Machines. Technologies. Materials.
Vol. 12 (2018), Issue 12

Table of Contents

  • Spatial gearing: Kinematic characteristics of the instantaneous contact

    pg(s) 481-485

    In this work, case of rotations transformation between arbitrary crossed shafts (axes of rotations) by means of high kinematic joints, which elements configure active tooth surfaces of hyperboloid gear mechanisms is treated. |Analytical dependencies, defining the law of rotations transformation are illustrated. This law of transformation in this concrete case is a constant function of the relations of the angular velocities of the movable links of the spatial three-link gear mechanism. The shown functions are applicable both to the synthesis of the studied transmissions, and for the determining and control of the kinematic errors of these transmissions, caused by manufacturing and assembly errors.

  • Development of a software application for design and 3D modeling of a control rod for a hydraulic recoil brake

    pg(s) 486-490

    The design of complex armament details is a challenging process that requires great amount of time and data collected from ballistic calculation of the artillery tube. The developed software product that calculates the recoil brake’s piston rod replaces the large amount of computational work required, reduces the probability of calculation errors and enables the designer to focus his creative thinking into the combination of different materials and construction dimensions. The ability to export the calculated piston rod profile afterwards allows for easy transfer of the information required into a 3D virtual reality and the use of 3D modeling for the construction of the piston rod and the recoil braking device.

  • Laser marking and cutting of plexiglas with CO2

    pg(s) 494-496

    The possibility of marking and engraving on plexiglas with CO2 laser has been studied. The experiments conducted have determined the influence of laser radiation on the plexiglas.
    These methods deal with methods of processing metals with a high energy laser beam on a solid (liquid or diode) base. Laser marking systems using different lasers and optical transfer systems can be used to mark an almost endless sheet of materials including metals, plastics, ceramics, glass, wood and leather

  • Computer modelling of radial-shear rolling of austenitic stainless steel AISI-321

    pg(s) 497-500

    In this paper the results of modelling of radial-shear rolling process of austenitic stainless steel AISI-321 are presented. The simulation in Simufact Forming program complex was performed. The conditions of simulation for radial-shear mill SVP-08 of Rudny industrial Institute were adopted. The various parameters of stress-strain state (effective plastic strain, effective stress, mean normal stress and Lode-Nadai coefficient) and also microstructure evolution with rolling force were considered. It is revealed that radial-shear rolling is an effective process for obtaining of high quality round billets from stainless steels of austenitic class.

  • Material-science aspects of formation and evolution of damages which define the resource exploitation of aluminum structures of airplanes

    pg(s) 501-502

    The work is devoted to the study of evolution of flaws in aluminium alloys of Al-Zn-Mg-Cu, Al-Cu-Mg-Мn alloying systems and to the determination of their connection with structural factors of the material such as the size and composition of intermetallic phases conditioned by heat treatment tempers, and also to the study of the effect of big number of physical factors on the long-term behaviour of structural elements of aluminium alloys, and to the determination of the rate of formation of corrosion damages in structural elements of the aircraft wing

  • The geometrical criterions of nanoparticles

    pg(s) 503-505

    The structure of the bulk crystals allow to determine the habit of the nanocrystales on their base only as a source point. It is impossible to neglect the size, form and influence of surface. The liquids surface relatively quickly passes to equilibrium form when free energy is minimum. Debye’s temperature is rather arbitrary parameter. Its determination is based on some approach. However this parameter is introduced to the reference books and is broadly used in the crystal physics. Proposed strategy allows defining habit maximum size of nanoparticles on the base well known physics representations. The L–value is determined the bounder between sizes where it can be done value description and where it’s necessary to take into account the particle sizes.

  • “Weight” of the of reciprocal lattice node in the cell/ super cell of these lattice

    pg(s) 506-509

    Geometrically, the reciprocal lattice is built on the basis of the lattice of the crystal according to the rule
    *
    a j ak jk , where
    the vectors
    *
    a j , ak are the periods of the crystal and reciprocal lattices corresponding  jk  0 at j  k and jk  1 at j  k (j, k = 1,2,3). The “weight” of the reciprocal lattice node, determined by the structural amplitude of the crystallographic plane corresponding to it, should not be zero, since in this case the reciprocal lattice node will be homologous to any point of the reciprocal space outside the lattice. Crystals with Bravais I, F, C – type cells in the reciprocal lattice are characterized by super cells, periods of which are n – times larger than ∗ = −1, where a is the period of the lattice cell. With respect to complex structures, even if they are single-element, the period of the super cell of the reciprocal lattice can exceed ∗ several times. For a diamond crystal ∗ = 4∗under the super cell of the reciprocal lattice it is necessary to use the smallest parallelepiped, the “weight” of all vertex nodes of which is not equal to zero.

  • Influence of carbon nanotubes and graphene on thermal and electromagnetic properties of PLA nanocomposites

    pg(s) 510-513

    This work investigate electromagnetic and thermal properties of poly(lactic) acid-based composites with graphene nanoplates (GNP) and multiwalled carbon nanotubes (MWCNTs), produced by solution blending method. It was found that the MWCNT carbon nanotubes are an effective filler for both absorption and reflection of electromagnetic waves in the GHz and THz frequency domains. The higher aspect ratio of carbon nanotubes, compared to industrial MWCNT, is the cause of better electromagnetic characteristics of nanocomposites prepared by solution blending method (SB). The DSC analysis of the samples shows that the glass transition is around 60oC, followed by cold crystallization with enthalpy and melting temperature around 150oC. The TGA analysis show, that the thermal stability of PLA polymer is improved by addition of 6% MWCNTs and GNP.

  • Micro-hardness of borid diffusion layers formed of semi permeable powder-metalurgical materials from the system Fe-C-Cu

    pg(s) 514-516

    Surface saturation with boron of Fe-C-Cu construction powder materials aims to improve the surface hardness of the articles and hence improve wear, contact strength and other mechanical properties. This study investigates the influence of single-component diffusion enrichment modes with boron of semi-permeable powder metallurgical samples from the Fe-C-Cu system. The powder samples on the basis of iron powders NC 100.24 to which 0,3 ÷ 2,5% Cu and 0,4% carbon were added were subjected to the study. Diffusion saturation with boron was carried out in semi-permeable saturation media with a composition of 84% Na2B4O7 + 12% SiC + 4% K2Cr2O7 at temperatures 850 ÷ 950 ° C for 2 ÷ 4 hours. Graphical dependencies are presented for the variation of the diffusion slit thickness in the longitudinal section of the test samples depending on their density, duration and saturation temperature. The experimental results obtained are compared with those obtained by combining pure iron samples with the same technological parameters.

  • Sprayed bronze and aluminum powders for restoring worn-out surfaces using gas-flame spraying

    pg(s) 517-519

    The information is given about small-sized equipment for producing sprayed powders of alloys based on copper and aluminum, intended for strengthening new and restoring worn-out surfaces by applying a gas-flame coating, as well as for the protection of parts against corrosion, process modes and powder properties. The high quality of the coatings obtained with the use of manufactured powders has been confirmed.

  • Selection of tribological plasma sprayed coatings using multi-criteria decision-making methods

    pg(s) 520-524

    Decision making methods have been examined within the context of conflicting criteria. Mechanical properties of a number of plasma sprayed coatings based on the modified alumina powder have been given for the purpose of comparative analysis. The modification has been performed by two different methods: 1) by cladding the alumina powder with Ti and Al metal sheaths where the PVD method has been employed; 2) by mechanochemical processing inside planetary ball mill with the titanium oxide nanopowder added. For coating selection, weighed characteristics technique has been used in conjunction with the digital logic and the proposed improved approach to the linear and non-linear data normalization. A conclusion has been made that the most effective, as far as the wear resistance parameter is concerned, are the coatings obtained as a result of the clad alumina powder spraying