Universal method suitable for judging stress-strain hybrid creep-controlled fatigue damage state

Abstract

The invention discloses a universal method suitable for judging a stress-strain mixed creep-controlled fatigue damage state. The method comprises the following steps: firstly, carrying out multiple groups of different strain-controlled pure fatigue tests and creep tests at the same temperature; then determining the relationship between the strain amplitude and the service life and the relationship between the inelastic strain energy density and the inelastic strain energy density rate; then carrying out a plurality of groups of strain control and stress-strain mixed control creep fatigue tests; further determining fatigue damage of each week according to the strain amplitude, and determining creep damage of each week according to stress evolution or strain evolution during load holding; predicting the service life of the material under the creep fatigue load based on the damage; and finally, judging the damage state of the sample at any moment according to the accumulated fatigue and creep damage of the sample and a bilinear damage criterion specified by the American ASME III-NH standard. According to the invention, the service life of the material under strain control and mixed control creep fatigue loads can be well predicted, and the damage state of the sample at any moment can be judged.

Description

technical field [0001] The invention relates to the field of life prediction and damage assessment, in particular to a general method suitable for judging stress-strain mixed controlled creep fatigue damage state. Background technique [0002] In the fields of aviation and electric power, many key high-temperature core components are often subjected to complex creep, fatigue and creep-fatigue interaction damage. Usually, the temperature changes caused by frequent start-up and shutdown make these components under the strain-controlled fatigue load, while the constant internal pressure or centrifugal force during the continuous and stable operation of the equipment makes the high-temperature components bear the constant stress-controlled creep load. Therefore, the traditional strain-controlled creep fatigue test currently used in the laboratory is difficult to reflect the real and complex operating conditions of the above-mentioned high-temperature components. In addition, si...

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Problems solved by technology

However, unlike the traditional strain-controlled creep fatigue loading, under the stress-strain mixed controlled creep fatigue loading, the creep deformation during the stress holding period is significant and the strain amplitude changes continuously with the cycle, which will inevitably affect the existing Therefore, it is necessary to invent a general method suitable for judging the stress-strain mixed-controlled creep fatigue damage state, so as to meet the identification of creep fatigue damage state under different loads.

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