Einlaufverhalten nasslaufender Lamellenkupplungen im Schlupfbetrieb

Forschung im Ingenieurwesen - Nasslaufende Lamellenkupplungen weisen zu Betriebsbeginn eine Phase des Einlaufens auf, in der sich das Reibungsverhalten durch Anpassung der Reibflächen...     

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

Ohne Zusammenfassung     

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 Bruchwiderstands an Oxidkeramik und Hartmetallen mit verschiedenen Methoden

Fracture Toughness Determination of Alumina and Cemented Carbide with Different Testing Methods Fracture toughness of a sintered alumina and two tungsten carbidecobalt materials was determined using four-point-bend specimens with straight through and chevron notches and with the short rod specimen. With the specimens with a straight through notch a lower K_Ic was measured for Al₂O₃ and a higher for WC-Co compared to the chevron-notched specimens. This behavior was explained by the different shapes of the crack growth resistance curves and the different critical notch radii. For Al₂O₃ a steeply rising crack growth resistance curve was measured in a controlled fracture test, for WC-Co a flatter curve was obtained. The effect of the shape of the crack growth resistance curve and of notch width on the evaluated toughness is discussed.     

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.     

Ein Verfahren zur Ermittlung der Rissentwicklung während des Feuerverzinkens

Hot‐dip galvanizing represents a very effective method to protect components against corrosion. During the hot‐dip galvanizing process, however, there is a risk that cracks form in the component. With an increase of the temperature of the zinc bath, the danger of crack formation also increases. This article describes a method to determine the start of the crack formation during hot‐dip galvanizing. With a few tests, this method allows to determine a stress‐strain limit (energy limit) below which no liquid metal assisted cracking (flüssigmetallinduzierte Rissbildung) can occur during the transient phase of hot‐dip galvanizing.     

Verfahren zur vollständigen Ermittlung der R‐Abhängigkeit des Rissausbreitungsverhaltens mit nur einer Probe

Procedure for the determination of the complete R‐dependency of the crack growth behaviour with only one specimen A new concept for fatigue crack propagation tests has been developed. Using a single specimen, it is possible to determine fatigue crack growth curves (da/dN ‐ ΔK) for every stress ratio between R = 0.9 and R = ‐1. Additionally, the new concept also provides threshold values for fatigue crack growth for different values of R and K_max. In combination with a continuous crack length measurement tool (such as the DC potential drop method) this testing procedure can be performed with minimal effort of personnel and time. The test procedure consists of a sequence of K_max‐constant tests with decreasing crack growth rates. As the applied K_max is increasing stepwise there should be no load history effects. According to the procedures described in the ASTM Standard E 647, the results using this new testing procedure fit very well to the da/dN ‐ ΔK curves generated with different specimens. The tests also fulfil all the requirements of ASTM Standard E 647.     

Prüfmethoden zur Ermittlung des Verhaltens von Polyolefinen bei der Einwirkung von Chemikalien

Methods to Determine the Behavior of Polyolefines in Contact with Chemical Agents Two test methods to determine the behavior of thermoplastics in contact with chemicals were compared. These are the immersion test and the internal pressure creep test of pipes filled with a chemical agent. Concerning the immersion test the mechanical properties of tensile bars after the test procedure were determined. The results only are valid for constructions without any load. In the internal pressure creep tests the influence of a chemical agent and the stress is considered simultaneously. By comparison with the long term behavior under the influence of water the chemical resistance factor is given. The test procedure and the evaluation of the results of the immersion tests were strown at two examples. A test station for internal pressure creep tests with pipes which are filled with a chemical agent is described. Many resistance factors were listed up and their application in two examples explained.     

Eine effiziente Methode zur Ermittlung des Schädigungsbereiches bei Wöhleruntersuchungen

An Efficient Method for the Estimation of the “French Damage Area” By a statistically planned and evaluated variant of French's method, the French damage line may be transformed into a quantitatively describable “damage area”. For this purpose a considerable amount of tests has to be applied (app. 400 specimens). A new evaluation of statistically planned investigations of Panagopoulos [23] showed two remarkable results:

• 100% probability of fracture is nearly related to 100% probability of damage
• the arcsin √-transformation is a well fitting model describing the distribution of damage.

A new efficient method for the estimation of the damage area based on this observations was derived and described. The damage area is discussed regarding two level and multi-level tests.     

Charakterisierung der Systeme zur Ermittlung der Hilbert-Transformation

This paper deals with the characterization of all systems needed to calculate the Hilbert-Transform of a given signal. The procedure to classify these systems is given. One main part of the paper describes the practical application of the procedure. The well known sine-function plays a significant role in the investigations. The advantages of the technique of this paper are also discussed.     

Anwendung des instrumentierten Kerbschlagbiegeversuchs zur Ermittlung von Referenztemperaturen nach dem Master‐Curve‐Konzept

Application of the Instrumented Impact Test for the Determination of Reference Temperatures Using the Master Curve Concept The instrumented impact test is suitable for the determination of fracture mechanical parameters. In this paper the determination of the dynamic fracture toughness values in the lower ductile‐to‐brittle transition region is presented. The fracture toughness is determined at the onset of cleavage fracture and evaluated by the Master Curve (MC) concept. The MC concept allows to quantify the variation of fracture toughness with the temperature within the lower ductile‐to‐brittle transition region. Limit curves of fracture toughness for defined failure probabilities and a reference temperature can be determined using this method. This paper presents the application of the master curve concept to the reference temperature determination through the thickness of reactor pressure vessel (RPV) steel plate. The reference temperatures determined dynamic fracture toughness values (T₀^dy) are compared with quasi‐static reference temperatures (T₀^st) and Charpy‐V transition temperatures (TT). T₀^dy, T₀^st and TT increase from the surface to the middle of the RPV steel plate. Compared with T₀^st, the T₀^dy values are higher approximately 70 to 90 K.     

Beitrag zur numerischen Ermittlung elastoplastischer Verzerrungen mittels Finiter Elemente

A Note On the Numerical Calculation of Elastoplastic Strains By The Method of Finite Elements The state of stress and strain of a plate with a circular hole (elastoplastic region) is calculated by the aid of two plane triangular elements (linear and quadratic displacement function) and the Prandtl-Reuss- and Hencky-equations. The procedure of initial strain is used, to approximate the plane stress state to the stress-strain curve of the material. The results agree well with experimental values from the literature. In general stresses and strains, calculated on the base of elements with quadratic displacement function, lie nearer to the measured values. In addition to that a different and exacter course of spreading of elastoplastic regions of material is found. Stresses and strains in regions of high gradients can be calculated more precisely with these elements. A comparison between stresses and strains, calculated by the Prandtl-Reuss- and Hencky-equations, showed very less differences.     

Ermittlung des Zeitstandverhaltens einer austenitischen Schweißverbindung

Evaluation of the Creep Rupture Behaviour of an Austenitic Welded Joint. Part I: Experimental Determination of the Creep Behaviour The creep rupture behaviour of a welded joint of 18% Cr-11% Ni-steel was investigated on specimens of different geometry and size. Differences in the creep rupture behaviour between welded joint specimens and specimens taken from the different zones of the welded joint are discussed. The plasticity-and creep behaviour of the different zones is described by constitutive equations.     

Application of connectionistic models for the evaluation of market structures Ansätze zur Ermittlung von Marktstrukturen mit Hilfe konnektionistischer Modelle

An often occurring problem in marketing research is the consumers' segmentation by means of so-called conjoint data. In this article different approaches based on neural networks are presented and evaluated within a procedure comparison. Observations of a Monte-Carlo-Simulation are used as data basis. The approaches will be compared to the traditional k-means method and a mixture regression analysis and parallels between these procedures will be pointed out. Why these methods lead to identical results will be shown and explained.     

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.