Verfahren zur Bestimmung der Messunsicherheit bei der Härteprüfung. Excel Datei zur Durchführung

Methods for the Determination of Uncertainty for Hardness Testing. EXCEL file for the Determination The determination of uncertainty for hardness testing [1, 2, 3] on the basis of the CRM hardness reference blocks according to GUM [4] are described. The application of an EXCEL based file for this determination of the uncertainty as part of the periodic check is presented.     

Neue Auswertungsmethode zur Bestimmung der Kennwerte der Dehnungswöhlerlinie und der Spannungs‐Dehnungs‐Kurve unter Berücksichtigung der Kompatibilität

New method for evaluation of the Manson‐Coffin‐Basquin and Ramberg‐Osgood equations with respect to compatibility A new method for determining the stress‐strain and strain‐life curves for metals is presented. The method involves fitting the curve to experimental data points in a three‐dimensional strain‐stress‐life space. With the plastic part of strain, stress and fatigue life as coordinates, a straight line is used for fitting the experimental data points. The material constants are calculated directly from the directional vector R and the coordinates of the point P , which determines the fitted straight line. It is shown that the assumption of equality of the plastic and elastic components in Manson‐Coffin‐Basquin and Ramberg‐Osgood equations leads to the so called compatibility condition. This new method retains the mathematical and physical relationships between the considered curves. The results obtained from this new method using high‐strength aluminium alloys subjected to different manufacturing conditions and different test temperatures are presented. These results are compared to results obtained with a conventional method for determining the fatigue parameters.     

Elastizitätstheoretische Lösung des kreisförmigen Einschlusses in unendlicher Scheibe mittels der Beziehungen zwischen Loch‐ und Einschlussproblem

The method applied for the derivation of an elastic solution of an infinite plate with a circular inclusion of mismatching stiffness under uniform remote tension stress is based on the special deformation characteristic of this inclusion geometry. Outgoing from the analysis of the plate with a circular hole is the exact solution of the general inclusion problem obtained by superposition of a specific inner stress field.     

Ermittlung von Berechnungskennwerten an Karosseriewerkstoffen – Bericht über ein Gemeinschaftsprojekt der Stahl‐ und Automobilindustrie

Determination of input data for numerical design of sheet steels – Report on a common research project of the steel and automotive industry Within the scope of a common research project of the steel and automotive industry, 20 sheet steels have been investigated to obtain input data for FE‐analysis. In detail, elastic, plastic and fatique characteristical values were determined by several testing institutes for a period of 3 years. The investigated sheet steels differ with regard to the microstructure and the steel concept. Beside several ferritic steels, multiphase steels like dual phase‐, complex phase‐ and TRIP steels as well as 2 austenitic stainless steels were characterised. The starting materials and selected steels with a defined predeformation and heat treatment were investigated. Within this project, the partners developed a testing and documentation precept in which the ways and means were fixed to reach the defined steel condition and to enable a standardised testing and data output for the material database, realised by the automotive industry. Before the actual elastic, plastic and fatique testing, a reception test for all steels was carried out to characterise the materials with regard to the microstructure, surface condition, chemical composition and mechanical properties, obtained in the quasistatic tensile test. The results of the different testing institutes (elastic, plastic and fatique) will be presented in separate publications in detail. As a result of this project it became obvious that the investigated steels can be divided into steel groups which show a similar strain hardening behaviour. Thus, a prediction of mechanical values and flow curves for cognate steels within one steel group seems to be possible. This subject will be the focus of further investigations within the scope of a new project started on January 1^st, 2003.