Abstract
The paper concerns 2D problem of an elastic thick-walled pipe with an initial thickness variation, subjected to internal pressure and mechanochemical corrosion. The inner perimeter of the pipe cross-section is elliptical, while the outer is circular. The linear Dolinskii corrosion kinetics model is used. In the general case, structural instability of initial boundary value problems with unknown evolving boundaries can cause the divergence of numerical procedures when modelling the processes under study. It is observed that the attempts to circumvent the divergence of numerical procedure can suppress the manifestation of mechanochemical effect and yield inaccurate results. Thus, it is necessary to find a compromise between competing computational processes. Calculations revealed that the variation of the initial pipe wall thickness within the acceptable pipe wall tolerance can noticeably accelerate the growth of stresses and, consequently, reduce the durability of the pipe. The applicability of analytical solutions for a perfect circular pipe with a reduced thickness, equal to the minimum thickness of the imperfect pipe, to the case under study is also discussed.
Highlights
Many pipelines are subjected to pressure and chemical exposure
The linear corrosion kinetics equation can be considered as an approximation of any other dependence
The outer surface is free. (II) The principal stress σ1 along the contour L is determined by solving the conventional boundary value problem stated in (I) by finite element method (FEM). (III) For a given time increment dt, the new shape of contour L is determined by Eq (3)
Summary
Many pipelines are subjected to pressure and chemical exposure. Simultaneous action of mechanical loads and aggressive environments can cause mechanochemical corrosion. The linear corrosion kinetics equation can be considered as an approximation of any other dependence. In cases of complex stress state, different authors used the von Mises stress, maximum normal stress, or mean stress as the equivalent stress in corrosion kinetics equations [3, 4, 5, 6, 7]. When the effect of the strain sign takes place [8, 9] and the principal stresses have different signs, additional experimental investigations are required. These situations can occur in pipes subjected to both internal and external pressure
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