Ermittlung des Verformungs- und Steifigkeitsverhaltens von bombierten Profilwellenverbindungen mit Evolventenverzahnung

Crowned shaft couplings with involute splines are an important transmission element in mechanical engineering and offer a wide variety of applications in the field of gears and transmissions. The advantages are the simple mount methods and the possibility to transmit large and impulsive torques. Especially the straight cylindrical involute splines are one of the most effective and powerful shaft-hub joints. One of the significant parameters for the design of shaft-hub joint is the knowledge of the deformation and stiffness behaviour. This exciting topic has filled a multitude of publications in the past decades. In the current technical literature exists no acceptable reference of contemporary dimensioning for specific gear tooth shapes. This includes crowned gear tooth shapes with involute splines which are for example applied in gear couplings. The following pages will show that the deformation and stiffness behaviour of gear tooth profiles according to DIN 3960 and DIN 5480 can be calculated simple and sufficient with current analytical methods.     

Ermittlung des Festigkeits‐ und Schädigungsverhaltens von Airbaggewebe bei verschiedenen Belastungszuständen und Dehnraten

Determination of strength‐ and failure behaviour of airbag fabric subjected to different types of loading This paper presents experimental investi‐gations of the material behaviour of a typical airbag fabric (Polyamid 6.6) at different loading types and strain rates. Fundamental results are a linear decrease of failure stress and a linear increase of failure strain with increasing temperature. Another important material parameter of airbag fabric, the burst pressure where the fabric bursts, was measured as 4‐5 bar. The determined material data are important for the fabrication of airbags.     

Verbesserung des Einzeldraht-Anemometer-Verfahrens zur Ermittlung des Grundgeschwindigkeitsvektors und des Reynoldsschen Spannungstensors

Ohne Zusammenfassung     

Zeiteffiziente Methodik zur Ermittlung des Reibungsverhaltens nasslaufender Lamellenkupplungen mit Carbon-Reibbelag

The tribological system friction lining, lubricant and load conditions determines the friction behaviour of wet multiple disk clutches. Due to numerous influencing parameters and their interactions, the friction behaviour cannot be predicted theoretically. Matching friction lining and lubricant requires experiments. In a research project of Forschungsvereinigung Antriebstechnik e.?V. (FVA) a two stage screening test was developed to determine the friction behaviour of carbon type friction linings reproducibly. After running-in, different load stages with different surface pressures and sliding velocities are performed. The conditioning behaviour of the tribological system is evaluated by endurance tests and further variations of surface pressure and sliding velocity. This test procedure is well suited to analyse the influence of lubricant on friction behaviour.     

Ermittlung des Spannungsintensitätsfaktors KI mit dem spannungsoptischen Verfahren

Determination of Stress Intensity Factor K_I by means of Photoelastic Technique A survey is given of the methods applied for determining stress intensity factor K_I by means of photo-elasticity. In this connection the scope of validity and the accuracy of these methods are discussed.     

Ermittlung der Verformungen und Spannungen einer gelochten Gummimembran mit Hilfe von Rasterverfahren

Zusammenfassung Für eine gelochte Gummimembran wird die Verformung mit einem Rasterverfahren in unterschiedlichen Laststufen experimentell ermittelt. Hierzu werden die Koordinaten eines Kreuzrasters auf der Gummioberfl?che mit der digitalen Bildverarbeitung automatisch bestimmt. Aus einem zuvor angepa?ten Stoffgesetz ergeben sich dann die Spannungen und die Schnittkr?fte in Lastrichtung. Durch Vergleich mit den bekannten ?u?eren Lasten wird die Genauigkeit des Verfahrens überprüft.     

Untersuchung der Phasengrenze eines fluiddynamischen Systems mit experimentellen und numerischen Methoden

The paper deals with the detection of the free surface in a rotating two-phase system. It consists of a cylindrical rotor with horizontal axis and a fixed plate as a scraping internal tool. The cylinder is partially filled with a viscous heavy liquid and is otherwise filled with air as thin passive phase. Depending on the filling degree and on a dimensionless parameter which indicates the relative influence of gravity and viscous forces within the liquid, different flow states can be observed. In order to visualize the phase interface, two different experimental techniques are applied, namely an optical method on the basis of laser light-sections and the X-ray computed tomography. In addition, the free surface is calculated by means of a numerical simulation of the two-phase flow. The results obtained with the different methods are compared each other and discussed.     

Ermittlung transversaler Eigenfrequenzen dünner Rechteckscheiben und Vergleich mit der Näherung von Timoshenko

Zusammenfassung In dieser Arbeit werden transversale Eigenfrequenzen dünner Rechteckscheiben ermittelt. Dabei wird die Frequenzdeterminante für die beidseitig gestützte und die eingespannte Scheibe ausgewertet. Die tiefsten Frequenzen sind in Diagrammen in Abhängigkeit vom Seitenverhältnis aufgetragen und werden mit den Werten aus der Theorie vonTimoshenko verglichen.

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Determination of transverse natural frequencies of thin rectangular plates and comparison with the timoshenko approximation

Summary In this paper transversal eigen-frequencies of deep rectangular beams are found. During the vibration the beam is supposed to be under conditions of plane stress. The frequency-determinant is presented for deep beams supported on both ends or clamped. The lowest frequencies are shown in diagrams as functions, of the edge ratio. The results are compared with those of the theory ofTimoshenko.

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Auszug eines Teiles der von der Fakultät für Bauwesen der TH. Hannover genehmigten Dissertation Ein Beitrag zur Berechnung von Eigenfrequenzen dünner Rechteckscheiben unter Berücksichtigung von randparalleler Orthotropie; Referent: Prof. Dr.-Ing. Th.Lehmann, Korreferent: Dozent Dr.-Ing.F. H. Schroeder. In der Dissertation ist außerdem der Einfluß unterschiedlicher Querdehnungszahlen und der Einfluß von Orthotropie untersucht worden, sowohl bei Quer- als auch bei Längsschwingungen.     

Verschleißprüfung und Verschleißverhalten von Hartmetallen

Wear testing and wear behaviour of cemented carbides Wear resistance is not a mater constant but a quantity of a system. For the judgement of a case of wear or for the choice of the suitable grade of cemented carbide it is necessary to investigate exactly the limiting conditions and the appearance of wear. The wear test can only be considered with exactly defined limiting conditions and only be compared with application of similar limiting conditions.     

Ermittlung mechanischer Kenndaten von Kohlenstoffaserverstärktem Kohlenstoff (CFC) mit dem Biege- und Zugversuch

Research on Mechanical Data of Carbon Reinforced Carbon (CC) in Bending and Tensile Mode CC is a ultra high temperature material used until 2200°C in inert atmospheres. The testing geometries of reinforced carbon (CC) are not standardized in West Germany today. Therefore the SIGRI GmbH has defined material specific geoand tensile mode. It is shown, that the tensile strength has a higher level than the bending strength when the laminate orientation is (0/90°). When the laminate has a (0/± 45/90°)-orientation, the relation is inverted. If the laminate orientation is known, the fracture mode can be predicted.     

Kraft-Eindringtiefe-Messungen mit verschiedenen pyramidenförmigen Indentern

Depth-sensing indentation measurements with different pyramidal indentors Depth-sensing indentation measurements are performed with a Vickers, a Berkovich and a Knoop indentor on bulk samples of ceramic, glass, metalls and of a polymer. The load-indentation data are evaluated in terms of an indentor specific energy density which is designated as hardness equivalent. A transformation principle for the different indentor specific hardness equivalents is introduced. The principle and the required transformation parameter is shown to be independent of the material investigated. The principle is based on the determining character of the displaced volume for the material resistance against the penetration of the indentor.     

Wasserstoff in Hochvakuumsystemen mit Turbomolekularpumpen bei verschiedenen Vorpumpen

The combination of diaphragm pumps with wide‐range turbomolecular pumps constitutes a small but powerful oil‐free high vacuum pumping system. Turbomolecular pumps show gas dependent compression ratios, the lowest for hydrogen. Thus, the high vacuum can be governed by the hydrogen partial pressure. In the present investigation the residual gas composition of a turbomolecular pump and different backing pumps shows no improvement if diaphragm pumps with low ultimate pressure are replaced by rotary vane or Roots pumps. In this case the ultimate pressure in the high vacuum chamber is basically determined by the ratio of outgassing to pumping speed and not by the product of compression ratio and backing pressure. However, the hydrogen partial pressure increased if the ultimate pressure of the diaphragm pump was raised. At a backing pressure of 0.5 mbar the high vacuum reached a stable value not improvable by reduction in backing pressure.     

Experimentelle Ermittlung des Ver‐ und Entfestigungsverhaltens durch zyklische plastische Verformung auf Basis von Biegewechselversuchen

Für Biegeprozesse mit wechselnder Beanspruchung werden Materialgrößen benötigt, welche die Ver‐ bzw. Entfestigung durch den Bauschinger‐Effekt berücksichtigen. Hierzu werden Biegewechselversuche an Drahtproben durchgeführt. Durch Ermittlung der ?bezogenen Maximalkraftdifferenz“ wird die Ver‐ bzw. Entfestigung quantitativ angegeben. Für eine Auswahl an Eisenwerkstoffen und Nichteisenmetallen werden entsprechende bezogene Maximalkraftdifferenzen bereitgestellt und miteinander verglichen. Aufgezeigt wird, welche Werkstoffe tendenziell verfestigen und welche eher eine Entfestigung erfahren. Auch der Einfluss des Verformungsgrades wird erläutert.     

Ermittlung des Zeitstandverhaltens einer austenitischen Schweißverbindung

Evaluation of the Creep Rupture Behaviour of an austenitic Welded Joint Part II: Numerical Calculations of the Creep behaviour For a welded joint of a 18% Cr-11%Ni-steel the stress and strain distribution is calculated by an inelastic finite-element-analysis using constitutive equations of the different zones. On the base of different criteria, the crack initiation time is calculated. The results are compared with test results of specimens with different geometry taken from different positions of the welded joint.     

Experimentelle und numerische Ermittlung dynamischer Risswiderstandskurven im Kerbschlagbiegeversuch

Experimental and numerical determination of crack resistance curves in the notched‐bar impact test The assessment of the reliability of components requires the knowledge of crack resistance curves, which are often not available due to lack of specimen material. More likely is the availability of typical material parameters such as the yield strength, tensile strength, uniform elongation, elongation at rupture as well as upper shelf impact energy and the lateral elongation of notched‐bar impact test specimens. The material model of Gurson describes ductile crack growth due to the nucleation, growth and coalescence of voids in the material. Although dependent on the material and temperature, the material parameters of the Gurson model are independent of the specimen geometry and rate of loading. This latter fact allows one to use the values of these parameters determined on statically‐loaded fracture mechanics specimens to model specimens with other geometries and subjected to different loading conditions, in particular to model impact loaded Charpy‐V specimens. A method is proposed to construct crack resistance curves based on available data of tension tests and on quasi‐static yield curves. Dynamic yield curves are determined using proven procedures as based on the analysis of the dislocation activation energy. The ductile damage parameters are then obtained via simulation of tests on notched tensile specimens and notched‐bar impact tests as well as the fitting to the upper shelf impact energy. In this way, the ductile damage parameters are determined, which in turn enable the determination of the required J‐resistance curves via simulation of ductile crack growth in fracture mechanics specimens. Thus, the application of the classical J‐integral concept gets possible. Furthermore, the independence of the identified material parameters from the geometry of the specimen then allows the use of the Gurson model to analyse the safety of structural components with cracks directly.     

Ultraschallprüfung an Faserverbundkunststoffen Grundlagen,Methoden der bildhaften Darstellung und Ergebnisse

Ultrasonic Testing of Composites Foundations, Methods of Imaging and Results Modern materials such as composites are more and more used for aircraft and space structures and in mechanical and automotive engineering. Therefore quality control of these materials is of increasing importance. The high resolution computer controlled ultrasonic testing technique in the frequency range of 1 to 100 MHz is able to inspect and to analyse even components with complex geometry. This report gives the foundations and clearly presents the possibilities of reports with A-, B-, C- and D-scans. For test pieces not only CFRP-specimens with a thickness range of 2 to 24 mm and with artificially inserted defects were used, but also devices of the mechanical engineering.