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EN
The aim of the study described herein was to design, construct and test a demonstrator of a system to control the direction of the resultant thrust vector of a rocket motor to be used in short range anti-tank missiles with a mass of up to 15 kg. The novelty of the system is that the direction of the resultant thrust vector is manipulated by means of moveable jet vanes integrated with a moveable nozzle diffuser through telescopic connectors. The technology demonstrator was built using different materials and different manufacturing processes. The first versions were 3D printed from plastic materials. Minor modifications to the design were made at an early stage. The final version had the main components made of aluminum using CNC machining. The system, with and without jet vanes, was tested on a specially developed test rig equipped with a multi-axis sensor to measure forces and torques. The nozzle performance parameters measured and analyzed in this study were the components of the thrust vector, the moments and the effective vectoring angle. The findings show that the experimental data are in good agreement with the results of earlier simulations and that the demonstrator is fully operational.
EN
Electrodynamic shakers are being used for years in dynamic tests of machines and devices. One of the main components of electrodynamic shakers is the armature suspension. Suspension is one of the factors responsible for the dynamic characteristics of the shaker. Various types of suspensions are used in shakers [1, 2]. Their role is to ensure the correct stroke of the armature and to keep the coil concentrically in the magnetic gap. As part of the research, the influence of the shape of the suspension springs of the electrodynamic shaker on its dynamic characteristics was evaluated. During the research, self-designed electrodynamic shaker was used, in which a suspension consisting of two-disc springs made of glass fiber with a thickness of 0.5 mm was used. Eight different spring types were prepared for the study. The tests were carried out in laboratory conditions on a previously prepared test bench. For each of the springs tested, dynamic frequency characteristics were determined for three frequency ranges: 10 - 100 Hz with a step of 10 Hz, 100 Hz - 1000 Hz and 1000 Hz - 10000 Hz with a step of 100 Hz. Studies show a significant influence of the shape of the springs used on the dynamic characteristics of the modal shaker. For the preselected springs, tests were carried out without and with a load. The characteristics determined during the research were analyzed, which allowed to indicate the optimal shape of the spring, due to the values of the generated force and the linearity of the dynamic characteristics [3, 4].
EN
The need to classify rocks in terms of workability stems primarily from the need to choose the appropriate, most effective diagnostic method (DM) and way of mining the given rock. Studying and measuring the workability of rocks is extremely difficult due to the fact that workability depends on many various factors. There are many DM for determining the workability of rocks, but none of them take into account the influence of all factors, hence the obtained results are only indicative. In the article, many DM and ways of determining the cutting resistance with the use of various devices are presented and characterized. The principles of their operations are presented, as well as the DM of measuring the cutting resistance and its utilitarian usefulness in forecasting the selection of mining machines on the basis of cutting for specific mining and geological conditions. The core of the problem is confirmed by the number of covered DM and tools in various research centers around the world. In the article, new tools measuring and evaluating the mechanical properties of the coal solid, all created in Poland, are presented. Their structure, principles of their operation, as well as the innovation of these solutions, are all presented. In this article, their ad-vantages and disadvantages are highlighted, as well as showing the DM which best represents the way of work of the winning machine. Therefore, the results achieved through the aforementioned DM can be understood as representative values.
EN
The article presents the results of the bearing capacity of reinforced concrete beams with and without damages of internal reinforcement. One of the main elements of the production of the reinforced concrete industry is beams. The analysis of the experimental tests showed that the bearing capacity of reinforced concrete beams with damaged tensile main reinforcement decreases according to control undamaged samples due to the reduction of the reinforcement cross-section. However, the bearing capacity of reinforced concrete beams with tensile main reinforcement Ø20А500C, damaged to the cross-section area equal the rebar Ø16mm is more on 3.7… 24.0% than the bearing capacity of reinforced concrete beams with undamaged Ø16mm rebar. This is due to the non-uniform material properties of used thermally strengthened reinforcement A500C. When during testing the tensile main reinforcement is damaged by drilling a hole, the most damages occur in the core with lower physical and mechanical characteristics. In contrast, the outer thermally strengthened layer with bigger physical and mechanical characteristics is damaged to a lesser extent. The analysis of the obtained results shows that during design of reinforced concrete beams with damaged, it is necessary to consider using thermally strengthened non-uniform steel A500C as tensile main reinforcement.
PL
W artykule przedstawiono wyniki badań laboratoryjnych wykonanych na belkach ze środnikami z blachy fałdowej o różnym profilu sinusoidalnym poddanych działaniu czteropunktowego zginania. Przeprowadzone badania wykazały, że kształt fali ma znaczny wpływ na nośność na ścinanie belek dwuteowych ze środnikiem sinusoidalnym. Uzyskane wyniki odniesiono również do wyznaczonej nośności normowej, która była na niższym poziomie, niż wynika to z badań doświadczalnych.
EN
This paper presents the results of laboratory tests performed on beams with corrugated plate webs of different sinusoidal profiles subjected to four-point bending. The conducted tests showed that the parameters of the waveform have a significant effect on the shear strength of I-beams with sinusoidal webs. The obtained results were also related to the determined norm load capacities, which were at a lower level than the experimental results.
EN
Purpose: The purpose of this paper is to analyse the obtained experimental data, which is advisable to use to verify the thermophysical model of the thermal regime of a separate premise while using ceramic electric heating panels for heating purposes. Design/methodology/approach: The experimental studies were carried out at the scientific thermophysics laboratory with the help of up-to-date equipment (including the design for these studies). After gathering experimental data, it was analysed, and with its help, a CFD model of the thermal regime of the laboratory premise would be verified. Findings: The conducted experimental studies showed that in the artificially created quasi- stationary thermal regime of the laboratory premise, the air temperature varied with height in a small interval. This makes it possible to state that when using ceramic electric heaters as heating devices, the air temperature is relatively evenly distributed over the height of the premise. Research limitations/implications: The research provides original experimental data and findings for further CFD modelling of the thermal regime of the premise while using heating ceramic panels. Practical implications: The mentioned in the paper research methods as well as obtained experimental data, could be used in further studies of modern heating systems. Another use of the results – during the validation of CFD models. Originality/value: The paper includes the design and methodology of creating the original experimental stand for research of the different heating systems types.
EN
The aim of the research is to develop a front bumper system that absorbs maximum impact energy as compared to the current bumper available in the market, Bumper design is based on increasing the area of the crumping zone to slow down the collision and observe the impacts taking place at the time of jerks and reduces the percentage of damage. To develop the system, the number of load cases tested numerically in passive safety simulation has increased significantly in recent years. The variety of applications may be divided into three main topics: structural crashworthiness of the whole car, passenger protection, and crashworthiness of components. Present theories and practices. To absorb impact, the front bumper of the car uses a spring-loaded system that is installed between the bumper and the support for the chassis structure. This system is made of metal and serves as the bumper's structural foundation. A honeycomb structure is being added to the bumper as a composite material together with a layer of galvanized iron as it is being created in this manner, which increases strength while weighing less. This arrangement design is suitable for psychoacoustics, varying velocity explicit analysis is performed with the approach of finite element analysis, experimental testing is carried out for the validation of the value and advanced manufacturing methods are implemented with statistical results, and one of the cheapest systems is developed as compared to the current bumper systems.
EN
This study aimed to approximate the operating characteristics of steam traps through experimental research and mathematical analysis. The research presented the phenomena leading to the development of steam traps, their relevance to power engineering and production plants, and the energy properties of water vapor for heat transport and exchange. The study also discusses problems that can occur in steam systems and how steam traps can prevent adverse phenomena. The experimental studies allowed the researchers to determine the operating characteristics of steam traps, and mathematical analysis extended the results to other cases.
EN
The study continues the advanced analytical modelling of the linear elasticity and viscoelasticity of thermosets and unidirectional glass fibre-reinforced thermoset-matrix (UFRT) composites. The thermosets are isotropic materials with viscoelastic shear strains and elastic bulk strains, and the fibres are isotropic and elastic. The modified homogenization theory for UFRT composites, based on the selected tasks of the linear theory of elasticity, is developed. The modifications include a volumetrically equivalent cylindrical representative volume cell, solutions determined for an isotropic fibre based on the solutions for a monotropic (transversely isotropic) fibre, and certain modifications in the third task of the theory of elasticity. The viscoelastic constants of the thermoset are derived analytically and validated by fitting of the simulation and experimental shear strains on a logarithmic time scale in the unidirectional tension creep test. The viscoelastic constants of the UFRT composite are derived analytically and validated by fitting of the storage compliances corresponding to the new viscoelastic model and one obtained from the viscoelastic-elastic correspondence principle. The tension creep experiment is performed on the selected structural unsaturated polyester resin. Identification and validation are carried out for that thermoset and the corresponding UFRT composite with long E-glass fibres. All the modelling hypotheses are confirmed.
EN
The aim of this study is to investigate the effect of partial substitution of cement by a smart mixture of waste materials, fly ash and Crepidula shells. The cement is replaced by fly ash and Crepidula accordingly in the range of 5, 10 and 15% by weight. This study focuses on three steps: (i) find the best formulation in terms of compression and hygrothermal behavior, (ii) build a prototype and follow the hygrothermal behavior with sensors, (III) data collection and development of a neural network model to predict the hygrothermal behavior of the prototype. The results showed that for a fly ash-Crepidula incorporation rate up to 10%, the mechanical properties are higher than the control mortar. Furthermore, the cement substitution by fly ash and Crepidula improves the thermal conductivity of concrete. With the cement replacement of 30%, a prototype was built to monitor the hygrothermal behavior. The data collected from the wireless sensors placed in the prototype are used to train and validate the artificial neural network model. The model used in this study is conducted with eight inputs and two outputs data. The investigation of the condensation risk and the mould growth shows that the chosen concrete mixture can avoid the condensation phenomenon. Indeed, the smart fly ash-Crepidula mixture provides high silica, aluminate, and calcium contents, which react with water originating from humid ambient air to form additional hydrates as a result of pozzolanic reaction and lead to a continuous strengths enhancement.
EN
The issue of indoor swimming pool ventilation is very complex, which is a serious problem in their proper design and modernization. The difficulty is that in Poland there are no uniform regulations and standards regarding the required values of ventilation air parameters, the method of calculating moisture emission and the value of me ventilation air volume flow rate. In research, design and modernization of ventilation systems for swimming pools, various methods are used to determine the emission of moisture from the water in the swimming pool basin and there is no complete information as to which of them best reflects the actual thermal-moisture and airflow phenomena. This paper presents a developed and validated research method related to the modeling of moisture emission from the pool water surface, which can be used for the modernization of ventilation systems in the existing indoor swimming pools, due to the need to improve thermal-moisture conditions.
PL
Problematyka wentylacji hal pływalni jest bardzo złożona, co stanowi poważny problem we właściwym ich projektowaniu i modernizacji. Utrudnieniem jest również to, że w Polsce brak jest jednolitych przepisów i norm odnośnie do wymaganych wartości parametrów powietrza wentylacyjnego, sposobu obliczania emisji wilgoci oraz wartości strumienia objętości powietrza wentylacyjnego. W badaniach, projektowaniu i modernizacji systemów wentylacji hal pływalni stosowane są różne metody wyznaczania emisji wilgoci z wody w niecce basenowej i nie ma pełnych informacji, która z nich najlepiej odwzorowuje rzeczywiste zjawiska cieplno-wilgotnościowe oraz przepływu powietrza. W niniejszym artykule zaprezentowano opracowaną i sprawdzoną metodę badawczą związaną z modelowaniem emisji wilgoci z lustra wody basenowej, która może być zastosowana przy modernizacji układów wentylacji w istniejących obiektach krytych pływalni, z uwagi na konieczność poprawy warunków cieplno-wilgotnościowych.
EN
Dynamic tests with different load ratios and frequencies provide designers with the necessary information to evaluate the longevity of different structures as well as minimize weight due to a possibly smaller factor of safety. The influence of loading frequency on the fatigue behaviour of an aluminium composite material (ACP) with an aramid honeycomb core was studied. The mechanical behaviour was assessed by three-point static bending tests, followed by cyclic flexural fatigue tests employing the fabricated sandwich samples, with loading frequencies of 5, 7.5 and 10 Hz. The experimental results were presented on a single graph in order to highlight the different behaviours for the adopted frequencies. Indeed, the tests allowed the authors to determine the different cycle number values necessary to achieve resistance losses of 10 and 25%, respectively. The experiments were carried out for the same loading level of 80% of the maximum force, which is taken as equal to the elastic limit in order to avoid the field of plastic deformations.
EN
This research presents an experimental study carried out for the modeling and optimization of some technological parameters for the machining of metallic materials. Certain controllable factors were analyzed such as cutting speed, depth of cut, and feed per tooth. A dedicated research methodology was used to obtain a model which subsequently led to a process optimization by performing a required number of experiments utilizing the Minitab software application. The methodology was followed, and the optimal value of the surface roughness was obtained by the milling process for an aluminum alloy type 7136-T76511. A SECO cutting tool was used, which is standard in aluminum machining by milling. Experiments led to defining a cutting regime that was optimal and which shows that the cutting speed has a significant influence on the quality of the machined surface and the depth of cut and feed per tooth has a relatively small impact on the chosen ranges of process parameters.
EN
The control of product shape and dimensions poses some problems in hot ring rolling. In the rolling process, material flows both circumferentially and axially, which leads to increased ring height. Changes in shape and dimensions of ring cross section depend on several process parameters, which makes it difficult to predict ring diameter. This paper presents the results of a study investigating the hot radial rolling process for C45 steel rings in terms of the effect of main roll feed speed on product geometry. It was found that the application of a higher feed speed of the main roll and thus of a greater ratio between this speed and circumferential speed of the main roll led to increased axial material flow and reduced cross-sectional defect known as ”fishtail”. Machining losses generated due to cross-sectional defects were also determined. Results were used to determine the feed speed to circumferential speed ratio ensuring the lowest possible cross-sectional defect and material consumption.
PL
Celem pracy był projekt i budowa laboratoryjnego stanowiska pomiarowego do wyznaczania współczynnika przewodzenia ciepła otulin izolacyjnych o pierścieniowym polu przekroju poprzecznego i określonej długości. Jest to szczególnie istotne zagadnienie w przypadku rurociągów ciepłowniczych, gdzie izolacja cieplna odgrywa znaczącą rolę przy poprawnej pracy instalacji. Pomiar współczynnika przewodzenia ciepła otulin izolacyjnych na zbudowanym stanowisku badawczym bazuje na metodzie rurowej, która polega na rozwiązaniu równania różniczkowego ustalonego przewodzenia ciepła w przegrodzie walcowej o nieskończonej długości. Stanowisko zostało wyposażone w dwie sekcje pomiarowe, na których możliwy jest jednoczesny pomiar dwóch różnych próbek badanych izolacji. Wykonano wstępne pomiary cieplne różnych materiałów izolacyjnych na każdej sekcji osobno oraz na obydwu sekcjach uruchomionych jednocześnie. Na podstawie przeprowadzonych pomiarów była możliwa weryfikacja poprawności budowy i działania stanowiska pomiarowego, jak również walidacja zastosowanej metody pomiarowej. Wykonano również pomiary temperatury za pomocą kamery termowizyjnej, dzięki czemu możliwe było ustalenie rozkładu temperatur na sekcjach pomiarowych. Otrzymane wartości współczynnika przewodzenia ciepła badanych materiałów izolacyjnych porównano z wartościami katalogowymi tych materiałów oraz dokonano analizy możliwych rozbieżności wyników.
PL
Istotnym ograniczeniem praktycznej implementacji obliczeń zmęczeniowych w praktyce inżynierskiej jest długotrwałość i przez to kłopotliwość przeprowadzenia badań eksperymentalnych prowadzących do wyznaczenia podstawowych charakterystyk. Z faktu tego wynika pewien nurt prac o charakterze naukowym nawiązujących do typowo analitycznych sposobów wyznaczania tych charakterystyk (np. prace Schijve [1]). Ze względu na dominujące znaczenie podejścia fenomenologicznego do nauki o zmęczeniu, próba zaproponowania metody analitycznej nie wydaje się ani niewłaściwa, ani niewystarczająca.
EN
The paper presents its own proposition of an analytical method for determining the S-N characteristic. The method is based on the value of the directional coefficient of the limited fatigue life line, determined based on the database of these parameters for a given group of materials. In addition, the parameters of the method are: tensile strength and number of load cycles assigned to the knee point of the characteristic.
17
PL
Gięcie jest metodą kształtowania wyrobów polegającą na plastycznym odkształcaniu materiału pod wpływem działania momentu zginającego. Odkształcenia sprężyste materiału będące efektem relaksacji części sprężystej naprężeń wewnętrznych po odciążeniu są jednym z podstawowych zjawisk decydujących o dokładności wymiarowo-kształtowej formowanych elementów.
EN
To improve gas hydrates dissociation technology, studies of heat transfer processes on the interfacial surface are significant. In the work, experimental and theoretical studies of the gas hydrates dissociation are presented. The scientific novelty is in establishing quantitative characteristics that describe the gas hydrates thermophysical parameters thermophysical characteristics influence on the heat transfer processes intensity on the interphase surface under conditions of gas hydrates dissociation. Based on the results of experimental studies, approximation dependences for determining the temperature in the depths of a dissociating gas hydrate array have been obtained. Gas hydrates dissociation mathematical model is presented. The practical significance of the research results is in determining quantitative indicators of the heat transfer processes intensity under the conditions of propane hydrate dissociation. The results of the work can be applied to designing equipment for gas hydrates storage and dissociation.
PL
Badania procesów wymiany ciepła na powierzchni międzyfazowej mają ogromne znaczenie dla poprawy technologii dysocjacji hydratów gazowych. W pracy przedstawiono eksperymentalne i teoretyczne badania dysocjacji hydratów gazu. Nowość polega na ustaleniu cech ilościowych, które opisują wpływ właściwości termofizycznych hydratów gazu na intensywność procesów wymiany ciepła na powierzchni międzyfazowej w warunkach dysocjacji hydratów gazu. Na podstawie wyników badań eksperymentalnych uzyskuje się zależności aproksymacyjne do określania temperatury na głębokościach dysocjującego układu hydratów gazu. Przedstawiono matematyczny model dysocjacji hydratów gazu. Praktyczne znaczenie wyników badań polega na określeniu ilościowych wskaźników intensywności procesów wymiany ciepła w warunkach dysocjacji hydratu propanu. Wyniki można zastosować w projektowaniu urządzeń do magazynowania i dysocjacji hydratów gazu.
PL
Artykuł dotyczy symulacji numerycznej przeprowadzonej z uwzględnieniem wyników badań eksperymentalnych. Autorzy zaprezentowali sposób obliczania prędkości wylotowej na podstawie średniego punktu trafienia. Badania zostały przeprowadzone na podstawie systemu broni - amunicji (Acccuracy Interantional A W - Lapua Magnum 250 gr Scenar). Symulacje przeprowadzono, stosując kalkulator balistyczny typu Kestrel.
EN
The article concerns the numerical simulation carried out for the price of experimental research. The authors presented a method of calculating the muzzle velocity at the mean hit point. The tests were carried out for the price of the weapon-ammunition system (Accuracy Interantional AW - Lapua Magnum 250 gr Scenar). The simulations were included in the prices for the Kestrel ballistic calculator.
EN
Purpose: Experimentally substantiate the possibility of using the developed jet-centrifugal spraying device in plants spraying technologies. Design/methodology/approach: Many years of experience in creating spraying devices for solving practical problems in various industries made it possible to propose a design diagram of a single-phase jet-centrifugal spraying device. The tests were aimed at achieving device characteristics that are acceptable for use in plants spraying technologies such as jet coverage distance, droplet size and droplet deposition area (spray diameter). For this a several tests series with different design parameters was done. Before testing, the tightness of the device body was checked (the holding time under a pressure of 1 MPa is not less than 2 minutes). Findings: Based on the obtained jet coverage distance, droplet size and droplet deposition area, the developed spray device of some modifications can be used in plants spraying technologies. However, it is necessary to determine the quality of the spray device according to the BCPC classification; the device should be tested with some insecticides, fungicides and in plants spraying technologies to develop recommendations for their use. Research limitations/implications: The influence of design features of developed jetcentrifugal spray device on the jet coverage distance, droplet size and droplet deposition area was studied. Practical implications: The results obtained are useful in the field of improving national plants spraying technologies in order to improve the quality of the plant protection agent application and reduce the loss of the drug into the environment. Originality/value: To ensure maximum efficiency the proposed design of the jetcentrifugal spray device can be upgraded directly by the farmer by installing interchangeable nozzles that are attached with a union nut. Replaceable nozzles have different diameters and modifications and can be selected depending on the required jet coverage distance and spraying dispersion according to the current environmental conditions.
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