Issue 41

A.S. Chernyatin et alii, Frattura ed Integrità Strutturale, 41 (2017) 293-298; DOI: 10.3221/IGF-ESIS.41.39 298 negative). Strong influence of the RS on the SIF of the crack A is not observing. However, the residual stress acts on SIF values in more manner then on T-stress values of crack A. The distribution of fracture parameters and the effect of the RS for the crack B are more complex. The SIF has an almost constant value along the crack front, whereas T-stresses have values great varied. It should be noted that there is the influence of the crack A on the state of the crack. C ONCLUSIONS he effect of residual stresses on surface fatigue crack propagation and fracture mechanics parameters of intersecting orthogonal cracks in the pipeline is discussed. The method on the basis of modified Foreman equation and program software for realization of gradual remeshing of the finite element model during incremental crack growth is developed. It is implemented for an numerical analysis of fatigue surface crack propagation in welded area of pipeline taking into account nonlinear distributed residual stress and constraint effect in the crack tip employing two-parameter fracture mechanics. In spite of the fact that the residual stress and the nonsingular T-stress have a significant influence on the crack growth rate. Final configuration of the crack front is close to the semi-elliptical configuration. Mutual influence of intersecting surface cracks and biaxiality effects on the nonsingular parameters T xx and T zz is observed. At the same time, their effect on the stress intensity factor is negligible. A CKNOWLEDGMENTS he authors acknowledge the support of the Russian Science Foundation (Project N 14-19-00383). R EFERENCES [1] Zhao, C.Y., Huang, P.Y., Zhou, H., Zheng, X.H., Numerical analysis of K I of semi-elliptical surface crack in steel structure strengthened with FRP under tensile load, J. App. Mech. Mat., 137 (2012) 42–49. [2] Roychowdhury, S., Dodds, R.H., Three-dimensional effects on fatigue crack closure in the small scale yielding regime - a finite element study, J. Fat. Fract. Eng. Mat. Struct., 8 (2003) 663–673. [3] Hamam, R., Pommier, S., Bumbieler, F. Mode I fatigue crack growth under biaxial loading, Int. J. Fatigue, 27 (2005) 1342–1346. [4] Hoshide, T, Tanaka, K., Stress-ratio effect of fatigue crack propagation in a biaxial stress field, J. Fat. Fract. Eng. Mat. Struct., 4 (1981) 355–366. [5] Forman, R. G., Study of fatigue crack initiation from flaws using fracture mechanics theory, J. Eng. Fract. Mech., 2 (1972) 333–345. [6] Chen, Y.Z., Evaluation of T-stresses in multiple crack problems of finite plate, J. Fat. Fract. Eng. Mat. Struct., 35 (2012) 173–184. [7] Razumovskii, I.A., Chernyatin, A.S., Experimental numerical method of loading estimation for structures with surface cracks, J. Machinery Manufacture and Reliability, 38-3 (2009) 247–253. [8] Williams, M.L., On the stress distribution at the base of a stationary crack, J. Appl. Mech., 24 (1957) 109–114. [9] Nakamura, T., Parks, D.M., Determination of elastic T-stress along three-dimensional crack front an interaction integral, Int. J. Solid and Struct., 29 (1992) 1597–1611. T T