Terletska Z. Resource assessment of structure elements with surface cracks under variable loading and corrosive environment

The thesis is dedicated to questions of determination of residual life of long-time functioning elements of structures. An energy approach for determination of durability of structure elements with surface cracks, subjected to variable loading, and under influence of aggressive corrosive environment is proposed. The approach is based on created by the author's mathematical models for determination of physicochemical fields near a corrosion crack contour and also for determination of the crack kinetics and the period of its critical growth. A mathematical model of loading of an underground oil pipeline in field environment is created. The model takes into account longitudinal tension - compression caused by clamping and two-frequency cyclic pressure loading. High frequency hydraulic oil pressure oscillations correspond to turbulence caused by pumping of oil. Low frequency pressure change is caused by breaks in pumping. Based on this model and above mentioned energy approach, the residual life of "Kremenchuk-Kherson" oil pipeline was calculated.