bluuebunny/crossref_metadata_2025 huggingface dataset:
Graphene-enhanced plasmonic nanohole arrays for environmental sensing in aqueous samples
Authors: Genslein Christa , Hausler Peter , Kirchner Eva-Maria , Bierl Rudolf , Baeumner Antje J , Hirsch Thomas
Published: November 2016

The label-free nature of surface plasmon resonance techniques (SPR) enables a fast, specific, and sensitive analysis of molecular interactions. However, detection of highly diluted concentrations and small molecules is still challenging. It is shown here that in contrast to continuous gold films, gold nanohole arrays can significantly improve the performance of SPR devices in angle-dependent measurement mode, as a signal amplification arises from localized surface plasmons at the nanostructures. This leads consequently to an increased sensing capability of molecules bound to the nanohole array surface. Furthermore, a reduced graphene oxide (rGO) sensor surface was layered over the nanohole array. Reduced graphene oxide is a 2D nanomaterial consisting of sp2-hybridized carbon atoms and is an attractive receptor surface for SPR as it omits any bulk phase and therefore allows fast response times. In fact, it was found that nanohole arrays demonstrated a higher shift in the resonance angle of 250–380% compared to a continuous gold film. At the same time the nanohole array structure as characterized by its diameter-to-periodicity ratio had minimal influence on the binding capacity of the sensor surface. As a simple and environmentally highly relevant model, binding of the plasticizer diethyl phthalate (DEP) via π-stacking was monitored on the rGO gold nanohole array realizing a limit of detection of as low as 20 nM. The concentration-dependent signal change was studied with the best performing rGO-modified nanohole arrays. Compared to continuous gold films a diameter-to-periodicity ratio (D/P) of 0.43 lead to a 12-fold signal enhancement. Finally, the effect of environmental waters on the sensor was evaluated using samples from sea, lake and river waters spiked with analytically relevant amounts of DEP during which significant changes in the SPR signal are observed. It is expected that this concept can be successfully transferred to enhance the sensitivity in SPR sensors.
Quelle reconstruction dans la campagne alsacienne au lendemain des guerres du XVIIe siècle ?
Authors: Boehler Jean-Michel
Published: November 2016

Mise à la mode historiographique au lendemain de la Seconde Guerre mondiale, la problématique de la « reconstruction » porte avant tout sur les réparations matérielles. Celle qui suit les guerres du XVIIe siècle, entre 1648 et les années 1720, tient compte à la fois des spécificités de la campagne alsacienne et du type de guerre pratiqué (rebondissement des conflits, dévastations et épuisement des ressources). Multiforme, elle est d’abord une reconstruction démographique, dans laquelle l’immigration tient une large part, le repeuplement bénéficiant, de la part du roi ou des seigneurs territoriaux, d’édits de défrichement particulièrement avantageux. Sur le plan économique, elle se solde souvent par un retour à l’âge d’or, mythique et idéalisé, des temps anciens : plus apparents que réels, les progrès qu’elle induit seront en effet tardifs (XVIIIe siècle) et relèveront souvent d’un simple rattrapage. De même, l’indispensable reconstruction religieuse et morale renoue également avec les valeurs traditionnelles et les usages séculaires. La reconstruction revêt ensuite, de la part des grands propriétaires fonciers, l’apparence d’une patiente reconstitution des droits face à l’usurpation des biens « caducs » et à l’instrumentalisation d’une emphytéose fréquemment usurpée par les exploitants. Sur le plan politique enfin, elle renforce l’autorité des princes territoriaux face au pouvoir souverain de l’empereur ou du roi.
Émile Salomon (1833-1913)
Authors: Umbrecht Véronique
Published: November 2016

Né à Strasbourg d’un père allemand et d’une mère alsacienne, Émile Salomon suit une double formation d’architecte à Paris à l’école des Beaux-arts de Paris puis à l’Akademie der bildenden Künste de Munich. Il contribue à la reconstruction de plusieurs quartiers après la guerre de 1870. Architecte attitré de la Fondation Saint-Thomas, il est chargé de redessiner le quartier du Temple Neuf, dévasté par les bombardements. Les dégâts de la guerre et la nécessité de reconstruire au plus vite incitent la municipalité et les particuliers à rénover un grand nombre de bâtiments. C’est à cette époque que le Consistoire protestant confie à Émile Salomon la transformation du quartier Saint-Thomas. Une nouvelle rue est percée, donnant un accès plus aisé à l’église Saint-Thomas. L’engagement d’Émile Salomon dans la défense et la valorisation du patrimoine alsacien ancré entre l’héritage français et allemand, ont nourri ses réflexions sur son art et lui ont permis d’affirmer un style spécifique, libre des pressions de la « germanisation » insufflée par les autorités allemandes.
L’épreuve de la reconstruction industrielle dans le Haut-Rhin après la Grande Guerre
Authors: Wisniewski Clément
Published: November 2016

Les deux départements alsaciens ne sont pas touchés par la guerre de la même manière. Alors que le Bas-Rhin occupe une position plus en retrait, le Haut-Rhin est traversé par la ligne de front. Les combats demeurent toutefois cantonnés sur les hauteurs vosgiennes, si bien qu’une partie de l’industrie haut-rhinoise installée dans les différentes vallées est détruite par les combats. D’autres usines sont également affectées par les aléas de la guerre : productions restreintes, chômage technique en raison des pénuries de matières premières, réquisitions de leur outillage… Pour faire face à cette multitude de dommages de guerre, une législation particulière résultant du droit allemand, français et du traité de Versailles, ainsi que des services administratifs propres à l’Alsace se mettent en place pour accompagner la reconstruction après-guerre. Toutefois, malgré une législation qui vise à favoriser leur réintégration dans l’économie nationale, les industriels alsaciens se trouvent pénalisés par des délais d’attente supérieurs aux autres régions dévastées pour le versement de leurs indemnités, prolongeant ainsi les difficultés causées par la Grande Guerre.
Reconstituer et reconstruire l’habitat rural après la Première Guerre mondiale : l’exemple des communes de la haute vallée de Munster (1919 - vers 1930)
Authors: Raimbault Jérôme
Published: November 2016

Au cours de la première année de la Grande Guerre, huit des neuf communes implantées en amont de la ville de Munster (Haut-Rhin), situées alors de part et d’autre de la ligne de front, sont anéanties dans des proportions supérieures à 90%. Plus d’une décennie est nécessaire pour mener à terme l’immense chantier de reconstitution de leur territoire et de reconstruction de leur habitat rural. Au sein d’un département nouvellement recouvré par la France, le service de la Reconstitution en Haute-Alsace va œuvrer dès 1919 au dédommagement des sinistrés et au relèvement des ruines. Il est chargé de l’application des lois prises par le gouvernement : loi sur les dommages de guerre (nommée aussi « Charte des sinistrés ») du 17 avril 1919 et loi sur les sociétés coopératives de reconstruction du 15 août 1920. Palliant les défaillances initiales de l’État, ces sociétés vont à partir de 1921 superviser et assurer la grande majorité des travaux de reconstruction des maisons et des fermes, en coordonnant l’activité des hommes de l’art, architectes et entrepreneurs. Cette entreprise d’une ampleur inédite donne la possibilité aux architectes de repenser les formes d’un habitat dont la sobriété est caractéristique de la moyenne montagne vosgienne. Prenant le dessus sur le courant moderniste, le courant régionaliste anime les architectes de la Reconstruction. Ceux-ci font renaître un habitat qui réinvestit les volumes et les distributions anciens et dont la modernité se manifeste par le choix des matériaux.
« Rendre à l’Alsace son beau visage » : la reconstruction des monuments historiques après 1945
Authors: Lefort Nicolas
Published: November 2016

L’Alsace est très gravement touchée par les combats et les bombardements de la Seconde Guerre mondiale : parmi les sinistres recensés, on compte de nombreux monuments classés et inscrits. Après 1945, leur restauration-reconstruction incombe au service des monuments historiques. Cette administration, rajeunie et réorganisée, est dotée de nouveaux moyens d’intervention mais elle dispose de crédits très insuffisants pour accomplir ses missions et doit composer avec les services du puissant ministère de la Reconstruction et de l’Urbanisme. Dans un premier temps, elle cherche à sauver un maximum d’édifices par des travaux de déblaiement, de mise hors d’eau et de consolidation provisoire. Sa politique de sauvegarde de l’aspect traditionnel des quartiers anciens et des villages pittoresques d’Alsace connaît des réussites et des échecs. Vient ensuite le temps des travaux définitifs qui doivent rendre aux monuments leur beauté et leur solidité tout en préservant leur authenticité. Les nombreuses restaurations, dirigées par l’architecte en chef Bertrand Monnet (1910-1989), posent des problèmes multiples sur le plan administratif, économique et technique. Elles soulèvent également des questions de doctrine, d’ordre archéologique et esthétique. Elles revêtent enfin des enjeux politiques et symboliques, nationaux et locaux, qui appellent des réponses variées : la reconstruction à l’identique, la restauration d’une unité de style, la reconstruction des parties détruites dans un style contemporain ou la dérestauration des parties transformées au XIXe siècle.
Une reconstruction controversée : l’église Saint-Arbogast de Herrlisheim (1945-1972)
Authors: Wehbé Jokine
Published: November 2016

L’ancienne église Saint-Arbogast de Herrlisheim (Bas-Rhin) avait été construite au XVIIIe siècle et partiellement classée monument historique en 1932. Le sanctuaire avait été gravement endommagé par la Seconde Guerre mondiale. Après 1945, il fut d’abord question de le reconstruire à l’identique. En 1972, on édifia finalement à sa place une nouvelle église de style moderne affirmé, réalisation de l’architecte en chef des monuments historiques Bertrand Monnet et de l’architecte des bâtiments de France Fernand Guri. Quatre phases de projet peuvent être distinguées entre ces deux dates ; elles témoignent de l’évolution de la position des acteurs (municipalité, clergé, service des monuments historiques et services de la reconstruction) et du renouvellement de l’art sacré. L’église actuelle est un édifice monumental d’un grand intérêt architectural sur le point d’être labellisé « Patrimoine du XXe siècle ».
Honneur et conflit
Authors: Liening Simon
Published: November 2016

Cet article est consacré au thème « honneur et conflit », étudié à partir de l’exemple de la participation militaire de la ville de Strasbourg à l’expédition vers Rome du roi Robert (1401-1402). Il s’intéresse à plusieurs conflits opposant le capitaine du contingent strasbourgeois d’un côté à ses hommes mais aussi au Conseil de la ville de l’autre. Dans ce cadre, les tensions intra-urbaines ainsi que la concurrence entre les différents groupes sociaux à Strasbourg ainsi qu’au sein du contingent revêtaient une signification particulière. La notion d’honneur est fondamentale pour comprendre la naissance comme la résolution de ces conflits. Cette étude de cas peut en effet mettre en évidence combien l’honneur était essentiel pour préserver la stabilité de l’ordre politico-social d’une ville à la fin du Moyen Âge. La relation entre ces deux notions était réciproque : le maintien ou la violation de l’honneur assurait ou mettait en danger l’ordre social existant, et inversement la préservation ou non de cet ordre avait des conséquences sur l’honneur des différents acteurs sociaux.
Entre Suède, Alsace, Paris et Versailles, les Lœwenhaupt au XVIIIe siècle : une identité hybride
Authors: Laperche-Fournel Marie-José
Published: November 2016

Cosmopolite et francophile, telle est au XVIIIe siècle l’aristocratie suédoise à laquelle appartient le comte Adam de Lœwenhaupt. Issu d’une famille illustre et cousin du maréchal de Saxe, en 1742, dans un contexte troublé, il quitte pour la France les rives de la Baltique, lieu de fortes migrations nobiliaires ; établi en Alsace où il épouse sa cousine, la baronne de Sainclair, il termine ses jours à Paris en 1775. Sur quelles bases, cette noblesse transnationale fonde-t-elle son identité ? Servant le roi avec fidélité, naturalisés, fréquentant la cour et les salons parisiens, le comte et ses apparentés semblent socialement et culturellement intégrés. Mais suédois, ils sont aussi luthériens. Désormais isolés en terre catholique, pour préserver leur rang et protéger leur confession, ils finissent par rétrécir au cercle de la parenté le jeu des alliances affichant par là même leur refus de se fondre dans la communauté d’accueil. En Alsace, Lœwenhaupt, « homme de guerre », face à Dietrich, son voisin, « baron du fer », affiche aussi sa singularité. Face aux valeurs bourgeoises qu’incarne ce dernier – le talent et l’argent ; des valeurs qui séduisent pour une large part la grande noblesse française –, le comte, à l’instar des petits nobliaux de province, réaffirme hautement les siennes, la naissance et l’honneur. Noblesse cosmopolite ouverte à des courants contradictoires, ces Suédois expatriés, les yeux rivés vers leur patrie, se forgent à l’étranger une identité hybride.
Au-delà de la vocation artistique : un recrutement sexuellement différencié des candidat-e-s à une carrière de plasticien-ne ?
Authors: Provansal Mathilde
Published: November 2016

Les artistes plasticiennes disparaissent du sommet des palmarès artistiques et continuent d’occuper une position dominée dans le monde de l’art contemporain. Pourtant, elles représentent près de la moitié de la population des artistes plasticien-ne-s (Gouyon & Patureau, 2014) et surtout elles sont majoritaires dans les écoles d’art depuis une trentaine d’années (Segré, 1993 ; Sotto, 2012). Nous analysons ici la mise en place de différenciations sexuées dans les parcours professionnels en privilégiant l’analyse d’un moment particulier qui précède l’entrée dans la carrière artistique, à savoir le recrutement au sein d’une école d’art. L’observation des oraux d’admission en première année de l’École des Arts Plastiques a permis de faire ressortir les critères des membres du jury pour départager les « ayant droit » à une carrière artistique et les outsiders. Nous montrons que les femmes font face à des représentations sexuées qui vont jouer très tôt sur leur passage en école d’art en vue d’une carrière artistique.
Investigation on Hardening and Softening Behavior of Steel after Rapid Strain Rate Changes
Authors: Dierdorf Jens , Lohmar Johannes , Hirt Gerhard
Published: November 2016

The design of industrial hot metal forming processes nowadays is mostly carried out using commercial Finite Element (FE) software codes. For precise FE simulations, reliable material properties are a crucial factor. In bulk metal forming, the most important material property is the materials flow stress, which determines the form filling and the necessary forming forces. At elevated temperatures, the flow stress of steels is determined by strain hardening, dynamic recovery and partly by dynamic recrystallization, which is dependent on strain rate and temperature. To simulate hot forming processes, which are often characterized by rapidly changing strain rates and temperatures, the flow stress is typically derived from flow curves, determined at arbitrary constant temperatures and strain rates only via linear interpolation. Hence, the materials instant reaction and relaxation behavior caused by rapid strain rate changes is not captured during simulation. To investigate the relevance of the relaxation behavior for FE simulations, trails with abrupt strain rate change are laid out and the effect on the material flow stress is analyzed in this paper. Additionally, the microstructure evolution due to the strain rate change is investigated. For this purpose, cylinder compression tests of an industrial case hardening steel are conducted at elevated temperatures and different strain rates. To analyze the influence of rapid strain rate changes, changes by one power of ten are performed at a strain of 0.3. As a reference, flow curves of the same material are determined at the initial and final constant strain rate. To investigate the microstructure evolution, compression samples are quenched at different stages, before and after the strain rate change. The results show that the flow curves after the strain rate change tend to approximate the flow curves measured for the final strain rate. However, directly after the strain rate change significant differences between the assumed instant flow stress and the real material behavior can be observed. Furthermore, it can be shown that the state of dynamic recrystallization at the time of the strain rate change influences the material response and relaxation behavior resulting in different slopes of the investigated flow curves after the strain rate change.
Benefits of Using Diamond Dies for Cold Alternate Drawing of Magnesium Alloys
Authors: Hristov Vladimir  Stefanov , Yoshida Kazunari
Published: November 2016

In recent years, due to its low density and high strength/weight ratio, magnesium alloy wires has been considered for application in many fields, such as welding, electronics, medical field (for production of stents). But for those purposes, we need to acquire wires with high strength and ductility. For that we purpose we proposed alternate drawing method, which is supposed to highly decrease the shearing strain near the surface of the wire after drawing, by changing the direction of the wire drawing with each pass and thus acquiring high ductility wires.We have done research on the cold alternate drawing of magnesium alloy wires, by conducting wire drawing of several magnesium wires and testing their strength, hardness, structure, surface and also finite element analysis, we have proven the increase of ductility at the expense of some strength.In this research we are looking to further improve the quality of the drawn wires by examining the benefits of using diamond dies over tungsten carbine dies. Using the alternate drawing method reduces the strength of the drawn wires and thus lowering their drawing limit. By using diamond dies we are aiming to decrease the drawing stress and further increase the drawing limit of the alternate drawn wires and also improve the quality of the finishing surface of the wires. With this in mind we are aiming to produce a good quality wire with low diameter, high ductility, high strength and fine wire surface.
Relationship between Molecular Structures of Organic-Sulfur Compounds and Metal Forming Performance
Authors: Takaki Tomohiro , Ito Shogo , Kitamura Kazuhiko , Yagishita Kazuhiro , Shibata Junichi
Published: November 2016

Oil with a chlorinated extremely-pressure additive (EP-additive) is effective to prevent galling in cold forming for stainless steel. However environmental issues have pressured the manufacture to replace this oil with high performance oil without chloride. Particularly, sulfur-based EP-additives are accepted as a practicable replacement for chlorinated EP-additives. Thus, the authors analyzed the structures of organic-sulfur compounds. Moreover, the effects of the molecular structures on the anti-galling performance are estimated by a cup internal ironing test. This test has been devised to classify the performance of sample oils by the ironing load and the damage on the workpiece after the test. Consequently, sulfurized olefin was superior to sulfurized ester and sulfurized fatty oil in cold ironing for stainless steel. It was also clarified that sulfur EP-additives generated iron sulfide and sulfate on the surface of stainless steel by using the surface analyses of X-ray photoelectron spectroscopy.
Effect of Microstructure and Mechanical Properties Formation of Medium Carbon Steel Wire through Continuous Combined Deformation
Authors: Polyakova Marina , Calliari Irene , Gulin Alexandr
Published: November 2016

The combination of different types of deformation can create a continuous method that ensures the formation of ultrafine-grain structure in medium carbon steel wire. The method is based on drawing operation combined with torsion and bending. Tools and equipment applied in the wire and cables manufacturing are used for the implementation of this method. As a result of the combined strain effect the ultrafine homogeneous structure is formed in the medium carbon steel wire. The wire has increased strength while maintaining the plastic properties when compared with the corresponding properties after drawing.
Metallic Multilayered Materials Produced by Constrained Compression
Authors: Kwiecień Marcin , Lisiecki Łukasz , Bajda Szymon , Majta Janusz , Krzyżanowski Michał
Published: November 2016

Investigation of the mechanical behaviour of multilayered metallic materials obtained during novel joining technique called Constrained Compression (CC) is presented. 316L stainless steel material was used in CC to achieve multi-layered structure. Microstructural study based on light microscopy was performed focused presumably on the joining areas of the deformed metallic laminate. The qualitative and quantitative assessment of the processing conditions, microstructure development and microhardness distributions showed the possibility of achievement good bonding quality. Experimental study was supported by numerical stress and strain analysis. It has been shown that determination of the optimum processing parameters allowed for improvement of the joining process, which in turn will enable to produce multilayered metallic materials on a larger scale.
A Method of Determining Unified Viscoplastic Constitutive Equations for Hot Forging Simulations
Authors: Politis Nicholas J. , Politis Denis J. , Davies Catrin Mair , Lin Jian Guo
Published: November 2016

Constitutive equations have been used extensively to accurately describe material properties over a wide range of temperatures and strain rates in numerical simulations. In this paper, an algorithmic method of determining the constants of such constitutive equations is presented. The Genetic Algorithm implementation utilising MATLAB is described, and example fits to experimental data are presented.
Deep Drawability and Bendability in Hot Stamping of Ultra-High Strength Steel Parts
Authors: Mori Ken-Ichiro , Maeno Tomoyoshi , Yanagita Yuzo
Published: November 2016

The deep drawability and bendability in hot stamping of ultra-high strength steel parts were examined. Although the cold drawability is greatly influenced by the blank shape, the limiting drawing depths for the square and circular blanks were equal for hot stamping because of small flow stress. In hot hat-shaped bending using draw-and form-type tools, the effect of the blankholder force generated with the draw-type tools on the springback was small, and the seizure for the form-type tools was smaller than that of the draw-type tools. Since both edges in contact with the electrodes are not heated for resistance heating, cracks were caused at the edges for resistance heating in the transversal directions in hot stamping of an S-rail with form-type tools, and thus it is required to control deformation of the non-heating zones.
Examination of the Effect of Variation in Stress Magnitude on the Amount of Transformed Retained Austenite in the Structure of TRIP Steel Wires
Authors: Siemiński Marek , Wiewiórowska Sylwia , Muskalski Zbigniew
Published: November 2016

A detailed analysis of the effect of variable stresses on the intensity of retained austenite transformation into martensite was carried out in the work. Tests were done for three bending stress (σmax) levels, lower than the value of the yield stress (R0.2) the material tested. Preliminary tests conducted for one bending stress value have shown that a certain amount of untransformed retained austenite remains in the material in spite of applying as many as 40 000 fatigue cycles. It is therefore necessary to determine whether and, if so, in what extent the magnitude of applied bending stress will increase or decrease that amount of retained austenite. It should be established whether, for different bending stress levels, the curves describing the variation in the volumetric fraction of retained austenite of the tested wire structure, will approximate asymptotically the same value, or the values will, after all, be different.The results of these studies have a practical dimension, since, e.g. a screw made of the TRIP steel, subjected to variable stresses in service, may undergo additional hardening to a varying extent, which will influence its mechanical properties, life and operation safety.The knowledge acquired from the studies will constitute a novelty in this scope of applications, and will be useful from the point of view of both the manufacturer and the user.
Investigation of the Unloading Yield Effect in Aluminum and Magnesium Sheet Metal Alloys at Room Temperature
Authors: Degner Julia , Suttner Sebastian , Merklein Marion
Published: November 2016

The reduction of CO2-emissions and the lowering of fuel consumption are two main objectives in the automotive industry. To reach these targets, conventional materials like deep drawing steels are substituted by new modern lightweight materials such as aluminum and magnesium alloys. During forming of sheet metal parts, the material experiences a plastic deformation, which can affect the part quality regarding the amount of springback or the occurrence of stretcher strain marks. In this context, a time dependent change of the material behavior can emerge after removing the part from the forming tool. Within this contribution, the influence of pre-strain and the unloading yield effect on the subsequent mechanical behavior of the aluminum alloy AA7020 and the magnesium alloy AZ31B are investigated. Additionally, the time dependency of mechanical properties is analyzed for different aging times from 5 seconds to one week after pre-straining. The results show a significant increase of unloading yield effect with increasing pre-strain during uniaxial tension.
Influence of Cutting Processes on Edge Cracking Sensitivity of Bright Finishing Alloys
Authors: Merklein Marion , Gnibl Tobias , Tsoupis Ioannis , Friedrichsen Martin , Beck Johannes
Published: November 2016

The economic application of various cutting processes in product development can lead to significant forming problems when changing from prototypes to serial parts. Every cutting process causes characteristic effects on the resulting edge and consequently specific edge cracking sensitivities. For exterior trim components of premium car models various bright finishing alloys are used but were not yet focus of scientific research. Within this study influences of laser beam cutting and machining on the edge cracking sensitivity of the alloys Al99.7Mg0.8Cu and EN AW-5505 are analyzed by executing hole expanding tests according to ISO 16630 enhanced with an offline evaluation method. To assess possible impacts on the resulting hole expansion ratios material and edge characterizations are conducted. Generated knowledge can support reducing forming problems occurring while changing from prototypes to serial parts.
Joining of Stepped Shaft and Disc by Forming
Authors: Hirota Kenji , Kitamura Kazuhiko , Ukai Yoshihiko , Matsunaga Keiichi
Published: November 2016

Joining by forming is an attractive assembly method for mass produced parts due to easiness in execution, no heat effect, various material combinations etc. and industrial applications have been increased in electric and automotive industries. In this paper, a disc plate and stepped shaft is assembled by forming. Assembling is achieved by indenting the disc with a stepped and grooved shaft up to a certain depth. Through the experiments using an aluminum disc and a steel shaft, the influence of the overlap length and penetrating depth of the stepped section on joining force, axial strength and dimensional change of the disc plate are investigated. Disassembling tests revealed that the joint by the proposed method had sufficient axial strength if the groove of the shaft was completely filled.
Production of Aluminium Based Interpenetrating Phase Composites Using Semi-Solid Forming
Authors: Seyboldt Christoph , Liewald Mathias , Heydt Daniel
Published: November 2016

The following paper deals with the production of Interpenetrating Phase Composites (IPC) using semi-solid forming technology. Therefore, adequate ceramic foams were selected and infiltrated by processing the aluminium alloy A356 in the semi-solid state. In the studies presented in this paper, the infiltrations of two ceramic materials (Al2O3 and SiC) with three different pore sizes (10, 20 and 30 ppi) were investigated. During the forming process the liquid phase fraction of the aluminium was varied to analyze infiltration effects in relation to the raw material´s liquid phase fraction. Afterwards, microsections of the produced specimens were analyzed in order to characterize their microstructure and the quality of infiltration. The results showed that completely filled composite components with good mechanical properties can be produced by infiltrating ceramic preforms with a semi-solid aluminium alloy.
Reducing Blanking Vibration with Active Vibration Control Using a Servo Press
Authors: Murakami Tomohiro , Yang Ming , Kishi Hiroshi , Mori Sigeki , Ohkawa Masahiro , Fujino Eiichi
Published: November 2016

Blanking noise and blanking vibration are causes of pollution. At the same time, blanking vibration disturbs the high precision of a press work product, and shortens the life expectancy of the press machine and the press die. Recently, the use of a servo press has been developed to improve these problems, using low speed blanking and pulse vibration banking. However, these methods lengthen the blanking time, so it is necessary to control the servo press properly in the case of blanking. In this study, we describe a principle for the reduction of blanking vibration when using a servo press, and we propose an active vibration control method for the reduction of blanking vibration. We used a crank servo press of 450kN in an experiment, which has a pulse motion of 10Hz. We conducted a simulation and an experiment of blanking using an active vibration control method, which we named “counter pulse blanking.” We confirmed that counter pulse blanking is effective in reducing vibration as a result of the simulation and the experiment.
Ultrasonic Wave Propagation Analysis for In-Process Monitoring of Stamping
Authors: Hagino Naoto , Komiya Seiji , Endou Jinichi , Ishihama Masao
Published: November 2016

The servo press has high potential for producing high precision mechanical parts. However, small gaps between dies and workpieces tend to exist even in servo press stamping, and the potential of the servo press has not yet been fully utilized. The reason for this is conventional presses do not have feedback control systems, and the lack of a suitable method of sensing contact information in real time causes deterioration in the accuracy of products. If slide motion could be controlled by contact information, the small gaps could be removed. To solve this problem, the authors have developed a method of monitoring the contact states between dies and workpieces during the stamping process. The method uses ultrasonic wave reflection and transmission at the contact surfaces and was proved to be able to monitor contact pressure by using a simple geometry experimental die apparatus. Finite-difference time-domain (FDTD) numerical simulation was conducted in this study to obtain better understanding of wave propagation through dies and workpieces. The results obtained from this FDTD simulation visualized wave propagation that could not be experimentally measured. Some of the major results obtained are as follows. 1) When a thin metal sheet is pressed between dies that have inclined stamping surfaces, ultrasonic elastic waves are reflected and transmitted multiple times. 2) Modal conversion occurs at the die-workpiece boundary in such a way that normal waves with an inclined incident angle are transformed into normal and shear waves. 3) Elastic waves sent out from an ultrasonic transducer are mixtures of normal waves with flat wave fronts along the propagation path axis, normal waves with circular or spherical wave fronts expanding from both sides of the transducer, and shear waves. These results brought about much useful information for setting ultrasonic transducers and analyzing collected signals.
Ultrasonic-Assisted Upsetting of Steel with 15 kHz Oscillation Frequency
Authors: Michalski Markus , Merklein Marion
Published: November 2016

Common limitations in bulk metal forming processes are the maximum available press force and forming characteristics of metallic materials. Conventional measures to overcome those limitations, such as forming at elevated temperature, are not always applicable. An alternative approach is the use of a superimposed axial tool vibration with ultrasonic frequency. This enables a considerable reduction of required forming forces. The underlying mechanisms of this phenomenon have so far mainly been investigated for frequencies above 20 kHz and easily deformable materials, like copper. Due to limitations concerning the system technology, materials with higher strength have been considered only to a very limited extent. In order to allow investigations on the deformation behavior of materials with higher strength during ultrasonic-assisted upsetting, a tool setup containing a 15 kHz oscillating system has been developed. It offers a larger loading capacity in comparison to industrially available systems with higher frequency. Ultrasonic-assisted upsetting experiments with varying amplitude and press velocity are carried out to examine vibration-induced changes in the flow behavior of steel S235JR. Changes in the material characteristics are analyzed by evaluating the mean upsetting force as well as the microstructure of the upsetting specimen before and after forming. The resulting forces show a strong process dependence regarding the oscillation amplitude. The static press velocity and contact status between tool and specimen also influence the process forces, but to a much lower extent than the amplitude. Concerning the microstructure a rising oscillation amplitude leads to an increased radial elongation and axial compression of ferrite grains at the strongly deformed specimen center.
Numerical Optimization and Practical Implementation of the Tube Extrusion Process of Mg Alloys with Micromechanical Analysis of the Final Product
Authors: Milenin Andrij , Kustra Piotr , Byrska-Wójcik Dorota , Plonka Bartłomiej , Petráňová Veronika , Hrbek Vladimír , Němeček Jiří
Published: November 2016

The paper is devoted to the development of a process of tubes extrusion from MgCa08 magnesium alloy. For optimization of extrusion process the Qform software was used. The numerical model of flow stress and fracture criterion for MgCa08 were obtained based on tension/compression measurements performed in a universal testing machine Zwick Z250. Predictions of the flow stress and deformations were modeled as well as the ductility of material. The process was optimized according to the plasticity and temperature criterions. In the optimization process, temperature of the billet and the speed of extrusion were determined. Based on the optimal parameters the extrusion of tubes with external diameter of 5 mm was performed in the laboratory press. On top of the macroscopic testing and calculations, investigations of the material microstructure and the micromechanical behavior of the material after the extrusion were performed by a combination of SEM and nanoindentation analyses. Micromechanical properties of the alloy were detected with the aid of statistical nanoindentation. Samples were characterized in terms of their microstructural defects, distribution of elastic modulus and hardness. Good particle dispersion and homogeneous-like distribution of micromechanical properties was found showing the efficiency of the extrusion process.
A Comparison of Input Data Used to Represent Phase Transformations during the Quenching of a Large Nuclear Forging
Authors: Howson Michael P. , Wynne Bradley P. , Davies Peter S. , Al-Bermani Sinan S. , Talamantes-Silva Jesus
Published: November 2016

The present work explores the importance of model parameters and input variables when simulating the quenching of thick sectioned nuclear forgings. The modelling approach adopted uses values of specific heat capacity, containing latent heat release, to simulate cooling curves; rather than calculating transformation kinetics based upon a mathematical model. Termed the effective specific heat (Cpeff), two different methods were used to establish values: differential scanning calorimetry (DSC) and thermos dynamic predictive software. Values were then included in finite element (FE) models to simulate the characteristic cooling at the mid-wall position in a thick section forging and were validated against production thermocouple data. The investigation found that the formation of ferrite, bainite and martensite or lower bainite were all represented by the data established using DSC and critical formation temperatures were comparable with others in the literature. Conversely, values calculated using the thermodynamic software failed to represent ferrite formation and predicted different critical transformation temperatures for bainite. The simulated cooling curve that used the software predicted Cpeff data was comparable to the thermocouple data either side of the bainite transformation, however during the transformation the effects of latent heat on cooling rate were over predicting leading to disparities. The equivalent DSC cooling curves produced a near exact match.
Development of the Technology of Various Large Bodies Manufacturing Based on Combined Methods of Deformation
Authors: Pesin Alexander , Drigun Ernest , Pustovoytov Denis , Pesin Ilya
Published: November 2016

Metallurgy and heavy engineering construction, which are considered the most energy-intensive industries, place great focus on complex shaped thick-gage plate metal items of equipment with wall thickness exceeding 40 mm and diameter/width of up to 4000 mm. Such items of equipment include large machine parts manufactured by means of hot plate stamping, such as bodies of rotation (for example, the segment of the radial surface of converter shell, the bottom part of degassing unit, etc.) utilized as pressure-operated devices, vessels, tanks and other facilities by metallurgical, petrochemical, oil and gas, and nuclear industries. Presently known manufacturing methods of such items of equipment, for instance, stamping methods, have a number of technological problems. In the present paper, creation and development of the theory and technology of manufacturing different large bodies based on the combination of plate rolling and stamping processes, as well as the combination of asymmetric rolling and plastic bending processes, are proposed. The goal was to develop a cost-effective technology of producing large-size bodies of rotation in the conditions of a thick-plate mill. The rolling of the package forms the basis of the first stage of the new process. The package consists of the upper (punch) base, the lower (matrix) base, and the blank plate situated between them. The economic benefit from installing the developed technology based only on the combination of asymmetric rolling and plastic bending processes was more than 1 million dollars. Casings on two converters were produced and installed in the oxygen-converter plant.
Extension of the Freiberger Model of Spread for the Calculation of Material Flow during Rolling of Long Products to a New Material Group of Mg Alloys AZ31, AZ81, WE43
Authors: Adamyanets Pavel , Schmidtchen Matthias , Kawalla Rudolf
Published: November 2016

This article shows the extension of an empirical model for the numeric calculation of the spread during rolling Freiberg in calibres developed at TU Bergakademie to Mg alloys AZ31, AZ81 und WE43.The material independent foundations were developed at the Institute of Metal Forming at TU Bergakademie Freiberg.The Freiberger spread model has, through numerous rolling trials and examinations of the material flow, been broadened. Furthermore, the results of the calculations were compared with these trials.The Freiberger model for spread takes the geometrical input and output parameters into consideration, as well as the material flow, the deformation rate v, the deformation temperature θ, the chemical composition of the material Cw, longitudinal tension CL, and friction Cμ between the rolling stock and rolls. And it further considers the diagonal ratio CA∗aKNn of the box pass and the filling ratio of the box pass m.
The Effect of Equivalent Strain on Punch Load for Cold Backward Extrusion of Copper Cans
Authors: Miłek Tomasz
Published: November 2016

The paper presents experimental and computer modelling (FEM) results of investigations into cold backward extrusion of copper cans. The simulations were performed using QFORM software based the finite element method (FEM). The samples used in investigations were pieces of copper rods having the diameter d0 = 24,5 mm and height h0 = 16 mm (h0/d0=0,65). The billets were heat treated (annealed). Heat treatment is used to increase the plasticity of the material before cold backward extrusion. The material was annealed at 550°C for a period of 1 h, and then subjected to solution treatment in water. The flat and conical punch-face shapes with different diameter of punch used for cold extrusion (ds=15mm; 16mm; 17mm; 19mm and 20mm, respectively). The deformation ratios of material in paper was defined as relative: strain of can bottom thickness εh =Δh/h0 (where Δh – the punch displacement, h0 – billet height), reduction in area εA= (A0-A1)/A0 and equivalent strain ε= ln (A0/A1) (where A0 – cross sectional area of the billet, A1 - cross sectional area of the die stamping). In investigations, computer calculated and experimental force waveforms as the function of displacement and εh were obtained. Comparing changes in forces in cold backward extrusion for different diameter of punch, it is stated that the load Pw increases with an increase in εh. The effect of equivalent strain ε on punch load Pw for cold backward extrusion of copper cans is presented. Both in experimental and modeling investigations, the axial force increased together with an increase in the equivalent strain.
Numerical Investigation of the Material Behaviour during Compression Tests for Samples with Rough Surfaces Represented in Different Geometry Scale Factors
Authors: Petrov Michael A. , Petrov Alexander N. , Petrov Pavel A.
Published: November 2016

In modern technological operation, the original sample could be provided by so-called pre-operation or pre-forming follows prior the main operation. In such case, the surface roughness of the tool set is directly owned by the surface of the pre-formed workpiece, as less rigid body compared with the tool set. In metal forming practice there are mainly several pre-forming processes, among them roll forging, cross-wedge rolling and electro-upsetting. In any non-convenient forging operation route, where pre-forming is done by casting, powder sintering or any additive technology (e.g. SLS, EBM), the surface roughness and wellness obtained pre-formed workpiece could influence stronger on the quality of the end part after main forging operation. In order to investigate the different materials’ behaviours depends on the surface artificial roughness the finite-element analysis (FEA) was carried out for the simple compression tests, thereby the cylindrical, made from aluminium and titanium alloys, and ring specimens, made from steel, were compressed between two flat dies with modelled zero and non-zero roughness at room and elevated temperatures. The behaviour of the lubricant (fluid phase) positioned between two neighboured peaks of the roughed surface was investigated in one direction material flow test as well. The results have shown the strong pressure increase in the bottom area of the peaks, which correspond the practice case, when the fluid phase is not completely evaporated after lubrication. Further, it can course the different microstructure evolution during hot forging operation and during cold bulk forming operation, additional surface pressure can result the material hardening near to the contact zone (not investigated here). In commonly, in observed results the peaks of the roughness can be easily broken due to enormous tangential stresses, as it is well known from the fundamental investigations. Moreover, the computation of geometry scaled tools and workpieces of the ring compression and one-direction material flow tests resulted the exponential dependency against the deformation forces.
The High Speed Wire Drawing Process of Steel Wires under Fluid Frictions Conditions
Authors: Suliga Maciej
Published: November 2016

The essential purpose of the work was to determine the phenomena that occur in multipass wire drawing process of high carbon steel wires with high speed in hydrodynamic dies and to assess their influence on moulding the wire properties after the drawing process. The multiparameter analysis of the issues has involved the theoretical dissection of the phenomena arising in high speed wire drawing process in hydrodynamic dies with the usage of the finite element method supported by the experimental multipass drawing process in industrial conditions. On the basis of numerical analysis the influence of drawing speed on wire temperature was estimated. For final wires the investigation of mechanical properties, topogrhaphy of wire surface, the amount of lubricant on the wire surface, the pressure of lubricant in hydrodynamic dies were determined.
Prediction of Localized Necking Based on Crystal Plasticity: Comparison of Bifurcation and Imperfection Approaches
Authors: Akpama Holanyo K. , Ben Bettaieb Mohamed , Abed-Meraim Farid
Published: November 2016

In the present work, a powerful modeling tool is developed to predict and analyze the onset of strain localization in polycrystalline aggregates. The predictions of localized necking are based on two plastic instability criteria, namely the bifurcation theory and the initial imperfection approach. In this tool, a micromechanical model, based on the self-consistent scale-transition scheme, is used to accurately derive the mechanical behavior of polycrystalline aggregates from that of their microscopic constituents (the single crystals). The mechanical behavior of the single crystals is developed within a large strain rate-independent constitutive framework. This micromechanical constitutive modeling takes into account the essential microstructure-related features that are relevant at the microscale. These microstructural aspects include key physical mechanisms, such as initial and induced crystallographic textures, morphological anisotropy and interactions between the grains and their surrounding medium. The developed tool is used to predict sheet metal formability through the concept of forming limit diagrams (FLDs). The results obtained by the self-consistent averaging scheme, in terms of predicted FLDs, are compared with those given by the more classical full-constraint Taylor model. Moreover, the predictions obtained by the imperfection approach are systematically compared with those given by the bifurcation analysis, and it is demonstrated that the former tend to the latter in the limit of a vanishing size for the initial imperfection.