Засновник і видавець Національний університет «Львівська політехніка». Виходить двічі на рік з 2015 року.
Ukrainian Journal of Mechanical Engineering and Materials Science = Український журнал із машинобудування і матеріалознавства : науковий журнал / Lviv Politechnic National University ; editor-in-chief Oleksiy Lanets . – Lviv : Lviv Politechnic Publishing House, 2022. – Volume 8, number 2. – 76 p.
Український журнал із машинобудування і матеріалознавства
(Видавництво Львівської політехніки, 2022-02-22) Yakovenko, Yevheniia; Voichyshyn, Yurii; Horbay, Orest; Lviv Polytechnic National University
Regardless of the vehicle's application, the thermal comfort of the vehicle's
occupants and driver is given increased attention. Maintaining a sense of thermal comfort, whether
for safety, health or occupant thermal well-being reasons, is one of the most important goals of
heating, ventilation and air conditioning (HVAC) systems. There are a significant number of
physical variables that affect thermal comfort. Therefore, evaluating thermal comfort has always
been a complex issue and has attracted the attention of researchers. The feeling of thermal comfort is
provided by factors that depend on the heat exchange between the human body and the external
environment. It is well known that one of the requirements to be fulfilled is to find a person in
thermal neutrality in the environment according to the comfort equation.
The article describes and evaluates the following indicators: DTS (dynamic thermal
sensitivity), TS (thermal sensitivity), PMV (predicted mean voice) and PPD (predicted percentage of
dissatisfaction). The most common models for evaluating thermal comfort, namely the Predicted
Mean Vote (PMV), Taniguchi’s model, Zhang’s model and Nilsson’s model in a variety of car cabin
conditions, have been reviewed. The limitations of these models in terms of the objectivity of the
results obtained are analysed.
(Видавництво Львівської політехніки, 2022-02-22) Dzyubyk, Andrij; Dzyubyk, Liudmyla; Shpak, Bohdan; Lviv Polytechnic National University
Currently, there is a tendency to increase the depth of gaseous and liquid fossils
extraction. Therefore, prospecting and developing new deposits is promising. There is also a need to
create new freshwater sources and implement relevant geological work based on this need. It is
essential to have information about the characteristics of the explored slabs and the geology of the
fields in general. Implementation of engineering and geological core drilling exploration is the most
acceptable and provides the necessary data. Here, the peculiarities of the technological schemes of
the process implementation make it possible to obtain separate sections of structures at a depth of the
drilling equipment. It is essential to use traditional equipment, recommended for decades and
provides the necessary results [1–3]. In the drilling process, you can achieve different diameters and
depths of wells execution, obtain fossil samples etc. Engineering and geological exploration drilling
is now taking on increased use in various industries . Therefore, the problem of providing highquality drilling tools, the stability of their operating characteristics, and the possibility of usage in
different conditions is an urgent need today.
Modern drilling problems determine the usage of components of the core set with the
appropriate physical and mechanical characteristics. Especially it relates to elements close to the
drilling tool and the place of fossil; destruction – drill pipe. It is installed immediately after the
crown core drill and receives almost the same loads and effects during working [1–3].
Conditions for the implementation of the process of core drilling are characterized primarily
by the effect on the elements of the significant axial and twisted core set forces. There is the
influence of the corrosive and active environment of the fossil in the washing and lubricating liquids
well, etc. High temperatures are also observed at the drilling sites , which negatively affect the
working tool and speed up its operation.
As a result, there is an intensive shock, and abrasive core pipe wear and operation indicators
change their constructive size. As a result, it is necessary to replace the operated drill string
periodically. Considering modern technical and economic factors, it may be decided to repair a pipe
to its original size in many cases. There are tasks for providing the appropriate characteristics of the
core pipe surface. It is possible to model such properties of the new surface that functionally the best
meet the conditions of the drilling process of a given geological formation.
The peculiarities of applying the therapeutic layer on the surface of the core pipe are
investigated in work. The experience shows that using electric arc surfacing under the flux layer is
expedient. This provides the necessary adhesion of the applied layer and promotes obtaining
resistance to the operation surface of the core pipe. At the same time, there is high-quality protection
and the possibility of additional alloying through the flux-slaggy welding bath.
Using electrode powder type wires creates conditions for flexibility to achieve the established
characteristics of functional layers [4–6]. The filling flux, located in the cross-section of the
electrode wire, can be easily changed by chemical composition. At the same time, it is possible to
make relatively small parties of a wire with the set characteristics.
The technological scheme justification about the core pipe surfacing is performed. It provides
the previous displacement of the electrode butt size from the zenith of the core pipe to prevent the
welding bath from spreading. The structural pipe size , the requirements for residual deformations,
and the conditions of shapping the welded layer show the practicality of welding on a helix.
(Видавництво Львівської політехніки, 2022-02-22) Zinko, Roman; Hlobchak, Mykhailo; Beshley, Andiy; Pitrenko, Oleksiy; Lviv Polytechnic National University; National Aerospace University “Kharkiv Aviation Institute”
Problem statement. Any methodology is based on knowledge about the problem.
The fullness and orderliness of the base determine further volumes and possible options for
implementing the methodology. Purpose. To analyze the existing ways of machine creations and
propose the new effective algorithm of machine creation using the mechanism of articulated
disjunction. Considering the research structure and improvement of the informational and program
technologies, changes to the traditional methodology of machine creation are made. The existing
paradigm: parametric and functional performance of the machine, the design of which is improved
based on existing machines, is a modification of predecessors' parametric and functional
performance. Proposed paradigm: parametric and functional performance of the new machine,
improved based on the subject area of technical solutions, methods of design and operational
conditions more precisely coincide with the technological process to realize what they are called.
Proposed hypothesis: there are such methodologies of design that provide an opportunity to provide
rational productivity within existing operational conditions. Methodology. Morphological space is
used to form qualitative features of the created machine. The peculiarity of the proposed
methodology is that the set of features of the created machine also contains subsets of processes and
phenomena in which the machine is involved. This allows assessing the compliance of the process in
which the machine is involved and the machine operation processes. Findings (results). The
algorithm of machine creation using the mechanism of articulated disjunction is proposed. It allows
the creation of the new construction at a given sequence of stages to improve at every step in a given
direction based on the determined criteria. Originality (novelty). Method of articulated disjunction,
which is based on the principle of formation of the set of necessary properties of the structural
elements of the machine based on a given primary criterion of machine efficiency. The essence of the
method of articulated disjunction is that the sample of elements that have common features and properties
is reformulated based on a given criterion. The proposed method provides an opportunity to determine
the advantages of one structure described by various factors, in comparison with others, based on the
criterion set. Practical value. The algorithm of synthesis and improvement of existing machines allows
for determining their main quality features in the initial stages of the design of machines.
(Видавництво Львівської політехніки, 2022-02-22) Lanets, Oleksii; Maistruk, Pavlo; Maistruk, Volodymyr; Derevenko, Iryna; Lviv Polytechnic National University
Problem statement. To ensure highly efficient inter-resonance modes of operation of
vibrating equipment, the oscillating masses of the system must have certain inertia-rigid parameters, as
well as a certain frequency of natural oscillations. The disadvantage of highly efficient inter-resonance
oscillatory systems is that the third reactive mass must be small, and therefore the use of complex and
large structures is impossible. Therefore, it is best to use the reactive mass as a continuous section. The
continuous section, which is a flexible body, optimally combines inertial and rigid parameters.
Scientific works have already considered the design of the vibrating table, in which the continuous
section is an ordinary rectangular plate hinged in the intermediate mass. This decision looks quite
promising. However, likely, the rectangular shape of the plate is not the best option to ensure
maximum energy efficiency. Purpose. Extend the method of calculating the natural frequency of
oscillations of the plates by the approximate Rayleigh-Ritz method using the general hyperboloid
equation to plates with variable cross-section for the proposed types of plates and check the results
with the calculation in Ansys software. Methodology. The calculations of the plates were performed
using the basic principles of the theory of oscillations, in particular the Rayleigh-Ritz method in the
software product MathCAD. Findings (results) and originality (novelty). Two types of elastic plates
with variable cross-sections are considered. In the first case, the shape of the plate was given by
quadratic functions, in the second case, it was described by trigonometric functions of cosine. In both
cases, the same conditions of attachment in the intermediate mass were observed. The calculation of
the first natural frequency of oscillations of the considered plates was performed using the approximate
Rayleigh-Ritz method with the assumption that the deflection of the plates occurs on the surface of the
hyperboloid. The reliability of the obtained results was verified by numerical calculation in the
software product Ansys. Practical value. It is assumed that the proposed types of plates can increase
the dynamic potential of the vibrating machine. Scopes of further investigations. For further study of
the considered types of plates as a continuous section of the inter-resonance vibrating machine, it is
necessary to calculate their deflections at forced oscillations.
(Видавництво Львівської політехніки, 2022-02-22) Rebot, Dariya; Babii, Artom; Lviv Polytechnic National University
A review of recent research in the field of vibration separation of bulk media has
been done. It was found that the productivity of the separation process is influenced not only by the
design characteristics of the vibrating separator, in particular the length, angle and capacity of the
working housing, but also the dynamic processes that occur in bulk medium during separation. The
efficiency of the separation process significantly depends on the mutual influence of the velocity of
the bulk medium along the separator sieve and its amplitude-frequency characteristics. Based on the
review, the relevance of further study of these parameters was established. Using the methods of
nonlinear mechanics, a mathematical model of the motion of the layer of bulk medium on the sieve
of the vibrating separator was built. The layer of bulk medium was modeled by an elastic beam,
which is in contact elastically, rigidly, or as hinged. Graphical dependences of the influence of the
frequency of external perturbation and the velocity of the bulk medium along the sieve of the
separator on its oscillation amplitude were obtained. The obtained mathematical model and graphical
dependences showed that small velocities of the medium layer lead to an increase in the amplitude
of oscillations of the bulk medium and a decrease in its frequency of oscillations, which increases
the permeability of medium particles and increases the productivity of the separation process. The
obtained researches allow us to increase the efficiency of the separation process, to regulate the
processes that take place in the bulk medium and to increase the speed of its passage through the
sieve openings. The constructed mathematical model can serve as a basis for further studies of the
influence of changes in the physical and mechanical characteristics of the bulk medium on its
dynamic parameters in the process of vibration separation.
(Видавництво Львівської політехніки, 2022-02-22) Pal, Vinay Kumar; Singh, Lokendra Pal; Sam Higginbottom University of Agriculture, Technology And Sciences Allahabad
In the research work presented in this study microstructure evolution at fracture
frontier of crept P92 weld, creep rupture life and effect of creep exposure time on microstructure
evolution in fine-grained heat affected zone were performed. Microstructure evolution and creep
rupture behavior of metal arc welded joint of P92 steel plate in the as-welded have been studied. The
different states of post weld heat treatment (PWHT). (i). post welded heat treatment at 760 °C for the 2h (ii). re-austenitizing at 1040 °C for 60 min
and air cooled and tempering at 760 °C for 2h. In
PWHT condition, most common type IV cracking was observed creep exposure 620 °C / 150 MPa.
The martensitic matrix fracture is also observed in PWNT 1 condition. A move away from the
fracture frontier, the cavities still remain in the microstructure while the martensitic matrix fracture
is difficult to observe. The line mapping also confirmed the increase in weight percentage of Cr and
Mo in M23C6. The elemental mapping of PWHT 2 condition is also carried out in FGHAZ which
confirm the formation of Mo and Cr-rich M23C6 precipitates.