Delayed fracture of plates under creep condition in unsteady complex stress state in the presence of aggressive medium

Simulation of Long-Term Destruction of Typical Structural Elements Influenced By an Active Medium and Unsteady Loading

“…To analyze the process of diffusion of the active medium into the material, an approximate method is proposed for solving the diffusion equation based on the introduction of a diffusion front propagating from the surface of a plate or shell (hereinafter, the plate and the shell are designated as a typical element) [2,5,6]. This approach allows one to divide the entire cross section of a typical element into perturbed (where the medium has already penetrated into the material) and unperturbed regions (where there is no penetration of the medium yet) and then track the movement of the boundary between these regions in time.…”

“…The effect of the active medium was taken into account by introducing into the linear fractional [6,8]…”

“…, , z r θ are the principal axes of the stressstrain state. Since the stress state in the considered shell is flat and homogeneous, the kinetic equations taking into account the vector parameter of damage Ω [12,13] will be taken in the following form [6]):…”

“…Similar hypotheses and approaches (linear fractional model, an approximate method for solving the diffusion equation, scalar and vector parameters of damage) were applied to study the long-term destruction of a plate in an active medium. In accordance with the formulation of the problem, the plate is in a non-stationary complex stress state under the piecewise constant action of bending moments 1 M and 2 M , distributed along the mutually orthogonal edges of the plate [6]. The table 1 shows the results of calculating the times to fracture * t ω and * t Ω using the scalar and vector damage parameters, respectively, for different values ICMIE 111-7…”

“…The influence of the active medium can be determined both by the diffusion penetration of its elements into the material, and by the corrosive effect, which is inherent in active chemical processes of interaction of working and / or environment with materials of structural elements. Of particular importance is the study of such processes during high-temperature longterm loading of metallic materials and structures under creep conditions [1][2][3][4][5][6][7].…”