Thermodynamische Aufgaben im Flugmotorenbau

Ohne Zusammenfassung VDI     

Thermodynamische Belastung von Seitenkanalverdichtern im Vakuumbetrieb

Like all turbo machines and rotating displacement machines side channel compressors are able to work in the pressure region and in the vacuum region. At present side channel compressors are used in vacuum operation only for the low vakuum region with an absolute suction pressure down to p_s = 10 kPa. The benefits of side channel compressors with the expansion flow in the breaker clearly grow contrasting the pressure operation mode and contrasting other compressor constructions with decreasing suction pressure. Therefore it is appropriate to make the working range of side channel compressors accessible also for the operation in the higher vacuum region down to the fine vacuum region because in this way side channel pumps open the possibility to cover the whole vacuum region from fine vacuum up to atmospheric pressure. This offers the advantage of using only high-speed turbo compressors in the vacuum region which have small construction dimensions, are simple designed and work lubrication free. These advantages also meet the desire of the vacuum technology for oil free delivery of gases and drawing off fumes.     

Thermodynamische Stoffdaten für Biogase

Thermodynamic analysis of apparatus designed for biogas and biogas production calls for the thermodynamic properties of these gases. In this paper newly fitted functions of the isobaric specific heat capacity c_p ^iG =c_p(T) are presented for the species nitrogen N₂, methane CH₄, carbondioxide CO₂, carbonmonoxide CO, water H₂O, sulfurdioxide SO₂, hydrogen H₂, oxygen O₂, sulfur hydrogen H₂S und Argon Ar. Equations for mixtures of these ideal gases are given and their application is shown by means of an example.     

Spannungs-Dehnungsverhalten und Lebensdauer ungekerbter und gekerbter Proben und Bauteile

Stress-Strain and Fatigue Life Behaviour of Unnotched and Notched Specimens and Components In contrast to unnotched specimens where the cross section and the surface area are uniformly deformed, when external loads are applied at the specimens, notched specimens and components show severe concentrations of stress and deformations at the notches. In the paper different type of notches are considered and the effect of the notches under different loading conditions (monotonic, cyclic loading) is described. Some possibilities for predicting the crack initiation of notched components are also outlined and the effect of corrosive environments is briefly discussed.     

Korrosionsverhalten und Deckschichtbildung auf Kupfer und Kupferlegierungen

Corrosion Behaviour and Film Formation of Copper and Copper Alloys Film formation processes on Cu, CuZn, CuAl and CuNi materials in NH₃- and Cl^?-containing aqueous solutions are discussed in a summary article by way of corrosion systems, some typical and some of practical significance, and the protection offered by these films against general corrosion is described. Also considered are localized corrosion phenomena to which Cu-base alloys with oxide films are typically exposed. A comparison of the resistance of the various alloying systems illustrates the particular danger of stress corrosion cracking of mechanically stressed metals. Finally, the type and structure of oxide surface films are discussed with respect to their effect on crack initiation.     

Weitbereich-Turbomolekularpumpen und Membranvorvakuumpumpen als trockene HV- und UHV-Pumpsysteme

The development of new turbomolecular pumps with increased critical backing pressures up to 30 mbar made it possible to use oilfree diaphragm pumps as backing pumps. The combination of a wide-range turbomolecular pump with a diaphragm pump represents an inexpensive, compact and technical dry vacuum pumping system for high and ultrahigh vacuum applications. The interaction of wide-range turbomolecular pumps with diaphragm pumps is discussed in terms of gas throughput, compression ratio, ultimate pressure and power consumption of the turbomolecular pump and selection criteria for the diaphragm backing pump are shown.     

Glatt- und Festwalzen an PKW Fahrgestell- und Antriebsbauteilen

Finsh and Solid Rolling of Automotive Running Gear and Drive Components Automotive parts, in particular running gear and drive components, are subject to high dynamic loads in regards to strength. When designing new parts, this is taken into account through dimensioning, material selection and constructional conception. Normally the mentioned measures will not be applied to old designs if, for example, they are subjected later to higher loads because of an increase in engine power output. Only the selection of different materials as well as strength increasing measures and methods remain for these parts. An important method is solid rolling. The examples of completed designs demonstrate the possible strength improvements, influence of rolling force on component strength as well as desired and undesired accompaniments. A comparison is made between solid rolling and other strength improving measures, such as inductive hardening. The results show the solid rolling method to be cost-favorable, very effective and safe in handling. The method has its limits in geometry (open rotation-symmetrical cross sections are required), size (component too large, cross section too filigreed) and application range (temperature) of components.     

Beanspruchung von Schiene und Rad beim Anfahren und Bremsen

Zusammenfassung In der vorliegenden Arbeit wird die strenge L?sung für den Spannungszustand in Rad und Schiene beim Anfahren und Bremsen gegeben unter der Voraussetzung, da? es sich um einen rein elastischen Vorgang handelt.     

Schmelzen und Behandeln von Metallen und Legierungen im Vakuum

The growing demands for better quality of metallic materials can only be met by the application of vacuum during the production of these metals and alloys and their field of application.     

Feinst‐ und Ultrafeinkornhartmetalle: Tendenzen und Anwendungen

Submicron‐ and Ultrafine‐Grained Hardmetals: Tendencies and Applications Submicron‐ and ultrafine‐grained hardmetals are WC‐Co alloys with average WC grain diameters of ≤ 0.8 μm and ≤ 0.5 μm, respectively. The variation of grain size towards finer‐grain carbides has the advantage that both hardness and transverse rupture strength increase as grain size decreases. This combination of properties, which contrasts with the well‐known counter‐running relationship between hardness and transverse rupture strength found in conventional hardmetals, opens up a wide area of application for submicron and ultrafine grained hardmetals. Since their introduction, these hardmetals have firmly established themselves in metalcutting operations, predominantly in the areas of milling and drilling and to a lesser extent in turning and broaching. Submicron‐ and ultrafine‐grained hardmetals, particularly in combination with suitable coatings, are gaining increasingly in importance in the machining of highly heat‐treated and abrasive work materials.     

Analyse und Modellierung des Kriechverhaltens von Kunststoffen und Metall-Klebverbindungen

Analysis and modelling of creep behavior of plastic and metal adhesive joints Empirical formulations and rhelogical models are used for determining material's characteristics of uniaxial loaded specimens, which are needed as input parameters for numerical FEM-calculation. The exponential formula established by Nutting was used where the parameters are calculated by means of minimal squared deviations, by graphical fitting and by combination of both methods mentioned. The strains of the plastic material and shear strains of epoxy adhesive layer are calculated by using the parameters obtained. Comparison of results indicate a difference in the degree of accuracy between the different theoretical approaches and the experimental results.     

Dekontamination von Vakuumpumpen und Komponenten aus der Halbleiter- und Elektronikindustrie

The safety aspect for the employees, environmental pollution control und product quality of the repaired components are common ideas of the new decontamination facility for vacuum pumps and components of semiconductor processes. There are a lot of rises by servicing and decontaminating vacuum components used in semiconductor equipment. The toxic materials used in the processes are still in the vacuum pump. It's not allowed that these materials are coming in the environment. This requirement comes from the health and safety reasons for the employees together with environmental aspects. The described decontamination facility near Munich is unique in Europe. Some companies have developed special machines for this facility. A cooperation with scientific and hygiene-technical support with the university of Giessen have made new progress in planning and operating the decontamination center. The decontamination facility meets the very thight criteria of the federal german pollution control and the other urban control authorities.     

Vakuum und Musik

In this contribution some experiments are described, which had the aim to improve the acoustic properties of sounding wood by heating in vacuum. The idea is that the resin in the wood is damping the acoustic vibrations and that it is possible to evaporate the resin from the wood. The resin has a high vapour pressure and may be evaporated in vacuum by temperatures which are tolerable for the wood. The experiment was performed on violins to make it possible to judge the quality of the tone from the instruments by hearing before and after evaporating the resin.