Electronic Scientific Journal
 
Diagnostics, Resource and Mechanics 
         of materials and structures
Рус/Eng  

 

advanced search

IssuesAbout the JournalAuthorContactsNewsRegistration

2019 Issue 2

2022 Issue 5
 
2022 Issue 4
 
2022 Issue 3
 
2022 Issue 2
 
2022 Issue 1
 
2021 Issue 6
 
2021 Issue 5
 
2021 Issue 4
 
2021 Issue 3
 
2021 Issue 2
 
2021 Issue 1
 
2020 Issue 6
 
2020 Issue 5
 
2020 Issue 4
 
2020 Issue 3
 
2020 Issue 2
 
2020 Issue 1
 
2019 Issue 6
 
2019 Issue 5
 
2019 Issue 4
 
2019 Issue 3
 
2019 Issue 2
 
2019 Issue 1
 
2018 Issue 6
 
2018 Issue 5
 
2018 Issue 4
 
2018 Issue 3
 
2018 Issue 2
 
2018 Issue 1
 
2017 Issue 6
 
2017 Issue 5
 
2017 Issue 4
 
2017 Issue 3
 
2017 Issue 2
 
2017 Issue 1
 
2016 Issue 6
 
2016 Issue 5
 
2016 Issue 4
 
2016 Issue 3
 
2016 Issue 2
 
2016 Issue 1
 
2015 Issue 6
 
2015 Issue 5
 
2015 Issue 4
 
2015 Issue 3
 
2015 Issue 2
 
2015 Issue 1

 

 

 

 

 

V. V. Nazarov

ANALYSIS OF TWO METHODS FOR CALCULATING THE ULTIMATE STRESSES OF CREEP AND CREEP RUPTURE PROCESSES

DOI: 10.17804/2410-9908.2019.2.028-036

It is well known that structural elements and parts operating in a loaded state at high temperatures can be subjected to irreversible deformation in time. The calculations of operating life (based on the corresponding mechanical models) may require the mechanical characteristics of the material, ones of which are starting creep stress and rupture stress (ultimate creep stresses) for a particular material at a given temperature. These mechanical characteristics cannot be determined from the diagram of the mechanical state of the material; they are measured in uniaxial tensile tests of cylindrical specimens at a constant tensile stress over time. The complexity of such tests will require alternative methods of calculating the desired mechanical characteristics. In this paper, instead of special tests, it is proposed to calculate the desired mechanical characteristics from approximations of secondary creep and creep-rupture strength. To this end, we have considered two fractional power-law functions with four material parameters (S. A. Shesterikov and M. A. Yumasheva, 1984), two of which have the physical meaning of starting creep stress and rupture stress: approximation of the nominal stress dependence of strain rate for secondary creep (1) and approximation of the nominal stress dependence of rupture time (2). The calculations used experimental data obtained for titanium alloy VT6 at 650 °C on cylindrical specimens, 5 mm in diameter and 25 mm in the base length. The parameters of the fractional power approximations were calculated by the iterative method, termed the Generalized Reduced Gradient Method (Microsoft Excel), under the condition of a minimum total error of the discrepancy between the experimental data and the approximating curve in the corresponding logarithmic axes. The analysis of approximation errors (1) and (2) has shown that error (1) is less than (2) and that the ratio of rupture stress to the starting creep stress is greater. It is concluded from the analysis of the results that it is better to use approximation (1) for calculating ultimate creep stresses.

Keywords: ultimate creep stresses, starting creep stress, rupture stress

Bibliography:

1.  Naprienko S.A., Orlov M.R. Damage of single-crystal turbine blades of GTP. Electronic scientific journal "Proceedings of VIAM", 2016, vol. 38, no. 2, pp. 20–31. DOI: 10.18577/2307-6046-2016-0-2-3-3. (In Russian).

2.  Ilyin S.I., Koryagin Yu.D., Lapina E.V. Creep of ultra-light magnesium alloys at low temperatures. Bulletin of the South Ural State University. Series Metallurgy, 2012, iss. 18, no. 15, pp.105–107. (In Russian).

3.  Kachanov L.M. Osnovy mekhaniki razrusheniya [Fundamentals of Fracture Mechanics]. Moscow, Nauka Publ., 1974, 312 p. (In Russian).

4.  Shesterikov S.A., Yumasheva M.A. Specification of equation of state in creep theory. Izvestiya AN SSSR. Mekhanika Tverdogo Tela, 1984, no. 1, pp. 86–91. (In Russian).

5.  Nazarov V.V., Lepeshkin A.R. A method of calculating creep limits. Diagnostics, Resource and Mechanics of materials and structures, 2017, iss. 1, pp. 36–42. Available at: http://dream-journal.org/DREAM_Issue_1_2017_Nazarov_V.V._et_al._036_042.pdf

6.  Lokoshchenko A.M., Nazarov V.V. Kinetic Approach to Studying the Creep Rupture of Metals under Biaxial Tension. Aviats.-Kosm. Tekh. Tekhnol., 2005, no. 10, pp. 73–78. (In Russian).

7.  Lokoshchenk A.M., Agakhi K.A., Fomin L.V., Pure bending of a beam made of differently strength material under creeping. Vestn. Samarsk. Gos. Tekhn. Univ. Ser Fiz.-Mat. Nauki, 2012, no. 1 (26), pp. 66–73. (In Russian).

8.  Fomin L.V. Description of creep rupture strength of tensile rod with rectangular and circular cross-section at high temperature air media. Vestn. Samar. Gos. Tekhn. Univ., Ser. Fiz.-Mat. Nauki (J. Samara State Tech. Univ., Ser. Phys. Math. Sci.), 2013, iss. 3 (32), pp. 87–97. DOI: 10.14498/vsgtu1228. (In Russian).

9.  Nazarov V.V. Short-Term Creep of Titanium Alloys VT5 and VT6 at High Temperature. Industrial Laboratory. Diagnostics of Materials, 2015, vol. 81, no. 6, pp. 57–60. (In Russian). Available at: https://www.zldm.ru/jour/article/view/88/89

10. Koval’kov V.K., Nazarov V.V., Novotnyi S.V. Procedure of high-temperature within complex stressed state. Zavod. Lab. Diagn. Mater., 2006, vol. 72, no. 4, pp. 42–44. (In Russian).


PDF      

Article reference

Nazarov V. V. Analysis of Two Methods for Calculating the Ultimate Stresses of Creep and Creep Rupture Processes [Electronic resource] // Diagnostics, Resource and Mechanics of materials and structures. - 2019. - Iss. 2. - P. 28-36. -
DOI: 10.17804/2410-9908.2019.2.028-036. -
URL: http://eng.dream-journal.org/issues/2019-2/2019-2_237.html
(accessed: 12/07/2022).  

 

impact factor
RSCI 0.42

 

MRDMS 2022
Google Scholar


NLR

 

Founder:  Institute of Engineering Science, Russian Academy of Sciences (Ural Branch)
Chief Editor:  S.V. Smirnov
When citing, it is obligatory that you refer to the Journal. Reproduction in electronic or other periodicals without permission of the Editorial Board is prohibited. The materials published in the Journal may be used only for non-profit purposes.
Contacts  
 
Home E-mail 0+
 

ISSN 2410-9908 Registration SMI Эл № ФС77-57355 dated March 24, 2014 © IMACH of RAS (UB) 2014-2022, www.imach.uran.ru