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Several potential benefits in joining thin, dissimilar and highly conductive metals in a solid-state environment make ultrasonic welding (USW) a popular method for building Li-ion battery packs. The USW method is highly complex and relies on multiple factors. In this study, aluminum (AA1100) and nickel (UNS N02200) dissimilar sheets were ultrasonically welded using various process parameters. Plastic deformation, microstructural development, and the corresponding mechanical characteristics of the joints were evaluated qualitatively and quantitatively. The joint strength and critical intensity factor values seemed to rise until the welding duration of 0.3 s, following which there was a subsequent drop in their values. Based on the mechanical analysis, it is observed that the optimal condition records an amplitude of 68 µm, a weld time of 0.3 s, and a clamping pressure of 0.24 MPa. It showed that the joint performance was significantly impacted by the plastic deformation and microstructural changes at the weld region. On the Al side, substantial plastic deformation was observed, and it was primarily attributed to the sonotrode knurls' penetration. The Al sheet's thickness was reduced by more than 40%. The microhardness readings at the welding region experienced diminution due to the acoustic softening effect. The cross-section and fracture surfaces of the Al/Ni weld exhibited several distinct microstructural characteristics, such as atomic diffusion, crimped interface, dimple pattern, and swirl pattern flow. Additionally, the diffusion zone is also investigated using X-ray diffraction analysis. These observations offer valuable insights for enhancing weld quality and controlling the overall welding process. [ABSTRACT FROM AUTHOR]

Recent trends in additive manufacturing (AM) are to produce geometrically complex structures at minimal wastage of material, time and cost without sacrificing part quality and mechanical performance and to introduce ease in processing and part removal. Here, a non-transferred arc (NTA)-based wire arc additive manufacturing (WAAM) system has been developed to achieve the above objectives, where the arc is only generated between tungsten electrode and consumable filler wire. No electrical contact with the substrate facilitate deposits even on the non-conductive substrate surface, which helps to remove the final deposits easily. The influence of deposition parameters (welding current, voltage, wire feed speed (WFS) and travel speed) on response characteristics (bead uniformity, height deviation, droplet diameter, and droplet transfer frequency) is studied on a multi-performance level using grey relational analysis (GRA). Then, single- and multi-bead layer is fabricated over SiO2 substrate for ease in part removal after complete fabrication. WFS is referred to as a key deposition parameter that influences all deposition characteristics. It has been observed that NTA-based WAAM results in high bead uniformity with minimal spatter and low bead height difference between start and exit arc point. Complete ferrite microstructure with few pearlites is observed on the deposits with similar elemental composition on the top, bottom and interface surfaces. X-ray diffraction (XRD) study reveals ferrite diffraction planes ({110}, {200}, {211} and {220}) with no intermetallic formations on deposits. Also, compressive residual stress with less variation in crystallite size, stress, strain and microhardness among the top, bottom and lateral deposit surfaces indicates the fabricated part's isotropic nature. [ABSTRACT FROM AUTHOR]

Recent developments in manufacturing require holes on composite materials, especially on the carbon fiber reinforced polymer (CFRP) with smooth hole periphery, low delamination, burr formation, taper, better circularity, and a high processing speed. Its non-conductive surface (epoxy layering) limits its machining through electrical discharge machining (EDM). To overcome this limitation, an aluminum fixture has been designed to guide the copper electrode of EDM for producing holes on a CFRP sheet of 1 mm thickness at low machining complexity, cost, time, delamination, burr in hole periphery and without affecting the material's surface quality and performance. Even components with high geometrical complexity can also be drilled through this approach. Here, a multi-quality analysis called grey relational analysis is developed for examining the hole quality attributes, considering peak current, pulse on and off time, and flushing pressure as input parameters. This approach points out the optimum factor level setting and critical parameters (pulse-on time and peak current) that regulate the hole attributes (entrance and exit diameter, circularity, taper, material removal, and tool wear rate). An artificial neural network model has been designed and trained through experimental data sets. This model can also be adopted during the determination of hole quality attributes when the parameter settings are beyond a defined boundary, as the regression analysis value is very close to 1, and model performance is 4.99e-10. Peak current = 4 A, pulse-on time = 25 µs, pulse-off time=25 µs, and flushing pressure = 0.6 MPa were the optimum drilling parameters. In the initial hole, average burr length is 391.75 μm, and delamination of 539.3 μm is noticed. But burr formation is very negligible with delamination of 350.7 μm being observed with uniform circularity (0.979), low taper angle (−0.81354°), and TWR (0.000069 g/min) under optimum drilling conditions through this drilling approach. [ABSTRACT FROM AUTHOR]