total variation seminorm. It may also be of interest to search for other types of functionals which serve the purpose of multi-material topology optimization. In particular, we note that the currently used formulation in ( 1.1 ) favors values u(x) = u i with small magnitude over other ones. Depending on the practical relevance of the u i , this may not be a desired effect. In this case, functionals should be constructed that favor different criteria (e.g., the weight or the price of different materials) while still keeping the “multi-bang” property feature of promoting controls with values only from the given set.
Metallic and composite structures have a wide application range in me- chanical and process engineering. They are subject to many different tasks which are going to be more complex with variable local specifica- tions. As an example, the geometry of a splined shaft-hub-connection leads obviously on the one hand to notch effect problems in special ar- eas and on the other hand a very high wear resistance is needed on the flanks. Manufacturing processes such as cold forming and combined cutting, are increasing the material properties for different requirements by local effects. To balance the contradictions between the material re- sistance and the local stress concentration by means of plastic behaviour versus wear resistance and hardness leads in a perfect way to a design with a single material but multimaterial properties.
Multi-material flow generally describes a situation where several distinct ma- terials separated by sharp material interfaces undergo large deformations. In order to model such flow situations in the context of geomechanics and geotechnical engineering, a theoretical framework is presented which intro- duces a possible two-phase coupled saturated granular material behavior among the different materials. This is achieved by extending the technique of local volume averaging to a hierarchy of three spatial scales, based on a product of two indicator functions. A homogeneous equilibrium mixture model is subsequently derived for an example flow consisting of bulk solid, bulk fluid, and undrained granular material with compressible constituents. The closure relations are provided at the macroscale, including those describ- ing granular behavior covering the full frictional-collisional flow regime and bulk material volume fraction evolution. The paper discusses the advantages and restrictions of the proposed mixture model and addresses its application and full-scale numerical implementation.
Keywords: wire arc additive manufacturing (WAAM); multi-material design; steel
The increasing importance of resource-efficient handling of raw materials is driving development to design components more efficiently. As a result, manufacturing processes are being changed and the trend is moving towards 3D printing processes, [ 1 – 5 ]. By means of generative manufacturing processes, such as wire arc additive manufacturing (WAAM), a more efficient use of materials can be realized, [ 6 ]. In addition, in arc-based generative manufacturing, a wide variety of alloy systems can be used and combined by changing the necessary filler material. Thus, among other things, graded components made of different materials can be realized [ 7 ].
In two previous papers [14, 98] we have developed an MMALE finite ele- ment method accounting for the two-phase coupled response of saturated sand. The present paper goes into more detail about the three main features of the MMALE method for geomechanical problems, which are (i) the mixture the- ory for multi-material elements, (ii) the determination of the stress field, and (iii) the technique to resolve material interfaces. Accordingly, the paper has the following structure. Section 2 provides an overview of the MMALE method. The mathematical modeling of three-scale mixtures is addressed in Section 3, where we summarize the special mixture theory and the homogeneous equilib- rium model derived in . In Section 4 we focus on stress decompositions in saturated granular material resp. dense granular suspensions which enable the description of those arbitrary compositions and mixture configurations present in geomechanical multi-material flow. Section 5 is concerned with the treatment of material interfaces and their evolution (motion) from a non-Lagrangian point of view, i.e. in multi-material elements. After deriving the governing equations and introducing the basic discretization techniques, we outline the volume of fluid (VOF) interface reconstruction and propagation methods implemented into our MMALE code and present some preliminary results. The paper closes with concluding remarks and outlook in Section 6.
Bei den Versuchen unter zyklischer Last konnte festgestellt werden, dass einige geklebte Proben deutlich früher versagten als andere. Allerdings konnte dies mit der Analyse der offengelegten Bruchflächen auf eine unzureichende Klebequalität zurückgeführt werden. Vereinzelt zeigten sich Lufteinschlüsse oder verstärkt auftretendes adhäsives Versagen. Läufe mit minderer Klebequalität oder zu starkem adhäsivem Versagen wurden nicht in der Erstellung der Wöhlerlinien berücksichtigt. Darüber hinaus konnte an den Scherzugproben eine andere, abweichende Versagensform beobachtet werden. Statt als kohäsives Versagen der Klebfläche, äußerte sich das Versagen, bei Unterschreiten einer abgrenzbaren Lastamplitude, im Material der gefügten Bleche. Dieses Materialversagen zeigte sich in dem jeweils eingesetzten Aluminium der materialsymmetrischen Verbindung Al s (1.5) − Al s (1.5) und der Multi-Material Verbindung St h (0.9) − Al s (1.5). Die Schwelle unterhalb welcher es zu einem Riss im Aluminium kommt, ergibt sich bei einer Lastamplitude von etwa 𝐹 a ≈ 4300 N. Da die Wöhlerlinie das Klebeschichtversagen abbilden soll, werden deshalb lediglich Kraftamplitu- den berücksichtigt werden, die oberhalb dieser Schwelle liegen. Abbildung 4.19 zeigt eine komplette Probentrennung (links) und einen weit fortgeschrittenen Materialriss (rechts). Dabei fällt auf, dass der Riss in der Regel entlang des Übergangsbereiches von Klebeschicht und Blechmaterial verläuft.
Although the relevance of sustainability is widely accepted, today´s markets are swarmed with unsustainable products. The underlying reason is the fact that industrial practice has not incorporated eco-design to a sufficient extent yet (Hübner, 2012). Among others, materials selection is a major factor of influence on the sustainability of products (Ashby, 2013). In practice, however, decisions on the selection of material are often made based on the product´s predecessor and the designer´s experience rather than well-founded analysis. Especially regarding the multi-material systems used in lightweight design, a methodical approach to materials selection has not been established yet. Commonly used product development processes (PDPs) lack adaption to the requirements and focus of specific design tasks. This is especially relevant to the consideration of sustainability aspects in early stages of product design (Baumann et al., 2002).
In der A380 wird dieses Material bereits in der Serie im Rumpfbereich verwendet. Mit der Umstellung von Alu-Legierungen zu GLARE war der erste Schritt zur Einführung von Multi-Material-Systemen im Rumpfbereich getan. Es lag somit relativ nah, dass der Leichtbauwerkstoff CFK mit einer Dichte von 1,6 g/m 3 und seinen optimalen
Stomakhin et al.  developed an augmented MPM that can handle phase- change, i.e. melting and solidifying. The approach is capable of simulating a wide range of materials in the same scene. A heat-equation solver that was adapted to MPM is used to handle temperature changes, with each material point additionally carrying temperature and phase state. The former is used to vary the Lamé parameters of the material, while phase only determines whether deviatoric stresses exist (solid phase) or not (fluid phase). This required a splitting of the constitutive model into deviatoric and dilational parts, which they achieve with a modification of the fixed corotated energy density function from . Their method also treats latent heat, which is heat that is needed for a phase change that does not trigger a change in temperature. They achieve this with temperature buffers on material points. In order to support a larger variety of materials, they furthermore extend the method to be able to handle incompressible and nearly incompressible materials without locking. This allows incompressible fluids and highly rigid solids to be simulated with MPM. Like typical incompressible fluid solvers, they use staggered marker and cell grids for this and adapt MPM accordingly. The dilational stress is used to derive pressure needed for their generalized Chorin-style projection approach that facilitates incompressibility. Deviatoric stress is handled by MPM as usual.
§ In der aktivitätsbezogenen Rechnung wird das Aufkommen und die Verwendung von Material und Energie dargestellt, die von den Aktivitäten der 58 Produktionsbereiche der inländischen Wirtschaft sowie der Haushalte ausgehen. Unter einem Produktionsbereich ist dabei die Gesamt- heit aller wirtschaftlichen Aktivitäten, die ausschließlich und vollständig die Güter einer Güter- gruppe erzeugen, zu verstehen. Durch die Verwendung der Gliederung nach homogenen Produk- tionsbereichen können die Daten zu umweltrelevanten Material- und Energieströmen sowie zu Umweltbelastungen direkt in Beziehung zu ökonomischen Kennziffern aus der Volkswirtschaft- lichen Gesamtrechnung gesetzt werden. Produktionsbereiche stellen somit das Bindeglied zwischen Wirtschafts- und Umweltdaten dar.
In this paper a multi-scale approach for shell structures is presented. With respect to shells the introduced RVE on the element Gauss point has a natural thickness h. This requires the formulation of special boundary conditions. The total set of equations contain equilibrium formulations on the structural level as well as on the level of Gauss points. It is possible to solve the whole set of equations simultaneously. Basically the formulation allows the mix- ture of element concepts. We have shown that it is possible to mix elements with conventional material description with elements, where RVE’s are introduced to describe the material behaviour. Calculations based on a multi-scale approach are very time consuming. Thus an adaptive strategy has been introduced to switch automatically between different discretization and material models. For this an indicator in dependence on the indicator of Zienkiewicz and Zhu (1987) has been proposed. The examples show the efficient practical applicability of the proposed method, also in the unloading regime. Further research may be focused on the formulation of indicators to switch between different material models.
Nanotechnologies and the idea of their convergence with other technosciences are rooted in the notion that they are capable of mobilizing nature in order to go beyond nature. At times this notion declares itself with surprising clarity and at others it is merely implied. Often it is rhetorical accompaniment to conventional research, and sometimes it pronounces far-flung possibilities. As a dream (or nightmare) of reason (Dupuy 2007, p.242), this visionary theme deserves close examination. The main purpose of this examination is to appreciate its queerness – in other words, the way in which this notion transgresses traditional categories and expectations, the way it tweaks language and stretches received concepts. The aim is not to question the significance of the notion, but to create a certain critical distance to it. Such distance is needed not only in regard to its technical feasibility, which ought not simply to be assumed by an all too obliging ethical discourse (Nordmann 2007a). Critical questions also need to be raised about the desires and hopes that are brought into focus by nanotechnological aspirations to enhance material nature. This is because quite independently of their fulfillment, these desires and hopes are producing effects even now which are far from insignificant. Especially one of these effects will come to the fore in the following pages: in our thinking about nature we are challenged by nanotechnologies to adopt an unthinking attitude of engineering rather than to reflect and debate, for example, the kind of materialism and reductionism that is associated with genetics. 1
Auf Grund der Halbduplexeinschr¨ankung wird eine h¨ohere Anzahl von Zeit-Frequenz Kommunikationsressourcen ben¨otigt im Vergleich zum Fall, wenn Vollduplexknoten ihre Nachrichten mit Hilfe einer Vollduplex-RS austauschen. Daher schlagen wir ein spektral effizientes Kommunikationsprotokoll f¨ ur Mehr-Gruppen Multi-Way (MGMW) Kommunikation vor, das eine Halbduplex-Mehrantennen RS verwendet. Die erforder- liche Anzahl von Kommunikationsphasen wird durch die maximale Anzahl von Knoten innerhalb der Gruppen bestimmt. In der ersten Kommunikationsphase, der soge- nannten Vielfachzugriffsphase (Multiple Access - MAC), senden alle Knoten ihre Datenstr¨ome gleichzeitig zur RS. Nachdem die RS die entsprechende Signalverar- beitung durchgef¨ uhrt hat, sendet die RS in den verbleibenden Kommunikationsphasen, den sogenannten Broadcast (BC) Phasen, die Datenstr¨ome an die Knoten, wobei sichergestellt wird, dass jeder Knoten den f¨ ur ihn vorgesehenden Datenstrom von seinen Kommunikationsgruppenmitgliedern empf¨angt.
Mechanism of solubility, D-mannose differs from D-glucose only in the stereochemistry at C-2. Therefore, it can fine that D-mannan is an insoluble fibrous material similar to its D-glucose analogue, cellulose. This behavior is attributed to the formation of stable crystalline regions in the solid in which the linear chains lie in close proximity. The inclusion of side chains spoils this crystallinity and thereby promotes the penetration of water and enhances solubility. Thus, commercial gums showing high substitution ratio, such as guar, tend to hydrate fully in cold water, while gums with limited substitution, such as locust bean gum, hydrate completely only in hot water. Commercial gums exhibiting high substitution ratio (i.e. guar gum) are better hydrated in cold water than gums with limited substitution (i.e. LBG), because the presence of side chain interferes with the formation of stable crystalline regions and promotes water penetration, thereby enhance solubility. This behavior is reflected in the viscosity of the hot- and cold-prepared solution. Galactomannans don’t hydrate instantaneously in water. At 25 o C, guar gum may require up to 120 min hydrate fully and yield its maximum potential viscosity. This time can be shortened by using a high-shear mixer, a fine powder or by increasing the temperature. However, at temperatures above 80 o C, thermal degration become significant and the maximum potential viscosity will not achieve. The rate and degree of hydration may be dramatically reduced by the presence of other solutes. When using galactomannans in formulated food, it is good practice, therefore, to hydrate these first in any free water present in recipe before adding the remaining ingredients.
with a beautiful object. For the visible colour-textures of all objects, like Long Skirt, are necessarily emplaced in space and time. They comprise but an anchor for our own ‘period eye’ (Baxandall 1972) 3 and the multiple kinds of relations, actions, thoughts and sensations that occur for each observer, bodily, as well as in the mind. Long Skirt, for example, forms but a single set of material fragments at Langde within a broader contextual realm, where the visitor’s own cultural ‘make-up’ couples the projected exoticism of its wearers and imagined creators, the quaintness of the wooden village architecture, sounds of jangling pressed silver fringing and village music and the taste of food and wine. Together with the ‘pristine’ beauty of the outlying rural surrounds, these fragments cause their sensory efficacy to be amplified. The model of the arbitrary linguistic sign may help to speculate upon this process by enabling us to locate meanings drawn by eye from colour as text, discursively, in time. But as we rarely, if ever, perceive the world through one sense alone, particularly in the case of fascination with Miao costume at Langde, it is necessary to consider a more embodied model of apprehension that recognises the unified nature of the human sensorium (Pinney 2002) to go on.
To investigate the effect of optical properties and color on all previous results, we repeated the rating experiment using greyscaled versions of the stimuli previously described. We hypothesized that optical properties would provide more cues to object identity and therefore, we would find faster responses to colored stimuli than to greyscaled ones. This hypothesis is supported in the literature-- Price and Humphreys (1989) found that surface information such as color was particularly helpful for recognizing structurally similar objects, and reported superior latency performance on colored photographs and computer images, compared to greyscale ones. For such objects, naming was more rapid with colored slides and appropriate colored line drawings than it was with line drawings or inappropriately colored line drawings. Using response latencies as a method, Davidoff and Ostergaard (1988) and later, Brodie (1991) uncovered a naming-latency advantage for colored over black and white depictions, finding that the advantage for color depictions was equally present for manufactured objects and natural ones. Wurm et. al. (1993) further concluded that colored depictions of food items congruent with the expected color of the food item were named faster than greyscale (incongruent) depictions of the same objects. Following from this literature, the following experiment sought to investigate the influence of color when making kinematic material property judgements.
Das Material ist für Schüler*innen ab Klasse 7 entwickelt und knüpft an die Bildungspläne der Länder an. Es besteht aus vier Themenblöcken mit Unterrichtsimpulsen und Arbeitsblättern. Die Unterrichtsimpulse geben Ihnen methodische und inhaltli- che Anregungen. Sie bauen aufeinander auf, können aber auch unabhängig voneinander genutzt werden und bieten Raum für Ihre individuelle Ausgestaltung. Die Arbeitsblätter können Sie direkt im Unterricht einsetzen; Hinweise zur Vor- und Nach- bereitung sowie Lösungshinweise finden Sie in den Unterrichts- impulsen. Erweiterte Aufgabenstellungen für eine vertiefte Auseinandersetzung sowie hilfreiche Links sind mit Symbolen gekennzeichnet.