Life prediction method suitable for various cyclic loads

A cyclic load and life prediction technology, applied in the fields of instrumentation, electrical digital data processing, informatics, etc., can solve the problem of lack of consideration of the variability of holding load stress, and achieve the effect of simple and easy operation and accurate cycle life prediction process.

Active Publication Date: 2020-07-17
NANJING UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The viscosity-based life prediction method lacks the consideration of the variability of the holding stress

Method used

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  • Life prediction method suitable for various cyclic loads
  • Life prediction method suitable for various cyclic loads
  • Life prediction method suitable for various cyclic loads

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] Table 1 is the test data of P92 steel at 625 °C, and the strain rate is 1×10 -3 . These include 5 sets of strain-controlled pure fatigue tests with strain amplitudes ranging from 0.5% to 1.6%, and 12 sets of stress-strain mixed-controlled creep fatigue tests. In order to further verify the life prediction ability of the model at different strain rates, a Zhang published a paper [Zhang SL, Xuan FZ. Interaction of cyclic softening and stress relaxation of 9–12% Crsteel under strain-controlled fatigue-creep condition: experimental and modeling. International Journal of Plasticity 2017; 98:45-64.] Seven sets of strain-controlled fatigue and creep fatigue data of P92 steel at 625°C with a strain rate of 2×10 -3 .

[0057] First calculate the fatigue dynamic viscosity v according to step S2 of the life prediction method of the present invention d-f and creep dynamic viscosity v d-c , and then calculate the total energy ΣW absorbed during the cycle according to step S3 of ...

Embodiment 2

[0062] The selected data are the test results of GH4169 alloy at 650°C in Wang Runzi’s doctoral thesis [Wang Runzi. Creep-fatigue life prediction model and application based on energy density dissipation criterion. Doctoral thesis. East China University of Science and Technology (2019)]. These include 4 sets of strain-controlled pure fatigue tests with strain amplitudes ranging from 1% to 2%, and 14 sets of strain-controlled creep fatigue tests.

[0063] First calculate the fatigue dynamic viscosity v according to step S2 of the life prediction method of the present invention d-f and creep dynamic viscosity v d-c , and then calculate the total energy ΣW absorbed during the cycle according to step S3 of the life prediction method of the present invention. Finally, a life prediction equation is established according to step S4 of the life prediction method of the present invention. Among them, according to the test data of the strain-controlled pure fatigue test, it is obtaine...

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Abstract

The invention discloses a life prediction method suitable for various cyclic loads, which comprises the following steps: carrying out any cyclic load test on a to-be-tested material, such as a strain-controlled pure fatigue test, a strain-controlled creep fatigue test or a stress-strain hybrid-controlled creep fatigue test; calculating fatigue dynamic viscosity and creep dynamic viscosity according to the test input parameters and the hysteresis curve of the half-life cycle; calculating the total energy absorbed in the cycle process according to the hysteresis curve of the half-life cycle; andfinally, establishing a life prediction equation by utilizing the relationship that the accumulated dynamic viscosity related to the fatigue dynamic viscosity and the creep dynamic viscosity is equalto the absorbed total energy, and predicting the cycle life of the to-be-tested material under the rest two cyclic load tests. According to the method, the cycle life under various cyclic loads can be simultaneously predicted by using the same group of parameters, and the method is widely applied to different materials to be tested.

Description

technical field [0001] The invention relates to the field of life prediction, in particular to a method for life prediction of different materials under multiple cyclic loads. Background technique [0002] Many core components serving at high temperatures in the electrical and aviation fields often suffer from complex creep, fatigue and creep-fatigue interaction damage. These components are subject to strain-controlled fatigue loads due to start-stop temperature variations, and subsequent stable operation is subject to stress-controlled creep loads. However, the strain-controlled creep fatigue load commonly used in laboratories cannot reflect such complex working conditions. At the same time, due to stress relaxation, it is difficult for the strain-controlled creep fatigue load to form a failure mode dominated by creep damage. However, this failure mode is The most common type of industrial equipment. Creep fatigue load controlled by stress-strain mixture, that is, strain ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F30/20G16C60/00G06F119/14G06F119/04
CPCG16C60/00Y02T90/00
Inventor 王小威张天宇姬云南巩建鸣姜勇张威
Owner NANJING UNIV OF TECH
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