Metal structure fatigue crack propagation life prediction method based on material R curve

A technology of fatigue crack growth and metal structure, applied in the direction of analyzing materials, measuring devices, instruments, etc.

Inactive Publication Date: 2012-11-14
AIR FORCE UNIV PLA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, as we all know, the R curve is not only related to the material properties, but also related to the thickness of the sample. Obtaining the crack growth resistance curve completely through experiments consumes a lot of resources and is not very convenient to apply.

Method used

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  • Metal structure fatigue crack propagation life prediction method based on material R curve
  • Metal structure fatigue crack propagation life prediction method based on material R curve
  • Metal structure fatigue crack propagation life prediction method based on material R curve

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Experimental program
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Embodiment Construction

[0064] Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

[0065] Step 1 Determination of material P-v curve:

[0066] The material of the test piece is 7050-T7410 aluminum alloy plate, and the size design is as follows: Image 6 As shown, the sample thickness is 6.7mm. The test determination of the material P-v curve meets the requirements of the navigation mark HB5261-83 "Metal Sheet KR Curve Test Method". The P-v curve obtained from the test is shown in Figure 7 .

[0067] Step 2 Fitting of material R curve expression:

[0068] Step (a), using the flexibility method to calculate the crack half-length a:

[0069] According to the "ASTM E561-08 Standard Test Method for K-R Curve Determination" standard, the formula for calculating the flexibility of CCT samples is:

[0070] 2 a W = 1.2235 x - ...

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Abstract

The invention relates to a metal structure fatigue crack propagation life prediction method based on a material R curve and is technically characterized in that based on the material crack propagation resistance curve (R curve) and crack propagation energy release rate theory, the effective energy release rate under fatigue load is defined as energy for crack propagation after a fatigue crack is completely expanded, the energy is equal to the consumed energy characterized by the crack propagation resistance curve in the same loading cycle, so that a fatigue crack propagation life prediction model capable of reflecting the physical nature of the crack propagation is proposed. By adopting the model, the crack propagation amount in each loading cycle can be calculated, the crack propagation life can be predicated through the accumulative calculation of the crack propagation amount, and the metal structure fatigue crack propagation life prediction method is suitable for predicting the fatigue crack propagation life of a metal structure in engineering and provides a reference method for tolerance evaluation of a structural damage.

Description

technical field [0001] The invention relates to a fatigue crack growth life prediction method for metal structures, in particular to a metal structure fatigue crack growth life prediction model based on material R curves. Background technique [0002] Typical major equipment in machinery, transportation and energy industries have been in service for many years. Reliable prediction of the life of cracked components is an important way to effectively improve the service performance of equipment and control the occurrence of failure accidents, because premature decommissioning means huge waste and economic loss, continued operation requires a reasonable life forecast to ensure safety. Metal materials are widely used in aviation equipment as the main load-bearing parts of the structure. This is particularly evident in the various types of main combat aircraft currently in service in my country. Even as the most advanced fighter F-22 in the world, the amount of composite materia...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/60G01N3/00
Inventor 何宇廷伍黎明崔荣洪张海威丁华邵青张腾
Owner AIR FORCE UNIV PLA
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