PSI - Issue 40

N.A. Makhutov et al. / Procedia Structural Integrity 40 (2022) 275–282 N. A. Makhutov, I. V. Makarenko / Structural Integrity Procedia 00 (2022) 000 – 000

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1990, Panasyuk V.V., 1974) it is possible to write the criterion equation of limiting fracture functions for both the weld W f  and the fusion region L f  .     i cw cL W L ,T ,t , , f , f       (6) The modern concept of forecasting the safety and resource of structures, according to the criterion of fracture 2 0 )}] / [1 {(1 1/ ) /(1 c c c          , also takes into account the kinetics of crack growth, from initial 0  to critical dimensions c  . On the basis of the basic equation of development of low-cycle destruction, the results of research and work (RD 50 – 200 -81, 1982, Makarov. I.I., Grudzinsky B.V., 1975, Makhutov N. A., 2005, Andreykiv A.E., 1982, Cherepanov G.P., 1976, Makhutov, N. A.,. Makarenko, I. V., 1986, , Makhutov N. A., Makarenko I. V, and. Makarenko L. V., 2004, Makhutov N.A., Makarenko I.V., Makarenko L.V., 2019, Panasyuk V.V., 1990, Panasyuk V.V., 1974, Makhutov N.A., Makarenko I.V., Makarenko L.V., 2004, ANSYS, 2010), we will write down equation (7) regulating the kinetics of the defect during the operation of the equipment, taking into account the physical and mechanical heterogeneity of the material of a wide class of austenitic stainless steel cyclically stable steels. Where:   is a settlement corner of an inclination of a modeled surface of fracture to the first main stress and   i e is the range of intensity relative elastic-plastic strain in a concrete local volume of metal on its contour. Factors а 1 and а 2 are the characteristics of the material. In (7) Ti i i e e e /      is the range of intensity local relative elastic plastic strain, Ti  is the local yield stress and bi  is the local ultimate strength. Moreover,   i e are obtained taking into account the mathematical model of the spatial distribution of the local yield strength in the welded joint Ti  and the local tensile strength bi  , as a function of the connection thickness and temperature (Makhutov N.A., Makarenko I.V., Makarenko L.V., 2004). The numerical experiment to determine the fields of elastic plastic strain by the finite element method was performed on the basis of the ANSYS software complex using a specially developed macro written in the APDL language and the use of three-dimensional quadratic interface elements with 16 nodes (ANSYS, 2010). For the analysis of deformation anisotropy, a mathematical model of the distribution of the mechanical properties of the material of the studied welded joints for a wide austenitic-stainless steel class (Makhutov N.A., Makarenko I.V., Makarenko L.V., 2004) is used, which makes it possible to determine the volumetric fields of their distribution.     f x y z T t Ti bi ( , , ), , ,    (8)  N 0      )(  i Ti bi ijk dN a e a l 2 2 2 1 ) sin (    . (7)

Here x, y, z, are the coordinates of the point of the welded joint. 5. Conclusions

On the basis of experimental, numerical and analytical results, functional dependences of such crack resistance characteristics as critical opening of cracks in the temperature range from 300 K to 77 K and thickness of welded joints of the steels under study were obtained. The results of the research can be used in the refined assessment of the strength and crack resistance of equipment elements, taking into account the anisotropy of properties in the welded joints of the steel under study when calculating the critical dimensions of the initial operational defects on the basis of deformation linear and nonlinear crack resistance criteria.