Understanding the machined material’s behaviour in electro-discharge machining (EDM) using a multi-phase smoothed particle hydrodynamics (SPH) modelling

Electro-discharge machining (EDM) has been extensively employed for machining hard alloys, and its simulations have been widely conducted using finite element analysis (FEA). However, the majority of mesh-based models depended on forecasting the crater profile only based on the temperature gradient, without offering detailed data regarding the machined material properties. It is crucial to understand the behaviour of the machined material in order to accurately assess the flushing efficiency, analyse the wear on the electrode, and examine the interaction between the debris generated during machining and the remaining workpiece. This is done to ensure that no recast material is left behind after the EDM process. For the first time, a meshless smoothed particle hydrodynamics multi-phase model was implemented to gain practical insights and comprehensively understand a very intricate phenomenon that occurs within a very short time. Additionally, this approach is utilised to investigate the characteristics of the materials being machined. We utilised our SPH model to simulate both the capacitance- and transistor-based EDM of Ti–6Al–4V and AISI304 steel. Our simulation considered the temperature-dependent thermal properties and latent heats of the materials. The accuracy of our model was confirmed by comparing its results with experimental, analytical, and finite element analysis (FEA) results. The machined material was observed during its removal from the surface, and the dimensions of the resulting crater, as well as its aspect ratio and the rate at which the material was removed, were predicted with an error ranging from 2 to 22%. This error is far lower than that of the typical finite element (FE) prediction. This model lays the groundwork for a more complex model that will more accurately represent EDM and other similar manufacturing processes

Investigation the effect of pulsed laser parameters on the temperature distribution and joint interface properties in dissimilar laser joining of austenitic stainless steel 304 and Acrylonitrile Butadiene Styrene

Direct laser joining of metal to plastic materials is one of the cost effective methods of joining. The demand for laser welding of stainless steels and thermoplastics is going on increase because of having many applications such as automotive, aerospace and aviation industries. This paper presents the experimental investigation of direct laser joining of stainless steel 304 and Acrylonitrile Butadiene Styrene (ABS). The effects of pulsed laser parameters including laser welding speed, focal length, frequency and power on the themperature field and tensile shear load was investigated. The results showed that excessive increase of the joint interface temperature mainly induced by high laser power density results in exiting of the more volume of the molten ABS from the stainless steel melt pool. Also, increasing the laser power density through decreasing the focal length or increasing the laser power led to an increase in the surface temperature, higher beam penetration and high volume of molten ABS. Decreasing the focal length from 5 to 2 mm significantly rose the temperature from 150 to 300 °C. By increasing the laser pulse frequency, the number of bobbles at the ABS interface surface remarkably increased where the temperature increased from 120 to 180 °C. The X-ray spectroscopy results showed the existence of the polymer elements on the metal surface at the joint interface zone. The tensile shear load clearly increased from 280 to 460 N with augmentation of laser average power from 180 W to 215 W. Applying higher levels of laser power has clearly decreased the tensile shear load due to creating bigger bobbles and more cavities at the adhesive zone

Forced convection around horizontal tubes bundles of a heat exchanger using a two-phase mixture model: Effects of nanofluid and tubes Configuration

In this paper, numerical simulation of laminar flow and heat transfer of nanofluid on a group of heat exchanger tubes is described. For better prediction of the behavior of the nanofluid flow on the tube arrays, two-phase mixture model was used. To achieve this aim, heat transfer and laminar flow of two-phase nanofluid as cooling fluid at volume fraction of 0, 2, 4, and 6% solid nanoparticles of silver and Reynolds numbers of 100 to1800 were investigated for different Configurations of tube arrays. The results indicated when the nanofluid collides with the tube arrays, the growth of heat boundary layer and gradients increase. The increase in the growth of boundary layer in the area behind the tubes was very remarkable, such that at the Reynolds number of 100, due to diffusion of the effect of wall temperature in the cooling fluid close to the wall, it had a considerable growth. Further, from the second row onwards, the slope of pressure drop coefficient diagrams was descending. Among the different Configuration s of tubes and across all the investigated Reynolds numbers, square Configuration had the maximum pressure drop coefficient as well as the highest extent of fluid momentum depreciatio

Synthesis and characterization of bio-nanocomposites: Functionalization of graphene oxide with a biocompatible amino acid

Graphene oxide (GO) is a complicated composite which can be synthesized from graphite or other carbon sources by a simple top-down method. Graphene is a two-dimensional carbon sheets which can be oxidized to synthesis its oxide structure. The graphene oxide sheets can be functionalized in order to be used actively in different areas. The graphene oxide nanocomposite materials have attracted researches and scientists’ attention due to their wade applications from electrochemical industry to drug delivery. In this novel work the authors have synthesized graphene oxide films and then functionalized with an amino acid, Lysine, and Cu in order to synthesize the Lysine-Cu-Graphene oxide combination. The novelty of this investigation is the authors have functionalized graphene oxide with l-lysine as an amino acid at diverse temperature. Also, this product is environmentally friendly product since it is soluble in aqueous medium and can be applied as an active antibacterial material. After the synthesizing process, the obtained materials had been characterized using different techniques such as Fourier-transform infrared spectroscopy (FTIR) to confirm the success of the functional reaction. Ultra violet visible (UV–Vis) spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal gravimetric (TG) analysis, were also utilized to approve the covalent attachment of Lysine and also to show the improvement in the thermal stability of GO

Speciation, physical and electrolytic properties of eutectic mixtures based on CrCl₃·6H₂O and urea

The electrodeposition of chromium is a technologically vital process, which is principally carried out using aqueous chromic acid. In the current study, it is shown that eutectic mixtures of urea and hydrated chromium(III) chloride provide a liquid which reduces the toxicological issues associated with the current aqueous Cr(VI) electroplating solution. Using EXAFS, mass spectrometry and UV-Vis spectroscopy, it is shown that chromium is present predominantly as a cationic species. Conductivities are higher than for most comparable ionic liquids. It is shown that the electrodeposition of chromium is electrochemically reversible, with a current efficiency much higher than in aqueous electrolytes. Surface tension and density measurements indicate that hole theory is a valid model to describe transport properties in these liquids. Bulk Cr deposits are not macrocrystalline but they are generally crack-free. The deposits have a hardness of 600 ± 10 Vickers and, as such, are comparable to deposits from aqueous systems

Understanding mind/body medicine from Muslim religious practices of Salat and Dhikr

There has been an increasing medical interest in Muslim religious practices in promoting well-being. Central to Muslim religious practices are salat (prayer) and dhikr (chanting). These two religious forms may be argued as comprising elements of mind/body medicine due to their positive effect on the psychoneuroimmunological response. The aim of this article was to further understand the mind/body aspects of Muslim salat and dhikr.Arthur Sanioti