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A Method for Predicting the Remaining Fatigue Life of Composite Bonded Repair Structures

A composite material and fatigue life technology, which is applied in the application of repetitive force/pulsation force to test the strength of materials, analyze materials, measuring devices, etc., can solve the problems of large amount of calculation and complicated steps, and achieve the effect of simplifying the steps.

Active Publication Date: 2019-06-25
QINGDAO CAMPUS AVIATION ENG COLLEGE OF THE PEOPLES LIBERATION ARMY NAVY
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Problems solved by technology

However, this method requires the fatigue life test data of the repaired structure to be obtained through experiments before calculating the remaining fatigue life. In many cases, this type of experiment cannot be implemented for complex composite bonded repair structures, and even if it can be implemented, it needs to be repeated. Calculating the magnitude of the stress intensity factor in the repaired structure, the steps are cumbersome and the amount of calculation is large

Method used

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  • A Method for Predicting the Remaining Fatigue Life of Composite Bonded Repair Structures
  • A Method for Predicting the Remaining Fatigue Life of Composite Bonded Repair Structures
  • A Method for Predicting the Remaining Fatigue Life of Composite Bonded Repair Structures

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Effect test

Embodiment 1

[0029] Using T300 / E51 carbon fiber composite patch to repair the damaged LY12CZ aluminum alloy plate with central crack by single-sided adhesive bonding, and predict the fatigue life of the repaired structure.

[0030] First, test the relationship between the crack growth rate of the damaged cracked plate and the amplitude of the stress intensity factor under alternating loads, and fit the data points in the logarithmic coordinate system Obtain the Paris formula material constants C and m under the test conditions, and the calculation result is C=6.3496×10 -12 , m=3.72972.

[0031] Secondly, the finite element modeling of the single-sided adhesive bonded composite structure with cracks was carried out. According to the characteristics of each material in the repair structure, three-dimensional solid element C3D8R, continuous shell element SC8R and three-dimensional viscous element COH3D8 are selected from the Abaqus software library for solid modeling. The location of each ...

Embodiment 2

[0039] The T300 / E51 carbon fiber composite patch was used to repair the LY12CZ aluminum alloy metal plate with a central crack by double-sided adhesive bonding, and the remaining fatigue life of the repaired structure was predicted.

[0040] First, the relationship between the crack growth rate and the stress intensity factor of the damaged cracked plate under the action of alternating load is obtained through experiments, and the data points are fitted in the logarithmic coordinate system Fit the material constants C and m under the test conditions in the Paris formula, where C=6.3496×10 -12 , m=3.72972.

[0041] Secondly, the finite element modeling of the double-sided adhesive bonded composite structure with cracks was carried out. According to the characteristics of each material in the repair structure, the three-dimensional solid element C3D8R, the continuous shell element SC8R and the three-dimensional viscous element COH3D8 suitable for metal plates, adhesive layers ...

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Abstract

The invention provides a method for predicting the residual fatigue life of a composite material adhesive bonding repair structure. The method comprises the following steps: (1) determining the material constants of an unrepaired structure; (2) establishing a model of a repaired structure, after the establishment, assembling entities, dividing grids, and creating constraints; (3) solving the relational expression between the stress intensity factor amplitude and the crack length; (4) according to the breaking tenacity of a metal material, based on the stress intensity factor output by software, determining the final failure crack length of the repaired structure; and (5) substituting the material constants, the final failure crack length, and the relational expression between the stress intensity factor change amplitude and the crack length into Paris formula, and calculating the residual fatigue life of the repaired structure through integration. The calculation steps are simplified, the prediction efficiency on the residual fatigue life of a composite material adhesive bonding repair structure is obviously improved, the calculation cost is reduced, and the development of the composite material adhesive bonding repair technology is promoted.

Description

technical field [0001] The invention belongs to the technical field of composite structure fatigue life prediction, and in particular relates to a method for predicting the remaining fatigue life of a composite material glued repair structure based on the assumption that the material constant is constant. Background technique [0002] The Paris formula is commonly used in fracture mechanics to describe the relationship between the crack growth rate and the change amplitude of the stress intensity factor at the crack tip, and its expression is [0003] [0004] in ΔK is the stress intensity factor of the crack tip; C and m are undetermined constants, which are related to materials, environments, etc. How to determine the material constants C and m is a key and difficult point in the process of solving the remaining fatigue life of the bonded repaired structure of metal plate composite materials with cracks by using the integral of Paris formula. The common practice in t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/32
CPCG01N3/32G01N2203/0005G01N2203/0066G01N2203/0073G01N2203/0682
Inventor 穆志韬金平李旭东刘治国孔光明马鸿儒
Owner QINGDAO CAMPUS AVIATION ENG COLLEGE OF THE PEOPLES LIBERATION ARMY NAVY
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