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Impact Damage Tolerance of Multilayer Epoxy-Glass Composites with Xps Core and Polyurethane Prepolymer Modified Matrix

Masiewicz Joanna, Przybyłek Paweł, Szczepaniak Robert, Zahorski Tomasz, Kostrzewa Marcin, Czyż Mateusz

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 6

218--226

EN

A significant need within the design of materials for vehicles or other engineering structures is to determine their potential to mitigate impact loads. The material acting as a shield during an impact absorbs energy, dissipating the excess in a process of irreversible deformation. In order to prevent this, or to limit the areas of damage as much as possible, have begun to be used materials that absorb impact energy without drastically compromising their strength. Energy Absorbing Composite Structures (EACS) have the ability to convert impact energy into some form of energy absorbed through deformation. Compared to homogeneous materials, a numer of factors also point to the increasing advantage of using composite sandwich structures, which, in addition to their high strength ratings, have a lower weight and a much more effective ability to absorb shock or impact load energy. This paper presents the results of damage tolerance testing of epoxy-glass sandwich composites with chemical modified matrix. The damage tolerance of the composites was determined using an Instron CEAST 9340 testing machine with an impact energy ranging from 5-35J and indicated the value at which visible damage to the composite occurs while it retains some of its strength properties. It was the most important test to determine the damage tolerance, but additional tests to characterise the strength of the composite more comprehensively were also performed. Experimental studies were used to present a methodology for the preliminary characterisation of the material strength and to analyse the relation between structure and mechanical response of the composite.

2

Testing the thermal properties of the insulating structures of a flight data recorder

Panas Andrzej J., Szczepaniak Robert, Krupińska Anna, Łęczycki Krzysztof, Nowakowski Mirosław

Acta Mechanica et Automatica

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2024

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Vol. 18, no. 2

244--251

EN

This paper deals with the problems faced during the research on the insulating structures used in the thermal shielding of flight recorders. These structures are characterised by specific properties determined by, among other aspects, their porosity. The complex and coupled heat-exchange phenomena occurring under the operating conditions of the recorders, and in numerous cases combined with mass exchange, require dedicated test methods. The paper characterises the origin of the research problem, presents a methodology for comprehensive testing of the thermal propertiesand uses the example of determining the insulating properties of the Promalight microporous structure ®-1000R. The authors focussed on thermal diffusivity tests performed by means of the oscillatory excitation method. The measurements were conducted on a test stand to determine the effect the type of gas filling had on the porous structure and the pore filling gaspressure effect on the temperature characteristics of apparent thermal diffusivity. The authors also conducted research on the structure’s resistance to direct flame exposure. The analysis of the obtained results enable recognition and characterisation of the key phenomena of heat and mass transfer; the numerical results exert a significant influence on their application.

3

An assessment of the reliability of CFRP composites used in nodes of friction after impact of UV-A impacts and thermal shocks

Krzyzak Aneta, Racinowski Damian, Szczepaniak Robert, Kosicka Ewelina

Eksploatacja i Niezawodność

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2023

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Vol. 25, no. 4

art. no. 174221

EN

This article describes the results of tribological research into epoxy-based composites reinforced with carbon fiber. The composites were subjected to accelerated tests simulating asemi-annual influence of environmental conditions of an elevated temperature, precipitation in combination with an influence of UV-A radiation of 0.83 W/m2 as well as cyclic thermal shocks causing a leap temperature difference of 116.5°C. The process of friction was conducted in conditions of dry friction and wet friction in the presence of water. The authors found apositive influence of a two-month impact of environmental conditions upon increasing wear resistance. They found a reduction in weight in conditions of friction with water. At the same time, a reliability analysis for the same boundary conditions showed an increased risk of critical composite damage. The article indicates areas of safe exploitation of composites and areas of the necessity of withdrawing composites from further exploitation under the assumed environmental and tribological loads.

4

The Possibility of Using the Finite Element Method for Determining Thermal Diffusivity on the Example of Nickel Using the Classic and The Modified Pulse Method

Szczepaniak Robert, Terpiłowski Janusz, Woroniak Grzegorz

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 6

274--287

EN

The main purpose of the work is to present the possibility of using the finite element method implemented in the COMSOL 3.5a program in the heat transfer symmetry 2D module to determine thermal diffusivity by the classic and modified pulse methods. The method of determining the thermal diffusivity by means of measuring and recording the course of the temperature difference between the extreme surfaces of the tested sample and changes in the temperature increase on the back surface after a laser shot at its front surface, assuming that the sample is adiabatic for a representative experimental course at a given temperature, is discussed. This paper presents the basic metrological conditions for the implementation of the modified pulse method for testing the temperature characteristics of thermal diffusivity on the example of nickel. The heat pulse generated by the laser method at the extreme surface of the sample for a thermostatic temperature of 341.8 °C was simulated. Using the inverse problem in both the classic and modified methods, the thermal diffusivity of the material in question was determined and these results were compared with the experimentally obtained values. The values of thermal diffusivity differ from those obtained experimentally by 3.3% for the classic method and approximately 2.5% for the modified method. A preliminary analysis of the influence of the number of nodal points on the numerical results obtained was also carried out and the results for the number of nodes between 64 and 17,000 change by only 1.1%. The paper presents a combination of experimental and numerical studies which is useful in science and simplifies the process of time-consuming experimental studies.

5

The Influence of Metal Reinforcement upon the Ablative Properties of Multi-Layered Composites

Przybyłek Paweł, Komorek Andrzej, Szczepaniak Robert

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 2

111--119

EN

Fibre-metal laminates combine both the properties of metal and composite materials, reinforced with fibres; first such laminates already appeared at the end of the 70s. Alongside with the emergence of spacecraft, in which the external plating heats up to temperatures even exceeding 3000 °C, there was a demand for new materials, with increased thermal resistance. Moreover, high thermal resistance is also required in the construction of different protective casings for sensitive equipment, e.g. flight data recorders. In order to protect a spacecraft from massive amounts of heat This article presents research findings, aimed at determining the influence of including metal reinforcement in the form of steel sheet upon the thermal resistance of a multi-layered polymer composite. The samples were exposed to a mixture of hot gases at a temperature of over 900 °C for a period of approximately 150 s. The most important parameter determined on the basis of experimental research was the temperature of the rear surface of the sample. It was observed, that the addition of metal reinforcement causes stabilization of the temperature of the back wall of the sample and a decrease in temperature of the rear wall surface of the insulating sample by approximately 45% and approximately 2-fold increase in the ablative mass loss.

6

The Influence of Conditioning on Dynamic Behaviour of Polymer Composites

Borowiec Marek, Szczepaniak Robert, Machado José

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 5

195--207

EN

The aim of this study is to determine the effect of environmental factors in the form of UV radiation and temperature on the amplitude-frequency behaviour of polymer composites (prepregs) based on a framework of thermosetting epoxy resin reinforced with high-strength R-glass fibres. Two series of composites with different fibre arrangements were prepared. The series had fibres arranged at angles of 30°, 45°, and 60°, at symmetric and asymmetric orientations in relation to the central layer. The composites were subjected to conditioning which simulated a six-month period of use in the spring and summer in the temperate warm transitional climate of Central and Eastern Europe. An UV QUV/SPRAY/RP accelerated aging chamber manufactured by Q - Lab Corporation was used for this purpose, and UV-A 340 lamps were used to simulate daylight. In addition, varying loads caused by sudden temperature changes were simulated using the Thermal Shock Chamber T/60/V2 Weisstechnik. Conditioned samples were tested using a TIRAvib 50101 electromagnetic exciter in combination with an LMS Scadias III controller and Test.Lab software. The results of the tests, in the form of amplitude-frequency diagrams in resonance regions, indicated that certain changes occurred as a result of the conditioning, which is a new development in the area of material tests. The results shed light on the effects of environmental conditions on the stiffness characteristics of composites, causing dynamic nonlinearities when operating at resonant frequencies.

7

Investigation of Carbon Nanotube Particles Addition Effect on the Dispersed Composite Structure Thermal Diffusivity

Omen Łukasz, Szczepaniak Robert, Panas Andrzej J.

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 5

280--288

EN

The article addresses the issue of the possibility of improving the thermal transport parameters of an epoxy resin, such as thermal diffusivity (TD) and thermal conductivity (TC), by the addition of carbon nanotubes (CNT) as a high thermal conductivity filler. In the case presented here, the effect of the addition of high TC carbon nanotubes to commercial epoxy resin LH145 cured with H147 hardener was investigated experimentally. The main parameter studied was thermal diffusivity. Measurements were carried out for samples of epoxy resin and epoxy resin matrix composites with dispersed CNTs with a volume fraction of carbon nanotubes ranging from 1% to 6%. A modified Ångström temperature oscillation method was used to obtain TD. Basic measurements were performed in the temperature range from 20 ºC to 80 ºC while maintaining high temperature resolution that allows to observe the TD changes with the temperature change. During extended temperature range additional differential scanning calorimetry studies, the effects after curing of the epoxy resin were also characterized. As a result, the temperature dependence of thermal conductivity was determined and data for determining thermal conductivity was obtained. However, the analysis of the obtained results did not show a significant dependence of the studied parameters on the amount of CNT additive for the studied compositions.

8

Selected Construction Properties of Hybrid Epoxy Composites Reinforced with Carbon Fiber and Alumina

Krzyżak Aneta, Relich Szymon, Kosicka Ewelina, Szczepaniak Robert, Mucha Mateusz

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 2

240--248

EN

The purpose of this study is to investigate the impact of the introduction of powder modifier into composite reinforced with carbon fabric on selected mechanical properties. The tests were performed on 16 groups of hybrid epoxy composites, including one reference group and 15 groups containing alumina with the grain size of F220, F240, F280, F320 and F360, added in the weight percent of 5%, 10% and 15%. This composite was made of certified components designed for application in the aviation industry. Test results indicated that an increase of alumina content by weight caused a decrease of strength of polymer composites in most tests. In addition, the value of the force transferred by the composite in the tensile test increased disproportionately to the cross section, which resulted in decreased strength, while the addition of alumina impeded the super-saturation of the carbon fabric, which caused discontinuities in the matrix material.

9

Young’s modulus of a carbon-reinforced composite at an elevated temperature

Szczepaniak Robert, Przybyłek Paweł, Komorek Andrzej, Sapiński Przemysław, Rowicki Artur, Tkaczuk Sławomir, Rypulak Andrzej, Stabryn Sebastian

Technologia i Automatyzacja Montażu

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2021

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nr 4

29--33

PL

Konstrukcje lotnicze są eksploatowane w zmiennych warunkach środowiskowych wpływających na właściwości kompozytów polimerowych, z jakich często wykonywane są elementy samolotów i śmigłowców. Jednym z takich czynników jest temperatura użytkowania, zmieniająca się podczas lotu w bardzo szerokim zakresie. W artykule zaprezentowano wpływ temperatury eksploatacji na właściwości kompozytu wyznaczane podczas próby rozciągania. Dodatkowo kompozyty przeznaczone do badań wygrzewano w trakcie przygotowania w różnych temperaturach (zgodnie z zaleceniami producenta żywicy będącej osnową). Kompozyty składały się z 7 warstw tkaniny węglowej przesyconych żywicą epoksydową L285 z utwardzaczem. W wyniku badań zauważono, że zmiana temperatury eksploatacji wywiera istotny wpływ na właściwości wytrzymałościowe kompozytu bez względu na temperaturę wygrzewania. Materiały wygrzewane w wyższych temperaturach cechowała większa wartość współczynnika sprężystości wzdłużnej i wytrzymałości na rozciąganie.

EN

Aviation structures are operated under varying environmental conditions, affecting the properties of polymer composites, which are often used to manufacture components for airplanes and helicopters. One of such factors is an operating temperature that changes during a flight in a very wide range. This paper presents the influence of an operating temperature upon composite properties determined during a tensile test. In addition, composites which are intended for the research were post cured during their preparation at different temperatures (in accordance with the recommendations of the resin manufacturer which constitutes a matrix base). The composites consisted of 7 layers of carbon fabric, and matrix of L285 epoxy resin, with a hardener. As a result of the testing it was noted that a change in the operating temperature exerts a significant effect on composite strength properties regardless of the post curing temperature. The materials post cured at higher temperatures were characterized by a greater value of the modulus of elasticity and tensile strength.

10

Wpływ warunków meteorologicznych na imisję pyłu zawieszonego oraz kształt smug kominowych w sezonie grzewczym

Wierzbińska Monika, Szczepaniak Robert

Polish Journal of Materials and Environmental Engineering

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2021

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Vol. 1 (21)

26--37

EN

The aim of the study was to analyze exhaust gas streaks emitted from emitters during the heating season in the city of Żywiec. The relationships between the shape of the streaks and the weather conditions (wind speed and direction, air temperature and humidity, atmospheric pressure, precipitation, dust concentration) were analyzed. The shape of the chimney streaks (streaks: looping, coning, fanning, lofting, fumigation) has a decisive influence on the quality of the atmospheric air in the vicinity of the emitters. The observations of the emitters were carried out for 92 days – at 6 a.m. and 6 p.m., to separate the conditions existing before the satisfaction of social and living needs (morning hours) and at the time of satisfying them (evening hours). At the same time, data of the state of the atmosphere obtained from the Żywiec-Zabłocie air quality station and from two weather stations: ŻAR BSP Międzybrodzie Żywieckie and IMWM-PIB Radziechowy were recorded. The article presents the results of measurements of the state of the atmosphere and the observation of streaks. Data analysis showed a direct influence of weather conditions on the shape of the streaks and thus on the air quality. Analysis of the results showed that during periods of thermal inversion, there was an increase in the immission of particulate matter in the ground layer of the atmosphere. These conditions were often accompanied by pollutant or loop-shaped chimney streaks. Moreover, the increase in wind speed resulted in a decrease in the concentration of dust pollutants in a given area and contributed to the formation of ventilation streaks. During the observation of pollutant and loop-type chimney streaks, the immission of suspended dust increased significantly, which resulted in deterioration of air quality in Żywiec.

11

Devices for the samples preparation for determination of impact strength of adhesive joints tested to clevage

Komorek Andrzej, Olesiejuk Konrad, Przybyłek Paweł, Szczepaniak Robert

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

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2019

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no. 4

99--107

EN

The impact strength tests of adhesive joints loaded for cleavage using a wedge-shaped impactor are generally described in the Polish Standard PN-EN ISO 11343. In order to conduct the tests, it is necessary to prepare bonded samples consisting of two specially formed elements. To form sample elements, it is necessary to take advantage of a special device, which is not adequately described in the standard. In view of the fact that the test method is quite common, some information, however general, with regard to the moulding device is available in the literature. Therefore, the authors have developed a device which was later validated in research with sample elements made from steel and an aluminium alloy. After the formation of adherends, it is necessary to connect them by means of a glued joint; however, it also requires a special handle due to an unusual shape of the samples. The handle is to stabilize samples and generate an appropriate clam required in the process of bonding at the time of making the connection. Both newly designed devices were made as prototypes so as to be able to check the correct operation of the designed constructions. Various tests were made in which the sample elements were moulded until obtaining a proper shape. During the test, particular elements of the device were adjusted so that the shape of the obtained samples would be in compliance with the parameters specified in the standard. On completion of the adjustments, it was possible to obtain specific repeatable elements. The obtained samples were inspected visually, and, on this basis, modifications were made. Then successive series of samples were prepared. Finally, the samples were subjected to a quality assessment. The results of the work are presented in the paper.

PL

W artykule zaprezentowano metodykę badań wytrzymałości udarowej połączeń klejowych na rozczepienie z wykorzystaniem impaktora w kształcie klina. Jest to metodyka opisana ogólnie w Polskiej Normie PN-EN ISO 11343, według której prowadzi się badania udarności połączeń klejowych. W celu przeprowadzenia badań wymagane jest przygotowanie próbek klejonych, składających się z dwóch odpowiednio uformowanych elementów. Do formowania elementów próbek niezbędny jest specjalny przyrząd, o którym nie można uzyskać żadnych informacji na podstawie Normy. Ze względu na to, iż metoda badania jest rozpowszechniona w świecie, pewne informacje dotyczące przyrządu formującego dostępne są w literaturze, jednak są to informacje ogólne. Dlatego samodzielnie opracowano tego typu przyrząd i przeprowadzono badania walidacyjne z elementami próbek wykonanymi ze stali i stopu aluminium. Po uformowaniu elementów próbek należy je połączyć za pomocą spoiny klejowej, do czego również jest wymagany specjalizowany uchwyt ze względu na nietypowy kształt próbek. Zadaniem uchwytu jest stabilizacja złożonych próbek oraz wytworzenie odpowiedniego docisku wymaganego w procesie klejenia w czasie wiązania kleju. Obydwa zaprojektowane urządzenia wykonano w formie prototypowej w celu sprawdzenia poprawności działania zaprojektowanych konstrukcji. Przeprowadzono próby kształtowania elementów próbek do wymaganej formy, podczas których poddawano regulacji poszczególne elementy przyrządu, tak aby kształt otrzymanych próbek był zgodny z parametrami określonymi w Normie. Po przeprowadzonych regulacjach możliwe jest uzyskiwania właściwych, powtarzalnych elementów. Powierzchnie klejone uformowanych elementów próbek przygotowano przez obróbkę strumieniowo-ścierną z odtłuszczaniem, a następnie naniesiono klej, złożono i zamocowano w uchwycie do klejenia w celu weryfikacji jego przydatności. Otrzymane próbki poddano oględzinom wzrokowym i na tej podstawie wprowadzono modyfikacje, a następnie wykonywano kolejne serie próbek oraz przeprowadzono ocenę ich jakości. W efekcie powstały dwa specjalizowane, pomocnicze przyrządy do przygotowania próbek do badań udarności. Wyniki badań zaprezentowano w artykule.

12

Analiza wpływu zastosowania wingletów na charakterystyki aerodynamiczne skrzydła szybowca MDM-1 Fox

Lamach Krzysztof, Szczepaniak Robert, Zahorski Tomasz, Stryczniewicz Wit

Zeszyty Naukowe / Wyższa Szkoła Oficerska Sił Powietrznych

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2017

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Nr 1

139--151

PL

W pracy przedstawiono analizę możliwości wykorzystania metody elementów skończonych do określenia wpływu rozpraszaczy wirów brzegowych (ang. winglet) na charakterystyki aerodynamiczne skrzydła szybowca MDM-1 Fox. Charakterystyki aerodynamiczne są odzwierciedleniem zmieniających się warunków opływu profilu (skrzydła) ze zmianą kąta natarcia. Poprawienie tych charakterystyk na etapie projektowania bądź modernizacji istniejących samolotów skutkuje wzrostem osiągów samolotu, co przekłada się na ekonomię oraz ekologię lotów w przypadku samolotów oraz doskonałość, szczególnie istotną w przypadku szybowców. W pracy przeprowadzono analizę wpływu zastosowania dwóch różnych typów wingletów na osiągi szybowca użytkowanego obecnie bez wingletów. W celu uzyskania wyników porównawczych symulację numerycznej mechaniki płynów wykonano z wykorzystaniem dwóch komercyjnych pakietów obliczeniowych. Uzyskane wyniki potwierdziły poprawność zaproponowanej metodyki.

EN

The authors of the article analyse the possibility of applying the finite element method to determine the impact of winglets on the MDM-1 Fox glider wing aerodynamic characteristic. Aerodynamic characteristics reflect changes in the airflow with the change in the angle of attack. An improvement in these characteristics during the design or modernization stage leads to the increase in the glider performance, which in turn translates into economy and ecology of flight for aircraft as well airworthiness, especially important for gliders. In the paper it was investigated how two different types of winglets affect the performance of the glider in which they are not currently applied. In order to obtain comparative results, simulation of numerical fluid mechanics was performed with the use of two commercial computational packages. The results obtained proved that the method suggested was correct.