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1
Content available Automated Design of Honeycomb Conformal Cooling Channels for Improving Injection Molding Quality
Luh Yuan-Ping, Chin Chien-Chuan, Iao Hong-Wai
Production Engineering Archives
|
2023
|
Vol. 29, Iss. 1
44--57
EN
The study of conformal cooling channel usually has adopted two assumptions in model design: the use of (1) a hot runner system and (2) a one-mold-one-cavity design. These assumptions substantially simplify the research. However, most molds are designed using a cold runner system and multiple cavities. These two assumptions may not apply to all commercial systems; hence, a design method for honeycomb CCCs for cold runner systems and multiple cavities is proposed in this study. Specifically, an algorithm was developed to automatically design CCCs for such systems. This algorithm can be used to reduce the cooling time, improve product quality, and ensure that the system temperature is relatively homogenous in practical situations. According to the result of this study, the honeycomb CCC models were more effective at maintaining a homogeneous temperature distribution, reducing shrinkage, and reducing warpage for both parts produced from the same two-cavity mold, thus ensuring consistent part quality.
2
Content available remote Termoizolacyjność materiałów pochodzenia celulozowego - tektura falista i plaster miodu
Noszczyk Paweł, Łątka Jerzy, Jasiołek Agata
Materiały Budowlane
|
2022
|
nr 11
154--156
PL
W artykule opisano badania doświadczalne wyznaczenia współczynnika przewodzenia ciepła materiałów pochodzenia celulozowego typu tektura falista i plaster miodu. Badania wykonano metodą stacjonarną w aparacie płytowym. Przeanalizowano wpływ wielkości pustek powietrznych oraz kierunku przepływu ciepła przez materiał na jego przewodność cieplną. Uzyskane wyniki wskazują na porównywalną termoizolacyjność do materiałów powszechnie stosowanych w budownictwie jako termoizolacje.
EN
The article describes the experimental tests to determine the thermal conductivity coefficient for materials of cellulosic origin, such as corrugated cardboard and honeycomb. The tests were performed using the stationary method in a plate apparatus. The influence of the size of the air voids and the direction of heat flow through the material on its thermal conductivity was analyzed. The obtained results indicate comparable thermal insulation to materials commonly used in construction as thermal insulation.
3
Content available Strength testing of a modular trailer with a sandwich platform
Mysior Marek, Pietrucha Grzegorz, Koziołek Sebastian
Eksploatacja i Niezawodność
|
2022
|
Vol. 24, no. 1
163--169
EN
The article presents the experimental strength evaluation of modular car trailers with a maximum permissible total mass of up to 3500 kg and its application to assess the mechanical strength of box-type car trailers. Tests were carried out using an original test bench dedicated to fatigue testing. They aimed to compare a trailer made in traditional technology with a trailer equipped with a load-carrying structure containing a sandwich panel. As a result of the conducted work, the displacement values of the measurement points were measured. The deformation form of the trailer made in the traditional technology was compared with the trailer containing the sandwich panel. The proposed method of experimental strength evaluation of modular car trailers enables a quantitative assessment of the mechanical strength of the load-carrying structures of trailers. This results in improved safety of trailer operation in road traffic by identifying the critical elements of the load-carrying structure at the early design phase before the trailer is allowed to run on the road.
4
Content available remote Designing a Three-Dimensional Woven Fabric Structure as an Element of a Baby Stroller
Bethalihem Samuel T., Barburski Marcin, Lemmi Tsegaye Sh.
Autex Research Journal
|
2022
|
Vol. 22, no. 2
148--154
EN
A baby stroller allows the transportation of a child over long or short distances. The materials used to produce the stroller make it heavy for users, which creates difficulties when lifting the stroller. The goal of this project was to design and fabricate a three-dimensional (3D) fabric structure that can be used as part of a stroller seat to improve its mechanical and physical properties. The idea of implementing a woven 3D system allows the development of an egg-shaped or shell-like structure as part of a stroller seat. The combination of double-woven material and honeycomb polypropylene (as the reinforcing material) was used to create a 3D composite structure. Single and double layers of polypropylene honeycomb sandwiched within layers of linen flax fabric were used to prepare the composite samples. Subsequently, tests on mechanical and physical properties, such as density, flexural strength, and tensile strength, were carried out. Analysis of the results showed that the composite with one layer of honeycomb has half the density of polyvinyl chloride.
5
Content available Studies on Flexural Properties and Construction of Failure Mode Map for Copper Sandwich Panels
Vino A, Kalaichelvan K., Sajith S., Kumaresan G.
Archives of Metallurgy and Materials
|
2022
|
Vol. 67, iss. 4
1371--1380
EN
This paper is focused on investigating the mechanisms associated with different failure modes of copper (C101) sandwich panels with honeycomb cores of different heights subjected to flexural loading. Honeycomb core is made up of copper strips which were formed to required shapes using Dies fabricated by Electric Discharge Wire cut machining technique. All the joints in the sandwich panel were established through Brazing technique. Three-point bending test was conducted as per ASTM standard C-393. It was observed that increase in height of the core resulted in panels with higher strength to weight ratio. It also exhibited higher stiffness to weight ratio and very high strain energy absorption ability. An increase in flexural strength was reported with a maximum of 43% improvement for 10.9 mm core compared to 6.9 mm core. Further, 81.75% increase in absorbed strain energy was reported for 10.9 mm thick panel compared to 6.9 mm. The Optical and scanning electron microscope (SEM) analysis confirmed the establishment of good bonding between the filler and the substrate. Energy-dispersive Spectroscopic (EDS) analysis revealed the presence of Cu, Al, Zn, SiO2 and CaCO3 in the substrate. Further it also revealed the presence of Cu, CaCO3 and GaP in the filler material. The failure mode map was constructed which can be used for predicting different types of failures more likely to occur for specific parameters of copper sandwich panel. The dominant failures occurred during testing was in good agreement with the prediction done through failure mode map. The appreciable results in the proposed research may be supportive in construction of cooling system. The structure development and process control are convenient in mass production in automobile industries.
6
Content available Influence of 3D Printing Parameters by FDM Method on the Mechanical Properties of Manufactured Parts
Zubrzycki Jarosław, Quirino Estrada, Staniszewski Michał, Marchewka Magdalena
Advances in Science and Technology. Research Journal
|
2022
|
Vol. 16, no 5
52--63
EN
The manufacturing of machine parts with additive methods (AM) is of significant importance in modern industry. The development of 3D printers and all 3D printing technology is impressive. The ability to make parts quickly and relatively cheaply with AM gives excellent opportunities in terms of e.g., shortening the production preparation time. Proper selection of printing parameters allows for a significant reduction of printing time and production costs. Unfortunately, this has different consequences. Due to the course of the printing process and the parameters that can be set, the same product produced with different parameters has different mechanical properties - mainly different strength. This paper presents the impact of 3D printing parameters on the strength of manufactured parts. Strength tests were carried out on samples made in accordance with DIN EN ISO 527-1:2019. The samples were printed in technology FDM from three different materials, i.e. PLA (completely biodegradable), PETG (recycled material), and Smart ABS (material with minimal shrinkage). The tested samples were made in three levels of print filling - 10%, 30%, and 60% and with different types of filling - line, mesh, and honeycomb. A series of static tensile tests were carried out to determine the strength of the samples produced with different printing parameters. Thanks to the obtained test results, it is possible to select the optimal printing parameters depending on the forecast load of the manufactured parts.
7
Content available Dissipation of Energy in Sandwich-Structured Equestrian Helmet – Numerical Analysis Under Overload Conditions
Bińczak Natalia, Kuryło Piotr
System Safety : Human - Technical Facility - Environment
|
2021
|
Vol. 3, nr 1
11--18
EN
Protection of the head structures is a requirement in many sports where a person is exposed to injuries that threaten life or health. In horse riding accidents occur often, resulting in serious head injuries. The analysis of the available literature shows that the helmets used now protect human head structures in a small percentage. The aim of the research was to analyze the degree of protection of the human head using available helmet structure and a new solution for the Energy absorbing layer in helmet that absorbs Energy from impacts. The research was divided into two stages. During the first one, a simulation was performer under dynamic conditions simulating the rider’s fall and the contact of the head with ground (impact from the side). In the second stage, three structures of the absorbing layers were developed, i.e. honeycomb, auxetic, mixed with three three wall thicknesses (1 mm, 2 mm and 3 mm respectively) and two materials were used: the currently used EPS and the aluminium alloy used in the motorcycle helmet.
8
Content available Review of Testing Methods Dedicated for Sandwich Structures with Honeycomb Core
Jędral Arnold
Transactions on Aerospace Research
|
2019
|
Nr 2 (255)
7--20
EN
This paper is a review of testing methods dedicated for sandwich type composite structures with honeycomb core. First, information about the composition of sandwich materials structures, their properties, types of core materials and applications in the industry is presented. Mechanical properties were compared in the case of different types of the core material. Later, tests methods needed to describe properties of those materials and normalization organizations which create them were mentioned. The testing methods were divided into two groups: mechanical and physicochemical tests. Mechanical properties are: compressive strength (two types of test), edge compressive strength, shear strength (in two directions) and tension strength (two types of test). Physicochemical properties are: material density, water migration, water absorption and thermal conductivity. Testing methods were described according to American Society for Testing and Materials (ASTM) standards. This article is based on professional literature and the author’s experience.
PL
Niniejszy artykuł jest przeglądem metod badawczych przeznaczonych do charakteryzacji materiałów przekładkowych z wypełniaczem typu plaster miodu (honeycomb). Na wstępnie zawarto informacje o budowie materiałów przekładkowych, ich właściwościach, podziale ze względu na rodzaj materiału wypełniacza, a także zastosowaniu w różnych gałęziach przemysłu. Porównane zostały właściwości wytrzymałościowe tych struktur w zależności od rodzaju materiału wypełniacza. W dalszej części wymienione zostały metody badawcze potrzebne do charakteryzacji materiałów typu honeycomb oraz organizacje normalizacyjne określające te metody. Zostały one podzielone na dwie kategorie: metody określające właściwości mechaniczne oraz właściwości fizyczno-chemiczne. Do właściwości mechanicznych należą: wytrzymałość na ściskanie (dwa rodzaje), ściskanie krawędziowe, ścinanie (w dwóch kierunkach) oraz rozciąganie (dwa rodzaje). Do właściwości fizyczno-chemicznych należą: gęstość materiału, absorpcja wody, migracja wody, a także przewodnictwo cieplne. Metody badawcze zostały opisane w oparciu o normy ASTM (American Society for Testing and Materials). Przedstawione informacje opierają się na literaturze fachowej oraz na doświadczeniu autora.
9
Content available remote Ocena jakościowa procesu deformacji regularnych struktur komórkowych wykonanych techniką druku 3D
Dziewit P., Janiszewski J.
Mechanik
|
2018
|
R. 91, nr 3
250--252
PL
Przedstawiono wybrane wyniki badań eksperymentalnych, umożliwiające przeanalizowanie procesu deformacji regularnych struktur komórkowych wykonanych techniką druku 3D w warunkach obciążenia quasi-statycznego. Zaprojektowane w środowisku CAD warianty topologii struktur wykonano metodą FDM (fused deposition modeling), a następnie poddano je badaniom w warunkach jednoosiowego testu na ściskanie. Punktem wyjścia do opracowania poszczególnych wariantów struktur była topologia plastra miodu. Aby przeanalizować wpływ materiału struktury na przebieg procesu deformacji, próbki wykonano z trzech komercyjnie dostępnych materiałów: PC-10, ABSplus i Nylon12. Na podstawie wyników badań oceniono wpływ kształtu komórki elementarnej oraz rodzaju zastosowanego materiału na przebieg deformacji struktury i wartość energii odkształcenia plastycznego.
EN
Presented are selected experimental results concerning the analysis of the deformation process of regular cellular structures manufactured using 3D printing under quasi-static loading conditions. The various structural topologies were designed and manufactured using the FDM (fused deposition modelling) and then tested in a uniaxial compression test. The starting point for the development of individual variants of structures was the honeycomb topology. In order to analyse the influence of the structure material on the deformation process, the samples were made from three commercially available materials: PC-10, ABSplus and Nylon12. Based on the results, the influence of the shape of the single cell and the type of material used on the deformation of the structure as well as the value of the plastic deformation energy were assessed.
10
Content available Out-of-plane static crushing of thin-walled honeycomb structures. Numerical and experimental investigation
Ciepielewski Radosław, Dybcio Paweł, Barnat Wiesław
Advances in Science and Technology. Research Journal
|
2018
|
Vol. 12, no 3
96--105
EN
Aim of presented study was to compare plateau stress in honeycomb structures under out-of-plane load calculated using Wierzbicki formula with numerical simulations validated using experimental trials. ALUBOND® Alucore honeycomb structure was examined. The results of theoretical, experimental and numerical investigation are reported. Two methods of modeling core behavior were evaluated using simulations. Full core geometry and simplified Y-shaped element were analyzed. Both approaches were compared with experimental out-of-plane compression tests. Aim of the study was to determine the influence of core geometrical parameters on obtained plateau stress value. Various foil thicknesses and cell sizes were studied numerically. The results showed, that initial and final deformation mode strongly depends on the geometry of the honeycomb structure. Force required to crush the core grew with increase of wall thickness, and decreased with increase of cell size. Calculations were performed using an implicit integration scheme implemented in the LS-DYNA software. Research showed the presence of plateau relationship between stress and geometric dimensions and structure response. Good agreement between results obtained by all methods was achieved. Basing on the results, conclusions concerning modeling honeycomb materials were drawn.
11
Content available What-if analysis of the labyrinth seal of the gas turbine rotor tip
Wróblewski W., Bochon K., Borzęcki T.
Transactions of the Institute of Fluid-Flow Machinery
|
2017
|
nr 136
3--21
EN
This paper presents a preliminary, numerical what-if analysis of selected geometrical parameters of the tip seal of the last stage of an aircraft engine turbine and the impact of the parameters on the leakage mass ow. The analysis is a part of the task of improving the rotor tip seal conguration in aircraft turbines. Calculations were carried out using the commercial computational uid dynamics code. A straight-through seal with two leaning ns and a honeycomb land was analysed. The computational model was prepared based on some simplications introduced to improve the eciency of the calculations. The rotor entire blade-to-blade channel was analysed, while the seal pitch was reduced to the dimensions of two honeycomb cells. The geometry of the ns themselves was simplied too. In the original variant, the n tips had caps to protect them from wear (shape deformation) due to rubbing. In the simplied model, the caps were omitted. The simplications did not change the leakage mass ow signicantly. Several variants of changes in the basic geometrical parameters of the seal were analysed to assess their eect on the leakage mass ow for altered ow conditions. Parameters such as the n thickness, the n inclination angle and the position of the ns and of the entire labyrinth were analysed. The best seal variant was selected, the ow phenomena were commented on and some points in the design of this type of the labyrinth seal were discussed.
12
Content available How much a geometrical model of a honeycomb seal can be simplied in the CFD calculation
Stajnke M., Włodarski W.
Transactions of the Institute of Fluid-Flow Machinery
|
2017
|
nr 136
55--64
EN
This paper presents the influence of geometry simplification on the results obtained in the computational fluid dynamics simulation. The subject of simulation was part of the honeycomb seal located at the inlet to high pressure part of a steam turbine. There were three diferent geometrical models assumed in the calculations. First one was two-dimensional case and two others were three-dimensional, one with the radius of curvature and one without. Numerical simulations were performed for 15 sets of boundary conditions to compare flow characteristics for each geometrical case.
13
Content available Experimental and numerical three-point bending test for sandwich beams
Czechowski L., Jankowski J., Kotełko M.
Journal of KONES
|
2017
|
Vol. 24, No. 3
53--62
EN
The article deals with an experimental investigation of mechanical properties of sandwich beams obtained from bending tests. The tested specimens consisted of foam or honeycomb core and face sheets made of aluminium alloys, plywood or composite material. The face sheets and the core were bonded with glue material. Beams of different dimensions, namely beam width, as well as core and face sheets thickness, were tested. Three point bending tests were carried out, which mid span deflections of the beam versus applied force were recorded. Experimental test results were compared with simulations on the basis of finite element method. The full, non-linear analysis, taking into account large displacements and using contact elements was performed. The obtained results are presented in loaddeflection diagrams. Some conclusions concerning ultimate loads and failure behaviour of tested beams made of different materials have been derived.
14
Content available Analiza numeryczna kompozytowej łopaty śmigła ogonowego
Konik R.
Prace Instytutu Lotnictwa
|
2016
|
Nr 3 (244)
175--188
PL
Analiza numeryczna/wytrzymałościowa kompozytowej łopaty śmigła ogonowego przeprowadzana została z wykorzystaniem oprogramowania MSC PATRAN/NASTRAN. Model obliczeniowy zbudowany został z wykorzystaniem następujących elementów: elementy belkowe (śruby mocujące okucie metalowe do konstrukcji kompozytowej), elementy powierzchniowe (dźwigar, pokrycie etc.) oraz elementy brylowe (okucie, wypełniacz komórkowy). Analizowane przypadki obciążeń: 1. zawis ustalony; 2. praca śmigła ogonowego w czasie zawisu śmigłowca, ze zmianą kąta nastawienia łopat śmigła ogonowego w zakresie 5-20 stopni w czasie jednej sekundy; 3. praca śmigła ogonowego w czasie lotu śmigłowca z prędkością 200 km/h ze zmianą kąta nastawienia łopat śmigła ogonowego w zakresie 5-20 stopni w czasie jednej sekundy. Przypadki z szybką zmianą kąta nastawienia łopaty zrealizowane zostały poprzez przyłożenie ciśnień do pokryć łopaty wynikające z danego stanu lotu, które odwzorowują uzyskiwaną siłę ciągu w danym manewrze oraz dodatkowo przykładana była siła odśrodkowa wynikająca z prędkości obrotowej w danym stanie lotu. Zastosowane materiały na okucie łopaty śmigła ogonowego - stal wysokostopowa (opcjonalnie tytan) natomiast na strukturę łopaty - kompozyty bez-autoklawowe oraz aramidowy wypełniacz komórkowy.
EN
Numerical strength analysis composite tail rotor blades were performed using software MSC PATRAN/NASTRAN. The model was prepared by using the following elements: beam elements (fasteners connected fitting to composite structures), shell elements (blade spar, skins, etc.) and solid elements (bracket, honeycomb). The loads calculation model was realized by applying pressure on the blade skins, thrust force resulting from the maneuver and centrifugal force resulted from the tail rotor speed, which reflects the critical cases of helicopter flight. The materials used on fitting the blade were high-alloy steel (alternative titan), while at the tail rotor blade it was composite out of autoclave and aramid honeycomb.
15
Content available remote Zagadnienia hydrostrumieniowego kształtowania materiałów stosowanych w lotnictwie
Borkowski P., Borkowski J., Bielecki M.
Mechanik
|
2016
|
R. 89, nr 8-9
1052--1053
PL
Przedstawiono istotne zagadnienia dotyczące stosowania wysokociśnieniowej strugi wodno-ściernej do kształtowania struktur materiałowych typu plaster miodu oraz spienione aluminium, które są używane w konstrukcjach lotniczych. Zastosowana metoda pozwala na jednozabiegowe wycinanie przestrzennych półfabrykatów o poosiowo zmiennych kształtach poligonalnych. Zaprezentowane efekty kształtowania takich obiektów oraz wyniki badań (SEM, SGP) jakości obrobionej powierzchni uprawniają do pozytywnej oceny przydatności tej metody obróbkowej.
EN
The paper presents important issues of high-pressure abrasive-water jet cutting of materials’ structures shaping (e.g. honeycomb and aluminum foam), which are used in aircraft constructions. The applied method allows the spatial single cutting of semi-finished products of axially variable polygonal shapes. Presented effects of such objects’ forming, as well as the results of the quality of the machined surface (SEM and SGP), allow for a positive assessment of the usefulness of such a method of machining.
16
Content available remote Characteristics of failure mechanisms and shear strength of sandwich composites
Greń K., Szatkowski P., Chłopek J.
Composites Theory and Practice
|
2016
|
R. 16, nr 4
255--259
EN
Sandwich composites are very popular nowadays due to their beneficial mechanical parameters and low weight. The aim of the paper was to investigate the failure mechanisms of different sandwich structures under shear stresses. Composites consisting of carbon laminate skins and cores with different geometry were tested. The core materials included various expanded polymer foams, balsa wood and honeycomb structures - aramid and cellulose. These material combinations enabled the authors to compare the specific shear strength and fracture energy of different sandwich structures, describe the factors which influence the behavior of materials under shear tension, and characterize the failure mechanisms. Sandwich composites were manufactured by two methods: the one-step method in which carbon fabric was laminated directly onto the core, and by the two-step method. The faces made employing the first method failed to meet the appropriate strength criteria, therefore the second method was used. In the first step, faces made of four layers of carbon fabric and epoxy resin were pre-manufactured by hand lay-up. After crosslinking, the faces were glued to the core and left in higher pressure conditions. Samples were cut to the required dimensions. Shear strength was tested by three point bending of a short beam. The method is simple and allows shear stresses to dominate in the sample. Tests were made on a testing machine, Zwick 1435. The density of the samples was considered as well, so as to compare their specific strength. The highest value of specific shear strength, (8.7 ±0.7)·103 Nm/kg, was demonstrated by the composite with balsa, whereas for the composite with the honeycomb it reached (3.3 ±0.3)·103 Nm/kg and for samples with foams (4.2 ±0.2)·103 Nm/kg. Additionally the failure energy was calculated for each material. The composite with aramid honeycomb had the highest value - it reached (9.3 ±0.5) kJ/m2 , while value of this parameter for balsa was the lowest: (3.3 ±0.3) kJ/m2 . The composite with balsa deformed elastically until break point and a crack between the layers appeared. The sandwich structure with the aramid honeycomb core is a promising material as it exhibited a multi-stage failure mechanism. Firstly, it deformed elastically, then the cells collapsed. Only in the composite with balsa and honeycomb with four-layer skins was shear the dominant failure mechanism. The composites with isotropic foams did not fulfill expectations, they deformed plastically and a notch appeared. That is why they need further examinations to increase their shear strength. In this study, the cracking mechanisms of the composites were evaluated based on microscopic observations using a digital microscope. Depending on the core geometry, the following mechanisms were identified: core shear for the honeycomb, delamination and crack for balsa, and notch appearance for the foam composites. The presented results are an introduction to further investigations of sandwich failure under different conditions.
PL
Kompozyty sandwich cieszą się dużą popularnością, ponieważ, posiadając niską masę, wykazują korzystne parametry wytrzymałościowe. Celem pracy było zbadanie mechanizmów zniszczenia różnego rodzaju kompozytów sandwich w warunkach ścinania. Przedmiotem badań przedstawionych w artykule są kompozyty przekładkowe, zbudowane z okładek - laminatów z tkaniny węglowej - oraz rdzeni o odmiennej geometrii. Jako materiały na rdzenie zastosowano różnego rodzaju pianki polimerowe, balsę oraz struktury typu plaster miodu - aramidową i celulozową. Dzięki modyfikacji składu kompozytu można było porównać wytrzymałość na ścinanie oraz pracę zniszczenia otrzymanych struktur „sandwich”, opisać czynniki wpływające na zachowanie się materiału pod wpływem naprężeń ścinających oraz mechanizmy zniszczenia. Do wykonania kompozytów wykorzystano dwie metody produkcji okładek - jednoetapową (przyklejenie jednej warstwy tkaniny węglowej osnową epoksydową bezpośrednio do rdzenia) i dwuetapową. Okładki wykonane pierwszą metodą nie spełniły oczekiwań wytrzymałościowych, dlatego zastosowano drugą metodę. Najpierw wykonano czterowarstwowe laminaty z tkaniny węglowej i żywicy epoksydowej za pomocą metody laminowania ręcznego. Laminaty te pozostawiono do usieciowania, a w kolejnym etapie utwardzone okładki przyklejono do rdzeni. Następnie próbki przycięto do wymaganych wymiarów. Do zbadania wytrzymałości na ścinanie wykorzystano test trójpunktowego zginania krótkiej belki. Jest to prosta metoda, która pozwala wytworzyć w próbkach dominujące naprężenia ścinające. Badania zostały przeprowadzone na maszynie wytrzymałościowej Zwick 1435. W pracy uwzględniono również gęstość próbek, dzięki czemu można było porównać ich wytrzymałość właściwą. Najwyższą wartość wytrzymałości na ścinanie właściwej, (8.7 ±0.7)·103 Nm/kg, uzyskał kompozyt z rdzeniem z balsy, podczas gdy dla kompozytu z aramidowym plastrem miodu wyniosła ona (3.3 ±0.3)·103 Nm/kg i dla pianek (4.2 ±0.2)·103 Nm/kg. Dodatkowo obliczono pracę zniszczenia poszczególnych materiałów. Dla kompozytu z plastrem miodu była ona najwyższa i wyniosła (9.3 ±0.5) kJ/m2, natomiast wartość tego parametru dla balsy była najniższa: (3.3 ±0.3) kJ/m2. Materiał z balsą odkształca się sprężyście do momentu pojawienia się pęknięcia w rdzeniu i oddzielenia się od siebie warstw. Kompozyt z plastrem miodu również jest obiecującym materiałem. Odkształcenie jego przebiega kilkuetapowo - najpierw sprężyście, a następnie poprzez zapadanie się komórek. Tylko te dwa materiały w połączeniu z czterowarstwową okładką węglową ulegają ścinaniu. Izotrotropowe pianki w badanym zestawieniu nie spełniły oczekiwań, zaobserwowany mechanizm zniszczenia to odkształcenie plastyczne i powstanie karbu, dlatego kompozyty te wymagają dalszych badań nad poprawą ich wytrzymałości na ścinanie. W pracy na podstawie zdjęć wykonanych na mikroskopie cyfrowym scharakteryzowano również mechanizmy pękania poszczególnych kompozytów. W zależności od ich geometrii obserwowano następujące mechanizmy zniszczenia: ścinanie rdzenia w kompozycie z plastrem miodu, pękanie rdzenia i delaminację warstw w kompozycie z balsą oraz pojawienie się karbu w strukturze z pianką. Przeprowadzone badania stanowią wstęp do dalszych eksperymentów nad mechanizmami zniszczenia kompozytów przekładkowych w różnych warunkach.
17
Content available remote Numerical Simulations and Experimental Study on Reduction of Wind Tunnel Turbulence Intensity
Kulak M., Karczewski M., Olasek K., Jankowski K.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
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2015
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nr 147
25--38
EN
Having an upgraded wind tunnel in the Institute of Turbomachinery (IMP) at the Lodz University of Technology, a series of CFD simulations has been performed in order to indicate the areas of possible flow quality improvement. It was decided to introduce the honeycomb section in order to diminish the lateral turbulence. Additionally, CFD simulations were performed in order to gain information about the level of turbulence reduction and the associated pressure loss. The paper presents results from both: the measurements of turbulence intensity before and after the installation of the honeycomb in the IMP wind tunnel, as well as the associated simulation results conducted for a WT model (virtual WT) in ANSYS CFX 13.0/14.0. Results of above research were presented on XX Fluid Mechanics Conference KKMP2012.
PL
W ramach rewitalizacji tunelu aerodynamicznego w Instytucie Maszyn Przepływowych (IMP) Politechniki Łódzkiej, przeprowadzono serię symulacji numerycznych mających na celu wyznaczenie obszarów pozwalających na potencjalną poprawę jakości przepływu. Podjęto decyzję o montażu prostownicy ulowej celem zmniejszenia intensywności turbulencji. Dodatkowo, przeprowadzono symulacje numeryczne określające osiągalny poziom redukcji turbulencji oraz strat ciśnienia. Artykuł zawiera wyniki pomiarów doświadczalnych intensywności turbulencji w kanale, przed i po montażu prostownicy ulowej w tunelu aerodynamicznym IMP oraz odpowiadające im rezultaty symulacji numerycznych wirtualnego modelu tunelu (przeprowadzone z użyciem ANSYS CFX 13.0/14.0). Powyższe wyniki zostały zaprezento-wane na konferencji KKMP2012.
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Content available remote Nietypowa analiza numeryczna pomostu kompozytowej kładki typu honeycomb
Ciurej H., Gwoździewicz P.
Materiały Budowlane
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2015
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nr 11
229--231
PL
Materiały kompozytowe są coraz częściej stosowane w budownictwie jako elementy nośne. Ich właściwości mechaniczne, niewielkie koszty eksploatacji (brak konieczności konserwacji) oraz coraz korzystniejsza relacja ceny do masy sprawiają, że konstruktorzy decydują się na konstrukcje kompozytowe. W artykule przedstawiono analizę numeryczną pomostu kładki dla pieszych, zaprojektowanego wg idei technologii honeycomb. Zastosowano kompozyt GFRP – polimer na bazie żywicy epoksydowej zbrojony włóknami szklanymi.
EN
Composite materials are increasingly being used in the civil industry as supporting elements. Their mechanical properties and low operating costs (no maintenance), as well as more favorable price-to-weight ratio make the designers decide to design composite carrying structures. The article presents a numerical analysis of a deck of the footbridge. The footbridge was designed as a self-carrying structure of honeycomb based on GFRP composite material.
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Content available remote Conjugate heat transfer analysis of the tip seal in the counter rotating low pressure turbine
Bochon K., Wróblewski W.
Archives of Mechanics
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2015
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Vol. 67, nr 3
253--270
EN
The aim of this study was to examine the phenomena associated with leakage flow through the tip seal with honeycomb land and to perform conjugate heat transfer (CHT) analysis of the entire tip area of the blade including the part of casing with rotating cavity above the seal. CFD analyses were performed using commercial software. For the complicated geometrical configuration of the seal region, a calculation model was proposed which enabled a satisfactory approach to flow and heat transfer phenomena. CHT analyses were performed for two cases characterized by different thermal conductivity of the metal. Fluid flow parameters which allowed to recognize flow structures, losses and mixing were taken into account. In CHT analyses, the flow structures for the cavity, the heat transfer conditions as well as the temperature distribution in the whole domain were obtained.
20
Content available remote Modal analysis of honeycomb panels and the influence of boundary conditions on the calculation
Vlach J., Pomp N.
Journal of Achievements in Materials and Manufacturing Engineering
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2014
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Vol. 66, nr 2
81--86
EN
Purpose: In this work we investigate the elastic properties of sandwich beams manufactured by using the LF Technology. Design/methodology/approach: The investigation of the behaviour of rectangular shaped sandwich specimens is focused on the modal analysis and the experimental determination of the samples damping properties. Panels are made by unique technique of dry lamination patented by Czech company 5M s.r.o. The Hexagonal cell honeycomb core is made of aluminium as well as the facesheets. The influence of the main directions of anisotropy and the different panel’s thicknesses on the natural frequencies are investigated. Findings: The results of experiments are compared with the theoretical calculations and finite element method(FEM)simulation results. Theories used for the calculations are the First-order shear deformation theory (FSDT) and the Reddy’s third-order shear deformation theory (TSDT). FEM model had mapped mesh with 20-nodes brick elements. Research limitations/implications: The results obtained from FEA were closest to the experimentally measured data, but still with a deviation. The main reason of different results are geometrical irregularities. While FEM model was too much idealistic, the specimens prepared for measurement were not precisely planar. The specimens with small thickness were more twisted and therefore we got bigger error in the measured data and consequently the bigger deviation in results. In the future, we would like to do further measurements to transfer the real specimen geometry with all irregularities to a FEM model and to do new computations. Originality/value: Originality of this work is modal analysis of honeycomb panels and the influence of boundary conditions on the calculation.
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