Parametric Construction Method of Numerical Model of Cylindrical Shell with Random Pitting

Abstract

The invention discloses a method for parametrically constructing a numerical model of a cylindrical shell with randomly distributed pitting corrosion. First, the dimensions of the cylindrical shell and pitting pits are parameterized in the finite element software, and the geometric model of the cylindrical shell is divided into uniform sizes. The geometric grid, and the corners of the geometric grid are used as the possible positions of pits; then random numbers are generated to determine the position and depth of pits, and each time a new pit is generated, it must be judged whether it is consistent with Existing corrosion pits overlap, if there is overlap, regenerate random numbers to determine the location of pits; use the geometric parameters of pits to construct a geometric model of pits on the cylindrical shell, and establish a random distribution of pits The overall geometric model of the cylindrical shell; finally, the overall geometric model is grouped, and the overall geometric model is divided into finite element grids, and the numerical model of the cylindrical shell with random distribution of pitting is constructed. The numerical model constructed by the present invention has universality and authenticity.

Description

Technical field [0001] The invention relates to a numerical model construction technology of a component subject to pit corrosion, in particular to a parameterized construction method of a numerical model of a cylindrical shell with random distribution of pit corrosion, which can simulate the random distribution of pit corrosion pits on a cylindrical shell and the random depth of wall thickness damage State, used to study the stress concentration problem of cylindrical shell structure caused by randomly distributed pitting damage, and reveal the law of pitting damage affecting the bearing capacity of the structure. Background technique [0002] The legs, subsea pipelines and other components of the pile-based platform have been in a corrosive marine environment for a long time. It is inevitable to weaken the bearing capacity of the components caused by corrosion. However, due to the complex corrosion mechanism, it reveals the degradation of the static and dynamic strength and fati...

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Problems solved by technology

[0003] In the study of the bearing capacity of pitting damage components, the API579-1 specification of the American Petroleum Institute proposed an empirical formula to calculate the remaining strength of metal pipelines in 8 standard pitting modes, but human factors have too much influence on determining the pitting mode

Chinese Patent Publication No. CN103558356A, titled "A Seamless Characterization Model for the Remaining Strength of Pitting Corrosion Metal Pipelines" proposes to use the proportion of pitting area m and remaining wall thickness ratio Rwt The two parameters characterize the pitting mode that includes and is between the 8 standard pittings, and introduce them into the API specification to calculate the remaining strength of the pitting pipeline, but it does not make essential innovations in the distribution mode of pitting , unable to reflect the influence of differences in pitting distribution patterns on the bearing capacity of members

The Chinese patent announcement number is CN203132482U, the name is "a pitting depth measuring instrument" and the Chinese patent publication number is CN103969472A, the name is "a kind of in-situ observation device and method of pitting formation process" and the literature respectively discloses the measurement The in-situ dynamic observation device and method for pitting depth and pitting formation process morphology features, the Chinese patent publication number CN102708588A discloses a three-dimensional reconstruction method for pitting damage morphology of metal flat plates, but these measuring instruments and methods are not Complex imaging equipment, sensors, advanced computing tools and other equipment and accessories must be used, and the testing process and methods are extremely complicated. At present, it can only solve the problem of model construction of specific pitting components, and cannot provide the necessary information for carrying out a large number of scientific researches. The mass computing model of

However, the numerical models of pitting components used in existing studies (only plates have been reported, and cylindrical shells have not been reported) can only be used to study the impact of pitting on components by uniformly distributing or constructing pitting on specified positions. The influence of the bearing capacity, the established numerical model is specific, lacks universality, cannot carry out a large number of theoretical research and analysis, and does not conform to the actual observed distribution of pitting corrosion

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