Multistage variable-temperature variable-load creep life evaluation method
An evaluation method and technology of creep life, which is applied in the direction of measuring devices, instruments, scientific instruments, etc., can solve the problems of inability to explain the influence of creep load sequence and interaction, inaccurate remaining life prediction results, limited applicability, etc.
Active Publication Date: 2021-04-30
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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Problems solved by technology
The most widely used residual life damage assessment method is the linear damage accumulation model, but this method will lead to inaccurate residual life prediction results in most cases, because the method cannot account for the effects of creep load sequence and interaction
[0003] In recent years, researchers have also developed several nonlinear damage accumulation methods to evaluate the remaining life, but these methods strongly rely on the fitting of experimental data in a certain temperature stress range to obtain relevant parameters. Intrinsic accuracy, difficult to extrapolate to a wide stress-temperature range
The current damage accumulation method for evaluating remaining life generally has limited applicability and is not generalizable
Method used
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[0095] In this example, the method for evaluating the remaining life of creep under variable temperature and load of the present invention is applied to the evaluation of the remaining life of Al-99.98 material under variable load and creep at 225°C, including the following steps:
[0096] (1) Carry out the high temperature tensile test of Al-99.98 material at 225°C to obtain the tensile strength σ at 225°C b .
[0097] (2) At 225°C, the stress is σ 1 and σ 2 The high temperature creep test, the corresponding creep rupture time is obtained, denoted as t f1 and t f2 .
[0098] (3) The variable load creep test is carried out at 225°C, and the stress is σ 1 lower creep t 1 time, followed by stress σ 2 lower creep t 2 time until creep rupture occurs. Multiple sets of different t 1 Time value of variable load creep test, record the corresponding t 2 value. The test data are shown in Table 1.
[0099] Table 1 Al-99.98 creep test data under variable load at 225°C
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The invention discloses a multistage variable-temperature variable-load creep life evaluation method which comprises the steps of obtaining tensile strength [sigma]bi corresponding to different temperatures Ti through a material high-temperature tensile test, where i is equal to 1, 2, 3... N; obtaining corresponding creep rupture time tfi under different stress temperature ([sigma]i, Ti) combinations through a material high-temperature creep test; establishing a linear relationship between the creep rupture time tf and the stress temperature (sigma, T); establishing a multistage variable-temperature variable-load creep load nonlinear damage accumulation model; and evaluating the creep residual life according to the multistage variable-temperature variable-load creep load nonlinear damage accumulation model established in the step 4. The method for evaluating the residual life of the creep load can be suitable for variable-temperature variable-load creep conditions in a wide stress temperature range, the result precision is high, and the extrapolation capacity is high.
Description
technical field [0001] The invention relates to a creep load remaining life evaluation method, in particular to a multi-stage variable temperature and variable load creep remaining life evaluation method. Background technique [0002] Estimating the remaining life of power plant materials, nuclear reactors, and rotor components at elevated temperatures is very difficult, especially when stress-temperature conditions vary significantly. High temperature damage is related to the loading history of the load, so it is very important to accurately evaluate the remaining life of the material when the loading conditions change. At present, the most widely used residual life damage assessment method is the linear damage accumulation model, but this method will lead to inaccurate residual life prediction results in most cases, because the method cannot explain the influence of creep load sequence and interaction. [0003] In recent years, researchers have also developed several nonl...
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IPC IPC(8): G01N3/08G01N3/18
CPCG01N3/08G01N3/18G01N2203/0017G01N2203/0071G01N2203/0067G01N2203/0222G01N2203/0226
Inventor 孙志刚赵旭牛序铭宋迎东彭秋洪常亚宁
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS