Browsing by Author "Thakur, V.K."

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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.
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.
Numerical modelling and analytical comparison of delamination during cryogenic drilling of cfrp
(MDPI, 2021) Balan, A.S.S.; Kannan, C.; Jain, K.; Chakraborty, S.; Joshi, S.; Rawat, K.; F Alsanie, W.F.; Thakur, V.K.
Carbon-Fibre-Reinforced Polymers (CFRPs) have seen a steady rise in modern industrial applications due to their high strength-to-weight ratio and corrosion resistance. However, their potential is being hindered by delamination which is induced on them during machining operations. This has led to the adoption of new and innovative techniques like cryogenic-assisted machining which could potentially help reduce delamination. This study is aimed at investigating the effect of cryogenic conditions on achieving better hole quality with reduced delamination. In this paper, the numerical analysis of the drilling of CFRP composites is presented. Drilling tests were performed experimentally for validation purposes. The effects of cooling conditions and their subsequent effect on the thrust force and delamination were evaluated using ABAQUS/CAE. The numerical models and experimental results both demonstrated a significant reduction in the delamination factor in CFRP under cryogenic drilling conditions. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.