Analysis of the mechanism of fatigue crack arrest in a cylindrical notched specimen


Cite item

Full Text

Abstract

The phenomenon of fatigue crack arrest in surface-hardened cylindrical specimens with stress concentrators is examined from the perspective of linear fracture mechanics. The stress intensity coefficient (SIC) is considered as the criterion, its scope determines the speed of fatigue crack growth in the case of cyclic loading. The calculations of the study were carried out by the Finite Elements Modeling method using the calculation complex ANSYS. The calculation complex ANSYS that uses the Finite Elements Modeling method in the form of displacements was applied to determine  the stress intensity coefficient under bending of  cylindrical surface-hardened and non- hardened specimens with the  diameter of 10 mm with  a semicircular notch with the radius of 0,5 mm. It is established that the stress intensity coefficient has two extremes in the initial area of the fatigue crack development: the minimum and maximum values. The results of the calculation indicate that the minimum value of SIC is lower than its threshold value below which the crack does not develop in the case of a cylindrical surface-hardened notched specimen. This fact is in good agreement with the results of tests of these specimens as non-propagating fatigue cracks were revealed in these specimens only. It is also established that the depth of a crack is approximately 0,02 of the minimum size of the section of a cylindrical specimen for the maximum value of the stress intensity coefficient. The study carried out validates the use of the criterion of average integral residual stresses to calculate the increase of the endurance limit of surface-hardened specimens and parts with stress concentrators due to compressive residual stresses.

About the authors

V. P. Sazanov

Samara National Research University

Author for correspondence.
Email: sazanow@mail.ru

Candidate of Science (Engineering)

Associate Professor of the Department of Strength of Materials

Russian Federation

References

  1. Kudryavtsev P.I. Nerasprostranyayushchiesya ustalostnye treshchiny [Nonpropagating fatigue cracks]. Moscow: Mashinostroenie Publ., 1982. 174 p.
  2. Kudryavtsev P.I., Morozova T.I. Razvitie ustalostnykh treshchin v stalyakh v svyazi s poverkhnostnym naklepom. Sb. statey «Issledovaniya po uprochneniyu detaley mashin». Moscow: Mashinostroenie Publ., 1972. P. 194-200. (In Russ.)
  3. Kudryavtsev P.I. Nekotorye osobennosti stroeniya treshchin ustalosti v nizkouglerodistoy stali. V sb. «Povyshenie prochnosti i dolgovechnosti detaley mashin». No. 110. Moscow: Mashinostroenie Publ., 1969. P. 105-113. (In Russ.)
  4. Troshchenko V.T., Pokrovskiy V.V., Prokopenko A.V. Treshchinostoykost' metallov pri tsiklicheskom nagruzhenii [Crack resistance of metals under cyclic loading]. Kiev: Naukova Dumka Publ., 1987. 256 p.
  5. Pavlov V.F., Kirpichev V.A., Vakulyuk V.S. Prognozirovanie soprotivleniya ustalosti poverkhnostno uprochnennykh detaley po ostatochnym napryazheniyam [Prediction of fatigue strength of surface hardened components by residual stresses]. Samara: Samarskiy Nauchnyy Tsentr RAN Publ., 2012. 125 p.
  6. Pavlov V.F. Influence of a value and a distribution of residual stresses in the surface layer of a part with a concentrator on the endurance limit. Report 1. Solid parts. Proceedings of Higher Educational Institutions. Маchine Building. 1988. No. 8. P. 22-26. (In Russ.)
  7. Pavlov V.F. The influence of a value and a distribution of residual stresses in the surface layer of a part with a concentrator on the endurance limit. Report II. Hollow parts. Proceedings of Higher Educational Institutions. Маchine Building. 1988. No. 12. P. 37-40. (In Russ.)
  8. Chirkov A.V., Sazanov V.P., Samoylov V.A., Larionova Y.S. Modeling of redistribution of residual stresses in the cylindrical specimens after advancing surface plastic forming. Vestnik of the Samara State Aerospace University. 2011. No. 3 (27), part 3. P. 171-174. (In Russ.)
  9. Ivanov S.I. K opredeleniyu ostatochnykh napryazheniy v tsilindre metodom kolets i polosok. Sb. trudov «Ostatochnye napryazheniya». Iss. 53. Kuibyshev: Kuibyshev Aviation Institute Publ., 1971. P. 32-42. (In Russ.)
  10. Kirpichyov V.A, Sazanov V.P., Surgutanov N.A., Shadrin V.K. On the connection between the stresses intensity coefficient and non-propagating crack critical depth. Proceedings of the Tenth Russian Conference on Solid Mechanics. V. 2. Samara: Samara State Technical University Publ., 2017. P. 23-26. (In Russ.)
  11. Broek D. Elementary engineering fracture mechanics. Leyden, 1974.

Supplementary files

Supplementary Files
Action
1. JATS XML
Download

Copyright (c) 2018 VESTNIK of Samara University. Aerospace and Mechanical Engineering

This website uses cookies

You consent to our cookies if you continue to use our website.

About Cookies