Long-term fracture of a composite rod under tension in creep conditions in the presence of an active medium

The stress-strain state and long-term strength of a composite tensile rod under creep conditions in the presence of an active environment are considered. The structure consists of a central rod and two symmetrically arranged rods relative to the central one, connected with perfect adhesion. The creep of each of the three parts of the rod is described by a power rheological model with different parameter values. To determine the time to failure, a kinetic equation is used to describe damage accumulation during creep, which has the same structure for all rods. The influence of the active environment is determined by the diffusion penetration of its elements into the rod material. An approximate method of solving the diffusion equation is used, based on introducing a diffusion front. The distribution of stresses over time is analyzed considering the penetration of the active environment into different parts of the rod with varying diffusion coefficients. A parametric analysis is carried out on the influence of stresses and parameters of the rheological models of the composite rod materials on the stress-strain state and long-term strength as elements of the rod system and the three-rod system as a whole. The relationship between time to failure and the ratio of diffusion coefficients of the active environment in the elements of the composite rod is determined.