Investigation of initial yielding in the small punch creep test
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Betül Gülçimen Çakan
Abstract
Unlike the uniaxial creep test results, the interpretation of small punch (SP) test results is not straightforward due to the complex deformation behavior of SP specimens. Accordingly, the reliability of correlations of SP creep test results with corresponding uniaxial tests is still not clear. One crucial point is that the initial yielding at the beginning of an SP creep test results in the hardening of the material before creep sets in and is thought to affect the creep properties. In this study, to clarify this effect, first an accurate numerical model of the SP creep test has been developed following which this model was used to study the influence of test parameters such as specimen thickness, punch diameter and the radius of the receiving hole on the initial yielding. Varying these parameters changes the deformation mechanisms and thus has a strong effect on the deflection-time curves along with the amount of initial plastic deformation. It was observed that decreasing specimen thickness and the punch diameter increased the initial yielding. Conversely, increasing the radius of the receiving hole resulted in higher initial yielding.
Kurzfassung
Gegenüber den Ergebnissen einachsiger Kriechversuche ist die Interpretation von Ergebnissen aus Zeitstandversuchen mit Einschlagmarken (Small Punch (SP) Creep Test) aufgrund des komplexen Deformationsverhaltens der SP-Proben nicht ohne weiteres möglich. Entsprechend ist die Zuverlässigkeit von Korrelationen zwischen Ergebnissen aus dem SP-Kriechversuch mit uniaxialen Zeitstandversuchen noch immer nicht geklärt. Ein kritischer Punkt ist hierbei, dass die Anfangsdehnung beim SP-Kriechversuch zu einer Verfestigung des Werkstoffes führt, bevor das Kriechen einsetzt, und es wird angenommen, dass dies die ermittelten Kriecheigenschaften beeinflusst. In der diesem Beitrag zugrunde liegenden Studie wurde zur Klärung dieses Effektes zunächst ein akkurates Finite-Elemente-Modell des SP-Kriechversuches entwickelt und danach dieses Modell verwandt, um den Einfluss der Versuchsparameter wie Probendicke, Dorndurchmesser und Radius des dadurch versachten Loches auf die Anfangsdehnung zu ermitteln. Eine Variation dieser Parameter verändert die Deformationsmechanismen und hat somit einen starken Einfluss auf die Verformungs-zeitkurven im Zusammenhang mit der anfänglichen plastischen Verformung. Es wurde beobachtet, dass abnehmende Probendicke und Dorndurchmesser die Anfangsdehnung erhöhen. Umgekehrt führt ein zunehmender Radius des resultierenden Loches zu einer höheren Anfangsdehnung.
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© 2018, Carl Hanser Verlag, München
Artikel in diesem Heft
- Inhalt/Contents
- Contents
- Fachbeiträge/Technical Contributions
- An investigation of the crash performance of magnesium, aluminum and advanced high strength steels and different cross-sections for vehicle thin-walled energy absorbers
- Model-based correlation between change of electrical resistance and change of dislocation density of fatigued-loaded ICE R7 wheel steel specimens
- Tensile strength of 3D printed materials: Review and reassessment of test parameters
- Numerical calculation of stress concentration of various subsurface and undercutting pit types
- Chemical composition of chosen phase constituents in austempered ductile cast iron
- Investigation of initial yielding in the small punch creep test
- Optimization and characterization of friction surfaced coatings of ferrous alloys
- Influence of the milling process on TiB2 particle reinforced Al-7 wt.-% Si matrix composites
- In-situ compaction and sintering of Al2O3 – GNP nanoparticles using a high-frequency induction system
- Strain-rate controlled Gleeble experiments to determine the stress-strain behavior of HSLA steel S960QL
- Thermography using a 1D laser array – From planar to structured heating
- Schichtdickenbestimmung von Oberflächenschutzsystemen für Beton mit Impulsthermografie
- Microstructure and mechanical properties of fly ash particulate reinforced AA8011 aluminum alloy composites
- High temperature compressive behavior of three-dimensional five-directional braided composites
- Dry sliding behavior of the aluminum alloy 8011 composite with 8 % fly ash
- Review on nanostructures from catalytic pyrolysis of gas and liquid carbon sources
Artikel in diesem Heft
- Inhalt/Contents
- Contents
- Fachbeiträge/Technical Contributions
- An investigation of the crash performance of magnesium, aluminum and advanced high strength steels and different cross-sections for vehicle thin-walled energy absorbers
- Model-based correlation between change of electrical resistance and change of dislocation density of fatigued-loaded ICE R7 wheel steel specimens
- Tensile strength of 3D printed materials: Review and reassessment of test parameters
- Numerical calculation of stress concentration of various subsurface and undercutting pit types
- Chemical composition of chosen phase constituents in austempered ductile cast iron
- Investigation of initial yielding in the small punch creep test
- Optimization and characterization of friction surfaced coatings of ferrous alloys
- Influence of the milling process on TiB2 particle reinforced Al-7 wt.-% Si matrix composites
- In-situ compaction and sintering of Al2O3 – GNP nanoparticles using a high-frequency induction system
- Strain-rate controlled Gleeble experiments to determine the stress-strain behavior of HSLA steel S960QL
- Thermography using a 1D laser array – From planar to structured heating
- Schichtdickenbestimmung von Oberflächenschutzsystemen für Beton mit Impulsthermografie
- Microstructure and mechanical properties of fly ash particulate reinforced AA8011 aluminum alloy composites
- High temperature compressive behavior of three-dimensional five-directional braided composites
- Dry sliding behavior of the aluminum alloy 8011 composite with 8 % fly ash
- Review on nanostructures from catalytic pyrolysis of gas and liquid carbon sources
