scholarly journals OS18-1-1 Determination of Creep Exponent and Coefficient by Indentation Creep

Author(s):  
Akihiko Hirano ◽  
Masao Sakane ◽  
Naomi Hamada
Keyword(s):  
2003 ◽  
Vol 24 (3) ◽  
pp. 307-317 ◽  
Author(s):  
Yue Zhu-feng ◽  
Wan Jian-song ◽  
Lü Zhen-zhou
Keyword(s):  

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2912
Author(s):  
Alessandro Schiavi ◽  
Claudio Origlia ◽  
Alessandro Germak ◽  
Andrea Prato ◽  
Gianfranco Genta

In this work, the experimental method and the calculation model for the determination of indentation moduli, indentation work, and indentation creep of metallic materials, by means of macroscale-level forces provided by a primary hardness standard machine at the National Institute of Metrological Research (INRIM) at the at room temperature were described. Indentation moduli were accurately determined from measurements of indentation load, displacement, contact stiffness and hardness indentation imaging and from the slope of the indentation unloading curve by applying the Doerner-Nix linear model; indentation work, representing the mechanical work spent during the force application of the indentation procedure, was determined by calculating the areas under the loading–unloading indentation curve, through fitting experimental data with a polynomial law. Measurements were performed with a pyramidal indenter (Vickers test). The applied force was provided by a deadweight machine, and the related displacement was measured by a laser interferometric system. Applied forces and the occurring indentation depths were simultaneously measured: the resulting loading–unloading indentation curve was achieved. Illustrative tests were performed on metals and alloy samples. Discussion and comments on the suitability of the proposed method and analysis were reported.


Author(s):  
Shinsuke Sakai ◽  
Yu Watanabe ◽  
Satoshi Izumi ◽  
Atsushi Iwasaki ◽  
Takeshi Ogawa

Authors reported in the previous paper [1] that indentation creep test is effective to evaluate the creep power law from small specimen. We derived the formulation and applied the proposed method to turbine rotor materials. Eventually, it was shown that the method is applicable for the evaluation of creep constitutive law especially under high stress region. Under the low stress region, however, the applicability of the method was not confirmed since it requires much time for the confirmation. As most necessary property for creep deformation is that for low stress region, the extension of the proposed method for the low stress region is considered extremely important. For this purpose, it is not appropriate to use steel materials for the confirmation because it consumes too much time to conduct creep indentation test under low stress. For solder materials, however, it is rather easier to conduct the creep indentation test under low stress because the creep phenomena occur even at room temperature. In this paper, we report the results of creep indentation test for solder materials and examine the applicability of the proposed method. Besides finite element analysis is performed to evaluate stress conversion factor which enables us to evaluate Norton’s law only from creep indentation tests.


2009 ◽  
Vol 1224 ◽  
Author(s):  
Wuzhu Yan ◽  
Bin Zhao ◽  
Zhufeng Yue

AbstractThe indentation creep test, especially the impression creep, exhibits a magic appealing in the determination of creep properties of small structures in industry for its simplicity, efficiency and non-destruction merits. Most of previous researches of indentation or impression creep neglect the effect of surface roughness of materials, which plays a crucial role in extracting creep properties of materials. The FE results showed that the surface roughness has no effect on the determination of creep exponent when the punching stress is larger than 150MPa. However, under a smaller punching stress the stress exponent is decreased due to the “Tuner” effect of asperities. The conclusions drawn in the present study provide an important guidance on experiment results amendment for impression creep technique.


Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 646 ◽  
Author(s):  
Manar Hassan ◽  
Spiros Zinelis ◽  
Monika Hersberger-Zurfluh ◽  
Theodore Eliades

The aims of this study were twofold: a) to characterize a wide array of time-independent and -dependent properties and b) to find possible correlations among the properties tested. Seven commercially available orthodontic adhesives were included in this study and ten cylindrical specimens were prepared from each material. Five specimens from each material were used for the characterization of Martens Hardness (HM), indentation modulus (EIT), and elastic index (ηIT), and the remaining five for the determination of indentation creep (CIT). Al the aforementioned properties were identified by employing an Instrumented Indentations Testing (IIT) device with a Vickers indenter. The results of HM, EIT, ηIT, and CIT were statistically analyzed by one way ANOVA and Tukey post hoc test, while the possible correlations among the aforementioned properties were determined by Spearman correlation test. Statistical significant differences were identified for all properties among the materials tested. Spearman correlation reveals that HM has a positive correlation with EIT. Both properties demonstrated a negative correlation with ηIT and CIT, while no correlation was identified between ηIT and CIT. Significant differences in the mechanical properties tested may also imply differences in their clinical behavior and efficacy.


2005 ◽  
Vol 2005.6 (0) ◽  
pp. 273-274
Author(s):  
Shinsuke SAKAI ◽  
Yu WATANABE ◽  
Satoshi IZUMI ◽  
Takeshi OGAWA ◽  
Kenichi YASUDA

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.


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