TECHNICAL MECHANICS
ISSN (Print): 1561-9184, ISSN (Online): 2616-6380

HOME    ABOUT THIS JOURNAL    EDITORIAL BOARD    GUIDE FOR AUTHORS    CURRENT    JOURNAL ISSUES    CONTACTS

UDC 539.376

Technical mechanics, 2017, 2, 99 - 108

STOCHASTIC METHOD FOR EXTRAPOLATION OF DIAGRAMS OF LONG- TERM STRENGTH OF STRUCTURAL MATERIALS

DOI: https://doi.org/10.15407/itm2017.02.099

I. A. Doyar

I. A. Doyar
Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine
Ukraine

      The research objective is to develop a stochastic method of basic diagrams for extrapolation of a long-term strength of structural materials to the lives exceeded the experiment duration by several orders. This method takes into account a random character of a long-term strength of materials and considers a hypothetic stress value as a totally analogue random quantity for a chosen life. Physically, it results in a gross correctness in comparison with the known deterministic methods, and the research novelty. Based on stochastic processing the long-term strength diagrams and methods of a regression analysis, the technique for identifying the unknown parameters of the method is developed. It was concluded that the theoretical results, obtained with this method, are in a good agreement with the long-strength experiments with samples made from the 18Cr-8Ni stainless steel. The above method can be used to predict the failure time of several structural materials that are widely employed for ma- chine-building, nuclear engineering and rocket technology, as well as in the development of standards, methodic recommendations for evaluating the structural materials lives in creep.

failure, long-term strength, method of basic diagrams, time to failure, probability distribution

1. Rabotnov Yu. N. Creep of Structural Elements. Moscow: Nauka, 1966. 756 pp. (in Russian).

2. Poshivalov V. P. On the approach to determination of time to failure in creep. Problemy Mashinostroenia i Nadezhnosti Mashin. 1993. No. 3. Pp. 56-60. (in Russian).

3. Doyar I., Poshyvalov V. Development of a stochastic model of failure of structural materials in creep at hardening stage. Eastern-European Journal of Enterprise Technologies. 2016. No. 3 (5). Pp. 25-31. (in Russian). https://doi.org/10.15587/1729-4061.2016.69653

4. Manson S. S., Haferd A. M. A linear time-temperature relation for extrapolation of creep and stress rupture data. NASA TN 2890. 1953.

5. Larson F. R., Miller J. Time-temperature relationship for rupture and creep stresses. Trans. ASME. 1952. V.74. Pp. 765-775.

6. Orr R. L., Sherby O. D., Dorn J. E. Correlation of rupture data for metals at elevated temperatures. Trans. ASM. 1954. V.46. Pp. 113-128. https://doi.org/10.2172/4425999

7. Kucher N. K., Prikhodko R. P. Method of extrapolation of long strength diagrams for heat-resistant materials. Visnyk TNTU. 2013. No. 2. Pp. 84-93. (in Ukrainian).

8. Krivenyuk V. V., Avramenko D. S., Prokhodko R. P. Correlation and extrapolation of results of long strength tests for chrome-nickel and chrome-molybdenum steels. Life, Reliability, and Safety of Heat-Power Equipment for Power Stations: Collected Papers. Ye. A. Grin (Ed.). Moscow, 2011. Pp. 127-134. (in Russian).

9. Krivenyuk V. V. Prediction of High-Temperature Creep and Long-Term Strength. Strength of Materials and Structures: Book Series. V. T. Troshchenko (Ed.). Kyiv: Pisarenko Institute for Problems of Strength of the National Academy of Sciences of Ukraine, 2012. V. 5. 752 pp. (in Russian).

10. Data sheets on the elevated-temperature properties of 18Cr-8Ni steel. NRIM Creep Data Sheet. 1986. No. 4B. 32 pp.

DOI: https://doi.org/10.15407/itm2017.02.099

Copyright (©) 2017 YA. F. Andrusyk

Copyright © 2014-2018 Technical mechanics