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

•The decision of diffusion equation is based on the introduction of a diffusion front.•The time to fracture of the plate is determined using a fractional linear creep model.•The times to fracture while using scalar and vector damage parameters are compared. Delayed fracture of bended rectangular plate is researched under creep condition in unsteady complex stress state considering the influence of the ambient medium. Using Rabotnov's kinetic theory, time to fracture of such plate is determined during sequential bending in different planes. Piecewise constant dependence of the bending moment direction and level on time is considered. The time to fracture of the plate is determined using a linear fractional creep model. The effect of the ambient medium on the creep and the creep rupture of the plate is attributed to diffusive penetration of the ambient medium elements into the material of the plate. An approximate method based on the introduction of a diffusion front is used to evaluate the diffusion process rate. The ambient medium effect is taken into consideration by introducing the function of cumulative average concentration into the constitutive and kinetic linear fractional equations. The times to fracture for the scalar and vector damage parameters are compared.