A Fatigue Life Prediction Method Based on Fatigue Crack Growth

Abstract

This paper discloses a fatigue life prediction method based on fatigue crack growth, which belongs to the technical field of fatigue life prediction. The method includes: pre-processing, iterative solution and crack propagation, which can be completed with the help of SESAM, ABAQUS and FRANC 3D platforms respectively. The specific steps include: S1 model modeling, S2 hydrodynamic analysis, S3 structural strength analysis, S4 three-dimensional crack propagation area construction Die, S5 crack insertion and grid update, S6 fatigue characteristic characterization, S7 incremental calculation judgment, S8 termination condition verification, S9 service life statistics. The invention characterizes the fatigue performance of the structure through the calculation of the stress intensity factor transfer function; it introduces the concept of equivalent damage accumulation rate for the first time, and successfully applies it to the simplification of irregular waves; it realizes the transformation from hydrodynamic force to structural strength and even cracks Inheritance and transmission of the internal force state of the structure during the expansion process; based on the sub-model and multi-scale model technology, the coupling analysis of the real-scale structure and the crack growth area was successfully carried out.

Description

A Fatigue Life Prediction Method Based on Fatigue Crack Growth technical field The invention belongs to the technical field of fatigue life prediction, be specifically related to a kind of fatigue life based on fatigue crack propagation Fate prediction method. Background technique For marine structures in service, the continuous uninterrupted wave force will cause the structure to be in alternating load for a long time. Under the action of load, it will inevitably lead to the generation and deterioration of fatigue. With the large-scale marine structures and high-strength steel in Widely used in construction, fatigue damage has become increasingly prominent, and it has gradually been recognized by the surveyors of various classification societies as the most important failure. one of the effective modes. The presence and propagation of fatigue cracks are often extremely destructive and can lead to reduced fatigue strength and load-carrying capacity. drop, even po...

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Problems solved by technology

The introduction and development of the S-N curve method has played a very positive role in the improvement of traditional structural types and the reduction of accident rates, but its inherent theoretical defects have greatly limited its further application potential, such as:

[0004] (1) The S-N curve method is not suitable for the assessment of the remaining life of the aging structure with existing defects;

[0005] (2) Since there is no unified failure criterion, the prediction results are highly discrete;

[0006] (3) The effects of loading sequence and material properties cannot be taken into account;

[0007] (4) Can not be accurately predicted based on the crack propagation path and crack morphology

Coupling analysis between models of different magnitudes is also a huge challenge for the application of fracture mechanics

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