Department of Mechanical engineering
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Item Machine learning-assisted wire arc additive manufacturing and heat input effect on mechanical and corrosion behaviour of 316 L stainless steels(Elsevier, 2024-10) Sinhmar, SunilPredicting the track forming factor or height-to-width ratio (H/W) in wire arc additive manufacturing is crucial for optimal path planning, heat distribution, structural integrity, distortion control, process efficiency, and defect prevention, ensuring high-quality and reliable components. Different analytical and numerical modeling methods have been introduced to predict the H/W ratio. However, the accuracy of these predictions is relatively low due to the challenges associated with handling complex and non-linear regression equations. This study addressed the challenges by implementing data-driven predictive modeling to predict the H/W ratio from the input process parameters. A stacking ensemble learning approach is employed, where a meta-model integrates predictions from multiple base learners to enhance overall performance. The model performance was evaluated by Coefficient of determination (R2), mean squared error (MSE), and mean absolute error (MAE). The model was validated by comparing the experimental and predicted values based on which five thin walls are printed with different heat inputs. The study also explores the impact of heat input on microstructure, mechanical, and corrosion properties. The findings indicate that a significantly low heat input (178 J/mm) and higher heat inputs (> 356 J/mm) decrease the wire utilization. With increasing heat input, ferrite content increases, microstructures become coarser, dendritic spacing increases, and ferrite transitions from lathy to skeletal. Further, lower heat input (235 J/mm) reduces δ-ferrite, suppresses atomic segregation, and increases Cr and Mo in the matrix. YS and UTS decrease with higher heat inputs, anisotropy decreases, and Vickers microhardness drops from 228 (178 J/mm) to 194 Hv (586 J/mm). Additionally, the corrosion resistance deteriorates with increasing heat input, as evidenced by higher pitting potential (Epit: 0.389 V vs. 0.368 V vs. −0.023 V) and lower corrosion current density (Icorr: 6.76 ×10−7 A/cm2 vs. 7.946 ×10−7 A/cm2 vs. 8.91 ×10−7 A/cm2) for heat inputs of 235 J/mm, 281 J/mm, and 356 J/mm, respectively.Item Investigation of corrosion and electrical resistance in laser welded Al-Cu joints for EV batteries(Elsevier, 2024-12) Sinhmar, SunilThis study investigates the correlation among the microstructure, electrochemical, and electrical properties of laser-welded Alsingle bondCu joints used in battery applications. Aluminium and copper thin sheets were laser welded at three power inputs (2000 W, 2100 W, and 2200 W), and joints were evaluated for their macro- and microstructural features, corrosion behaviour, electrical resistance, and temperature rise during current supply. Results indicated that higher power inputs led to deeper weld penetration and increased intermetallic formation, impacting corrosion resistance and electrical characteristics. Electrochemical impedance spectroscopy (EIS), immersion, and Tafel tests confirmed that joints welded at 2200 W exhibited superior corrosion resistance than others, and this was attributed to a uniformly mixed Alsingle bondCu region. The electric characteristics of the joints were assessed by supplying electric currents of 100 A, 150 A, and 200 A. In comparison to a weld joint developed at 2000 W, the electrical resistance of weld joints developed at 2200 W increased by 44.5 %, 37.87 %, and 39.31 % at 100 A, 150 A, and 200 A current supplies, respectively. Electrical resistance measurements revealed a direct correlation with weld quality and temperature rise, with implications on battery performance. These findings underscore the critical role of joint quality in optimizing battery performance.Item Effect of weld profile geometry on dissimilar laser welded joints for battery applications(Springer, 2025-10) Sinhmar, SunilA transition from fossil fuels to greener technologies like batteries is essential for a sustainable future. This study explores the impact of weld profile geometry on laser-welded aluminum–copper (Al–Cu) dissimilar lap joints at a constant power input of 2.1 kW, relevant for bus-bar connections in electric vehicle battery manufacturing. Two weld profiles: parallel line and circular, were compared in terms of microstructure, mechanical strength, electrical resistance, and corrosion behavior of the joints. Microstructural analysis showed that the circular weld exhibited deeper penetration and a wider Al2Cu intermetallic layer, while the parallel profile had a thinner, sharper, and uniform interface. Mechanical tests indicated that the circular profile achieved 66% higher peak load and better ductility. It also showed lower electrical resistance and reduced temperature rise under currents of 50 A, 100 A, and 150 A, suggesting improved conductivity than parallel line weld. However, electrochemical testing revealed higher corrosion current density and severe interfacial degradation in the circular profile due to its broader, uneven intermetallic zone. The findings emphasize that weld profile geometry significantly influences joint behavior, and optimized weld design can enhance performance without increasing power input, particularly relevant for battery interconnects and lightweight electronic applications.