Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
Browse
5 results
Search Results
Item 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.Item Effect of equiaxed grains and secondary phase particles on mechanical properties and corrosion behaviour of CMT- based wire arc additive manufactured AZ31 Mg alloy(Elsevier Ltd, 2023) Manjhi, S.K.; Sekar, P.; Bontha, S.; Balan, A.S.S.Wire arc additive manufacturing (WAAM) has drawn tremendous attention for manufacturing large and complex components of lightweight material at a moderate cost due to its high deposition rate and energy efficiency. Generally, WAAM-Mg alloy comprises columnar and columnar dendrite grains due to high cooling rates and thermal gradients responsible for anisotropic mechanical properties. To overcome this challenge, in this work, CMT-WAAM, which generally uses comparatively low heat input (33% lower than conventional WAAM), was used to deposit AZ31 Mg thin wall. The metallurgical characterization of the deposited thin wall of the top (T), middle (M) and bottom (B) sections reveals equiaxed grains of average sizes ∼ 58, ∼ 63 and ∼ 38 µm, respectively. In addition, TEM results exhibit the formation of secondary phase particles, i.e., β-Mg17Al12 and ɳ-Al8Mn5. Further, the ultimate tensile strength (UTS) and % elongation (% EL) in the travel direction (UTS = 224 MPa, % EL= 23.47%) are superior to that obtained in the build direction (UTS = 217 MPa, % EL = 20.82%). The corrosion resistance of WAAMed AZ31 Mg alloy is higher than wrought (cold rolled) AZ31 Mg alloy in Hank's balanced salt solution (HBSS). The results of this study reveal the potential of CMT-WAAM to deposit different grades of Mg with desired microstructure, mechanical properties and corrosion resistance. © 2023 CIRPItem 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 Effect of age hardening precipitates on the corrosion performance of laser Powder-Directed energy deposited CuNi2SiCr(Elsevier B.V., 2024) Urs, S.S.; Thanumoorthy, R.S.; Aswith Babu, I.; Doddamani, M.; Bontha, S.; Balan, A.S.S.This study explores Laser Powder ? Direct Energy Deposition (LP-DED) processing of CuNi2SiCr and the effect of heat treatment on corrosion behavior. The findings pave the way to increasing the life of the components and the possibility of refabrication upon failure. LP-DED manufactured CuNi2SiCr was subjected to solution treatment followed by age-hardening at 500? for 1,3,5 and 7 h. The microstructure analysis showed the formation of Cr3Ni precipitates due to a higher cooling rate in the LP-DED process. Upon aging, Ni3Si, Ni2Si, and CrSi2 precipitates evolved. Due to the Orowan phenomenon, microhardness increases with the aging time as the number of precipitates along the grain boundary increases with the aging time. The 5-hour aged sample exhibited the best corrosion resistance due to precipitation coherency in the matrix and the medium-sized precipitates with uniform precipitation-free zones (PFZ) in the grain boundary. © 2024 Elsevier B.V.Item Effect of burnishing strategies on surface integrity, microstructure and corrosion performance of wire arc additively manufactured AZ31 Mg alloy(KeAi Publishing Communications Ltd., 2025) Manjhi, S.K.; R, O.; Bontha, S.; Balan, A.S.S.AZ31 Mg alloy is an emerging material that has received considerable attention in aerospace, automotive, and temporary biodegradable implant applications owing to its attractive properties, such as low density, high specific strength, and biodegradability. Nevertheless, some shortcomings in Mg alloys are their low ductility, which is associated with challenging its manufacturing, and poor corrosion resistance associated with unreliable components. Therefore, a cold metal transfer wire arc additive manufacturing (CMT-WAAM) process is used to manufacture AZ31 Mg alloy and achieved 29.4 % ductility by controlling the gas porosity, keyhole porosity, and internal cracks. Further, severe plastic deformation is induced on the surface of deposited parts by low plasticity burnishing (LPB) with parallel and cross-pattern burnishing to modulate their surface to slow down the kinetics of the corrosion damage. The average surface roughness (Sa) of the cross-burnishing pattern is 0.235 ?m, which is 123.6 % lower than the parallel burnished and 261.7 % lower than the milled specimens. The residual stress (RS) of WAAM is 40 MPa with a tensile nature; however, it is drastically reduced and develops compressive RS of 45 MPa under a parallel burnishing pattern and 62 MPa under a cross-burnishing pattern. Moreover, LPB with cross pattern deformed ?395 ?m depth of WAAMed AZ31 workpiece, which is ?45 % higher than deformed depth (?272 ?m) by parallel pattern burnishing. The electrochemical corrosion rate of the WAAM specimen is 9.71 mm/year, and it is reduced to 1.82 mm/year under LPB caused by compressive residual stress and grain refinement. © 2024 The Authors