Papers by Keyword: Aluminium

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Authors: Christina Radlbeck, Mathias Rengstl, Senta Pessel, Martin Mensinger
Abstract: DIN EN 1999-1-3 presents a comprehensive framework for fatigue design of aluminum structures. Various structural details and joints are included. For safety checks against High-Cycle Fatigue, three design concepts are available: Safe-Life-Design, Damage-Tolerant-Design and Design assisted by Testing. Respective safe-life-design lines are based on a databank including results from stress controlled Wöhler fatigue tests. The phenomenon of Low-Cycle-Fatigue (<105 cycles) is treated in Annex F, giving design regulations for selected structural details. Thereby, the influence of different alloys and thus different yield strength values is not considered. In addition, plasticizing effects under high stress ranges are neglected. In general, engineers face the following questions: Which cycle numbers require (Low-Cycle-) fatigue design and thus where is the limit for static design? Furthermore, how to define the maximum allowable stress range? Respective answers are investigated in a current research project carried out by the Chair of Metal Structures, TU Munich.In this contribution, the state of the art of fatigue design according to DIN EN 1999-1-3 is presented. European design concepts are discussed in view of available data and new developments in research, quality control, fabrication of specimen as well as testing techniques. The focus is then laid on Low-Cycle Fatigue. A new concept, including the influence of alloy type and the effects of plasticizing, is worked on. To this purpose an extensive testing program has started, including a large number of strain-controlled-tests.
Authors: Hugo Biscaia, João Cardoso, Carlos Chastre
Abstract: The bonding between two different materials or between same materials is a quite popular method. Unlike fastener joints, it avoids undesirable stress concentrations and doesn't demand an intrusive application to ensure the good performance of the joint. However, depending on the configuration of the adhesively bonded joint, its performance responds differently and the choice (if possible to make) on the best configuration, i.e. the configuration that originates the highest strength and/or stiffness, may be hard to make. Within this context, several configurations of aluminium-to-aluminium bonded joints unstrengthened and strengthened with fiber reinforced polymers (FRP) were modelled using a commercial finite element code. The linearity and nonlinearity of the FRP composite and the aluminium were considered, respectively, and the adhesively bonded joints were subjected to a regular displacement that intended to simulate a tensioning load. Also, the nonlinearities of the interfaces were considered in the form of nonlinear cohesive adhesive laws. The fracture Modes I and II were defined trough a bond-slip relation with a bi-linear shape and the Mohr-Coulomb failure criterion is used for the coupling of the cohesive adhesive laws of the interface when the debonding process of the bonded joint configuration implies the interaction between both fracture modes, i.e. the joint is under a mixed-mode (Mode I+II) situation. The results are presented and discussed and the configurations of the bonded joints are all compared through bond stress distributions and load-slip responses. The study herein presented is, therefore, a contribution to the analysis of the structural integrity of bonded joints between FRP composites and aluminium substrates, helping also on the choice of the most adequate bonded joint configuration and corresponding reinforcement to be used and applied in practice.
Authors: Viktor Alexandrovich Gulevskiy, Pavel Stanislavovich Golovinov, Anna Sergeevna Knyazeva, Nikolay Alexeevich Kidalov
Abstract: The article describes a technology for producing carbon-graphite-aluminium composite by non-autoclave gasless impregnation of a carbon-graphite skeleton by matrix alloy of aluminium and presents the results of testing, application areas and assessment of the properties of obtained composites as well.
Authors: Muhammad Tayyab Naqash, Antonio Formisano, Gianfranco De Matteis
Abstract: Curtain wall systems are considered as envelop of a building, generally made of a lightweight material such as aluminium. The curtain wall façade does not carry any weight from the building, rather it transfers loads that are incident upon it to the main building structure through connections with floors or columns. This paper addresses some key issues in satisfying the respective limit state design checks. Two mullion profiles 85mm and 125mm deep of three manufacturers are analysed showing that the different extrusions of mullion profiles does not have any drastic effect on its structural behavior. Due to the versatility and lightweight, aluminum has many advantages when used as a curtain wall framing material, but it has the distinct disadvantage of being three times more deformable than steel. Therefore, the fulfillment of serviceability limits is an important issue when designing the framing members, in order to avoid damage of connected glasses. Also, the importance of connections and steel insert are highlighted. Finally, some completed and in-progress ALUTEC projects with different curtain wall systems are presented. The paper is therefore interesting for the Façade Engineers involved in the design of curtain walls.
Authors: Vasiliki Ntaskagianni
Abstract: Offshore lifts can be performed by platform cranes, crane vessels, helicopters or modular structures. The challenge of an offshore lift lies in performing it in inaccessible locations on the platform and minimizing the cost and the offshore time. Platform cranes often cannot reach the lifting object, and crane vessels and helicopters provide solutions which increase the operation costs. On the contrary, aluminium modular structures provide solutions which can make a challenging lift efficient and successful without incurring high costs.
Authors: Jean Brice Mandatsy Moungomo, Donatien Nganga Kouya, Victor Songmene
Abstract: The recycling of alumium alloys has been growing in interest and applications during the last fourthy years and has become a cost effective, ecological and reliable way to produce aluminium parts. The aluminium scraps that can be recycled include cans and machining chips. The machining processes produce chips of various sizes and shapes, wet or dry, oxidised or not, depending on type of process and the machining conditions, parameters and tools used. Some processes produce metallic dusts and fine chips while other produce large or medium size chips. In some industries such as mould making and aeronautic industries, the chip removal can easily represent 80% of the initial workpiece mass. The type of chips produced during machining can have a great impact on chip management, on part quality, on machine and tool reliability and on part manufacturing costs. The machining chips can be recycled using casting, sintering or pressing and extrusion processes depending on the goal targeted. The selection of the recycling process must take into account the targeted applications, the chip (composition, sizes and cleanliness) and its mechanical properties. Depending on the nature of process to be used and the machining chip generation conditions, some treatments might be necessary prior to transportation and recycling. Parts made with recycled chips can either be bi-phase metal matrix composites materials or usual one phase material with mechanical properties and wear properties comparable or not to the parent alloys. Over the last decades, several chip recycling processes have been proposed for aluminium alloys. This article review the aluminium chips formation, treatement methods, the recycling processes and their impact on recomposed parts’ performance: strength, ductility, corosion and wear resistances.
Authors: Cyriel Clauwaert
Abstract: In the past five years a number of master’s theses have been conducted at Belgian Technical Colleges and Universities to (re)introduce knowledge of aluminium as a structural material, given that courses offered in Belgium are oriented towards steel and concrete design and no specific course on aluminium exists. The present contribution highlights the different subjects covered in these theses and illustrates the results obtained. Emphasis is placed on the methodology used to design and innovate with aluminium, taking into account the Eurocode rules that apply to the design of specific aluminium structures. For this, appropriate use was made of existing software that allows for the detailed calculation of section reduction and unity checks.
Authors: Felice Rubino, Paola Ammendola, Antonello Astarita, Federica Raganati, Antonino Squillace, Antonio Viscusi, Riccardo Chirone, Luigi Carrino
Abstract: Metallic foams are known for their interesting physical and mechanical properties such as high stiffness, very low specific weight, high compression strength, unusual acoustic and thermal properties and good energy absorption characteristics. These materials are currently manufactured by means of several different processes. The limit of these conventional technologies is the impossibility to produce foams with complex geometry.This paper deals with the study of an innovative method to produce complex shaped precursors for aluminum foams through cold gas dynamic spray deposition process (CGDS). Aluminum alloy (Al-Si) fine powders were previously mixed with the blowing agent (titanium-hydride, TiH2). The mixing process was carried out by means of sound-assisted fluidized bed apparatus that allows to obtain an homogeneous mixture of the two elements. The mixed particles were then sprayed by means of the CGDS process on a stainless steel sheet that simulates the real component to be reinforced with the foam. Subsequently the obtained precursor was heated up in a furnace The produced metal foam was characterized using optical and electron microscopy in order to study the cell morphology and distribution.The obtained results showed the effectiveness of this method to produce aluminum foams with complex shape.
Authors: Alexander P. Ilyin, Liudmila O. Root, Andrei V. Mostovshchikov
Abstract: The problems of hydrogen energetic as well as a method of high pure hydrogen obtaining are presented in the paper. It was suggested to use the reaction of aluminium nanopowder with water, as the reaction proceeds with high rate even at ambient conditions (the rate of hydrogen emission reached 18 ml/(s∙g)) and high degree of conversion (up to 100 %). The unreasonableness of the replacement of aluminium nanopowder to coarse-grained powder in this reaction due to the low efficiency is shown in the article. As a solution for pure hydrogen obtaining, a phenomenon of self-heating of aluminum nanoparticles and the resulting hydrogen, as well as the effect of its high-temperature diffusion through the membrane of ultrahigh molecular weight polyethylene were used.
Authors: M.A. Platonov, I.S. Sulimova, Irina D. Rozhikhina
Abstract: The paper considers carbon, silicon and aluminum reduction of barium and strontium from natural materials by thermodynamic modeling in conditions of out-of-furnace steel treatment. X-rays phase and differential thermal methods of analysis were applied to investigate the samples of natural barium and strontium containing material. A process flowsheet of steel treatment by barium-strontium modifier in induction furnace was developed on the basis of carried out research.
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