Faculty Publications
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Item Experimental Investigation and Parametric Optimization on Hole Quality Assessment During Drilling of CFRP/GFRP/Al Stacks(Springer, 2020) Janakiraman, A.; Pemmasani, S.; Sheth, S.; Kannan, C.; Balan, A.S.S.Carbon fiber/glass fiber-reinforced aluminum (Al) stacks are becoming predominant in the aerospace industries owing to their synergistic effect on numerous properties obtained by the combination of metal and composite material. This necessitates an investigation work to be performed on the machining characteristics of this special category of Al stacks. This research work focuses on studying the influence of cutting speed, feed rate and machining environment on thrust force, delamination and roughness of the finished surface of hybrid Al stacks. Dry, minimum quantity lubrication (MQL), and cryogenic environments are considered in this work. The impact of cutting speed on the responses is observed to be negligible in contrast to the feed rate. Moreover, the drilling under cryogenic environment is found to improve the surface finish and mitigated the delamination, while drilling under MQL environment minimized the thrust force. Regression models are also developed to determine the output responses. High-quality holes in aluminum stacks can be obtained under cryogenic conditions over other machining environments as revealed by multi-objective optimization. © 2020, The Institution of Engineers (India).Item Exploring grinding and burnishing as surface post-treatment options for electron beam additive manufactured Alloy 718(Elsevier B.V., 2020) Karthick Raaj, R.; Vijay Anirudh, P.; Karunakaran, C.; Kannan, C.; Jahagirdar, A.; Joshi, S.; Balan, A.S.S.Numerous additive manufacturing (AM) techniques have been developed over the past decade. Features like immense freedom of intricate part design and shorter lead time make AM routes promising for a wide range of applications spanning aerospace, marine and automobile sectors. Among the various metal AM processes, Electron Beam Additive Manufacturing (EBAM) is being widely explored to realise the potential of Ni-based superalloys and Ti alloys for varied high-performance applications. A novel attempt has been made in this paper to assess the surface integrity of as-built EBAM nickel-based superalloy 718 (AB) subjected to grinding (G), Low Plasticity Burnishing (LPB) and their sequential combination. Apart from their influence on sub-surface microstructures, the effect of process variables during the above post-treatments on the residual stress profiles was also investigated. Results revealed that G + LPB results in about 0.6 ?m lower surface roughness, 17% improved microhardness compared to AB + LPB, and higher compressive surface residual stress as compared to LPB processed EBAM samples. The sequential grinding and LPB - improved microhardness, was also found to extend about 500 ?m more when compared to the LPB process. The G + LPB, which is greatly influenced by the prior grinding, smoothens the surface and thus results in a better surface finish. Highest hardness, superior surface finish, reduced porosity and improved compressive residual stress were observed in samples that adopted the AB + G + LPB sequence over other samples, with the LPB step at 40 MPa yielding the best results. © 2020 Elsevier B.V.Item Effect of cryogenic grinding on fatigue life of additively manufactured maraging steel(MDPI AG, 2021) Balan, A.S.S.; Kannan, C.; Kumar, A.V.; Hariharan, H.; Pimenov, D.Y.; Giasin, K.; Nadolny, K.Additive manufacturing (AM) is replacing conventional manufacturing techniques due to its ability to manufacture complex structures with near?net shape and reduced material wastage. However, the poor surface integrity of the AM parts deteriorates the service life of the components. The AM parts should be subjected to post?processing treatment for improving surface integrity and fatigue life. In this research, maraging steel is printed using direct metal laser sintering (DMLS) process and the influence of grinding on the fatigue life of this additively manufactured material was investigated. For this purpose, the grinding experiments were performed under two different grinding environments such as dry and cryogenic conditions using a cubic boron nitride (CBN) grinding wheel. The results revealed that surface roughness could be reduced by about 87% under cryogenic condition over dry grinding. The fatigue tests carried out on the additive manufactured materials exposed a substantial increase of about 170% in their fatigue life when subjected to cryogenic grinding. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Item 4D printed stereolithography printed plant-based sustainable polymers: Preliminary investigation and optimization(John Wiley and Sons Inc, 2021) Danish, M.; Vijay Anirudh, P.; Karunakaran, C.; Vasudevan, V.; Mathew, A.T.; Koziol, K.; Thakur, V.K.; Kannan, C.; Balan, A.S.S.The increasing demand for applying shape memory polymer to tissue culture and biomedical engineering has opened up research opportunities in the field of 4D Printing. The biocompatibility of the scaffolds as a culture medium resulted in the use of plant-based polymers to provide an ambient environment for the growth of cells. This research investigates the 4D printing of acrylated epoxidized soybean oil (AESO), a plant-based shape polymer. The objective of the present work is to establish the relationship between the 4D printing parameters (laser power frequency and print speed) and different properties of the printed material viz. tensile stress, surface roughness, wettability, recovery time, strain fixity and glass transition temperature. The maximum fixity was about 85%, while the recovery time as low as 1.6 s. The print parameters are optimized using regression modeling and multi-objective optimization techniques. The shape memory effect of the polymer is demonstrated by printing samples at the optimized conditions. Dynamic mechanical analysis is performed to evaluate the variation in the glass transition temperature of AESO at specific print parameters. The adoption of an optimal set of laser frequency and print speed is found to improve the properties of AESO, while built by micro stereolithography (micro-SLA). © 2021 Wiley Periodicals LLC.Item 4D printing of smart polymer nanocomposites: Integrating graphene and acrylate based shape memory polymers(MDPI, 2021) Chowdhury, J.; Anirudh, P.V.; Karunakaran, C.; Vasudevan, V.; Mathew, A.T.; Koziol, K.; F Alsanie, W.F.; Kannan, C.; Balan, A.S.S.; Thakur, V.K.The ever-increasing demand for materials to have superior properties and satisfy functions in the field of soft robotics and beyond has resulted in the advent of the new field of four-dimensional (4D) printing. The ability of these materials to respond to various stimuli inspires novel applications and opens several research possibilities. In this work, we report on the 4D printing of one such Shape Memory Polymer (SMP) tBA-co-DEGDA (tert-Butyl Acrylate with diethylene glycol diacrylate). The novelty lies in establishing the relationship between the various characteristic properties (tensile stress, surface roughness, recovery time, strain fixity, and glass transition temperature) concerning the fact that the print parameters of the laser pulse frequency and print speed are governed in the micro-stereolithography (Micro SLA) method. It is found that the sample printed with a speed of 90 mm/s and 110 pulses/s possessed the best batch of properties, with shape fixity percentages of about 86.3% and recovery times as low as 6.95 s. The samples built using the optimal parameters are further subjected to the addition of graphene nanoparticles, which further enhances all the mechanical and surface properties. It has been observed that the addition of 0.3 wt.% of graphene nanoparticles provides the best results. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Item Grinding parameters prediction under different cooling environments using machine learning techniques(Taylor and Francis Ltd., 2023) Prashanth, G.S.; Sekar, P.; Bontha, S.; Balan, A.S.S.Selection of optimum process parameters is vital for performing a sound grinding operation on Inconel 751 alloy. This paper co-relates the relationship between the most influential input parameters like cutting velocity, depth of cut, feed rate, and environmental conditions to the output parameters, namely, tangential grinding forces, normal grinding forces, temperature, and surface roughness. Three types of machine-learning (ML) algorithms such as support vector machine (SVM), Gaussian process regression (GPR), and boosted tree ensemble techniques are employed to develop a ML model for predicting the output variables during grinding operation of Inconel 751. In order to develop a better ML model, K-fold technique is employed on a total of 81 datasets which are extracted from experimental studies. ML models developed from different algorithms are compared based on performance metrics like R2 score and root-mean-square error (RMSE). GPR algorithm exhibits best results with relatively better R2 score and RMSE value in predicting grinding forces and temperature at wheel work interface. From analyzing the ML models, it is found that cooling environments determined the output grinding parameters to a greater extent when compared with the input grinding parameters. © 2022 Taylor & Francis.Item Effect of Wire-EDM textures on corrosion performance of Bio-Degradable Mg alloy(Elsevier B.V., 2024) Aswith Babu, I.; Kumar Manjhi, S.; Sekar, P.; Narendranath, S.; Balan, A.S.S.Magnesium (Mg) is the most suitable material for biodegradable implant applications owing to its nontoxic behaviour and comparable Young's modulus to human bone. However, poor corrosion resistance limits its application. Therefore, surface texturing can be a more suitable and cost-effective technique to mitigate these issues. Hence, wire electric discharge machining (WEDM) is used to create various textures (wavy texture, microchannels, and micro-pillars) and investigate their influence on the corrosion resistance of Mg-Zn-Ca alloy. The results revealed that micropillar texture exhibited significantly lower surface roughness (Ra = 1.049 µm) and a higher contact angle indicative of hydrophobicity (130.3°), resulting in superior corrosion resistance (corrosion rate: 0.816 mm/year) compared to other textures and standard WEDM surfaces. These findings suggested that textured surfaces generated through WEDM hold the potential for enhancing the corrosion resistance of biodegradable Mg implants. © 2024 Elsevier B.V.Item The role of surface integrity and microstructure on the machinability of AZ31 Mg alloy fabricated through the CMT-WAAM process(Springer Science and Business Media Deutschland GmbH, 2025) Manjhi, S.K.; Bontha, S.; Balan, A.S.S.This investigation explores the porosity, microstructure and mechanical properties of AZ31 Mg alloy fabricated by cold metal transfer-based wire arc additive manufacturing. The X-ray computed tomography (XCT) analysis reveals an average porosity volume of 0.20% with an equivalent diameter range of 0.312–0.783 mm. The as-built part exhibited equiaxed microstructure with different average grain sizes in the built direction (BD) (62.5 ?m) and travel direction (TD) (45.3 ?m). Consequently, mechanical properties in BD and TD are different. Moreover, this study also explores the optimization of milling parameters and the effect of porosity, different grain sizes and secondary phase particles on cutting force, surface roughness, chip formation, and changes in microstructure during milling operation of as-built components. The BD shows higher cutting force with more fluctuation, higher surface roughness, less chip curliness and low microstructure influence depth than TD. EBSD results found that the TD specimens undergo continuous dynamic recrystallization (CDRX) during machining owing to higher plastic deformation and sub-grain rotation, which transforms low-angle grain boundaries (LAGBs) to high-angle grain boundaries (HAGBs), resulting in grain size reduction from 45 ?m to 5 ?m up to 25 ?m depth, which is higher than that of BD. The comparison results of the milled sample in BD and TD show that the TD direction milling (Vc: 157.079 m/min, ft: 0.01 mm/tooth and dc; 1.5mm) gives more favourable outputs. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.