Austenitic stainless steel pipeline nonlinear fatigue damage life evaluation processing method

Abstract

The invention discloses an austenitic stainless steel pipeline nonlinear fatigue damage life evaluation processing method. The method comprises the following steps: S1, defining of a fatigue damage model of a to-be-evaluated pipeline material, S2, fatigue damage correlation analysis: obtaining the life corresponding to the stress of each loading step from the SN curve of the pipeline material, determining the damage Di of the loading step sigma i according to the fatigue damage model in the step S1, and determining the equivalent operation times n (i+1), eff, the total cycle times of the loading step i+1 and the fatigue damage of the corresponding loading step i+1 under the stress sigma i+1 loading condition, S3, calculation of fatigue damage correlation analysis under different load stepsto obtain equivalent operation times, accumulation and calculation of fatigue damage until the damage is equal to 1, and statistical calculation of fatigue life. The invention provides a nonlinear damage model, provides a stress fatigue life prediction method under different load step loading conditions, and provides technical support for accurate evaluation of the fatigue life of a pipeline material.

Description

technical field [0001] The invention relates to the field of on-line safety monitoring of nuclear power plant equipment, in particular to a method for evaluating and processing the life of nonlinear fatigue damage of austenitic stainless steel pipelines. Background technique [0002] Austenitic stainless steel pipes are widely used in nuclear power plants, and fatigue damage is one of the important aging mechanisms for nuclear power pipe failures. Since fatigue damage accumulates with increasing number of cycles, cumulative fatigue damage analysis plays an important role in the load history of the structure. The core problem of cumulative fatigue damage analysis is how to establish the random fatigue cumulative damage criterion, the purpose of which is to use this criterion to predict the fatigue damage under the action of the load history under the given conditions of constant amplitude fatigue test data and random fatigue load history. The damage accumulation of life can ...

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Problems solved by technology

[0003] At this stage, the linear damage law (LDR) proposed by Miner is widely used in the industry. The main defect of the LDR method is that it has nothing to do with the load level and load sequence, and it lacks the description of the relationship between loads.

However, studies have shown that the loading sequence has a significant impact on the fatigue life, especially when the cycle of a small load range is carried out after a large load range is loaded, the life cumulative damage value of some materials is not always equal to 1, and the results predicted by the LDR method are sometimes biased. in danger

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