Dependence of Creep-Rupture Lifetime for Rods under Tension in an Aggressive Environment on the Shape of a Single-Cell Cross-Section

Resumo

The long-term strength of rods under tension in an aggressive environment is investigated. We consider rods of various shapes of a single-cell cross-section (circle, square, and rectangles with different aspect ratios), provided that the areas of these cross-sections are equal. To determine the level of inclusions from aggressive environment into the rod at different time moments, approximate diffusion equations based on the motion of diffusion fronts from the rod surface are used. The high accuracy of the obtained approximation is shown. To assess the influence of an aggressive environment on long-term strength, the Yu. N. Rabotnov kinetic theory with two structural parameters (material damage and concentration of environment elements in the rod material) is used. The dependence of the time to rupture for the rods with various cross-section shapes under the same level of tensile stress is obtained. It is shown that the time to rupture for a rod with square cross-section under the indicated conditions exceeds the time to rupture for a rod with circular cross-section. In the case of rods with the same cross-section shape, the relation of the cross-section perimeter to time to rupture for the rod is considered. The minimum time to rupture for the considered rods is observed for rods of rectangular cross-section with the smallest thickness