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Purpose: The industrial application of continuous glass fabric-reinforced polymer composites (GFRPCs) is growing; however, the manufacturing boundedness of complex structures and the high cost of molds restrict their use. This research proposes a three-dimensional (3 D) printing process for GFRPCs that allows low-cost and rapid fabrication of complex composite parts. Design/methodology/approach: The composite is manufactured using a digital light processing (DLP) based Vat-photopolymerization (VPP) process. For the composites, suitable resin material and glass fabrics are chosen based on their strength, stiffness, and printability. Jacob's working curve characterizes the curing parameters for adequate adhesion between the matrix and fabrics. The tensile and flexural properties were examined using UTM. The fabric distribution and compactness of the cured resin were analyzed in scanning electron microscopy. Findings: The result showed that the object could print at a glass fabric content of 40 volume%. In DLP-based VPP printing technology, the adequate exposure time was found to be 30 seconds for making a GFRPC. The tensile strength and Young's modulus values were increased by 5.54 and 8.81 times, respectively than non-reinforced cured specimens. The flexural strength and modulus were also effectively increased to 2.8 and 3 times more than the neat specimens. In addition, the process is found to help fabricate the functional component. Originality/value: The experimental procedure to fabricate GFRPC specimens through DLP-based AM is a spectacular experimental approach. [ABSTRACT FROM AUTHOR]

In this article, we investigated the effects of different functional groups in graphene on the mechanical performance of epoxy nanocomposites fabricated using the in-situ polymerization method. This study considered pristine graphene and three different varieties of functionalized graphene (–NH2, –COOH, and –OH) with varying weight percent (i.e., 0.25, 0.5, and 1.0 wt%). The functional groups grafted of graphene have been confirmed through Fourier transforms infrared (FTIR) spectra. Microstructural features and fracture surfaces were also examined by field-emission scanning electron microscopy with energy-dispersive X-ray spectroscopy. In comparison to pure epoxy, –OH functionalized graphene/epoxy nanocomposites showed a maximum improvement of 37.24% in tensile strength and 38.05% in flexural strength. The improved mechanical properties of epoxy nanocomposites were attributed to homogeneous dispersion, graphene bridging, and better interfacial contact between epoxy and graphene. The effect of pristine and functionalized graphene on the mechanical properties of epoxy nanocomposites was studied. Nanocomposites were fabricated for three different wt% (0.25, 0.5, and 1.0) of graphene nanofillers. Field emission scanning electron microscopy (FE-SEM) with EDX was used to examine the microstructural features of fractured surfaces. Graphene enhanced the mechanical properties of epoxy nanocomposites. [ABSTRACT FROM AUTHOR]

In this paper, an attempt is made to explore the possibilities of modifying the dielectric by adding alumina (Al2O3) nanopowder for improving the machining performances. The performance of newly developed nano powder-mixed electrical discharge machining (NPMEDM) process is compared with conventional EDM. Peak current, gap voltage and pulse-on time are taken as considerable process parameters to investigate material removal rate (MRR), surface roughness (SR), recast layer thickness, surface morphology, surface topography and induced residual stress. It is observed that the nanopowder-mixed dielectric medium gives better surface finish and higher metal removal rate as compared to conventional dielectric. The value of MRR increases from 32.75 to 47 mg/min and surface roughness improves from 2.245 to 1.487 μm. Thereafter, atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) investigation of the machined surface reveals that presence of micro-crack, micro-hole and uneven deposition decrease substantially during NPMEDM process. Also, induced tensile residual stress on the machined surface significantly reduces in this modified process. Further, the basic mechanism of these processes are investigated by analysing pulse train discharge waveforms and reveals the better sparking stability of NPMEDM process, which results in the higher MRR and better surface quality. [ABSTRACT FROM AUTHOR]

The present study focuses on the hydrodynamic erosion of tantalum in the form of the disintegration depth when exposed to periodic impingements of water clusters. Discrete water clusters were generated using a pulsating water jet at excitation frequencies of 20 and 40 kHz to modulate the continuous jet into a pulsating jet. The influence of the technological parameters, such as the excitation frequency (20 and 40 kHz), supply pressure (20, 30, and 40 MPa), nozzle diameter (0.3 and 0.5 mm), and time exposure (0.25–128 s), on the erosion depth of tantalum was observed. The disintegration depth trend showed a proportional nature with the number of impingements directed to the tantalum surface keeping all other technological parameters constant. An increase in the water flow rate from 0.76 l/min (p = 20 MPa, d = 0.3 mm) to 3 l/min (p = 40 MPa, d = 0.5 mm), reduces the time exposure required for the initiation of disintegration from 4 s (80,800 impingements with f = 20 kHz) to 1 s (40,600 impingements with f = 40 kHz), respectively. The effect of change in the excitation frequency from 20 to 40 kHz was observed in form of an increase in the erosion depth from 1587 to 1762 μm at p = 40 MPa, d = 0.5 mm, and t = 128 s. The surface morphology observed using scanning electron microscopy revealed erosion features, such as craters, micro-holes, surface upheaving, and tearing, on the tantalum surface. No significant change in the mean micro-hardness values were observed near the periphery of the eroded cavity as compared to original material due to high-density of tantalum which obstruct the propagation of shock waves into the material. The outcome of the study enhances the knowledge regarding the hydrodynamic erosion of high-density materials (ρ > 15 kg/mm3) in response to the water flow rate, frequency, and time exposure. • The hydrodynamic erosion mechanism of tantalum using a pulsating waterjet was studied. • Three erosion regions were approximated within an exponential increase in impingements. • A proportional relation between the number of impingements with the erosion depth was observed. [ABSTRACT FROM AUTHOR]