DREPO UNIZA (University of Zilina)
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Kinematic analysis of parallel mechanisms using Screw theory
No full textThe aim of this paper is to summarise the mathematical basics of the Screw theory and its application in mechanics. The paper provides methodology for finding the degrees of freedom of the effector, as well as for determining its mobility. Furthermore, we give an input-output equation for velocities for the parallel mechanism, that allows to obtain the velocities of the effector and also of the actuated kinematic couples. These algorithms are applied to a planar parallel 3-RTR mechanism where we determine the degrees of freedom and mobility of the moving platform. We determine the input-output equation for velocities, and based on this we investigate the singularities of the moving platform
An engineering design of a rail adapter for a light lorry, a steel-steel type
No full textTransportation is a quite complex system for relocation of passengers and goods for longer of shorter distances. Nowadays, a combination of several types of transport is typical for the most countries. Land transport includes road transport and railway transport. There are number of types of vehicles used for these individual kinds of transport. The most of them are able to move only on a road or on a railway track. However, there are a quite narrow group of vehicles, which can move both on a road and on a railway track. There are called rail-road vehicles. In principle, there are derived from road vehicle. The main objective of this rticle is to present an engineering design of an adapter for a light lorry. The work brings the main structural units of the rail-road vehicle and compares its properties with the previous engineering design. Despite, there are rail-road vehicles, this engineering design is characterized, that the adapter allows to set railway wheels to main track gauge
Influence of temperature on Barkhausen noise in Co a Gd
No full textThe present paper deals with Barkhausen noise emission in Gd. Barkhausen noise emission was investigated in the temperature range mainly below the Gd Curie temperature when the spontaneous magnetization in Gd occurs. Barkhausen noise from the heavy rare-earth Gd is compared with Barkhausen noise emission from the transition metal Co measured at the same magnetizing and other conditions. This study demonstrates that Barkhausen noise emitted from Gd is much weaker than that originating from Co. This is a consequence of different spin exchange interaction among the neighbouring atoms, domain wall thickness as a well as domain wall energies. Moreover, Barkhausen noise is temperature sensitive especially for Gd sample as a result of the altering magneto-crystalline anisotropy
Evaluation of the change in the microgeometry of the metal surface with respect to the phosphating application time
Full text linkThe contribution is focused on the analysis of the microgeometry of metal surfaces after applying a conversion layer using phosphating. The types of basic materials used in the experiment are uncoated deep drawn steel DC04 and hot-dip galvanized microalloy steel HX340LAD+Z. During the application of the conversion layer, the changes of the microgeometry parameters of the surfaces were studied with respect to the phosphating time, which was 3, 5 and 10 minutes. The paper also deals with the statistical evaluation of roughness parameters of pre-treated surfaces. The achieved results provide information for other technological operations such as the creation of adhesive joints, where the correct anchoring of the adhesive is important for
the load-bearing capacity of the joints
Parametrically modulated oscillator in the asymptotic case
Full text linkThis article deals with the asymptotic solution in analytical form of some second-order linear differential equation with time-dependent parameters. Time-periodic modulation of the parameters of the oscillatory system can lead to interesting phenomena. The analytical solution is compared with the numerical solution obtained by the Runge-Kutta method in the MATLAB environment. The convergence conditions of this analytical method are discussed
Possibilities of using artificial intelligence in logistics
Full text linkThe paper focuses on the topic of the possibilities of using artificial intelligence in logistics. It provides basic information about the given topic, which is presented in the theoretical basis. It describes the definition, history and development and objectives of logistics. It also deals with aspects of Logistics 4.0 and the definition and history of artificial intelligence. The core of the work divides individual options between logistics platforms using artificial intelligence and logistics technologies using artificial intelligence, the principle of operation of which is subsequently described. The conclusion is devoted to the evaluation of the current state of use of artificial intelligence in the logistics industry. It also contains an overview of the advantages and disadvantages of the mentioned possibilities of use
The issue logistics in the scalding of forming tools and the issue of wear of active parts
No full textThe article deals with the specific issue of the logistics of forming tools within the company. The submitted contribution in a brief overview points to possible situations that may arise in the production process when applying forming tools. It is also pointed out the possibilities of solving the situations that arise in the production preparation stage. An addition is also pointing out the issue of wear and tear of active parts of clippers and their renovation
Barkhausen noise after shot-peening of duplex steel AlSi 318
No full textThis paper deals with surface integrity and the corresponding Barkhausen noise after shot peening of duplex steel AlSi 318 under variable shot-peening conditions such as number of passes and applied air pressure. Surface state is investigated from the point of view of surface roughness and surface plastic deformation. Barkhausen noise is decreasing along with increasing surface coverage as well as increasing air pressure. The duplex matrix is considered being stable with respect of volume fraction between austenite and ferrite and the whole Barkhausen noise signal originates from ferromagnetic ferrite. Progressively developed plastic deformation increases dislocation density in the surface as a result of surface bombardment by shots which in
turn shift Barkhausen envelopes into higher magnetic fields
Research of hybrid aluminium castings using foam cores
No full textThe paper focuses on the technological challenges posed by the production of experimental hybrid castings by overcasting technology. Theoretically, using this technology provides lower casting weight while maintaining positive mechanical properties and improves the energy absorption capability of the component. The effect of the pressure used during the foaming of the cores on the relative density of the metal foam component was experimentally evaluated. The challenge of the technology is the interface between the casting and the oxide coated core surface. Surface-treated cores were cast and their interfaces were observed microscopically. The experimental results showed a positive effect of the presence of AlPO4 in the interface to prevent the penetration of liquid metal into the pores of the foam core
The construction of a flexspline harmonic drive
No full textFlexspline is one of the most important components of harmonic drive. Flexspline is very adversely stressed during operation. In essence, stresses from deformation by the generator, stresses from the transmitted load and local stresses from the bending of the teeth in the tooth gaps act in it. Flexspline is radially flexible, but torsionally very stiff. When the wave generator is inserted into the Flexspline, the gear takes on its elliptical shape. When designing a flexible wheel, it is very important to determine and correctly choose its geometric properties