Anchor chain fatigue life prediction method

Abstract

The invention discloses an anchor chain fatigue life prediction method, and belongs to the technical field of fatigue life. The method is realized through a fatigue crack propagation method and comprises the steps of pretreatment, iterative solution and crack propagation which can be realized by means of SESAM, ABAQUS and FRANC 3D platforms respectively, and the specific steps comprise S1 model modeling, S2 hydrodynamic analysis and S3 mooring analysis. S4, modeling of an anchor chain finite element model; S5, crack insertion and grid updating; S6, incremental calculation judgment; S7, termination condition inspection; the crack is described by two parameters of crack depth and crack length, and the shape of the updated crack is accurately calculated by using an ellipse formula; development from a mooring tension time history to crack propagation is achieved, the fatigue performance of the anchor chain under the real sea condition can be effectively represented, and the remaining life of the anchor chain can be accurately predicted.

Description

technical field [0001] The invention belongs to the technical field of fatigue life, and in particular relates to a method for predicting the fatigue life of an anchor chain. Background technique [0002] For the mooring system of offshore floating structures, the reciprocating motion of the structure and continuous wave load will cause the anchor chain to be under the alternating load all the time during the service period, which will lead to the occurrence and deterioration of fatigue damage. With the development of offshore development to the deep sea and the extensive application of floating structures, the fatigue damage of anchor chains has become increasingly prominent, and has been recognized as one of the most important failure modes of anchor chains by a large number of classification societies, institutions, and scholars. The initiation and propagation of fatigue cracks in the anchor chain will significantly reduce the fatigue strength and bearing capacity of the ...

AI Technical Summary

Problems solved by technology

[0004] (1) The S-N / T-N curve method cannot consider the initial defects introduced during the manufacture, transportation and installation of the anchor chain, and seriously overestimates the fatigue performance of the anchor chain;

[0005] (2) S-N / T-N cannot consider issues such as load sequence and material properties;

[0006] (3) It is impossible to accurately predict the life of the anchor chain based on the crack propagation path and crack morphology;

Anchor chains can withstand more than one million cyclic loads during their service life. If such a large number of cyclic loads are directly applied to iterative calculations, the workload is huge and the calculation efficiency is low, which is not conducive to the fast fatigue life of anchor chains based on fracture mechanics. predict;

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