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 three stages of creep deformation of high-temperature materials. The steps of the method are as follows: (1) obtaining an engineering creepdeformation-time curve of the materials through tests, and converting the curve into a real creep strain-time curve; (2) normalizing the real creep strain-time curve. (3) expressing the parameters k,eta, alpha in the creep model as the function of stress and temperature; (4) fitting parameters of creep model with experimental data; (5) embedding the creep model into the finite element software torealize the creep analysis of the actual structure. In accordance with that present invention, eta, alpha can well describe the phenomenon that the creep rate decreases gradually and tends to be stable due to the movement of dislocations in the first and second stages of creep, In addition, the normalized time term of fracture life can reflect the microscopic damage such as creep voids and cracks, so as to characterize the phenomenon of rapid increase of creep rate 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, and belongs 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 conditions 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. Howeve...

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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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