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

280

(a)

(b)

(

, , ) t T

f

f

W  



(

, , ) t T

f

f

L  



Fig. 4. (a) Limit surfaces of fracture functions: for weld

; (b) for metal alloying zone

;

CW

CL

and experimental points.

Critical crack openings for both the weld and the fusion zone are shown by experimental points in Fig. 4. So at a thickness of 70 mm and a temperature of 77 K for a weld δ CW = 0.8 mm, and at T = 300 K, δ CW = 3.3 mm The critical crack opening surfaces described by equations (4) and (5) as functions of temperature and thickness can be used to estimate the limiting state of cracked structures. The calculated values of crack opening in the structure are determined by the equations of nonlinear fracture mechanics (the works of Panasyuk V.V. and Andreykiv A.E.) for comparison with the crack openings determined in the experiment. From Fig.4a it follows that the critical opening of cracks in the welded joint at room temperature (line-ABC) increases with increasing thicknesses, followed by a decrease at large thicknesses of 0.10 m (section-CD). Disclosure decreases with a decrease in temperature to cryogenic. At T = 77K with a decrease in thickness (section DEF) the opening increases. And with an increase in temperature at small thicknesses of 0.025 m (line-FGA), there is an increase in critical crack opening. With increasing temperature, there is an increase in the critical opening of cracks, both for WS and for LS and the weld metal is more plastic. With an increase in the thickness of the joint, , allow analyzing the criterion fracture of inhomogeneous metallic materials. As a result, for the spatial elastic plastic loading of bodies with cracks on the basis of the strain criterion of fracture (Makhutov N. A., 2005, Makhutov N. A., Makarenko I. V, and. Makarenko L. V., 2004, Makhutov N.A., Makarenko I.V., Makarenko L.V.,2019) and the criterion k  - model (Panasyuk V.V., there is a decrease in plasticity for the seam material. The given equations, for critical opening of cracks ( , ) f t T Cj    