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Assessment and test method and device for I-type interlaminar fracture toughness GIC of fiber-metal laminates (FMLs)

A fiber metal laminate and interlaminar fracture toughness technology, which is applied in the direction of applying stable tension/pressure to test the strength of materials, which can solve the problems of significant anisotropy, large test error, and small extensibility of composite materials, and improve the The effect of interlayer interface performance, avoidance of out-of-plane displacement, and simple test operation

Inactive Publication Date: 2018-01-23
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the multi-layer structure of fiber metal laminates, compared with traditional materials, composite materials have less extensibility, significant anisotropy, and complex internal structures
The structure on both sides of the laminate after the prefabricated crack is unbalanced. When the peel load is applied to the laminate with the prefabricated crack, the performance difference between the outer layer metal and the inner layer reinforcement material causes the unloaded end of the laminate to shift upwards during the loading process, resulting in Severe out-of-plane displacement phenomenon; and the double cantilever beam test is only suitable for the interlayer fracture toughness test of the interlayer interface of the even-numbered layer structure, and does not consider the laminate structure under different structures and layers, and does not consider some tests The interlayer fracture toughness of the interface between the first layer metal, the second layer metal or the middle layer metal of different structural laminates and the composite material is required. There are certain differences in the interlayer fracture toughness of different interfaces. If only double cantilever beams are used to test the middle layer The interface will cause large experimental errors, which cannot effectively reflect the I-mode interlaminar fracture toughness of the laminate structure system, and thus cannot reflect its real interlaminar interface performance, which is not conducive to guiding the design and application of fiber metal laminates

Method used

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  • Assessment and test method and device for I-type interlaminar fracture toughness GIC of fiber-metal laminates (FMLs)
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  • Assessment and test method and device for I-type interlaminar fracture toughness GIC of fiber-metal laminates (FMLs)

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] The first step is the single cantilever beam sample preparation, select Al alloy thin plate and polypropylene fiber reinforced polypropylene composite material 0° / 90° alternate lamination 4 / 3 structure laminate, the length of the laminate is 200mm, the width is 20mm; the first layer The interface between Al alloy and polypropylene fiber reinforced polypropylene composite material was put into a 55 mm long aluminum foil as a prefabricated crack, and a 3 mm thick glass fiber reinforced plastic laminate was bonded to the lower surface of the Al plate to enhance the rigidity of the sample. Connected to one end of the prefabricated crack in the laminate for applying load displacement;

[0042] The second step is to clamp the prepared single cantilever beam sample to the clamping device, start the universal testing machine, load the sample at a constant rate of 3mm / min (pull upward), and continuously record the load and displacement values. Record the location of the crack. ...

Embodiment 2

[0048] The first step is to prepare the single cantilever beam sample, select the composite material composed of Ti alloy thin plate and polyimide resin, the length of the laminate is 180mm, and the width is 25mm; put the aluminum foil with a length of 50mm at the interface between the Ti plate and the resin as a prefabricated crack, use Araldite epoxy resin bonded glass fiber / epoxy resin honeycomb to the lower Ti board, and bonded the piano hinge to one end of the prefabricated crack in the laminate for applying load displacement;

[0049] In the second step, the prepared single cantilever beam sample is clamped on the clamping device, and the universal testing machine is loaded at a constant rate of 1 mm / min, and the load and displacement values ​​are continuously recorded, and the crack position is recorded. Stop loading when the length of the crack outside the pre-crack reaches 3mm-5mm; unload at a constant rate lower than 25mm / min, after unloading, mark the tip of the pre-...

Embodiment 3

[0055] The first step is the preparation of the single cantilever beam sample. Select the 3 / 2 structural laminate of Al alloy thin plate and glass fiber reinforced epoxy resin composite material with 0° unidirectional lamination. The length of the laminate is 180mm and the width is 25mm; the length of the interface is 50mm polytetrafluoroethylene film is used as the prefabricated crack, Araldite epoxy resin is used to bond the glass fiber / epoxy resin honeycomb to the lower Al plate, and the piano hinge is bonded to one end of the prefabricated crack in the laminate for applying load displacement;

[0056] In the second step, the prepared single cantilever beam sample is clamped on the clamping device, loaded at a constant rate of 5mm / min, the load and displacement values ​​are continuously recorded, and the crack position is recorded. Stop loading when the length of the crack outside the pre-crack reaches 3mm-5mm; unload at a constant rate lower than 25mm / min, after unloading, ...

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Abstract

The invention discloses an assessment and test method and device for I-type interlaminar fracture toughness GIC of fiber-metal laminates (FMLs). The device comprises a pedestal (6), a supporting unit,a clamping unit, a universal tester and a fiber metal laminate sample; the fiber metal laminate sample is of a bar-cuboid single-cantilever beam sample, a sheet or a thin film is placed in the material interface at one end of each fiber metal laminate to serve as a precrack, a strengthening block is adhesively fixed on the lower underside of the fiber metal laminate, and an upper padding plate (7) and a lower padding plate (8) are adhesively fixed to the upper and lower sides of the other end of the fiber metal laminate. With the method, reference is provided for formulating test standard ofthe I-type interlaminar fracture toughness of the FMLs in China, and the effective method is provided for assessment of other interlaminar properties.

Description

technical field [0001] The invention belongs to the technical field of performance evaluation of fiber metal laminates, in particular to a type I interlaminar fracture toughness G of fiber metal laminates IC Evaluation test methods and devices. Background technique [0002] Fiber metal laminates (Fiber Metal Laminates, FMLs) is a kind of interlayer hybrid composite material formed by alternate lamination of metal sheets and fiber composite materials and solidified under a certain temperature and pressure, also known as hyperhybrid laminates. (Super Hybrid Laminates). FMLs combines the characteristics of traditional fiber composite materials and metal materials, and has high specific strength and specific stiffness, excellent fatigue performance and high damage tolerance. These advantages make FMLs widely used in aerospace, automobile, bridge and nuclear power industries. a wide range of applications. [0003] The biggest feature of the fiber metal laminate structure is th...

Claims

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Application Information

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IPC IPC(8): G01N3/08
Inventor 陶杰华小歌李华冠陆一陈虞杰
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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