Volume 51, Issue 3

Kurzfassung Im vorliegenden Beitrag wird dargestellt, wie das Normungsbedürfnis für den Kerbschlagbiegeversuch entstand und sich die Normungsarbeiten auf den verschiedenen Ebenen (national, europäisch und international) entwickelten. In einer Übersicht sind die unterschiedlichen nationalen und übernationalen Normen für den Kerbschlagbiegeversuch (Prüfverfahren, Prüfung und Kalibrierung der Prüfmaschinen, Kalibrierung von Referenzproben) gegenübergestellt, und die neue Norm DIN EN ISO 148 wird schwerpunktmäßig erläutert.

In this study the resistivity effect of laboratory-produced S 2 Cl 2 as an additive in Portland cement PC 32.5 which was hydrated at the water/cement ratio of 0.5 and room temperature against sulfate attack in the curing solution of 0.35M sodium sulfate was investigated. Hydrated cement products were determined by using X Ray Diffraction (XRD) and Thermogravimetry—Differential Thermal Analyses (TG-DTA) techniques. The additive substance, S 2 Cl 2 in Portland cement, was used 5 and 10 percent by weight. The highest compressive strength value was found as 36.7 MPa in case of hydrated cement PC 32.5, samples containing 5% S 2 Cl 2 (additive) after curing time of 28%21 days.

In this paper we present a novel time-domain boundary element method (BEM) for dynamic crack analysis in two-dimensional (2-D) linear elastic and layered anisotropic materials. Stationary cracks subjected to impact loading are considered. The homogeneous layers are considered by the multi-domain BEM formulation. On the external boundary and the interfaces, the classical displacement boundary integral equations are used, while the hypersingular traction boundary integral equations are applied on the crack-faces inside the homogeneous layers. The time-domain elastodynamic fundamental solutions for anisotropic solids are used in the present method. The spatial discretization is performed by a Galerkin-method while a collocation method is adopted for the temporal discretization. An explicit time-stepping scheme is developed to compute the discrete boundary data and the crack-opening-displacements.

An infrared camera with InSb detector has been used for measurements of the temperature distribution along tensile and compression samples to be tested at elevated temperatures. Three different materials (titanium, magnesium and carbon steel alloys) with different geometry and heating cycles have been tested simultaneously with thermocouples. The results of the temperature measurements with infrared camera are compared with the measurements by thermocouples. The advantages of using infrared thermal images are discussed in detail. There exist also some obstacles in using an infrared camera for precise measurements of the samples temperature distribution in a Gleeble machine. The IR camera serves as a complementary device and can not substitute thermocouple measurements.

A Cu-Cr-Zr alloy (Alloy C18150) was investigated for tribological behavior in the presence of electric current flow. Experiments involving adhesive wear were conducted under atmospheric conditions at a constant load of approximately 40 N over a duration of 30 minutes, at three different current values (1 A, 2.5 A and 10 A) and two different DC polarities (%/—), and at three different rotational speeds (1 m/s, 2 m/s and 4.2 m/s). Weight loss measurements were noted and wear behavior was evaluated using surface analysis including SEM and EDS. It was observed that friction speed and its related temperature affected the material loss. It has been considered that the compounds Cr 2 O 3 and Cr 2 Zr, which form at the surface for positive and negative current flow, respectively, are responsible for this material loss. The wear behavior demonstrated favorable results with current, with wear resistance increasing at higher current intensity, regardless of polarity.

Ferro-manganese and ferro-chromium particles (FeMn p and FeCr p ) were added to a copper matrix and examined for applications requiring wear resistance and rupture strength. Cu/FeMn p , Cu/FeCr p and Cu/FeMn p /FeCr p metal matrix composites (MMCs) were prepared using a powder metallurgy technique to get a homogeneous distribution of particles in controlled amounts. Powders were mixed, compacted, and sintered in a protective argon gas environment. In a wear test, the MMCs showed a favorable resistance to weight loss when pressed against a moving AISI 304 stainless steel wear plate. Rupture strength was determined using a standard transverse rupture test. Fractographs taken of wear and ruptured surfaces together with rupture strength measurements were correlated with the amount and type of particle reinforcement and MMC hardness. The formation of Metal Carbide (MC) and Metal Oxide (MO) around reinforcing particles was also considered. Transverse rupture strength was found to decrease after exceeding a specific amount of reinforcement.

Kurzfassung Die Betriebsfestigkeitsprüfung der Gesamtfahrzeugstrukturen von Flurförderzeugen wird derzeit durch konventionelle Verfahren erreicht. Diese stoßen bei immer kürzer werdenden Entwicklungszeiten und dem stetig steigenden Kostendruck an ihre Grenzen. Daher wurde im Rahmen eines Forschungsprojektes zwischen Jungheinrich und dem Institut für Fahrzeugtechnik und Antriebssystemtechnik an der Helmut-Schmidt-Universität Hamburg das Potenzial von servohydraulischen Prüfständen zur Betriebsfestigkeitsprüfung von Flurförderzeugen untersucht. Im vorliegenden Beitrag wird der Einsatz von servohydraulischen Prüfständen für Schubmaststapler vorgestellt. Die Prüfstandskonzepte werden nach den Gesichtspunkten der Signalwiedergabegüte, Effizienz und Wirtschaftlichkeit untersucht und bewertet.

Modern infrared (IR) thermography as a non-contacting, high resolution and full-field measurement technique offers a promising tool for various applications in experimental fatigue studies. Despite the tremendous advances in IR-camera, computer and data processing technology, infrared measurements have so far rarely been applied to the assessment of localized fatigue phenomena. The aim of this paper is to present basic considerations and experimental results of an application of infrared thermography for damage studies during fatigue tests on mild steel S355. For this purpose high-resolution infrared image sequences have been acquired during high cycle fatigue testing. The data is analyzed with respect to linear thermoelastic and nonlinear phenomena, which allows characterizing the local fatigue behavior. Experimental studies on unnotched, mildly notched, and welded specimens under different testing conditions are presented. The results confirm the high potential of the application of infrared thermography during experimental fatigue studies.