Efficient and power-dense electrical machines are critical in driving the next generation of green energy technologies for many industries including automotive, aerospace and energy. However, one of the primary requirements to enable this is the fabrication of compact custom windings with optimised materials and geometries. Electrical machine windings rely on highly electrically conductive materials, and therefore, the Additive Manufacturing (AM) of custom copper (Cu) and silver (Ag) windings offers opportunities to simultaneously improve efficiency through optimised materials, custom geometries and topology and thermal management through integrated cooling strategies. Laser Powder Bed Fusion (L-PBF) is the most mature AM technology for metals, however, laser processing highly reflective and conductive metals such as Cu and Ag is highly challenging due to insufficient energy absorption. In this regard, this study details the 400 W L-PBF processing of high-purity Cu, Ag and Cu–Ag alloys and the resultant electrical conductivity performance. Six Cu and Ag material variants are investigated in four comparative studies characterising the influence of material composition, powder recoating, laser exposure and electropolishing. The highest density and electrical conductivity achieved was 88% and 73% IACS, respectively. To aid in the application of electrical insulation coatings, electropolishing parameters are established to improve surface roughness. Finally, proof-of-concept electrical machine coils are fabricated, highlighting the potential for 400 W L-PBF processing of Cu and Ag, extending the current state of the art.

This work analyzed the mechanical and vibration characteristic of the banana fiber sandwich layer with core AISI 304 steel wire mesh (WM). The following specimen configurations were prepared by hand lay-up method by varying fiber orientation in the skin layer: S = 0/0/0/0, S1 = 0/0/WM/0/0, S2 = 0/90/WM/90/0, S3 = 0/45/WM/-45/0 and S4 = 0/30/WM/60/0. The primary mechanical properties of the sandwich composite specimens were obtained by conducting Tensile, Flexural, and Impact strengths as per ASTM standards, whereas secondary vibration characteristics by experimental modal analysis. The presence of core WM enhances the primary properties especially in S1 attributed to the 0° fiber orientation with high load carrying capacity, natural frequency (Mode I, II), and stiffness. Whereas the specimen with angular fiber orientation (S2, S3, S4) in the skin layer exhibits higher damping showcasing their ability to dissipate energy. Specimen ‘S3ʹ acts as a performance change over with 45/-45 fiber in the skin layer. Morphology study of a test of a specimen with ‘WM’ shows the participation of matrix, banana fiber, and WM in load transfer mechanism with varied failure pattern. Hence, this type of composite structure can be preferred to use in structural and automobile applications by properly orienting the fiber in the skin layer.

Natural fibers are being extensively used in recent technological and structural applications due to the need for biodegradable materials. This paper deals with extraction of new cellulosic fiber from the stem of Nelumbo nucifera (Nn) (lotus) and the investigations via physical, structural and thermal properties on the alkali-treated fiber were carried out. The XRD analysis of the Nn fiber provides the crystallinity index of about 52.53% that implies its high crystalline structure and own associated strength. The FTIR analysis proves the presence of alcoholic and alpha keto carboxylic acid in Nn fiber. Thermal stability of Nn composite is found around 210°C and the TGA results prove that the extracted as well as alkali-treated fibers provide a good reinforcement to the matrix, which can be well synthesized mechanically improved biocomposites. Test samples of three different weight % of Nn fiber with the epoxy basement are designated as L10, L15 and L20 to measure the tensile and flexural strength. Test sample with L20 as weight % exhibits better Young’s and flexural modulus. Alkali treated Nn composite is an important candidate for the natural fiber reinforcement and such a category can serve as a good material for household applications.