Test analysis method for bolt connecting piece fatigue crack expanding

A technology of fatigue crack growth and analysis method, which is applied in the field of experimental analysis of fatigue crack growth life prediction, and can solve problems such as unseen experimental analysis research methods and crack growth models

Inactive Publication Date: 2011-04-20
AIR FORCE UNIV PLA
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For the fatigue crack growth analysis of symmetrical and asymmetric straight and oblique lug connectors under the action of straight and oblique loads, there is no systematic test analysis and research method at home and abroad, and there is no corresponding crack growth model

Method used

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  • Test analysis method for bolt connecting piece fatigue crack expanding
  • Test analysis method for bolt connecting piece fatigue crack expanding
  • Test analysis method for bolt connecting piece fatigue crack expanding

Examples

Experimental program
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Embodiment Construction

[0098] The present invention will now be further described in conjunction with the embodiments and accompanying drawings:

[0099] Test piece: the case where the straight lug is subjected to axial tensile load.

[0100] The ear piece material is 30CrMnSiA steel, with a thickness of 6.7, a total of 4 pieces. Size as shown? shown.

[0101] Step 1 Test the installation of the lugs:

[0102] Step (a): machining a penetrating notch with a depth of 1 mm along the radial direction at the edge of the hole at one end of the ear piece, the direction of which is perpendicular to the load direction; smooth the surface of the ear piece at the end of the notch along the load direction;

[0103] Step (b): connect the notch end of the lug with the fork ear of the crack end fixture (1) through bolts, and connect the other end with the fork ear of the crack-free end fixture (2;

[0104] Step (c): Use the lower chuck of the testing machine to clamp the end of the crack-end fixture (1, and th...

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Abstract

The invention relates to a test analysis method for lug connecting piece fatigue crack expanding, which is technically characterized by installing a test lug on a testing machine; then loading and producing fatigue crack on the lug; adopting a stress intensity factor comprising a straight lug pulled and loaded lengthwise, the straight lug loaded obliquely smaller than 45 degrees, a symmetrical oblique lug pulled and loaded lengthwise, the symmetrical oblique lug loaded obliquely smaller than 45 degrees, an asymmetrical oblique lug pulled and loaded lengthwise and the asymmetrical oblique lug loaded obliquely smaller than 45 degrees to the corresponding delta K; taking a slope factor of 1g(da / dN)-1g(delta K) line as a constant n in the Paris formula, an intercept of a straight line and axis y as a constant C in the Paris formula, and obtaining the Paris formula when the stress ratio is R; and the lug fatigue crack expanding life NC is estimated according to the obtained Paris formula. The invention has the advantages that the applicability is wide, and the test analytical method plays a directive role in researching the lug hole edge fatigue crack expanding properties under various pulling and loading conditions.

Description

technical field [0001] The invention relates to a test and analysis method for fatigue crack propagation life prediction, in particular to a test and analysis method for fatigue crack growth of a lug connector, which provides the expression of stress intensity factors of various typical lug connectors under loads in different directions and a set of fixtures for fatigue testing of lug connectors. Background technique [0002] The lug structure is widely used in various mechanical equipment. At present, in terms of damage tolerance design analysis, only the case where the straight lug is subjected to longitudinal tensile load can only be solved. For the case where the lug connector is subjected to an oblique load, there is no suitable model method to determine the crack propagation characteristics and residual strength requirements. It needs to be studied through theoretical and experimental analysis. The corresponding fixture design is the basis of the experimental analysis...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/08
Inventor 何宇廷伍黎明安涛王卓健周瑞祥张登成郭基联
Owner AIR FORCE UNIV PLA
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