A method and model for describing three stages of creep deformation of high temperature materials

Abstract

The invention discloses a method and a model for describing the three stages of creep deformation of high-temperature materials. The steps of the method are: (1) Obtain the engineering creep deformation-time curve of the material through tests, and convert it into real creep strain -time curve; (2) normalize the true creep strain-time curve; (3) express the parameters k, η, and α in the creep model as functions of stress and temperature; (4) simulate (5) Embed the creep model into the finite element software to realize the creep analysis of the actual structure. The present invention can well describe the phenomenon that the creep rate gradually decreases and tends to be stable due to the movement change of dislocations in the first stage and the second stage of the material through the parameters k, η, and α. In addition, the fracture life The normalized time term can reflect microscopic damage such as creep voids and cracks, and thus characterize the phenomenon that the creep rate increases rapidly in the third stage of creep.

Description

technical field [0001] The invention relates to a method and a model capable of completely describing three stages of creep deformation of high-temperature materials, belonging to the technical field of high-temperature structural strength. Background technique [0002] Creep usually refers to the phenomenon that the deformation increases with time under the condition of constant temperature and load / stress. Its main feature is that when the temperature of the structure reaches a certain level, even if the internal stress is much smaller than the yield strength of the material, it can still produce obvious creep. The hot-end parts of aero-engines, especially the rotating parts, are subjected to high temperature and high stress, and obvious creep phenomenon will occur during use. [0003] Currently commonly used creep models include time hardening model and strain hardening model, but these models can only describe the first stage or the first two stages of creep. However, ...

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Problems solved by technology

[0004] In order to develop a creep model that can better reflect the physical process of creep and facilitate engineering applications, solve the problem that the built-in models in the current commercial finite element software cannot describe the three stages of creep, so that the model can describe the creep deformation The overall process can reflect the microscopic physical process of creep. The purpose of this invention is to provide a method and model for describing the three stages of creep deformation of high-temperature materials.

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