A low-cycle creep-fatigue life evaluation method under high-temperature multi-axis spectral loading

Abstract

The invention relates to a low-cycle creep and fatigue life evaluation method under the conditions of high temperature and multiaxial spectrum load. The method comprises the following steps of reading a stress strain history in a multiaxial loading spectrum data block, working out equivalent strain, and finishing a loading history; repeatedly extracting by adopting a relative equivalent strain multi-axis counting method; working out all repeated fatigue damage by adopting a unified multiaxial fatigue damage life prediction model; accumulating the fatigue damage to work out the total fatigue damage; working out equivalent creep stress by utilizing the original loading history; working out creep damage Dc according to the equivalent creep stress and the stress history by combining a creep lasting equation; working out the total damage D caused by a multiaxial load spectrum block at the high temperature; and estimating the multiaxial creep and fatigue life. According to the method, the fatigue damage under the multiaxial stress and the creep damage under the multiaxial stress can be respectively calculated in the whole loading spectrum data block, the fatigue material constant at the room temperature is adopted in the calculation of the fatigue damage, and lasting equation material constant recommended by specification is adopted in the calculation of the creep damage; through experimental verification, the method has a good prediction effect.

Description

technical field [0001] The invention relates to the field of fatigue strength, in particular to a multi-axis block-loaded low-cycle creep-fatigue life evaluation method under high temperature conditions. Background technique [0002] High-temperature creep fatigue strength design is an important content in the strength design of high-temperature components such as aero-engines and gas turbines. The load forms of parts and equipment in actual service are complex and diverse, and it is impossible to completely reproduce the actual service load history in the design stage, and the use of load spectrum blocks to simulate the load of parts has become an indispensable means of fatigue strength design of parts , creep fatigue is an important reason for restricting high-temperature components such as aero-engines and gas turbines. Therefore, low-cycle multiaxial creep-fatigue damage estimation and life prediction under block loads have been widely used in the design of these high-te...

AI Technical Summary

Problems solved by technology

[0003] At present, high-temperature creep fatigue damage and life prediction models are mostly used in the fatigue and creep strength design under uniaxial stress, while the high-temperature components in actual service are often served under multi-axial loads, the traditional uniaxial fatigue and uniaxial creep The theory often cannot meet the needs of the strength design of these high-temperature components.

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