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A Fatigue Life Design Method for Aircraft Bolts

A design method and fatigue life technology, applied in the direction of calculation, special data processing applications, instruments, etc., can solve the problem of not considering the influence of bolt fatigue life, and achieve the effect of convenient calculation process, clear analysis steps and correct theoretical basis

Active Publication Date: 2016-06-01
XIAN AIRCRAFT DESIGN INST OF AVIATION IND OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when this detailed fatigue rating DFR calculation method analyzes the life of bolts, it only considers the influence of tensile stress on fatigue life for tension bolts, and does not consider the influence of shear load on fatigue life of bolts.

Method used

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  • A Fatigue Life Design Method for Aircraft Bolts
  • A Fatigue Life Design Method for Aircraft Bolts
  • A Fatigue Life Design Method for Aircraft Bolts

Examples

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Comparison scheme
Effect test

Embodiment 1

[0036] A fatigue life design method for aircraft bolts, comprising the following steps:

[0037] Known: bolt material is medium-strength steel, bolt diameter D=20mm, bolt heat treatment σ b It is 1103MPa. Target life flight times N m =10000, fatigue reliability factor FRF=2.

[0038] Step 1. Using finite element software, determine the tensile stress σ of the bolt under each peak and trough in the aircraft load spectrum: Among them, F is the axial load borne by the bolt, and D is the diameter of the bolt;

[0039] Step 2. Using finite element software, determine the shear stress τ of the bolt under each peak and trough in the aircraft load spectrum: ; Among them, Q is the shear load borne by the bolt, and D is the diameter of the bolt;

[0040] Step 3. Using the fourth theory of strength, determine the equivalent tensile stress σ of the bolt under each peak and trough in the aircraft load spectrum req : Among them, σ is the bolt tensile stress, τ is the bolt shear st...

Embodiment 2

[0051] A fatigue life design method for aircraft bolts, comprising the following steps:

[0052] Known: Bolt material is medium-strength steel, bolt diameter D=18mm, bolt heat treatment σ b It is 1103MPa. Target life flight times N m =10000, fatigue reliability factor FRF=2.

[0053] Step 1. Using finite element software, determine the tensile stress σ of the bolt under each peak and trough in the aircraft load spectrum: Among them, F is the axial load borne by the bolt, and D is the diameter of the bolt;

[0054] Step 2. Using finite element software, determine the shear stress τ of the bolt under each peak and trough in the aircraft load spectrum: Among them, Q is the shear load borne by the bolt, and D is the diameter of the bolt;

[0055] Step 3. Using the fourth theory of strength, determine the equivalent tensile stress σ of the bolt under each peak and trough in the aircraft load spectrum req : Among them, σ is the bolt tensile stress, τ is the bolt shear stre...

Embodiment 3

[0075] A fatigue life design method for aircraft bolts, comprising the following steps:

[0076] Known: bolt material is titanium alloy, bolt diameter D=18mm, bolt heat treatment σ b It is 1103MPa. Target life flight times N m =10000, fatigue reliability factor FRF=2.

[0077] Step 1. Using finite element software, determine the tensile stress σ of the bolt under each peak and trough in the aircraft load spectrum: Among them, F is the axial load borne by the bolt, and D is the diameter of the bolt;

[0078] Step 2. Using finite element software, determine the shear stress τ of the bolt under each peak and trough in the aircraft load spectrum: Among them, Q is the shear load borne by the bolt, and D is the diameter of the bolt;

[0079]Step 3. Using the fourth theory of strength, determine the equivalent tensile stress σ of the bolt under each peak and trough in the aircraft load spectrum req : Among them, σ is the bolt tensile stress, τ is the bolt shear stress;

[...

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Abstract

The invention belongs to the technical field of design of aircrafts, and relates to a method for designing the fatigue life of aircraft bolts. The method for designing the fatigue life of the aircraft bolts is provided according to the stress characteristics of the bolts and from the field of researching of fatigue damage tolerance. The method for designing the fatigue life of the aircraft bolts is correct in used theoretical basis and clear and simple in analyzing step, and computer automatic iterative computations are convenient to carry out in the computing process. The method for designing the fatigue life of the aircraft bolts solves the problem that the influences on the fatigue life of the bolts by tensile stress and shearing stress need to be taken into consideration when the fatigue life of the bolts is designed. According to the method for designing the fatigue life of the aircraft bolts, the tensile stress and the shearing stress of the bolts are calculated according to the loading characteristics of the bolts, then the tensile stress and the shearing stress borne by the bolts are converted into equivalent tensile force based on the fourth strength theory, the inherent performance DFR value of the bolts is calculated according to the self structural characteristics of the bolts, and lastly the bolts are designed by adopting the detail fatigue rated value (DFR) method.

Description

technical field [0001] The invention belongs to the technical field of aircraft design and relates to a fatigue life design method of aircraft bolts. Background technique [0002] The aircraft structure is composed of tens of thousands of parts connected by fasteners (bolts or rivets), and there are hundreds of thousands of fasteners connecting these parts. Obviously, the fatigue performance of bolts will directly affect the safety of the aircraft. Under the repeated action of alternating stress on these bolts, the stress state of the thread changes, making the load distribution on each thread uneven, and the interlocking force between the threads intensifies, which may easily cause wear or damage to the bottom hole thread, or cause the bolt to The roots are broken. Therefore, the fatigue life of bolts should be given enough attention. [0003] According to the main stress state of bolts, bolts can be divided into tension bolts, shear bolts, and tension-shear composite bo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F17/50
Inventor 翟新康王新波张彦军
Owner XIAN AIRCRAFT DESIGN INST OF AVIATION IND OF CHINA
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