Synergetics Principles and Regularities Fracture of Materials under Low Cycle Fatigue Conditions

The work examines the synergetic principles of fatigue fracture, which make it possible to identify the fundamental mechanical characteristics of materials and evaluate the kinetics of damage during the destruction of metals through critical parameters that control bifurcation points. In this case, fatigue failure is considered as a kinetic process depending on the order of supply of cyclic loading energy. Based on the principles of physical mesomechanics and synergetics, it is shown that the mechanical characteristics of a cyclically loaded tribocontact are important material parameters that determine the level of strain energy introduced in each loading cycle at each scaling level. It has been revealed that for practical purposes in tribocontacts it is necessary to ensure that the tension between the coating and the substrate corresponds to the maximum elasticity of the materials, according to the Griffiths criterion, and for viscous materials, a different value of the critical stress is considered — the Irwin-Oravan modification. Criteria for transient contact modes are given, considering that the coating must undergo changes in full agreement with the substrate when the system deforms under cyclic load. The research results in assessing the mechanical characteristics of materials of the coating-substrate system can be used as diagnostic signs in analyzing the development of damage to tribocontacts operating under cyclic fatigue loading conditions.

1. Janahmadov A.Kh. and Javadov M.Y. Synergetics and Fractals in Tribology. — USA. Swissland: Springer. — 2016

2. Panin V.E. Sinergeticheskie principy fizicheskoj mezomehaniki // Fizicheskaja mezomehanika. — 2000 (3), № 6, 5—36 (in Russian)

3. Sih G.G. and Tang X.S. Scaling of Volume Energy Density Function Reflecting Damage by Singularities at Macro-, Meso- and Microscopic Level // Thear Appl. Fract. Mech. — 2005 (43), no. 2, 211—231

4. Janahmadov A.Kh. Mesomechanics of the Frictional Contact in Low-Cycle Fatigue Conditions // Journal of Friction and Wear. — 2022 (43), no. 3, 203—208

5. Shugurov A.R., Panin A.V., Dmitriev A.I., Nikonov A.Ju. Zakonomernosti mnogourovnevogo razrushenija pokrytij Ti-Al-N v processe odnoosnogo rastjazhenija // Fizicheskij Mezomehanika. — 2020 (23), № 5, 56—68 (in Russian)

6. Cyr E., Muhammadi M., Mishra R.K., and Inal K. A Three Dimensional (3D) Thermos-Elastoviscoplastic Constitutive Model for FCC Polycrystals // Int. J. Plasticity. — 2015 (70), 166—190

7. Zhang T., Zhou K., and Chen Z. Strain Rate Effect on Plastic Deformation of Nanocrystalline Copper Investigated by Molecular Dynamics // Materials Science and Engineering — 2015 (648), 23—30

8. Lazzarin P., Berto F., Gomez F.J. and Zappalorto M. Some Advantages Derived from the Use of the Strain Energy Density over a Control Volume in Fatigue Strength Assessments of Welded Joints // Int. J. Fatigue — 2008 (30), no. 8, 1345—1357

9. Huang R., Prevost J., Huang Z., and Suo Z. Channel-Cracking of Thin Films with the Extended Finite Element Method // Eng. Fract. Mech. — 2003 (70), 2513—2526

10. Shanjavskij A.A. Masshtabnye urovni processov ustalosti metallov // Fizicheskaja Mezomehanika. — 2014 (E17), № 6, 87—98 (in Russian)

11. Janahmadov A.Kh. Mezomehanika frikcionnogo vzaimodejstvija. — Baku: Apostrof-A. — 2022 (in Russian)

12. Basquin O.H. The Exponential Law of Endurance Tests // Am. Soc. Test. Materials Proc. — 1910 (10), 625—630

13. Lawn B.R., Evans A.G., and Marshall D.B. Elastic/Plastic Indentation Damage in Ceramics: The Median/Radial Crack System // J. Am. Ceram. Soc. — 1980 (63), 574—581

14. Pharr G.M. Measurement of Mechanical Properties by Ultra-Low Load Indentation // Mater. Sci. Eng. — 1998 (A253), nos. 1–2, 151—159

15. Leyland A. and Matthews A. Optimization of Nanostructured Tribological Coatings // in Nanostructured Coating / ed. by A. Cavaleiro and J.Th.M. DeHosson. — Springer Science + Business Megua, LLC. — 2006, 511—538