Design, Simulation and Optimization of an Additive Laser-Based Manufacturing Process for Gearbox Housing with Reduced Weight Made from AlSi10Mg Alloy

The gas turbine engine's (GTE) development aims for the increasing the efficiency, strength, reliability and safety of its components. To create competitive engines, housing parts and components with high functionality and reduced weight are needed. Especially difficult in the design and production are the gearboxes for aviation GTE. Traditional technologies based on precision casting or material forming operations have significant limitations due to the complexity of fulfilling multiple different requirements. Nowadays, one of the progressive production techniques is additive manufacturing. The article presents the results of computational and experimental studies that substantiate the applicability of laser additive technology to reduce the mass of body parts by up to 15% while ensuring their strength properties. The physical and mechanical characteristics of aluminum alloys acceptable for the manufacturing of housing parts were analyzed. The necessary characteristics of the powder alloy of the Al-Si system and the technological parameters of the L-PBF of the modified housing of the gear reducer are established. Using the finite element method (FEM) the L-PBF process was numerically simulated and the technological modes for synthesis of the AlSi10Mg alloy powder were optimized. With the help of a serial 3D printer ProX320DMP, the prototype of a gear housing was manufactured.

Quasi-Static Research of ATV/UTV Non-Pneumatic Tires

The non-pneumatic tire (NPT) is a type of wheel whichdevelopment is related to the beginning of automotive development. The non-pneumatic tire (NPT) is a type of tire that does not contain compressed gases or fluid to provide directional control and traction. Nowadays, this type of wheel is more and more often used in special purpose vehicles, e.g., in military vehicles and working machines. The main feature of the non-pneumatic tire is a flexible support structure (including the part of the wheel between the tread and the rim). This paper presents the results of research aimed at determining the influence of the geometry of the NPT’s (intended for All-Terrain Vehicle - ATV / Utility Task Vehicle - UTV) load-bearing structure on its quasi-static directional characteristics. The experimental tests included the determination of the radial stiffness of research objects on a non-deformable flat surface and on a single obstacle, as well as the determination of the degree of deformation for the elastic structure and belt. The significant influence of the elastic structure’s shape and the elastomer, as the material forming the NPT, on its radial stiffness was revealed.

Modeling and analysis of compaction roller deformation for fiber placement

The fiber reinforced resin-based composite materials have the characteristics of high specific modulus and strength, impact resistance, creep resistance, and seismic resistance, which are widely used in the aviation, automotive, and marine industries. As one of the advanced composite material forming technologies, the fiber placement can manufacture the large-curvature composite parts with the high efficiency, high quality, high repeatability and low cost. The rubber compaction roller will deform under the pressure, in which the deformation will increase the contact area between the pressure roller and the substrate, and improve the interlaminar bonding degree. Due to the different deformation of the compaction roller caused by the different laying pressures, the deformation process of the fiber compaction roller was analyzed. By establishing the pressure stress distribution model for the compaction roller, the contact pressure, the downward deformation of the compaction roller and the deformation contact area between the compaction roller and the substrate are obtained. The mapping relationship among the contact curves of the substrate is verified by using the experiments.

ARTIFICIAL LIGHT SOURCE AS A COMPONENT CONSTITUTING THE SCULPTURE

Light, which is the main source in which plastic arts produce meaning by processing it, indirectly takes place in all works of art with its different colors and tones throughout the history of art. With the use of new materials and techniques in art with the modern period, it is seen that the light itself, that is, the light source, is also included in art works as a medium. This situation allowed the artists to create brand new perceptions and effects. With the second half of the 20th century, the use of artificial light source in sculpture as an element belonging to the sculpture is encountered. Some of the artists selected as examples in this study were chosen in terms of being the first example in terms of the material they used, the way they used the light source and the diversity of the content they produced with these materials. Light, which is one of the primary conditions for perception in sculpture; In this study, the material forming the sculpture, such as transparency and reflection, is not based on its interaction with its structure, but as an element that forms a part or whole of the sculpture. It is aimed to show the effect of using artificial light source in sculpture on expression and perception through selected examples.

Insight into the dynamics of non-Newtonian carboxy methyl cellulose conveying CuO nanoparticles: significance of channel branch angle and pressure drop

Branching channels are commonly emerged in a considerable variety of engineering applications, in which most of the fluids present non Newtonian behavior, such as in chemical processes. It is noted that in the material forming process, when one suspends nanoparticles in a basic non Newtonian fluid, a completely new non Newtonian fluid is formed with different rheological characteristics from the former ones. In our present numerical research, considering the side branches inclined at varying angles, we focus on the fluid flow and heat transfer of the laminar power-law nanofluid in a rectangular branching channel under the influences of generalized Reynolds number. Both the consistency coefficient and power-law index of the non Newtonian nanofluid, different from those of the base fluid, are described by empirical formula, dependent on the nanoparticle quantity. Finite element method is applied in the research. It is found that a smaller branch angle α can cause a larger fluctuation in pressure near the branched region. Furthermore, negative pressures exist both in the main and side branch with some certain inclination angle. Above all, the new extensive results of velocity contours, temperature, concentration contours along with pressure drop of the changing rheological models provide detailed information for studies on non Newtonian nanofluids in many intricate industrial applications.

Carbon-Free Solution-Based Doping for Silicon

Molecular doping is a method to dope semiconductors based on the use of liquid solutions as precursors of the dopant. The molecules are deposited on the material, forming a self-ordered monolayer that conforms to the surfaces, whether they are planar or structured. So far, molecular doping has been used with precursors of organic molecules, which also release the carbon in the semiconductor. The carbon atoms, acting as traps for charge carriers, deteriorate the doping efficiency. For rapid and extensive industrial exploitation, the need for a method that removes carbon has therefore been raised. In this paper, we use phosphoric acid as a precursor of the dopant. It does not contain carbon and has a smaller steric footprint than the molecules used in the literature, thus allowing a much higher predetermined surface density. We demonstrate doses of electrical carriers as high as 3 × 1015 #/cm2, with peaks of 1 × 1020 #/cm3, and high repeatability of the process, indicating an outstanding yield compared to traditional MD methods.

Distributed Feedback Laser Based on Tunable Photonic Hypercrystal

In this work, we investigate the generation of light in a distributed feedback (DFB) laser composed of periodically arranged layers of hyperbolic medium and active material forming a 1D photonic hypercrystal (PHC). The scope of our study covers the analysis of laser action in the presence of different types of dispersion that are achievable in a hyperbolic medium. Using the example of a PHC structure consisting of graphene-based hyperbolic medium, we demonstrate the possibility of controlling laser action by tuning effective dispersion. Our analysis reveals the possibility of obtaining a single-frequency generation with high side-mode suppression and controllable wavelength of operation. Moreover, we present a new mechanism for the modulation of laser amplitude arising from voltage-controllable dispersion of hyperbolic medium.

The Ionization Energies of Dust-Forming Metal Oxide Clusters

Stellar dust grains are predominantly composed of mineralic, anorganic material forming in the circumstellar envelopes of oxygen-rich AGB stars. However, the initial stage of the dust synthesis, or its nucleation, is not well understood. In particular, the chemical nature of the nucleating species, represented by molecular clusters, is uncertain. We investigated the vertical and adiabatic ionization energies of four different metal-oxide clusters by means of density functional theory. They included clusters of magnesia (MgO)n, silicon monoxide (SiO)n, alumina (Al2O3)n, and titania (TiO2)n with stoichiometric sizes of n = 1–8. The magnesia, alumina, and titania clusters showed relatively little variation in their ionization energies with respect to the cluster size n: 7.1–8.2 eV for (MgO)n, from 8.9–10.0 eV for (Al2O3)n, and 9.3–10.5 eV for (TiO2)n. In contrast, the (SiO)n ionization energies decrease with size n, starting from 11.5 eV for n = 1, and decreasing to 6.6 eV for n = 8. Therefore, we set constraints on the stability limit for neutral metal-oxide clusters to persist ionization through radiation or high temperatures and for the nucleation to proceed via neutral–neutral reactions.

Effect of Pulse Current on Mechanical Behavior of High Temperature Titanium Alloy Ti55

The effects of pulse current on the tensile properties of high temperature titanium alloy Ti55 were investigated by pulse current assisted uniaxial tensile test under different electrical parameters. It was found that with the increase of peak current and pulse width, the tensile properties of Ti55 are significantly improved. At the same time, the pulsation effect of current on the mechanical properties of Ti55 was investigated. The results show that the tensile displacement of low pulsation group was higher, while the elongation of high pulsation group was higher. In order to explore the mechanism of pulsation effect of current, EBSD was adopted. The results indicated that high pulse current can significantly promote the dislocation movement and recrystallization. In addition, some macrozones was found in low pulsation group, which indicated that high pulsation current was more suitable for material forming than low pulsation current.