bluuebunny/crossref_metadata_2025_split huggingface dataset:
Research of surface quality of structural components made using additive technology of electric arc welding
Authors: Balanovsky A E , Osipov S A , Shmakov A K 
Published: November 2019

Abstract
A brief analysis of the existing methods of additive technologies with reference to the aviation industry is carried out. The prospects of this direction are shown taking into account the possibility of production of aircraft parts on the principle of “bottom-up”. The results of researches of additive technology of electric arc surfacing in carbon dioxide of complex parts are presented. In the course of the carried out studies technological peculiarities of the technology connected with the parameters of welding arc, melting of cladding wire have been found out. Arc current has the greatest influence on the appearance of the molding. The wire feed rate affects the height of the welded roll. It is shown that the stability of the welded rolls formation depends on the modes of metal transfer, which depend on the conditions of wire feeding and insertion into the melt bath.
Roughness of holes in metal and polymer composite bags
Authors: Chashhin N S , Pashkov A E , Ivanov Y N , Sturov A A 
Published: November 2019

Abstract
The article presents the results of the research on the influence of cutting modes on the parameters of surface roughness during finishing of holes in mixed packages containing composite and metal materials. The object of the study is a mixed package containing layers of polymer composite material (CFRP), as well as layers of titanium and aluminum alloys. The main technological equipment used in the study is an automatic drilling machine. Cutting tool -carbide six-toothed reamer. For carrying out of researches ranges of variation of modes of cutting have been chosen and the plan of experiment by means of software Statistica 6 is made. Two factors are considered under the plan of experiment: speed of cutting and delivery, the parameter of the allowance on expansion is introduced as the block factor. The models of multifactor dispersion analysis, which determine the influence of modes on the roughness of holes, were obtained empirically. Optimization of cutting modes has been carried out, the surface of desirability has been constructed, and recommendations on the choice of technological parameters of the process have been given.
Peculiarities of making bolt and rivet connections with interference when assembling the aircraft MS-21
Authors: Chernykh E V , Zaidès C A , Kudryavtsev A A 
Published: November 2019

Abstract
In this paper the peculiarities of installation of fasteners with tension during assembly of MS-21 aircraft are considered. In particular, we considered the aspects of the necessity of using bolt and rivet connections with tension during the assembly of the aircraft fuselage. We have developed a finite element model of the installation process with the rivet bolt in the hole of the package using the system of finite element analysis Simufact. We used the Elastoplastic Concept of Material Behaviour with Nonlinear Hardening Section. And obtained the characteristics of the stress-strain state of the bolt-ribbon joint elements at various moments of rod retraction, including at the predicted moment of shank tear off. It has been revealed that it is expedient to bring the retraction force up to the value close to destructive one. Determined the residual deformations after removal of axial load from the rod. It is proved that it is necessary to actualize the existing normative and technical documentation with specification of the value of the tool impact force on the rivet bolt rod.
Study of the microspructure of the alloy AMG3 after friction stir welding
Authors: Guseva E A , Konstantinova M V 
Published: November 2019

Abstract
The article contains data on the results of the study of the microstructure of samples of AMg3 alloy, which was subjected to melt and stir welding. For this purpose the methods of optical and electron microscopy, as well as the method of diffraction of backscattered electrons were used. It was found that there were four zones in the area of the welded seam, each of which had its own microstructure. The reasons of formation of this or that microstructure taking into account the influence of temperature difference and plastic deformation in the welding zone are explained.
Mathematical model to calculate key parameters of forming irregular lateral cuttings on sheet articles to eliminate such defects as “under-forging”
Authors: Mironenko V V , Larionova Y N 
Published: November 2019

Abstract
The paper considers irregular lateral cutting beyond OST 1.52468-80. It shows that standard methods do not provide solutions to forming of either element of a workpiece. The study suggests methods to find parameters of forming and technical characteristics of a part containing the given element. It also proposes method allowing eliminating such defects as “under-forging”. The results are compared with finite element analysis of forming and natural experiment. The paper makes the conclusion on the possibility of applying the suggested formulas.
Dynamics modeling of surface treatment with end spherical cylindrical milling cutters
Authors: Ponomarev B B , Gabanov E V , Nguen Sh Kh 
Published: November 2019

Abstract
The designs of modern vehicles and aviation can be traced to a constant increase in the range of parts that have complexly shaped free-form surfaces. Production of such quality parts requires new methods of automated mechanical engineering and particularly program operated multi-purpose five-coordinate machine processing. The paper is dedicated to dynamical modelling of surface treatment of materials by spherical cylindrical milling cutter. The simulation results are the basis for the formation of optimal conditions for machining free-form surfaces and determining combinations of tilt and advance angles and their optimization for positioning the tool for end milling of surfaces on five-axis CNC machines.
Vibration suppression methods at high performance drilling
Authors: Savilov A V , Pyatykh A S , Timofeev S A 
Published: November 2019

Abstract
This article discusses the possibility of suppressing vibrations when drilling holes with spiral drills. This article presents two methods of suppressing vibrations: modal analysis and modulation of cutting speed (changes in spindle speed - Spindle Speed Variation - SSV). There is a description of the considered methods with an indication of their advantages and disadvantages. The article also points out to experimental data that characterize the possibility of suppressing vibrations when drilling holes and a comparative analysis of various methods of suppressing vibrations when machining holes in samples of their structural steel. There is an assessment of the possibility of joint application of modal analysis methods and modulation of cutting speed during high-performance drilling.
Studying the dynamics of cutting process by a face mill cutter
Authors: Svinin V M , Nikulin D S 
Published: November 2019

Abstract
An overview of stepped end mills use for rough cutting of large allowances and finishing cut of flat surfaces is given, where they ensure a reduction in cutting forces, an increase in dynamic stability and performance rate. The study of oscillations in the direction of the longitudinal feed of the spindle and workpiece subsystems, as well as the spindle torsional subsystem, has been carried out by the simulation modeling method. Detailed pictures of the oscillations of these subsystems are obtained. Careful analysis of these oscillations using the basic principles of the regeneration theory of self-oscillations allows establishing their nature and mutual influence. It is established that the main reason for the increased dynamic stability of the stepped end mill as compared to the standard one is the reduction of the power load due to the group cutting scheme and an increase in the uniform distribution of the frequency spectrum of the cutting moment due to the variability of the actual angular pitch of the teeth. The revealed pattern serves as a methodological basis for the creation of progressive designs of stepped end mills. When developing them, it is necessary to look for new patterns of the relative position of the teeth when varying the difference in diameters of the stages and angular steps.
Comparative study of residual stresses when turning HSS-5 steel with varying feed
Authors: Tikhonov A G , Pashkov A E 
Published: November 2019

Abstract
The purpose of this article is a comparative analysis of the parameters of residual stresses in the steel HSS-5 after turning with a change in the longitudinal feed. The tasks posed in this study are: calculating the impact of the feed during turning on the parameters of residual stresses formed in the surface layer of the material; comparing the results of radically different methods for studying residual stresses. When conducting research, the method of XRD-analysis and the mechanical method for calculating residual stresses were used. The presented methods are most widely used in the determination of technological residual stresses in samples of various metals and alloys. These methods are widely used both under laboratory and in production conditions; they are characterized by satisfactory accuracy and convergence of results.
Relationship between tool tilt angle, shoulder plunge depth and process energy input for pin-less friction stir welded thin Ti-6Al-4V sheets
Authors: Gili A B , Hattingh D G , Bernard D 
Published: November 2019

Abstract
This paper reports on the initial process development towards evaluating pin-less friction stir welding as a feasible alternative joining technology for Ti-6Al-4V sheets. Initial research results were derived from “bead on plate” welds with a pin-less tool on 3 mm Ti-6Al-4V sheets to assist with decision making for joining 1 mm Ti-6Al-4V sheets. The study evaluates the shared influence of tool tilt angle and shoulder plunge depth on weld profile and process energy input for a pin-less tool. An experimental approach was followed, performing bead on plate welds with three tool tilt angles (0°, 1° and 2°) respectively at shoulder plunge depths from 0.15 mm to 0.25 mm in 0.05 mm increments. From critically evaluating the hardness profile and heat effected area below the tool shoulder, the shared influence of tool tilt angle and shoulder plunge depth could be analysed to give an indication of the best parameter combination for performing solid state welds on 1 mm Ti-6Al-4V sheet. Additionally, the thinning effect on the weld region was evaluated and compared to welds made with a pin. Future work will include quantifying surface residual stresses on the material and the relationship these stresses exhibits with the varying tool tilt and shoulder plunge depth. This work will assist in selecting weld parameter combination that will minimize tensile residual stresses in critical areas. Knowledge gained from this study forms the basis for the overall process development for joining 1 mm Ti-6Al-4V sheets by pin-less friction stir welding.
The effects of Ru, Cu, Zr and Hf on mechanical properties in Ti-Pt high temperature shape memory alloys
Authors: Mashamaite M P , Chauke H R , Ngoepe P E 
Published: November 2019

Abstract
Shape memory alloys (SMAs) have been widely used in the fields of actuators and aerospace industry due to their pseudo-elasticity and shape memory effect which are displayed in phase transformations. The martensitic transformations (MT) of TiPt is much higher, at approximately 1273 K and this is considered to be of potential technological interest for elevated temperature SMA applications. TiPt based alloys exhibit very low shape memory effect due to low critical stress for slip deformation compared to the stress required for martensitic transformation, hence it is necessary to enhance the mechanical properties of the equiatomic alloy. The first principles approach was employed to study the effect of the third element (M = Ru, Cu, Zr, and Hf) on the TiPt shape memory alloy. The supercell approach in VASP was used to substitute Pt with Ru and Cu, Ti with Zr and Hf on the TiPt structure to evaluate their mechanical stability from elastic properties for actuators and higher temperature applications. The Ti50Pt50-xRux and Ti50Pt50-xCux decreases in density with increase in Ru and Cu concentration, whilst the Ti50-xZrxPt50 and Ti50-xHfxPt50 substitution increases with an increase in their concentration, which result in larger lattice parameters. The heats of formation suggest that Ti50Pt50-xRux substitution is more thermodynamically stable than Ti50Pt50-xCux substitution, and Ti50-xHfxPt50 substitution is more stable than Ti50-xZrxPt50. The elastic properties suggest that the ternary structures become mechanically stable with an increase of the third element. The Ti50Pt50-xRux and Ti50Pt50-xCux substitution became more ductile with the increase in concentration. Zr and Hf substitution became more ductile at higher compositions (31.75 – 43.75 at.%). The Ru and Hf substitutions have potential to be used for high-temperature applications.
Effects of Mo content on the microstructural and mechanical properties of as-cast Ti-Mo alloys
Authors: Moshokoa N , Raganya L , Obadele B , Olubambi P , Machaka R 
Published: November 2019

Abstract
The effects of Mo content on the mechanical and microstructural properties of as-cast Ti-10Mo wt.% and Ti-15Mo wt.% alloys were measured in order to evaluate their possible use in biomedical applications. The microstructure and phase analysis of as-cast specimens were studied using an optical microscopy and X-ray diffraction (XRD). The micro-Vickers hardness properties of the alloys were examined using Vickers equipment and the elastic modulus was determined using the tensile test. Results indicated that the Mo content influenced the structure-property relationship. The relative density increased significantly with the addition of Mo, the optical microscopy results showed that CP Ti was characterised with an α’-phase lamellar structure and with the addition of Mo, the microstructure composed of β phase with equiaxed grains of different sizes with sub-grain boundaries were observed. The measured XRD patterns showed that the CP Ti consisted of α’-phase and with the addition of Mo, the resultant alloys consisted of the β-phase. The micro-Vickers hardness and elastic modulus increased significantly after the addition of 10 wt.% Mo and then decreased significantly when the Mo content was raised to15 wt.%.
Investigation of graphene-based nanocomposite for hydrogen storage
Authors: Baloyi S J , Ngqalakwezi A , Nkazi D , Ntho T A 
Published: November 2019

Abstract
In this study, a simple, fast, and green one-pot method was developed for the preparation of Ni/Graphene nanocomposite for the storage of hydrogen. The precursor graphene oxide was prepared from expanded graphite flakes using a modified Hummer’s method. Graphene oxide was reduced effectively using natural reducing agents such as lemon juice as eco-friendly potential reducing agents instead of harmful hydrazine (N2H4). The characterization of as-synthesized graphene oxide and Ni/graphene nanocomposites were performed by powder X-ray diffraction (p-XRD), high-resolution electron microscopy (HRSEM) with energy dispersive spectroscopy (EDS) analysis and transmission electron microscopy (TEM) before investigating the performance for hydrogen storage. It was observed from the results obtained that the synthesized graphene contains thin stacked flakes of shapes having a well-defined multi-layered structure at the edge. And the round shaped Ni nanoparticles of 13 nanometres in size were dispersed around the graphene structure. The hydrogenation capacity of the Ni/graphene nanocomposites were tested using thermogravimetric analysis (TGA). The prepared Ni/graphene nanocomposites exhibited good hydrogen storage capacities.
Influence of Heat Treatment on Microstructure and Mechanical Properties of Ni-Fe-Co Ternary Alloy Prepared via Spark Plasma Sintering
Authors: Bopape I M C , Shongwe M B , Ogunmuyiwa E N , Rominiyi A L , Jeje S O 
Published: November 2019

Abstract
The use of nickel-based superalloys has extended to different fields such as turbines, rocket motors, chemical equipment, space vehicles and power plants due to their excellent mechanical properties. This study investigates the effect of heat treatment on the microstructure and microhardness of spark plasma sintered Ni-Fe-Co ternary alloy. 50wt.% Ni and varying percentages of Fe and Co powders were milled and fabricated by Spark Plasma Sintering (SPS) technique at a temperature of 900 °C, pressure and holding time were kept at 50 MPa and 10 min respectively. The sintered compacts were heat-treated at 1000 °C, soaked for 1 hr and quenched in distilled water for 5 min. Subsequently, the sintered and heat-treated samples were characterized by scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS) and X-ray Diffraction (XRD) to determine the microstructural evolution and phase transformation accompanying the process. XRD results revealed the evolution of strengthening phases in the heat treated of the samples. The as-sintered and heat-treated compacts Vickers hardness was also investigated before and after the heat treatment. The results show a general improvement in the microstructure after the heat treatment which translated to the observed increase in the hardness of the heat-treated samples.
Effect of nickel powder particle size on the microstructure and thermophysical properties of spark plasma sintered NiCrCoAlTiW-Ta superalloy
Authors: Ogunbiyi O F , Jamiru T , Sadiku E R , Adesina O T , Salifu S A , Beneke L W 
Published: November 2019

Abstract
The spark plasma sintering technique (SPS) was used to consolidate admixed elemental powder in order to fabricate NiCrCoAlTiW-Ta superalloy. Nickel which is the key element that formed the matrix powder particle size was varied in the range of 3-44, 45-106 and 106-150 μm. The effect of varying the starting powder particle size, on the formation of intermetallic phases was investigated. Also, important thermophysical properties in the development of superalloys for high temperature applications were investigated by using laser flash machine, in the range of 100-800 °C. The constituents of the microstructure for the sintered alloy includes, the gamma (γ) matrix phase (Ni), precipitated intermetallic gamma prime (γ’) phase Ni3(Al, Ti) and the precipitated solid solution strengthening elements (Cr and W). There was an increase in the density with decreasing powder particle size. Also, the averave grain size increased with increasing powder particle size. The thermophysical properties obtained, which include thermal conductivity and diffusivity increase with increasing temperature. Non-linear behaviour and inflection points were observed as the temperature increases due to short range order and disorder phenomenon which is associated with superalloys. The powder particle size has little or no significant effect of the thermophysical behaviour as the pattern observed were almost the same.
Fretting Biocorrosion Behaviour of Titanium-Zirconia composites in Foetal Bovine Serum
Authors: Semetse L , Obadele B A , Raganya L , Geringer J , Olubambi P A 
Published: November 2019

Abstract
This work aims at studying the fretting biocorrosion response of newly developed Ti-6Al-4V/ZrO2 in simulated body fluid. Ti-6Al-4V alloy with different volume fractions of ZrO2 produced via powder metallurgy techniques were spark plasma sintered to produce Ti-6Al-4V composites with improved properties. The microstructures of the resulting spark plasma sintered composites were examined using a scanning electron microscope (SEM). Fretting corrosion tests were conducted for each material composition with a special device used for fretting corrosion investigations with a cylinder-on-flat configuration. The tests were done in foetal bovine serum maintained at ambient temperature. Open circuit potential, dissipated energy and coefficient of friction were monitored throughout the experiments. The results show that the microstructures produced after zirconia additions were very different from those observed in pure Ti-6Al-4V. The presence of zirconia promoted the formation of globular zirconia-rich agglomerates throughout the matrix, leading to more improved fretting biocorrosion properties of Ti-6Al-4V.
Prospects of graphite - polypropylene/epoxy blend composite for high performance bipolar plate in polymer electrolyte membrane fuel cell
Authors: Alo O A , Otunniyi I O , Pienaar HCVZ 
Published: November 2019

Abstract
Conductive polymer composites (CPCs) are very promising candidate materials for bipolar plates (BPs) in polymer electrolyte membrane fuel cells (PEMFCs). However, a major challenge facing application of CPCs in PEMFC BPs is the difficulty in achieving high electrical conductivity while maintaining adequate mechanical strength. Therefore, a good balance between electrical conductivity and mechanical strength is critical in the development of high-performance CPC BPs. In this study, CPCs consisting of polypropylene (PP)/epoxy blend filled with graphite were investigated for application as BP material, which will combine electrical conductivity and mechanical strength that meet the performance requirements for PEMFC BPs. The CPCs, with 30 – 80 wt% graphite powder, were produced by melt mixing followed by compression molding. The morphology, in-plane electrical conductivity, and flexural strength of the composites were investigated using the scanning electron microscopy, four-point probe method, and three-point bending test, respectively. The results obtained were compared with the technical targets for PEMFC BPs by the United States Department of Energy (DOE). All the PP/epoxy/graphite composites exhibited flexural strength that satisfies the DOE target of > 25 MPa while the composite with 80 wt% graphite content showed the best in-plane electrical conductivity.
Influence of warm temperature (0.3-0.5Tm) uniaxial compression on the distribution of reinforcing particles in a 2124-Al/10%SiC MMC
Authors: Gxowa-Penxa Z , Chown L H , Govender G 
Published: November 2019

Abstract
Experimental work was carried out to study the influence of uniaxial compression tests, performed on a Gleeble 3500, on the distribution of reinforcing particles in SiC reinforced Al Metal Matrix Composites (MMCs). Al MMC powder (2124-Al with 10 vol. %SiC) was produced through blending in a high energy ball mill. Unreinforced 2124-Al and Al MMC powders were compacted at ambient temperature (i.e. cold compaction) and the green compacts were then sintered at 490°C for 1 hr. Warm temperature (280°C) uniaxial compression tests were performed on a Gleeble 3500 thermomechanical simulator at a strain rate of 5 s-1, strain of 0.3 and a soaking time 20 minutes.
Microstructures of the uniaxially compressed 2124-Al with 10% SiC MMC revealed that deformation had an influence on the distribution of reinforcing particles. Reinforcing particles were only distributed inside 2124-Al grains that had undergone deformation (evident through change in shape of grains). This finding supports statements made in literature regarding the positive influence of deformation on the distribution of reinforcing particles. Engineering stress-strain curves showed that reinforcing 2124-Al with 10 vol. % SiC had a positive effect on flow stress as the 10%SiC MMC had a flow stress of 153 MPa while the flow stress of the unreinforced 2124-Al was 95 MPa. An improvement in hardness was also observed where the MMC had a higher hardness than the unreinforced Al alloy; further indicating that reinforcing the Al alloy improved properties.