CN111896352A - Sample for testing shear performance of foam core material, manufacturing method and testing method - Google Patents
Sample for testing shear performance of foam core material, manufacturing method and testing method Download PDFInfo
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- CN111896352A CN111896352A CN202010930118.XA CN202010930118A CN111896352A CN 111896352 A CN111896352 A CN 111896352A CN 202010930118 A CN202010930118 A CN 202010930118A CN 111896352 A CN111896352 A CN 111896352A
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- foam core
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/04—Chucks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
Abstract
The invention discloses a sample for testing the shearing performance of a foam core material, a manufacturing method and a testing method, wherein the sample for testing the shearing performance of the foam core material comprises a foam core material body, and an upper skin layer and a lower skin layer which are bonded and cured on the upper surface and the lower surface of the foam core material body; wherein, the upper opposite side of the sample is provided with an upper notch and a lower notch. Firstly, processing an upper notch and a lower notch on the opposite side of a rectangular blank formed by an upper skin layer, a foam core material and a lower skin layer to form a sample structure; re-stretching the shear specimen, recording the maximum load Fb after the tensile shear failure, and calculating the maximum load by a calculation formula
The shear stress of the foam core was determined. The method is not easy to generate the instability phenomenon in the test process, and the data obtained by the test has strong representativeness. The invention is suitable for the shear performance test of the foam core material.
Description
Technical Field
The invention belongs to the technical field of plate shearing performance testing, relates to shearing performance testing of a foam core material, and particularly relates to a sample for testing the shearing performance of the foam core material, a manufacturing method and a testing method.
Background
The sandwich plate structure of the foam core material has the characteristics of light weight, high rigidity, corrosion resistance, electromagnetic shielding and the like, and is widely applied to the field of aerospace at present. The resin-based fiber surface layer in the foam core material sandwich plate structure mainly bears the positive stress caused by bending deformation; the middle is a core material, and light materials such as foam are selected, so that enough section moment of inertia and bending rigidity are provided for the structural member, and the structural member bears shear stress. The shear performance, the compressive rigidity and the strength of the foam core sandwich plate structure are important standards for measuring the quality of the foam core sandwich plate structure at present.
The existing compression shear test method for the foam core material sandwich plate is difficult to obtain effective test data, most of failures do not occur to the shear failure of the foam core material sandwich plate, but the foam core material is directly separated from a clamp because the interface between the foam core material and a surface layer is easy to peel, so that the test data is invalid, repeated test tests are needed to obtain the effective data meeting the requirements, and the relative test efficiency is very low.
On the other hand, there is no generally applicable test standard in the industry to perform an effective tensile shear test on the foam core material, and most of the tests are to improve the structure of a clamp used for a compression shear test of the sandwich panel of the foam core material so as to reduce the occurrence of the situation that the foam core material is separated from the clamp in the test process. During the shearing performance test, carry out the installation of specific anchor clamps to foam core sandwich panel, not only additionally increased anchor clamps, made operation process more loaded down with trivial details, and the joining of specific anchor clamps often can restrict the size of foam core sandwich panel, is difficult to test the foam core of various differences, can not fundamentally solve the problem, and application scope is less.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide a sample for testing the shearing performance of a foam core material, a manufacturing method and a testing method, so as to avoid the occurrence of instability in the testing process and achieve the aim of improving the testing efficiency.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a sample for testing the shearing performance of a foam core material comprises a foam core material body, an upper skin layer and a lower skin layer, wherein the upper skin layer and the lower skin layer are bonded and cured on the upper surface and the lower surface of the foam core material body; the upper surface and the lower surface of the sample are respectively provided with an upper notch and a lower notch along the thickness direction of the sample, and the upper notch and the lower notch are positioned at two sides of the center of the sample and have the same length from the center of the sample; the upper and lower incisions extend through the entire sample in the width direction of the sample.
As the limitation of the invention, the depths of the upper notch and the lower notch are both half of the whole thickness of the sample, and the widths of the upper notch and the lower notch are both 1-2 mm.
As another limitation of the invention, the width W of the foam core body120-25 mm, length L1120 to 250mm, and a thickness H12-13 mm.
As a further limitation of the invention, the thickness H of the upper and lower skin layers2The thickness of the foam core material is 0.5-3 mm, and the width and the length of the foam core material are the same as those of the foam core material body.
As another limitation of the present invention, the upper skin layer and the lower skin layer are made of any one of prepreg fiber, glass fiber reinforced plastic, or carbon fiber composite.
The invention also discloses a manufacturing method of the sample for testing the shearing performance of the foam core material, which comprises the following steps in sequence:
s1, adhering and curing an upper skin layer and a lower skin layer on the upper surface and the lower surface of the foam core material body respectively, and processing to form a rectangular blank;
s2, separating the upper surface of the rectangular blank from the center L of the rectangular blank3On one side of the square blank, an upper notch is processed along the thickness direction of the square blank, and the upper notch is along the width of the square blankThe whole rectangular blank is penetrated in the direction of degree;
s3, separating the lower surface of the rectangular blank from the center L of the rectangular blank3Processing a lower notch on the other side of the rectangular blank along the thickness direction of the rectangular blank, wherein the lower notch penetrates through the whole rectangular blank along the width direction of the rectangular blank to form the sample for testing the shearing performance of the foam core material;
s4, the sample for testing the shearing performance of the foam core material forms a length L between the upper incision and the lower incision of the two opposite side processes3The shear deformation zone of (a).
In step S1, the foam core body is molded and cured together with the upper skin layer and the lower skin layer; or the upper skin layer and the lower skin layer are formed separately and then are bonded and cured with the foam core material body through the adhesive.
As another limitation of the present invention, in step S1, the width W of the rectangular blank is 20-25 mm, the length L is 120-250 mm, and the thickness H is 2.5-16 mm.
As a further limitation of the present invention, in step S2, the width W of the upper notch31-2 mm, depth T1Is H/2; in step S3, the width W of the undercut41-2 mm, depth T2Is H/2.
The invention also discloses a test method for testing the shearing performance of the foam core material, which utilizes the sample for testing the shearing performance of the foam core material, and comprises the following steps in sequence:
s1', clamping a universal plate stretching clamp of the universal testing machine at two ends of a sample for testing the shearing performance of the foam core material, and stretching and shearing the sample;
s2', after tensile shear failure, recording the maximum load Fb, and calculating the formula
Obtaining the shear stress tau of the foam core material;
wherein W is the width of the rectangular blank; l is3The length of the shear deformation zone is the sample.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following beneficial effects:
(1) according to the invention, the upper incision and the lower incision are processed on the opposite sides of the upper surface and the lower surface of the sample to form the shear deformation zone, so that the shear performance test of the foam core material sandwich plate is realized. The formed sample can be subjected to the shearing performance test by utilizing the universal sample machine to standard the plate sample stretching clamp, no additional clamp is needed, the operation is simpler, the situation that the sample is separated from the clamp in the whole test process can be reduced, the validity of test data is ensured, and the test efficiency is improved.
(2) According to the invention, the size of the foam core material, the upper skin layer, the lower skin layer, the upper incision and the lower incision is limited, so that the formed sample has stronger representativeness, and the data obtained by testing can better reflect the shearing performance of the sandwich plate of the foam core material. The standard is generally applicable to foam core material sandwich plates with different models and structures, and provides a reliable reference basis for manufacturing foam core material sandwich plate samples in the industry. The invention further improves the accuracy of the data on the premise of ensuring the effective test data.
(3) The testing method adopted by the invention can effectively solve the problem that the test data is invalid because the interface between the foam core material and the surface layer is easy to separate, relatively reduces the testing times, simplifies the testing steps and improves the testing efficiency.
In conclusion, the method is simple to operate, the instability phenomenon is not easy to occur in the test process, the data obtained by the test is high in representativeness, and the shearing performance of the foam core material sandwich plate can be well reflected. The invention is suitable for the shear performance test of the foam core material sandwich plate.
Drawings
The invention is described in further detail below with reference to the figures and the embodiments.
FIG. 1 is a schematic structural view of example 1 of the present invention;
FIG. 2 is a longitudinal sectional view showing the structure of embodiment 1 of the present invention.
In the figure: 1. a foam core body; 2. an upper skin layer; 3. a lower skin layer; 4. an upper notch; 5. a lower incision; 6. and (4) clamping.
Detailed Description
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the description of the preferred embodiment is only for purposes of illustration and understanding, and is not intended to limit the invention.
Example 1 a sample for testing shear properties of a foam core
The upper incision 4 and the lower incision 5 are machined on the upper side and the lower side of the sample formed in the embodiment, a shearing deformation area is formed between the upper incision 4 and the lower incision 5, and the occurrence of instability can be reduced when a shearing performance test is carried out, so that the validity of test data is ensured.
As shown in fig. 1 to 2, the present embodiment includes a foam core material body 1, and upper and lower skin layers 2 and 3 adhesively cured on upper and lower surfaces of the foam core material body 1, and a composite structure of the upper skin layer 2, the foam core material body 1, and the lower skin layer 3 forms a test piece for testing shear performance of the foam core material. The upper surface and the lower surface of the sample are respectively provided with an upper notch 4 and a lower notch 5 which are 1-2 mm wide along the thickness direction of the sample, the upper notch 4 and the lower notch 5 are located on two sides of the center of the sample, and the upper notch 4 and the lower notch 5 penetrate through the whole sample along the width direction of the sample. In order to ensure that the whole sample is uniformly stressed when being subjected to shear failure in the shear performance test process, in this embodiment, the distances between the upper notch 4 and the lower notch 5 and the center of the sample are the same, specifically as shown in fig. 2, and the depths of the upper notch 4 and the lower notch 5 are half of the whole thickness of the sample.
The width W of the foam core body 1 is such that the data obtained from the test better reflects the shear performance of the foam core in order to make the sample more representative1Limited within the range of 20-25 mm and the length L1Limited within the range of 120-250 mm, and a thickness H1Limiting the size of the particles to be within the range of 2-13 mm; and the thickness H of the upper skin layer 2 and the lower skin layer 32The width and the length of the foam core material are both limited within the range of 0.5-3 mm and are both the same as those of the foam core material body 1.
When the sample is manufactured, the upper skin layer 2 and the lower skin layer 3 can be made of prepreg fiber materials or other composite materials (glass fiber reinforced plastics, carbon fiber composite materials and the like formed by a wet process). The upper skin layer 2 and the lower skin layer 3 can be cured and molded together with the foam core material body 1, or the upper skin layer 2 and the lower skin layer 3 can be molded separately and bonded with the foam core material body 1 through an adhesive.
The sample provided in this example has a foam core material body 1 with a width W1Is 25mm, length L1Is 250mm and has a thickness H1Is 13 mm; width W of upper skin layer 2 and lower skin layer 32Are all 25mm, length L2Are all 250mm, and have a thickness H2Are all 3 mm; the width of the upper incision 4 and the lower incision 5 is 2 mm. In the embodiment, the upper skin layer 2 and the lower skin layer 3 are both made of prepreg fiber materials, and are bonded and cured with the foam core material body 1 into a whole through an adhesive.
Examples 2-6A test specimen for testing the shear properties of a foam core
The sample structures formed in examples 2-6 were identical to the sample structure formed in example 1, except for the dimensional parameters involved, as detailed in table one.
Example 7 method of making a sample for testing the shear properties of a foam core
This example is a sample prepared according to example 1 for testing the shear properties of a foam core, comprising the following steps performed in sequence:
s1, after the upper surface layer 2 and the lower surface layer 3 are respectively bonded and solidified on the upper surface and the lower surface of the foam core material body 1, a rectangular blank with the width W of 20-25 mm, the length L of 120-250 mm and the thickness H of 2.5-16 mm is processed. The foam core material body 1, the upper skin layer 2 and the lower skin layer 3 can be molded and cured together; the skin layer 2 and the lower skin layer 3 can be formed separately and then bonded and cured with the foam core material body 1 through an adhesive.
In the embodiment, the foam core material body 1, the upper skin layer 2 and the lower skin layer 3 are molded and cured together; the width W of the rectangular blank formed by processing is 25mm, the length L is 250mm, and the thickness H is 16 mm.
S2, separating the upper surface of the rectangular blank from the center L of the rectangular blank3One side of the rectangular blank is processed to form a width W along the thickness direction of the rectangular blank31-2 mm, depth T1An upper cut 4 of H/2, the upper cut 4 extending through the entire rectangular blank in the width direction of the rectangular blank. In this embodiment, the upper slit 4 has a width of 2 mm.
S3, separating the lower surface of the rectangular blank from the center L of the rectangular blank3The other side of the rectangular blank is processed to form a width W along the thickness direction of the rectangular blank41-2 mm, depth T2And the lower cut 5 is H/2, and the lower cut 5 penetrates through the whole rectangular blank along the width direction of the rectangular blank to finally form a sample for testing the shearing performance of the foam core material. In this embodiment, the width of the lower slit 5 is 2 mm.
S4, the test specimen for testing the shear properties of the foam core formed a length L between two opposite upper cuts 4 and lower cuts 53The shear deformation zone of (a).
Example 8A test method for testing shear properties of foam core
This example utilizes the test specimens described in example 1 for testing shear performance of a foam core for shear performance testing of a foam core comprising the following steps performed in order:
firstly, a sample is prepared, and the preparation method of the sample is the same as the preparation method of the sample for testing the shearing performance of the foam core material in the embodiment 7; after the sample is manufactured, clamping the universal plate stretching clamps 6 of the universal testing machine at two ends of the sample, and performing a stretching shear test; after the tensile shear failure, recording the maximum load Fb, and calculating the maximum load by the formula
The shear stress τ of the foam core was determined.
Wherein, Fb: maximum load when the sample is damaged by tensile shearing; (Unit/N)
W: the width of the sample; (unit/m)
L3: the length of the shear deformation zone of the sample. (unit/m)
Although the present invention has been described in detail with reference to the above embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described above, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A sample for testing shear performance of a foam core, characterized by: the foam core material comprises a foam core material body, and an upper skin layer and a lower skin layer which are bonded and solidified on the upper surface and the lower surface of the foam core material body; the upper surface and the lower surface of the sample are respectively provided with an upper notch and a lower notch along the thickness direction of the sample, and the upper notch and the lower notch are positioned at two sides of the center of the sample and have the same length from the center of the sample; the upper and lower incisions extend through the entire sample in the width direction of the sample.
2. The test specimen for testing shear performance of a foam core material according to claim 1, characterized in that: the depth of the upper notch and the depth of the lower notch are both half of the whole thickness of the sample, and the width of the upper notch and the width of the lower notch are both 1-2 mm.
3. A test specimen for testing the shear properties of a foam core according to claim 1 or 2, characterized in that: width W of foam core body120-25 mm, length L1120 to 250mm, and a thickness H12-13 mm.
4. A method for testing the shear performance of a foam core according to claim 3A sample, characterized by: thickness H of upper and lower skin layers2The thickness of the foam core material is 0.5-3 mm, and the width and the length of the foam core material are the same as those of the foam core material body.
5. The test specimen for testing shear performance of a foam core material according to any one of claims 1 to 2 and 4, characterized in that: the upper skin layer and the lower skin layer are made of any one of prepreg fibers, glass fiber reinforced plastics or carbon fiber composite materials.
6. A manufacturing method of a sample for testing the shearing performance of a foam core material is characterized by comprising the following steps: comprises the following steps which are sequentially carried out:
s1, adhering and curing an upper skin layer and a lower skin layer on the upper surface and the lower surface of the foam core material body respectively, and processing to form a rectangular blank;
s2, separating the upper surface of the rectangular blank from the center L of the rectangular blank3Processing an upper notch on one side of the rectangular blank along the thickness direction of the rectangular blank, wherein the upper notch penetrates through the whole rectangular blank along the width direction of the rectangular blank;
s3, separating the lower surface of the rectangular blank from the center L of the rectangular blank3On the other side of the rectangular blank, a lower notch is processed along the thickness direction of the rectangular blank, and the lower notch penetrates through the rectangular blank along the width direction of the rectangular blank to form a sample for testing the shearing performance of the foam core material according to any one of claims 1 to 5;
s4, the sample for testing the shearing performance of the foam core material forms a length L between the upper incision and the lower incision of the two opposite side processes3The shear deformation zone of (a).
7. The method of making a sample for testing the shear properties of a foam core of claim 6, wherein: in step S1, the foam core material body, the upper skin layer and the lower skin layer are molded and cured together; or the upper skin layer and the lower skin layer are formed separately and then are bonded and cured with the foam core material body through the adhesive.
8. The method of making a sample for testing the shear properties of a foam core according to claim 6 or 7, wherein: in step S1, the width W of the rectangular blank is 20-25 mm, the length L is 120-250 mm, and the thickness H is 2.5-16 mm.
9. The method of making a sample for testing the shear properties of a foam core of claim 8, wherein: in step S2, the width W of the upper notch31-2 mm, depth T1Is H/2; in step S3, the width W of the undercut41-2 mm, depth T2Is H/2.
10. A test method for testing the shear performance of a foam core material is characterized by comprising the following steps: use of a test specimen for testing the shear properties of a foam core according to any one of claims 1 to 5, comprising the following steps carried out in sequence:
s1', clamping a universal plate stretching clamp of the universal testing machine at two ends of a sample for testing the shearing performance of the foam core material, and stretching and shearing the sample;
s2', after tensile shear failure, recording the maximum load Fb, and calculating the formula
Obtaining the shear stress tau of the foam core material;
wherein W is the width of the rectangular blank; l is3The length of the shear deformation zone is the sample.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010930118.XA CN111896352A (en) | 2020-09-07 | 2020-09-07 | Sample for testing shear performance of foam core material, manufacturing method and testing method |
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| CN202010930118.XA CN111896352A (en) | 2020-09-07 | 2020-09-07 | Sample for testing shear performance of foam core material, manufacturing method and testing method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112881128A (en) * | 2021-02-04 | 2021-06-01 | 航天科工防御技术研究试验中心 | Tensile sample for additive manufacturing lattice structure material and tensile test method |
| CN113203608A (en) * | 2021-03-22 | 2021-08-03 | 中国船舶重工集团公司第七二五研究所 | Welded-state multilayer metal composite material interface tension-shear fatigue sample and test method |
-
2020
- 2020-09-07 CN CN202010930118.XA patent/CN111896352A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112881128A (en) * | 2021-02-04 | 2021-06-01 | 航天科工防御技术研究试验中心 | Tensile sample for additive manufacturing lattice structure material and tensile test method |
| CN112881128B (en) * | 2021-02-04 | 2023-03-21 | 航天科工防御技术研究试验中心 | Tensile sample for additive manufacturing lattice structure material and tensile test method |
| CN113203608A (en) * | 2021-03-22 | 2021-08-03 | 中国船舶重工集团公司第七二五研究所 | Welded-state multilayer metal composite material interface tension-shear fatigue sample and test method |
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