradation, the condensable fraction was less viscous liquid oil at low temperatures (up to 450°C), whereas with increase of temperature (from 475°C) the fraction became viscous and waxy. The recovery of condensable fraction increased from 30.8 wt.% at 400°C to 71.45% at 450°C and further increased to a maximum of 86.65wt.% at 500°C in absence of catalyst. The catalyst increased the yield of the condensable product and decreased the reaction time. The highest yield of liquid fraction at 450°C was 79.5 wt.% with 1:2 catalyst to plastics ratio. The composition of the oil obtained at optimum reaction condition was characterised by gas chromatography-mass spectroscopy (and found consisting of paraffins and olefins with mainly C10-C16 components. Fuel properties of the oil obtained by different standard methods are similar to petrochemical fuels. © 2014 Inderscience Enterprises Ltd.