Wyniki wyszukiwania - BazTech

1

High-Velocity Impact of 2-Phase WC/Co Composite Plate - Beginning of the Process

Postek E., Sadowski T.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

265--274

EN

2-phase composites are often used for high demanding parts that can undergo impact loads. However, most of the papers on dynamic loading concerns layered composites. In our opinion, the impact loads are not considered thoroughly enough. Good examples of 2-phase composites are: (1) a WC/Co cermet or (2) a monolithic ceramic Al2 O3 /ZrO2 . The WC/Co cermet is often modelled as having ductile elasto-plastic Co matrix and ideally elastic WC grains. It is because of very high crushing resistivity of the WC. In this paper, we present an extension to earlier elaborated models ([44]) with the assumption of ideal elasticity of the grains. The new and general numerical model for high-velocity impact of the 2-phase composites is proposed. The idea of this novelty relies on the introduction of crushability of grains in the composite and thermo-mechanical coupling. The model allows for description of the dynamic response both composite polycrystals made of: (1) 2 different purely elastic phases (e.g. Al2 O3 /ZrO2 ) or (2) one elastic phase and the second one plastic (e.g. cermet WC/Co), or (3) 2 elasto-plastic phases with different material properties and damage processes. In particular, the analysis was limited to the cases (2) and (3), i.e. we investigated the WC/Co polycrystal that impacted a rigid wall with the initial velocity equal to 50 m/s.

2

The Influence of the Use of Fasteners with Different Stiffness in Hybrid Joints Subjected to Complex Mechanical Loads

Sadowski T., Nowicki M., Golewski P.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 4

1263--1268

EN

To this day, most of the papers related to hybrid joints were focused on single and double lap joints in which shear deformation and degradation was the dominant phenomenon. However, in real constructions, complex state of loads can be created by: a) torsion with shear, b) bending with shear, c) torsion with tensile. Analytical and numerical computation for simple mechanical joints is known, however, the introduction of an adhesive layer to this joint makes the load transferred both through: (1) the adhesive and (2) mechanical fasteners. There is also an interaction between the amount and stiffness of mechanical fasteners and the strength of the adhesive layer. The paper presents the results of numerical calculations for the bending with shear type of load for the hybrid structural joint and corresponding simple joints by: (1) pure adhesion and (2) rivets with different quantity maintaining the same cross-sectional area. A total of 9 simulations were performed for: (1) 4 types of pure rivets connections, (2) pure adhesive joint and (3) 4 kinds of hybrid joints. The surface-based cohesive behavior was used for creation of the adhesive layer, whereas the rivets were modelled by connector type fasteners, which simplify complexity of the numerical model. The use of connectors allowed for effort assessment taking into account damage in both types of connections. Application of connector elements can be useful for larger structures modelling, e.g. aircraft fuselage, where the number of mechanical joints is significant and complex load conditions occur.

3

Numerical and Laboratory Tests of Aluminum Profile Connection Using the "Popular Lock"

Golewski P., Sadowski T.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

339--346

EN

Aluminum profiles play an important role in civil engineering (facades, walls with windows) as well as in mechanical engineering (production lines, constructions of 3D printers and plotters). To ensure quick assembly, disassembly or changed the dimensions of constructions it is not possible to use such methods as welding, adhesive or riveting joints. The solution may be to use the so-called "popular lock”. It is a mechanism, the closure of which is caused by tightening of the conical screw, joining the "T" profile in the node. In order to properly design using the presented type of connection, it is necessary to know its strength and stiffness both in simple and complex loads states, also including imperfections. In the literature there is no information about the operation of the construction node with the so-called "popular lock”. The paper presents the results of experimental tests for connections subjected to uniaxial tensile test, paying special attention to the defects that may appear during the assembly. In the next step, a 3D solid connection model was created. Numerical simulations were performed in the Abaqus / Explicite program for both uniaxial tensile test and bending tests in two planes. Limit values of loads above which there is a plastic deformation of the material were determined. Determination of stiffness and strength of a single node allowed to make a simplified connector model. Using the numerical model, the analysis was performed taking into account the influence of imperfections on the work of the entire connection.

4

Application of Thermo-Bimaterial Effect in Designing of Snap-Fit Joints

Golewski P., Sadowski T.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 3

1095--1100

EN

Snap-fit connections have been used for many years in various fields of technology and everyday objects. They often have complex shapes, which is allowed by the processing technology of the polymers from which they are made, but they are not designed to carry loads. Changing the material to a metal or fiber composite allows these types of joints to be used as replacements for rivets or screws, but there are problems with the closing technique – an increase in closing force due to the large Young’s modulus ofthese materials relative to polymers without reinforcement. One of the methods to solve this problem may be the use of a thermo-bimetallic effect consisting in heating both or one of the connection parts to the appropriate temperature. This kind of treatment results in deflection of the beam of the clip (Fig. 1), followed by assembly with zero force or less in relation to the case without heating.The paper presents the results of numerical simulations for the connection in which the beam of the clip consisted of two materials: (1) a fiber composite designed to carry loads, (2) thin metal layer tied with the composite and designed to create a thermo-bimetallic effect. In the case of this solution, the main parameter is the difference in coefficients of linear thermal expansion of both materials. The paper presents results for two cases of connection work: closing and opening. The calculations were carried out in the Abaqus/Standard solver using thermal-displacement steps.

5

Rozwój deformacji i uszkodzenia cienkościennych łączonych profili skrzynkowych, pod wpływem trójpunktowego cyklicznego zginania

Nowicki M., Sadowski T.

Rudy i Metale Nieżelazne Recykling

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2018

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R. 63, nr 6

11--14

PL

Artykuł przedstawia wyniki testów laboratoryjnych trójpunktowego cyklicznego zginania aluminiowych belek skrzynkowych łączonych za pomocą warstwy adhezyjnej oraz nitów. Aluminiowe profile omega połączono z płaską aluminiową płytką za pomocą kleju z grupy Loctite, nity zrywalne o średnicy 4 mm, oraz kombinacji tych łączników. Belki o wymiarach 84 x 36 x 300 mm poddano quasi statycznemu cyklicznemu obciążeniu w dwóch położeniach: profil omega w górnej lub dolnej pozycji. W badaniach wykorzystano maszynę wytrzymałościową MTS oraz system cyfrowej korelacji obrazu. W artykule przeanalizowany został rozwój deformacji profili wraz z ich uszkodzeniem, oraz propagacja uszkodzenia warstwy adhezyjnej pomiędzy łączonymi elementami w różnych przypadkach obciążenia.

EN

The paper presents the results of laboratory tests of three-point cyclic bending of aluminum box beams connected by adhesive layer and rivets. Aluminum omega profiles were joined with a flat aluminum plate using Loctite adhesive, 4mm diameters rivets, and a combination of these connectors. Beams of dimensions 84 x 36 x 300 mm were subjected to quasi static cyclic loading in two positions: omega profile on the top or bottom position. Material Testing System (MTS) strength and Digital Image Correlation system (DIC) were used. The work has analyzed the development of deformation profiles and their damage, and the propagation of damage to the adhesive layer between the joined elements in different load cases.

6

Parametric Study of Geometry Effect on Response to Applied Loadings of Metallic Honeycomb Structures by Virtual Testing of Mesoscale Models

Pietras D., Sadowski T.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

953--961

EN

In this paper were conducted virtual tests to assess the impact of geometry changes on the response of metallic hexagonal honeycomb structures to applied loadings. The lateral compressive stress state was taken into consideration. The material properties used to build numerical models were assessed in laboratory tests of aluminium alloy 7075. The modelling at meso-scale level allow to comprehensive study of honeycomb internal structure. The changes of honeycomb geometry elements such as: fillets radius of the cell edges in the vicinity of hexagonal vertexes, wall thickness were considered. The computations were conducted by using finite element method with application of the ABAQUS finite element method environment. Elaborated numerical models allowed to demonstrate sensitivity of honeycomb structures damage process response to geometry element changes. They are a proper tools to perform optimization of the honeycomb structures. They will be also helpful in designing process of modern constructions build up of the considered composite constituents in various branches of industry. Moreover, the obtained results can be used as a guide for engineers. Conducted virtual tests lead to conclusion that simplification of the models of internal honeycomb structure which have become commonplace among both engineers and scientist can lead to inaccurate results.

7

Wpływ dokładności wykonania elementów połączenia zatrzaskowego na przebieg montażu

Kuczmaszewski J., Pieśko P., Zawada-Michałowska M., Sadowski T., Łogin W.

Technologia i Automatyzacja Montażu

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2017

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nr 4

27--31

PL

W pracy przedstawiono analizę wpływu dokładności wykonania elementów połączenia zatrzaskowego na przebieg montażu, a w szczególności na wartości sił zamykających. Jednym z najbardziej efektywnych i łatwych sposobów łączenia elementów jest połączenie zatrzaskowe, które jest stosowane do montażu struktur wielkogabarytowych. W ramach pracy opracowano i przebadano przebieg montażu w aspekcie dokładności wykonania elementów mechanicznego połączenia, które wykonano z dwóch materiałów tj.: stopu aluminium EN AW-2024 (pokrywa) oraz kompozytu polimerowego (podstawa) na osnowie żywicy epoksydowej wzmacnianej włóknem szklanym (TSE). Na podstawie przeprowadzonych badań zauważono, że w aluminiowej pokrywie występują plastyczne deformacje elementów zatrzasku, objawiające się zwiększeniem jego średnicy w górnej części. Może to wynikać z zalegania naprężeń własnych powstałych zarówno w procesie wytwarzania półfabrykatu (efekt historii technologicznej), jak i wygenerowanych podczas obróbki skrawaniem. Dodatkowo w trakcie zamykania połączenia zauważono charakterystyczny podział na trzy etapy: w pierwszym zaobserwowano wyraźny wzrost siły niezbędnej do uzyskania wymaganego odkształcenia sprężystego, następnie stabilizację siły wciskania oraz ostatecznie gwałtowny wzrost wynikający z całościowego odkształcania konstrukcji. Początkowe rozbieżności w wartościach siły zamykającej są prawdopodobnie rezultatem różnic w wartościach odchyłek wykonania otworów w podstawie. Wykonana analiza pozwala stwierdzić, iż mierzone wartości odchyłek wymiarów mieszczą się w założonych tolerancjach, co oznacza, że mechaniczne połączenie zatrzaskowe zostało zaprojektowane i wykonane poprawnie.

EN

The paper presents an analysis of influence of machining accuracy of snap fit joint elements on assembly process, in particular on values of closing forces. One of the most effective and easy ways to bind elements is a snap fit joint which is used for the assembly of large-size structures. As a part of experimental study assembly process was developed and studied in aspect of machining accuracy of elements of mechanical joint. They are made of two materials i.e.: aluminum alloy EN AW-2024 (cover) and polymer composite (base). It has an epoxy resin matrix and is reinforced with glass fibres (TSE). Based on the conducted study, it has been noted that in aluminum cover are plastic deformations of snap elements, showing by increasing its diameter at the upper part. It can be result of internal stresses created in both blank manufacturing process (effect of technological history), and generated during machining. Additionally, du ring binding characteristic division into three phases has been observed: at first, clear increase of force necessary to achieve the required elastic deformation, then force stabilization and finally a sharp increase due to deformation of overall structure. Initial differences in the values of closing force are probably the result of differences in deviation values of performed holes in the base. The conducted analysis leads to the conclusion that the measured deviation values of dimensions fit in the established tolerances, which means that the mechanical snap fit joint was designed and manufactured properly.

8

Rekonstrukcja niekompletnych obrazów za pomocą metod aproksymacji modelami niskiego rzędu

Sadowski T., Zdunek R.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2017

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T. 7, nr 4

44--48

PL

W pracy badano zadanie rekonstrukcji brakujących pikseli w obrazach poddanych losowym zaburzeniom impulsowym w kanale transmisyjnym. Takie zadanie może być sformułowane w kontekście interpolacji obrazu na nieregularnej siatce lub aproksymacji niekompletnego obrazu za pomocą modeli dekompozycji obrazu na faktory niskiego rzędu. Porównano skuteczność czterech algorytmów opartych na dekompozycjach macierzy lub tensorów: SVT, SmNMF-MC, FCSA-TC i SPC-QV. Badania przeprowadzono na obrazach niekompletnych, otrzymanych z obrazów oryginalnych przez usunięcie losowo wybranych pikseli lub linii tworzących regularną siatkę. Najwyższą efektywność rekonstrukcji obrazu uzyskano gdy na estymowane faktory niskiego rzędu narzucano ograniczenia nieujemności i gładkości w postaci wagowej filtracji uśredniającej.

EN

The paper is concerned with the task of reconstructing missing pixels in images perturbed with impulse noise in a transmission channel. Such a task can be formulated in the context of image interpolation on an irregular grid or by approximating an incomplete image by low-rank factor decomposition models. We compared four algorithms that are based on the low-rank decomposition model: SVT, SmNMF-MC , FCSA-TC and SPC-QV. The numerical experiments are carried out for various cases of incomplete images, obtained by removing random pixels or regular grid lines from test images. The best performance is obtained if nonnegativity and smoothing constraints are imposed onto the estimated low-rank factors.

9

Cracking of two-phase ceramics under uniaxial compression deformation

Sadowski T., Marsavina L., Craciun E. M.

Engineering Transactions

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2017

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Vol. 65, iss. 1

39--44

EN

Two-phase ceramics have a non-linear and complex overall response to applied loads due to composition of two different phases with initial porosity, development of limited plasticity and internal microdefects. These microdefects cause stress concentrations and locally change the state of stress, which results in the development of mesocracks leading to macrocracks. In this article, a multiscale approach was applied to the modelling of the two-phase ceramics response under compression deformation. This allowed to include different phenomena at micro-, mesoand macro-scales.

10

Numerical modelling of hydraulically bonded mixture with rubber admixture due to applied mechanical loadings

Pietras D., Sadowski T.

Budownictwo i Architektura

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2017

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Vol. 16, nr 3

95--102

EN

Abstract: In this paper the application of the Extended Finite Element Method (XFEM) to anticipate change of the behaviour of composite with complex internal structure after use of the admixtures was presented. The response to mechanical loadings of bent beams made of hydraulically bonded mixture with rubber admixture was considered. The impact of the rubber granulate on the value of fracture energy was analysed. Moreover, the influence of an interfacial transmission zone quality on the achieved effect was assessed. Calculations were conducted by means of the muli-scale numerical model which was built in ABAQUS finite element method environment. The results derived indicate beneficial effect of rubber granulate on fracture energy of hydraulically bonded mixture.

11

Optimization of a thin-walled element geometry using a system integrating neural networks and finite element method

Golewski P., Gajewski J., Sadowski T.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 1

435--442

EN

Artificial neural networks [ANNs] are an effective method for predicting and classifying variables. This article presents the application of an integrated system based on artificial neural networks and calculations by the finite element method [FEM] for the optimization of geometry of a thin-walled element of an air structure. To ensure optimal structure, the structure’s geometry was modified by creating side holes and ribs, also with holes. The main criterion of optimization was to reduce the structure’s weight at the lowest possible deformation of the tested object. The numerical tests concerned a fragment of an elevator used in the “Bryza” aircraft. The tests were conducted for networks with radial basis functions [RBF] and multilayer perceptrons [MLP]. The calculations described in the paper are an attempt at testing the FEM - ANN system with respect to design optimization.

12

Modelling and Experimental Testing of Hybrid Joints Made of: Aluminium Adherends, Adhesive Layers and Rivets for Aerospace Applications

Sadowski T., Golewski P.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 3

1577--1583

EN

The contemporary demands in different branches of engineering require application of new multi-component materials and structural systems. Appropriately chosen joining technology can offer significant enhancement of structural system performance in terms of effectiveness, reliability, safety and other design criteria. The modern applications of complex joints are of great technological interest as they permit to combine and to enhance the individual effects of each kind of joint. This is of great importance for modern applications in different branches of engineering: aerospace, mechanical and civil. Therefore in this paper we will focus on the analysis of mechanical response of adhesive joint of aluminium strips reinforced by rivets. The aim of the paper is to investigate experimentally the mechanical behaviour of adhesive joint of aluminium strips reinforced by rivets for industrial applications in aerospace. The considered joint was subjected to uniaxial loading. The tests in this paper were performed for: • classical adhesive joint in order to investigate material parameters for numerical modelling of the hybrid joint • hybrid joining of the structural elements in order to investigate the reinforcement effect. The experiments with application of digital image ARAMIS system allowed for on-line monitoring of the deformation process of the considered joining elements. The particular distributions of displacement fields at the joint surface were estimated for any stage of loading process. Numerical modelling was performed for experimentally investigated specimens. The materials parameters, necessary for calculation, were estimated from experiments. FEA modelling was done with the help of ABAQUS code.

13

Application of Conjugate Simulation for Determination of Temperature and Stress Distributions During Curing Process of Pre-Impregnated Composite Fibers

Golewski P., Sadowski T.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2295--2301

EN

The composites made of continuous fibers in the form of unidirectional and fabric prepregs are widely used in many fields of engineering for the production of lightweight and durable parts or whole structures. To achieve this, we not only need to possess knowledge of the composite mechanics, but also have to master the technology. In most cases, particularly for parts with advanced geometric shapes, autoclaving technique is used. The success of the carried out process occurs when the prepreg reaches the proper temperature throughout its volume in the specified time, where there are no overheated or unheated zones as well as when the prepreg is correctly pressed against the mold. In order to ensure adequate stiffness, the mold has much greater thickness than formed composite and the stiffening ribs. The result is that the time required for prepreg heating is greatly extended. To prevent this, the appropriate electric heaters embedded in the silicone grips are used. The paper presents problems related to the mold structures and application of numerical methods aiming at early verification of the temperature and stress distribution. The coupled analysis of CFD (computational fluid dynamic) and heat transfer structural simulations were performed in Abaqus program. The studies were carried out for the airfoil fragment. A total of 12 simulations were conducted, 6 cases in which heat was supplied only from air flowing through the autoclave and 6 cases which included heaters inside the silicone grips. In the result the inhomogeneity of prepreg heating for each of the mold geometry was compared, and the average temperature was obtained after 60 seconds from the process initiation. Both the pressure inside the silicone grips (before inserting the mold into the autoclave) and the non-uniform temperature distribution result in the formation of stresses whose values were analyzed for molds made of aluminum. For this purpose the temperature dependent elastic – plastic material model was used for aluminum molds.

14

Assessment of collapse diagrams of rigid polyurethane foams under dynamic loading conditions

Linul E., Serban D. A., Marsavina L., Sadowski T.

Archives of Civil and Mechanical Engineering

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2017

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Vol. 17, no. 3

457--466

EN

This paper investigates the collapse diagrams (energy-absorption and efficiency diagrams) under dynamic compression tests (drop tests) with an impact loading speed of 3.09 m/s. Experimental tests were carried out at room temperature on seven different types of closed-cell rigid polyurethane foams with densities of 40, 80, 100, 120, 140, 145 and 300 kg/m3 respectively. Based on the measured load–displacement curves, authors plotted the variation of peak stress, energy-absorption and efficiency attributes with respect to density for each type of foam, highlighting the optimum foam density (100 kg/m3). The influence of density and loading direction (in-plane and out-of-plane) on the main mechanical properties are also discussed. Following the investigations it was observed that both efficiency and energy absorption diagrams shows similar results, leading to the conclusion that both methods are reliable. Considering the test setup, a finite element analysis model was developed that aimed to replicate the experimental procedures. Simulations were performed in the commercial software Abaqus/Explicit using the implemented Elastic/Crushable foam constitutive model and using the static and dynamic test data for calibration. The energy-absorption and efficiency diagrams obtained from simulations were compared with the experimental data.

15

Cienkościenne zamknięte profile aluminiowe łączone za pomocą warstwy adhezyjnej – charakterystyka przy trójpunktowym zginaniu

Sadowski T., Nowicki M.

Przegląd Budowlany

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2016

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R. 87, nr 2

30--33

PL

Profile cienkościenne znajdują obecnie szerokie zastosowanie w budownictwie. Wykorzystywane są jako materiały konstrukcyjne, elementy stolarki czy elementy wykończeniowe. Jednak łączenie ich za pomocą kleju to jeszcze dość mało rozpowszechnione metody, chociaż w ostatnim czasie wzrasta zainteresowanie technikami klejenia konstrukcji metalowych w budownictwie. Opracowanie przedstawione w pracy dotyczy analizy klejonego cienkościennego profilu aluminiowego o przekroju poprzecznym omega, który poddano 3-punktowemu zginaniu. W artykule przedstawiono wyniki badań laboratoryjnych oraz modelowania numerycznego quasi-statycznego zginania tych elementów w dwóch ułożeniach profili.

EN

Nowadays, thin-walled profiles are widely used in building industry. They are used as construction materials, woodwork elements or finishing elements. However, joining them with the use of an adhesive material is not a widely recognized method yet, although recently growing interest in techniques of gluing the metal structures in building industry could have been observed. The study presented in this paper discusses the analysis of glued thin-walled aluminum profile with omega cross-section, which has been subject to 3-point bending. The article presents the results of laboratory testing and of numerical modeling of quasi-static bending of these elements in two profile positions.

16

Cracks in interfaces and around their junctions in WC/Co composite

Postek E., Sadowski T.

Engineering Transactions

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2016

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Vol. 64, iss. 4

589--596

EN

WC/Co ceramic metal-matrix composites are characterized by very high mechanical properties that allow for application of the composites mostly in production of different types of cutting tools. By combining in a composite structure a phase of brittle hard wolfram carbide (WC) grains with a metallic interface of cobalt (Co) that exhibits plastic properties, a geometrically complex microstructure with significantly different mechanical properties of the combined phases is created, see Fig. 1a. The presence of the elastic-plastic interface material, i.e. Co binder, in the composite structure is the reason for initiation of technological defects – mainly material porosity. During material loading pores start to coalesce and finally one can observe creation of microcracks system distributed along interfaces. The aim of the paper is to show the previously formulated model [1, 2] of the polycrystalline composite to be extended towards cracks development around the junctions of the interfaces. The obtained numerical results indicate that in the junctions high stress concentrations were observed, which leads to crack initiation and its further unstable propagation, and finally the composite failure. Results indicate that the first crack appears close to the junction and that the load carrying capacity of the sample is overestimated if a crack model in the interfaces is not assumed.

17

Analiza procesu odkształcenia cienkościennych belek skrzynkowych, łączonych różnymi metodami, pod wpływem trójpunktowego zginania

Sadowski T., Nowicki M., Pietras D., Golewski P.

Rudy i Metale Nieżelazne Recykling

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2015

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R. 60, nr 12

694--699

PL

Przedstawiona praca zawiera wyniki badań laboratoryjnych oraz analiz numerycznych trójpunktowego zginania aluminiowych belek skrzynkowych. Analizowane elementy, o przekroju poprzecznym omega zostały połączone na kilka różnych sposobów z płaskimi płytkami tworząc przekroje zamknięte. Łączniki j akie zostały tu u żyte to k leje z g rupy L octite o raz nity zrywalne o średnicy 4 mm, a także kombinacje tych połączeń. Belki o wymiarach 84 × 36 × 300 mm poddano quasi statycznemu obciążeniu w dwóch położeniach: profil omega w górnej lub dolnej pozycji. Dla każdej z tych pozycji wykonano taką samą liczbę analiz i testów. Ponadto praca zawiera wyniki analiz numerycznych dla profili jednolitych. Przedstawione wyniki prezentują charakter odkształcenia profilu w zależności od jego położenia względem obciążenia oraz od rodzaju użytego łącznika. Można tu także wyraźnie zaobserwować rozkłady naprężeń w elementach oraz poziom delaminacji łączonych warstw w różnych przypadkach obciążenia.

EN

This paper presents results of laboratory tests and numerical analyzes of three-point bending of aluminum box beams. The analyzed omega profiles are combined in different ways with the flat plates to form a closed profile. Various combinations of made of Loctite adhesives and rivets having a diameter of 4 mm were applied to get different types of connections. Specimens of dimensions 84 × 36 × 300 mm were subjected to quasi-static loading in two positions: omega profile on the top or bottom position. The experimental tests were modeled numerically with application of the ABAQUS program. Moreover, the work contains also numerical analyzes of uniform profiles made of pure aluminium material. The results represent modes of the deformation profile, depending on its position relative to load and on type of connectors. Distributions of stresses in the elements and the level of delamination of the adhesive layers combined in various cases of the thinwalled box beams were presented.

18

O sprężaniu betonowych zapór wodnych

Mucha J., Żyła M., Sadowski T., Szydłowski R.

Materiały Budowlane

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2015

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nr 9

94--95

PL

Wznoszenie masywnych zapór wodnych zapoczątkowano w starożytnej Mezopotamii i na Bliskim Wschodzie. Pierwszym zaporom stabilność zapewniała ich ogromna masa. Obecnie zapory są kotwione do podłoża kotwami dużej mocy. Rozwiązanie takie zapewnia stabilność zapór przy zmniejszonej ich masywności. W artykule, na przykładzie wzmocnienia zapory Eder w Niemczech, przedstawiono system sprężania zapór wodnych oraz wynikające z tego korzyści.

EN

Erection of dams was initiated in the ancient Mesopotamia and in the Middle East. The stability of the first dams was achieved by the large mass of masonry and concrete material. The development of ground anchoring system enabled post-tensioning of the dams. The dam stability is ensured with reduced material mass. This paper present the example of Eder Dam (Germany) strengthening with prestressing tendons and derived advantages from prestressing.

19

The Influence of Geometrical Parameters in Socket - Pin Connections on the Value of Opening Force

Sadowski T., Golewski P.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2743--2750

EN

The paper presents an analysis of the influence of a number of technological aspects of both the socket and the pin on the value of the force required for joint disconnection. A number of numerical simulations were made in Abaqus program to examine effects of such parameters as: presence of an interference fit, use of spherical latches, application of different rigidity of the pin by making cuts with variable width and length, use of different angles of inclination of the working part of the connection. Models of different simple joints presented in this work, can also operate in large structures forming panels of aircraft structures. For this purpose one of the analyzed geometry of the connection was applied to create a 3-D panel model of the structural element in CAD - SolidWorks program. All analysed models with different geometries were subjected to simulation of opening process. The corresponding critical forces were estimated for the beginning of the failure process. The detailed discussion of all model parameters was included to specify their influence on the whole disconnection of joints. It should be noted that aerospace structures work under complex loading states and further numerical studies are required to extend the presented results.

PL

W pracy przedstawiono analizę wpływu kilku zagadnień technologii wykonania zarówno gniazda jak i trzpienia na wartość siły potrzebnej do rozłączenia połączenia. Przeprowadzono szereg symulacji numerycznych w programie Abaqus, badając wpływ takich parametrów jak: występowanie wcisku, użycie sferycznych zatrzasków, zastosowanie różnych sztywności w trzpieniu poprzez wykonanie rozcięć o zmiennej szerokości i długości, zastosowanie różnych kątów pochylenia części roboczej gniazda. Prezentowane w pracy modele pojedynczych połączeń mogą także funkcjonować w większych strukturach tworzących panele konstrukcji lotniczych. W tym celu, dla jednego z analizowanych rozwiązań geometrii wykonano model CAD panelu w programie SolidWorks, który następnie poddano symulacji otwierania. Należy jednak zwrócić uwagę, że konstrukcje lotnicze pracują w złożonych stanach naprężeń i tym samym konieczne są dalsze badania numeryczne prezentowanych rozwiązań.

20

Skew Bending of Aircraft Fuselage Panels with “L” and “C” Stringers Mounted by Hybrid Joint

Sadowski T., Golewski P.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

2813--2820

EN

A section of fuselage skin with dimension 30 x 200 mm was subjected to numerical study and loaded by skew bending (Fig. 3). The thickness of the skin was 0,6 mm, the length of a leg of an angle “L” profile stringer was 12 mm with 1mm thickness. The angle of inclination α of the load plane to the skin plane varies in the range from 10° to 90° with 10° increment. The elastic - plastic material model of D16T aluminum alloy was used in simulations of the fuselage skin as well as for “L” and “C” profile stringers. In the material model description damage of aluminum alloy was taken into account. An adhesive layer with thickness of 0,1mm was modeled using cohesive elements with the failure mode depending on the shear strength and the tensile strength. The paper presents a comparative analysis of the considered structural elements with application of the unsymmetrical “L” profile or the symmetrical “C” profile with the same cross section area. All numerical studies were performed in Abaqus program. Finally, one can conclude that the stiffness of the structural element with application of the symmetrical “C” profile stringer is stronger, whereas the mechanical response of both versions of the hybrid joint significantly depends on the angle of load inclination α.

PL

Badaniom numerycznym poddano wycinek poszycia o wymiarach 30x200mm, który następnie poddano obciążeniu poprzez ukośne zginanie, Rys. 3. Grubość blachy poszycia wynosiła 0,6 mm, długość ramienia kątownika równoramiennego 12 mm i grubość ramienia 1mm. Kąt nachylenia α płaszczyzny obciążenia w stosunku do płaszczyzny poszycia zmieniał się w granicach od 10° do 90° z przyrostem co 10°. W symulacjach zastosowano model sprężysto – plastyczny materiału dla poszycia i kształtownika jakim był stop aluminium D16T. W opisie modelu materiału uwzględniono także uszkodzenie stopu aluminium. Warstewka kleju o grubości 0,1 mm była modelowana z wykorzystaniem elementów kohezyjnych, dla których także uwzględniono uszkodzenie przyjmując dane producenta, takiej jak wytrzymałość na ścinanie oraz na rozciąganie. W pracy przedstawiono analizę wpływu zmiany obecnie stosowanego niesymetrycznego kształtownika (kątownik), kształtownikiem symetrycznym (ceownik) o takim samym polu przekroju poprzecznego. Wszystkie badania numeryczne przeprowadzono w programie Abaqus.