Plasmalichtquellen – Stand und Ausblick

Plasma Light Sources – Presence and Future Plasma light sources can at present fulfill all demands of general lighting with high efficiency. A further increase of the luminous efficacy and a high flexibility concerning the color temperature with simultaneous substitution of mercury as a filling substance – these are possible options. Solid‐state light sources will only start after some years to seriously compete with certain groups of plasma lamps     

Reinforced masonry beams under shear load – Proposals for future designs / Bewehrte schubbeanspruchte Mauerwerksbalken – Vorschläge für zukünftige Bemessungen

This article is written against the backdrop of the work of the European standardisation committees on the amendment of EN 1996‐1‐1 [N 4] which will also exert an influence on the design of reinforced masonry in Germany. This paper focusses on the design approaches of DIN EN 1996‐1‐1 for untensioned reinforced masonry beams under shear load in the ultimate limit state (ULS). Proposals are made to discuss their revision. The contents of E DIN 1053‐3 [N 3] and of the final draft of the guideline ”Flat Lintels” [7] are taken into account.     

Reinforced bending load‐stressed masonry – Suggestions for future designs / Bewehrtes biegedruckbeanspruchtes Mauerwerk – Vorschläge für zukünftige Bemessungen

European standardization bodies are currently working on the amendment to EN 1996‐1‐1, which will also affect the evaluation of reinforced masonry in Germany. For that reason, discussion suggestions are being made here for revisions to lay the groundwork for building materials evaluations and especially, evaluations of bending load‐stressed masonry walls or beams at their serviceability limit state (SLS) for load‐bearing capacities. Information already presented in E DIN 1053‐3:2008‐03 [N3] is being incorporated as well. Characteristic values for the compressive strength of the masonry parallel to the bed joints f_k,∥ are essential for the design of reinforced masonry, although they are currently not included in national application documents for Germany. For the time being, they can be mathematically calculated using conversion factors for the characteristic compressive strength values vertical to the bed joints f_k or by using the declared axial compressive strengths of the masonry units. The ultimate strains for masonry in general should be set consistently at ?_mu = ∣–0.002∣ as several masonry types do not exhibit higher compressive strain values. The use of steel strains higher than ?_su = 0.005 does not change any measurement results. Varying stress‐strain curves of the constitutive equations on masonry under compressive strain (parabolic, parabolic‐rectangular, tension block) lead to differing values of recordable bending moments despite having the same mechanical reinforcement percentage at higher normal forces. Therefore, clear guidelines should be made for the type of applicable constitutive equation for masonry walls under compressive strain. With the introduction of a tension block, the number values of the reduction factors λ for the compression zone height x, which is dependent on limit strains, and where applicable, reduced compressive strength, need to be determined, as with reinforced concrete construction. A modification of the bending moment based on the second order theory according to [N4] is presented for the calculation of reinforced masonry walls in danger of buckling. The use of reduction factors for the load capacity of the masonry cross section, such as for unreinforced masonry, does not appear to be appropriate as buckling safety evidence because here, the design task is the determination of a required reinforcement cross section.     

Nanotechnology – Markets & Trends. Nanotechnologie – Märkte und Trends

The world of nanotechnology is gaining more and more interest from the scientific point of view as well as for industrial applications. Promising product and process innovations that are based on nanotechnology have stimulated the involvement of industry and the financial community. Rather than an evolutionary oriented top‐down approach pushing critical dimensions from microns down into the nanometre range, the real potential of nanotechnology lies in the creation of novel functional structures of superior performance by controlling structures on a scale between 1 and 100 nanometres with completely changed properties. Making use of these novel properties of known materials is highly attractive for applications in a variety of fields, underlining that nanotechnology is regarded as key technology of the 21st century a promising product and process innovations that are based on nanotechnology have stimulated the involvement of scientific community and the industry, because nanotechnology is not only scientific artwork but is currently used in a considerable number of products in a multibillion‐dollar marketplace.     

Herausforderungen an Füge‐ und Oberflächentechnik für zukünftige Leichtbaukonstruktionen im Automobilbau

For the reduction of the weight of vehicle hot‐rolled magnesium alloys as well as carbon fiber reinforced plastics (CFK) shall be integrated into the body structure. Both light weight materials electrochemically are not compatible with galvanized steels or aluminium alloys, unless great efforts of corrosion protection measures are taken. From electrochemical investigations an oxidceramic surface layer deposited by plasmachemical oxidation can be recommended as a promising solution. The low‐porous oxidation deposit with limited insulation effect can be painted by e‐coat in high quality after joining in the body shop and before the full paint system will be deposited. In opposite to magnesium CFK parts have, however, electrochemically a very noble character causing galvanic corrosion of attached metallic parts when the carbon fibers are not fully embedded in the matrix or damaged by the cutting. Only joining elements made from stainless steels or titanium alloys (e. g. Ti‐6Al‐4V) are suitable for the joining of CFK by screwdriving and riveting technology to avoid galvanic corrosion. From view of compatibility of materials, a severe anodic corrosion risk can be eliminated by isolation through adhesive bonding in the flanges and an additional sealing to prevent from electrolyte ingress.     

Sekundärneutralteilchen-Massenspektrometrie SNMS – derzeitiger Stand und weitere Entwicklungen

Secondary neutral mass spectrometry (SNMS) based on electron gas postionization is described with regard to its historical developments, its fundamental properties and figures of merit. The quantifiability of SNMS signals, the low detection limits and the excellent depth resolution are shown to be the outstanding potentialities of SNMS. Recent and ongoing instrumental developments are described. In particular, the novel high frequency mode HFM of SNMS allows the analysis of completely or partially insulating samples in almost the same way as the conventional direct bombardment mode for conducting materials. A new generation of SNMS instruments is designed such that X-ray induced Photo Electron Spectroscopy XPS can be incorporated in situ as an option.     

Vakuumbeschichtung von Architekturglas ‐ Ein historischer Abriss

Vacuum Coating of Architectural Glass ‐ A Historic Review Coatings on architectural glass nowadays are used to minimize the energy necessary for heating or cooling of buildings, as transparent conductors for photovoltaics, for mirrors or glazings with low reflection, and for self‐cleaning windows. Modern architectural glass coaters are able to handle panes with a size of up to 3.21m x 6m and have an annual throughput of 5 to 10 millions of square meters per year. Coating technologies for these dimensions require an extreme amount of experience in the physics of thin films. The most important deposition processes are chemical processes at atmospheric pressure and magnetron sputtering under high vacuum. This article reports on the history of vacuum coating of architectural glass.     

Ermüdungslebensdauerbewertung von Warmumformwerkzeugen – Ein Überblick über den Stand der Forschung und Anwendung

Hot work tools are subjected to complex thermal and mechanical loads during hot forming processes. Locally, the stresses can exceed the material's yield strength in highly loaded areas. During mass production, this leads to cyclic plastic deformations and thermomechanical fatigue of the tools, which can be a major lifetime limiting factor. However, established concepts for thermomechanical fatigue life assessment of hot work tools do not exist, since this aspect first reached attention in the last years with the needs for higher resource and energy efficiency as well as optimized manufacturing processes (e. g. in the frame of Industrie 4.0). Hence, in this paper, the contemporary industrially used concepts for dimensioning hot forming tools regarding the tooling fatigue life are presented. Furthermore an overview of existing plasticity and lifetime models is given. The models are divided in phenomenological and mechanism based models. The review shows that further research is essential in this field.     

Mauerwerksbefestigungen für zweischalige Fassaden – Stand der Technik

Double‐leaf masonry façades are becoming very popular due to their outstanding thermal and sound insulation properties, their durability and their ability to maintain the climate within a building (see Figure 1). Proper fastening of the facing shell is crucial if these benefits are to be effectively exploited in the long‐term and if building owners are to be given high investment security. The following article provides detailed information and explanations on product solutions that are both technically sound and cost‐effective.     

EUV‐Lithographie für zukünftige IC‐Chips. EUV‐Lithography for Future IC‐Technology

In the past the overwhelming success of the semiconductor industry was based on the realisation of ever smaller structures on chips in ever shorter periods. This allowed to increase the computational speed of the processors and the amount of data that can be stored in a memory chip. This reduction of the critical dimension was mastered within optical lithography by transition to smaller wavelengths. Those lithography technologies that are currently in the development or test phase, based on 193 nm or as well 157 nm laser sources, will not achieve dimensions around 50 nm. A fundamental change of technology is thus emerging. The currently favored basis for dimensions of 50 nm and below is EUV lithography, based on an optical technology with an exposure wavelength of 13,4 nm. This substantial reduction of the wavelength also implies a radical change of the methodology used up to now.