Ein Konzept zur Dauerfestigkeitssteigerung autofrettierter Bauteile unter Innendruck

A Design Concept for Autofretted Parts under Pulsating Internal Pressure Autofrettage improves the endurance limit of pressurisized parts. The endurance limit is determined by crack arrest. The design concept first estimates the mean endurance limit, i. e. at a failure probability of 50 percent. This first step is explained in detail by the aid of a cross bore and validated by experimental results of this typical design feature. In a second step the allowable pressure range is predicted for defined low failure probability, typical for series production parts.     

Experimentelle und numerische Untersuchungen zur Kennzeichnung von Sinterteilen mittels gezielt eingebrachter Fremdpartikel

Experimental und numerical investigation on the marking of sintered parts by the targeted application of particles Sintered parts from steel as well as light metal alloys are becoming popular in many industrial sectors due to their advantageous product properties. Beside the good utilization of raw material and the variability in alloying the sinter technology offers the opportunity to mark parts in a unique and invisible manner. Spheric particles are used as information carrier. A quadratic 4x4 matrix with a maximum of 16 particles is placed inside a sinter part for first experiments. The defined places and number of particles result in an identification number. After sintering process the two materials are inseparably connected. The readout of the data is realized with x‐ray or computer tomography due to different physical properties of the particles and the powder material.     

Bestimmung von Ausgas- und Desorptionsraten mittels Restgasanalysator

Determination of Outgassing and Desorption Rates by Means of Residual Gas Analysis Especially when using plastic materials in vacuum chambers it is essential to know the amount of gases outgassing from the surface of those materials. Depending on the so-called outgassing or desorption rate one can decide if the proposed plastic material is suited for the desired application and how the vacuum system has to be configured, so that the use of the particular material makes sense. The article will demonstrate by means of 2 examples that there exist temperature-dependent outgassing behaviors of different materials. It also gives an overview of the measuring equipment set up to determine the outgassing rates.     

Untersuchungen zur Ermittlung und Bewertung von Schädigungsvorgängen in Klebverbindungen mittels Schallemissionsanalyse

Investigations to Determine and Evaluate Damage Processes of Adhesive Bonds by Means of Acoustic Emission The damage process in metal adhesive bonds under quasistatic loads was monitored by means of acoustic emission analysis (AEA). Metallographic investigations allow the correlation between acoustic emission data and microscopic failure processes in the bondline of single lap adhesive joints. The influence of specimen geometry on the initiation of damages is discussed for several types of adhesives. Furthermore the relation between the preparation of the adherent surface and the onset of acoustic emission is as well described as the influence of manufacturing defects on the mechanical behaviour and the acoustic emission activity.     

Oberflächenaktivierung von Kunststoff mittels Plasma zur Haftvermittlung

Plasma activation of polymer surfaces for the adhesive bonding — a survey of praxis Several techniques are used for the permanent joining of components. In applications where welding or soldering cannot be applied due to the great heat development, the use of plasmas can prepare even otherwise chemically inert surfaces for the bonding process. This article presents the basic chemical concepts of this technique as well as its practical realization using the example of adhesion of polymers among themselves and to metals.     

Eine Anmerkung zur exakten Nachbildung von Aktienindizes mittels einer Multiplikator-Rundungsmethode

Um einen Aktienindex exakt nachzubilden, mu? man die Gewichtungsfaktoren des Indexes mit dem gewünschten Index-Vielfachen multiplizieren und erh?lt so die Anzahlen der jeweils zu haltenden Aktien. Rundet man diese Anzahlen auf herk?mmliche Art, so weicht man vom gewünschten Nachbildungsergebnis h?ufig weiter als n?tig ab. In dieser Arbeit wird ein leicht zu implementierender Algorithmus vorgestellt, der dieses Problem auf Basis einer Multiplikator-Rundungsmethode l?st. Als konkretes Anwendungsbeispiel wird gezeigt, wie man dieses Verfahren beim Nachbilden des Deutschen Aktien-Indexes (DAX) anwenden kann. Dabei finden auch im Xetra-Handel übliche Stückzahlrestriktionen Berücksichtigung. Der Algorithmus reduziert den Nachbildungsfehler und damit auch den daraus resultierenden Tracking-Error auf einen Bruchteil des Wertes, den man bei herk?mmlicher Rundung erh?lt.     

Konzept zur Verbesserung der Meerwasserbeständigkeit von Wälzlagerstahl

To develop corrosion‐resistant hardenable bearing steels for seawater applications the contents of Mo and Cr were raised in respect to X65Cr14 and the carbon content was lowered by making use of the soluble N content. The steels X51CrN(14)14 and X51CrMoN(14)15‐3, to be molten under normal pressure, and steel X33CrMoN(32)15‐3, to be processed under an N₂ pressure of = 4.7 bar, promise a higher resistance to pitting corrosion and a lower liability of coarse eutectic carbides in segregated areas without discernible disadvantages in respect to hardness and retained austenite. The study has led to a pre‐selection of promising new steels just by thermodynamic calculations and empirical equations without time‐consuming and costly experiments.     

Datenverwaltungssysteme zur Speicherung von Beanspruchungs- und Schwingfestigkeitsdaten

Data Management Systems for Load and Fatigue Strength Data Load and fatigue strength data, which result of tests with technical components, can be stored and managed in computer systems and then worked up to programs for different kinds of special problems. The present report shows the difference between data files and data base systems and the problems by storing and managing the experimental values. Data base systems can be divided into textual and factual data base systems. The report shows further, that factual data base are the best method to store an extensive data collecting.     

Lebensdauer- und Dauerfestigkeitsabschätzung von zugdruckwechsel- und zugschwellbeanspruchtem Stahl mittels Temperaturmessung

Estimation of the Endurance and the Fatigue Limit of Steel by Measuring Specimens′ Temperatures. Microplastic deformation processes are pre-requisites for fatigue crack formation within metallic materials. If the testing frequency of a specimen, cyclically stressed by a progressively-increasing load test, is not too low it is no great metrological problem to ascertain that special stress amplitude, σ_f,th (f ? fatigue limit, th ? thermometrical), at which specimen's temperature begins to rise due to the start of ‘remarkable’ microplastic deformations. Investigations of this kind, recently carried out by rotating bending showed a very good correspondence between σ_f,th and a statistically ascertained estimate of the fatigue limit, \documentclass{article}\pagestyle{empty}\begin{document}$ \hat \sigma _{({\rm P} \simeq {\rm 0}\%{\rm)}} $\end{document} (P ? Probability of fracture), derived from comparatively performed Wöhler-tests. The purpose of this paper is to investigate the relationship between σ_f,th and \documentclass{article}\pagestyle{empty}\begin{document}$ \hat \sigma _{({\rm P} \simeq {\rm 0}\%{\rm)}} $\end{document} for some carbon steels when cyclically stressed by push-pull and pulsating tensile loading, respectively. Both, unnotched and notched specimes were tested. Moreover, thermometrically monitored Wöhler-tests revealed that temperature measurements can provide a short-cut prediction of specimens′ lives. Above all it has to be mentioned that a reliable clue is gettable at a very early experimental stadium whether the cyclic stressed specimen will later become a ‘break’ or – normally much later – a ‘run-out’.     

Charakterisierung von Glas und Glasbeschichtung mittels oberflächensensibler Sondenverfahren

The presented results of investigations by surface and microanalytical methods confirm the suitability of electron beam and scanning probe techniques for process monitoring, support of process development and defect analyses in the glass industry. More and more glass and coating specialists use the high tech service provided by an external laboratory with its wide range of experience and knowledge.     

Simulation des Betriebsverhaltens von Schraubenkompressoren: Ein Vergleich von Rechnung und Messung

Due to the increasing international competition, the application of numerical methods to simulate the machine behaviour of screw type machines becomes more and more important. The insertion of a simulation system depends decisively on the quality to imitate complex physical processes with high reality. To judge this quality it is necessary to verify the calculated results. This article exemplary presents the comparision of calculated and measured values of a dry running screw type compressor.     

Ein Beitrag zur Auslegung von Verdrängermaschinen mit harmonischen Polygonprofilen

Ohne Zusammenfassung     

Theoretische und experimentelle Untersuchungen zur Torsion von Kastenquerschnitten

Ohne Zusammenfassung     

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.