Unification of the calculation methods and tests for strength, life time and crack resistance

It is showed that for all facilities of the machine-building engineering complex the solution of the problems of strength, life time and crack resistance is confined to scientifically grounded determination of the admissible design parameters of the life time and keeping the levels of stresses and deformations of the bearing elements of the objects in question within the permissible limits. This requirement is extended to the basic operational design parameters — durability in cycling and time, size of the flaws, temperature, and deformation rate. Then the equations of state corresponding to the indicated cases, supported by the necessary computational and experimental information, provide a possibility to assess the conditions for attaining the limiting states of the objects under consideration by the values of corresponding margins. The developed approach is used in analysis of traditional methods of design, manufacture and the operation of the equipment which are based on determinate criteria of static, long-term, cyclic, dynamic, and temperature strength, as well as on the standard characteristics of the mechanical properties of structural materials, analysis of the rated and limiting stress states of bearing structures with allowance for the margin values of stresses, strains and life time. An emphasis is made on the necessity of going to the generalized analysis of the fracture criteria on the basis of multifactor computational and experimental methods of margin determination when calculating strength, life time and crack resistance. According to the considered approach it is stated that the general formulation and solution of fundamental problems of analysis and provision of nominal and abnormal operation of technogenic objects is based on their straight quantitative connection with the problems of constructing equations of state, solving the boundary value problems and formulating the criteria of limiting states along with assessment of the margins of strength, life time and crack resistance. A complex and mutually consistent system of deformation and fracture curves is constructed proceeding from the characteristics of the mechanical properties of materials inherent to the estimates of the stress-strain and limiting states. Linear (elastic) and nonlinear (elasto-plastic) approaches to construction of kinetic equations characterizing in general the processes of nucleation and development of damage and fracture zones which are responsible for margin reduction are considered and analyzed as most important ones.

1. Makhutov N. A., Fortov V. E. Machinery Manufacture of Russia: Prospects and Risks of Evolution. — Moscow: Nauka, 2017. — 104 p. [in Russian].

2. Makhutov N. A. Strength and safety: fundamental and applied researches. — Novosibirsk: Nauka, 2008. — 528 p. [In Russian].

3. Makhutov N. A., Gadenin M. M. Development of fundamental and applied researches in the field of machine sciences with use of strength, safe life, survivability and safety criteria / Zavod. Lab. Diagn. Mater. 2018. Vol. 81. N 10. P. 41 – 52. DOI: 10.26896/1028-6861-2018-84-10-41-52 [in Russian].

4. Problems of strength, technogenic safety and constructional materials science / Ed. by N. A. Makhutov, Yu. G. Matvienko, A. N. Romanov. — Moscow: LENAND, 2018. — 720 p. [in Russian].

5. Makhutov N. A. Safety and risks: system researches and developments. — Novosibirsk: Nauka, 2017. — 724 p. [in Russian].

6. Makhutov N. A., Gadenin M. M. Basic researches of problems of technosphere objects safe service on the basis of strength, resource and risk criteria / Probl. Mashinostr. Avtomat. 2018. N 3. P. 7 – 24 [in Russian].

7. Gadenin M. M. Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal stated / Inorganic Materials. 2013. Vol. 49. N 15. P. 1352 – 1356. DOI: 10.1134/S0020168513150053.

8. Morozov E. M., Zernin M. V. Hertzian Problem of Fracture Mechanics. — Moscow: Knizhny Dom «LIBROCOM», 2017. — 544 p. [in Russian].

9. Makhutov N. A., Gadenin M. M. Analysis of limit states and emergency situations types at an estimation of a safety service life time / Probl. Mashinostr. Avtomat. 2019. N 2. P. 4 – 16 [in Russian].

10. PNAE G-7-002-86. Rules and norms in nuclear energetics. Strength calculation norms for equipment and pipelines of nuclear engine installations. — Moscow: Énergoatomizdat, 1989. — 525 p. [in Russian].