Embedded body for nondestructive testing of composite material, layered reference block and preparation method of layered reference block

Abstract

The invention discloses an insert for nondestructive testing of a composite material, a layered reference block and a preparation method of the layered reference block. The insert for nondestructive testing of the composite material comprises a first sub-insert with a first diameter and a second sub-insert with a second diameter, a second sub-insert having a second diameter smaller than the first diameter; the two first sub-embedded bodies are oppositely arranged, and the edges of the two first sub-embedded bodies are fixedly connected, so that a closed air enrichment body is formed between the two first sub-embedded bodies; the second sub-embedded body is located between the two first sub-embedded bodies, and the second sub-embedded body is fixedly connected with one of the first sub-embedded bodies. The stable embedding body for nondestructive testing of the composite material can be formed, resin can be prevented from being immersed into the embedding body in the curing process, and gas in the embedding body can be prevented from being immersed into the resin in the pressing process to form natural defects.

Description

Technical Field

[0001] The invention belongs to the technical field of nondestructive testing of composite materials, and in particular relates to an embedding body for nondestructive testing of composite materials, a layered comparison test block and a preparation method thereof. Background Art

[0002] The non-destructive testing layered comparison test block is a test block with a certain size of material with large acoustic impedance pre-placed inside the composite material part to simulate the formation of layered defects. It is used for equipment calibration and defect judgment comparison during the internal quality inspection of the composite material part. The quality of the non-destructive testing layered comparison test block determines the result of the internal quality judgment of the composite material part to a certain extent. Therefore, it is very important to manufacture high-quality layered comparison test blocks for the internal quality judgment of composite materials.

[0003] The traditional method of manufacturing a delamination comparison test block is to pre-place a double-layer tetrafluoroethylene film inside a composite material part, and simulate the delamination defect through the air layer formed between the double-layer tetrafluoroethylene films. Due to the difference in fluidity between resins, the quality of the delamination comparison test block manufactured by this method is not stable enough. If the resin has good fluidity, the resin is easy to penetrate between the double-layer tetrafluoroethylene films during the curing process, resulting in unclear echoes and thus failing to form the expected delamination defects. At the same time, the gas between the double-layer tetrafluoroethylene films is easy to penetrate into the surrounding resin during the pressure process and form natural defects around the preset defects. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides an embedding body for nondestructive testing of composite materials, a layered comparison test block and a preparation method thereof, which can form a stable embedding body for nondestructive testing of composite materials, can prevent the resin from penetrating into the embedding body during the curing process, and can prevent the gas in the embedding body from penetrating into the resin during the pressure process to form natural defects.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: In a first aspect, an embedding body for nondestructive testing of composite materials is provided, comprising: a first sub-embedding body having a first diameter; a second sub-embedding body having a second diameter smaller than the first diameter; two of the first sub-embedding bodies are arranged opposite to each other, and the edges of the two first sub-embedding bodies are fixedly connected, thereby forming a closed air-enriched body between the two first sub-embedding bodies; the second sub-embedding body is located between the two first sub-embedding bodies, and the second sub-embedded body is fixedly connected to one of the first sub-embedded bodies.

[0006] Furthermore, the axis of the second sub-embedded body coincides with the axis of the first sub-embedded body.

[0007] Furthermore, the total thickness of the second sub-embedded body and the two first sub-embedded bodies is less than or equal to 0.1 mm.

[0008] Furthermore, the second sub-embedded body and the first sub-embedded body are both adhesive release cloths.

[0009] In a second aspect, a method for preparing a layered comparison test block for non-destructive testing of composite materials is provided, comprising: preparing an embedded body, wherein the embedded body is the embedded body for non-destructive testing of composite materials as described in the first aspect; performing hot pressing treatment on the embedded body; embedding the embedded body after the hot pressing treatment into a composite material ply to form a layered comparison test block for non-destructive testing of composite materials.

[0010] Furthermore, preparing the embedded body includes: connecting the second sub-embedded body to one of the first sub-embedded bodies by gluing; arranging the two first sub-embedded bodies opposite to each other and gluing the edges of the two first sub-embedded bodies, with the second sub-embedded body located between the two first sub-embedded bodies, thereby obtaining the embedded body.

[0011] Furthermore, the embedded body is subjected to a hot pressing treatment, including: arranging auxiliary materials according to the requirements for arranging auxiliary materials when curing the layered comparison test blocks for non-destructive testing of composite materials; hot compacting the embedded body according to the curing system requirements of the layered comparison test blocks for non-destructive testing of composite materials, so as to expel excess gas inside the embedded body to avoid the formation of natural defects during the final curing while compressing the thickness of the embedded body as much as possible.

[0012] Furthermore, the embedded body after the heat pressing treatment is embedded in the composite material ply, including: paving the first ply, and performing the first vacuum hot compaction after the first ply is paved; after the first vacuum hot compaction, the embedded body after the heat pressing treatment is placed at the set position of the first ply, and twist strips are wrapped around the embedded body, and then the combination formed by the first ply, the embedded body and the twist strips are subjected to a second vacuum hot compaction; after the second vacuum hot compaction, the second ply is paved on top of the embedded body, and vacuum hot compaction is performed for a third time; after the third vacuum hot compaction, auxiliary materials are arranged and cured according to the production requirements of layered comparison test blocks for non-destructive testing of composite materials, so that the embedded body after the heat pressing treatment is embedded in the composite material ply.

[0013] In a third aspect, a layered comparison test block for nondestructive testing of composite materials is provided, wherein the layered comparison test block is made by the method for preparing a layered comparison test block for nondestructive testing of composite materials described in the second aspect.

[0014] Furthermore, a layered comparison test block for nondestructive testing of composite materials includes: an embedded body, a first layer located below the embedded body, a second layer located above the embedded body, and a twist strip wrapped around the embedded body.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention forms a stable embedding body for non-destructive testing of composite materials by setting a first sub-embedded body with a first diameter; a second sub-embedded body with a second diameter smaller than the first diameter; the two first sub-embedded bodies are arranged opposite to each other, and the edges of the two first sub-embedded bodies are fixedly connected, thereby forming a closed air-enriched body between the two first sub-embedded bodies; the second sub-embedded body is located between the two first sub-embedded bodies, and the second sub-embedded body is fixedly connected to one of the first sub-embedded bodies; and can prevent the resin from penetrating into the embedding body during the curing process, and can also prevent the gas in the embedding body from penetrating into the resin during the pressure process to form natural defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the relative position relationship between a first sub-embedded body and a second sub-embedded body in an embedded body for non-destructive testing of composite materials provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of the structure of a layered comparison test block for nondestructive testing of composite materials provided by an embodiment of the present invention; In the figure: 1, first ply; 2, embedded body; 21, first sub-embedded body; 22, second sub-embedded body; 3, twisted sub-strip; 4, second ply. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0018] Embodiment 1 like Figure 1 As shown, an embedding body for nondestructive testing of composite materials includes: a first sub-embedding body 21 having a first diameter; a second sub-embedding body 22 having a second diameter smaller than the first diameter; the two first sub-embedding bodies 21 are arranged opposite to each other, and the edges of the two first sub-embedding bodies 21 are fixedly connected, so as to form a closed air enrichment body between the two first sub-embedding bodies 21; the second sub-embedding body 22 is located between the two first sub-embedding bodies 21, and the second sub-embedding body 22 is fixedly connected to one of the first sub-embedded bodies 21.

[0019] The present invention takes the preparation of an embedded body for nondestructive testing of composite materials with a diameter of 6 mm as an example to further illustrate the structure and preparation method of the embedded body for nondestructive testing of composite materials of the present invention.

[0020] In the present invention, both the first sub-embedded body 21 and the second sub-embedded body 22 are made of adhesive release cloth.

[0021] The method for making an embedding body for nondestructive testing of composite materials includes: bonding the adhesive surface of a layer of adhesive release cloth with a diameter of 4 mm (the second sub-embedded body 22) to the adhesive surface of a layer of adhesive release cloth with a diameter of 6 mm (the first sub-embedded body 21), placing the adhesive release cloth with a diameter of 4 mm in the center on the adhesive release cloth with a diameter of 6 mm (i.e., keeping the axis of the second sub-embedded body 22 coincident with the axis of the first sub-embedded body 21), and then bonding the non-adhesive surface of another layer of adhesive release cloth with a diameter of 6 mm to the adhesive release cloth with a diameter of 6 mm in the aforementioned combination, and the edges of the two layers of adhesive release cloth with a diameter of 6 mm overlap. A closed air enrichment body is formed by wrapping a layer of adhesive release cloth with a diameter of 4 mm with two layers of adhesive release cloth with a diameter of 6 mm. At this point, the production of the embedding body for nondestructive testing of composite materials is completed.

[0022] The present invention can produce a composite material nondestructive testing embedding body with a total thickness of less than or equal to 0.1 mm between the second sub-embedded body 22 and the two first sub-embedded bodies 21. In the present invention, the first sub-embedded body 21 and the second sub-embedded body 22 can also be made of other single-sided adhesive materials as required.

[0023] Embodiment 2 Based on the embedded body for non-destructive testing of composite materials described in Example 1, this embodiment provides a method for preparing a layered comparison test block for non-destructive testing of composite materials, the method comprising: preparing an embedded body 2; hot pressing the embedded body 2; embedding the embedded body 2 after the hot pressing treatment into a composite material ply to form a layered comparison test block for non-destructive testing of composite materials.

[0024] (1) Preparation of embedded body 2: First, the second embedded body 22 is connected to one of the first embedded bodies 21 by gluing; then, the two first embedded bodies 21 are arranged opposite to each other, and the edges of the two first embedded bodies 21 are connected by gluing, and the second embedded body 22 is located between the two first embedded bodies 21, so as to obtain embedded body 2. The specific manufacturing method can be prepared by the manufacturing method of the embedded body for nondestructive testing of composite materials in Example 1, so as to obtain embedded body 2.

[0025] (2) Performing hot pressing treatment on the embedded body 2: moving the embedded body 2 onto the glass platform, arranging the auxiliary materials according to the requirements for arranging the auxiliary materials during the curing of the layered comparison test blocks for non-destructive testing of composite materials; performing hot compaction on the embedded body 2 according to the requirements for the curing system of the layered comparison test blocks for non-destructive testing of composite materials, so as to expel the excess gas inside the embedded body 2 to avoid the formation of natural defects during the final curing and compress the thickness of the embedded body 2 as much as possible.

[0026] (3) Embedding the hot-pressed embedded body 2 into the composite material ply: Laying the first ply 1 (the first ply 1 is the ply located below the embedded body 2), and performing the first vacuum hot compaction after the first ply 1 is laid. The purpose of this hot compaction step is to remove the air trapped between the prepreg layers at the location where the embedded body 2 is placed; after the first vacuum hot compaction, place the hot-pressed embedded body 2 at the set position of the first ply 1, and wrap the twist strip 3 around the embedded body 2, and then perform the second vacuum hot compaction on the assembly formed by the first ply 1, the embedded body 2 and the twist strip 3. This step The purpose is to eliminate the air entrapment between the embedded body 2 and the first layer 1 and reduce the upper fiber bridging problem caused by the step difference of the embedded body; after the second vacuum hot compaction, the second layer 4 is laid on the top of the embedded body 2, and the third vacuum hot compaction is performed to ensure that the second layer 4 is completely fitted with the embedded body 2; after the third vacuum hot compaction, the auxiliary materials are arranged and cured according to the production requirements of the layered comparison test block for non-destructive testing of composite materials, so that the embedded body 2 after the hot pressing treatment is embedded in the composite material layer, and the layered comparison test block for non-destructive testing of composite materials is formed through curing and other processes, such as Figure 2 shown.

[0027] The present invention discharges excess gas inside the embedded body by hot compaction to avoid the excess gas from penetrating into the surrounding prepreg to form natural defects during final curing; at the same time, the thickness of the embedded body is compressed as much as possible by hot compaction to avoid the formation of bridging natural defects due to the step difference of the embedded body when the upper prepreg of the embedded body is laid.

[0028] The present invention performs hot compaction before and after the placement of the embedded body and after the prepreg on the upper part of the embedded body is laid, so as to effectively remove excess gas inside the prepreg to avoid the formation of natural defects, and at the same time, twisted strips made of single yarn are wrapped around the defects to reduce the natural defects of upper fiber bridging caused by the step difference of the embedded body.

[0029] The present invention can effectively solve the problems of unclear echo of traditional autoclave delamination defect simulation delamination comparison test blocks, failure to form expected delamination defects, and formation of natural defects around embedded defects, greatly improves the manufacturing quality of non-destructive testing delamination comparison test blocks, brings convenience to product testing, and improves the product testing pass rate.

[0030] Embodiment 3 Based on the embedding body for non-destructive testing of composite materials described in Example 1 and the method for preparing a layered comparison test block for non-destructive testing of composite materials described in Example 2, this embodiment provides a layered comparison test block for non-destructive testing of composite materials, the layered comparison test block is provided with the embedding body for non-destructive testing of composite materials described in Example 1, and is made by the method for preparing a layered comparison test block for non-destructive testing of composite materials described in Example 2, comprising: an embedding body 2, a first ply 1 located below the embedding body 2, a second ply 4 located above the embedding body 2, and a twist strip 3 wrapped around the embedding body 2, such as Figure 2 shown.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An embedding body for nondestructive testing of composite materials, characterized in that: include: A first sub-embedded body (21) having a first diameter; A second sub-embedded body (22) having a second diameter smaller than the first diameter; The two first sub-embedded bodies (21) are arranged opposite to each other, and the edges of the two first sub-embedded bodies (21) are fixedly connected, so that a closed air-enriched body is formed between the two first sub-embedded bodies (21); the second sub-embedded body (22) is located between the two first sub-embedded bodies (21), and the second sub-embedded body (22) is fixedly connected to one of the first sub-embedded bodies (21).

2. The composite material nondestructive testing embedding body according to claim 1, characterized in that: The axis of the second sub-embedded body (22) coincides with the axis of the first sub-embedded body (21).

3. The composite material nondestructive testing embedding body according to claim 1, characterized in that: The total thickness of the second sub-embedded body (22) and the two first sub-embedded bodies (21) is less than or equal to 0.1 mm.

4. The composite material nondestructive testing embedding body according to claim 1, characterized in that: The second sub-embedded body (22) and the first sub-embedded body (21) are both adhesive release cloths.

5. A method for preparing a layered comparison test block for nondestructive testing of composite materials, characterized in that: include: Preparing an embedding body (2), wherein the embedding body (2) is an embedding body for nondestructive testing of composite materials according to any one of claims 1 to 4; Performing a heat pressing treatment on the embedding body (2); The embedded body (2) after the heat pressing treatment is embedded in the composite material ply to form a layered comparison test block for non-destructive testing of the composite material.

6. The method for preparing a layered comparison test block for nondestructive testing of composite materials according to claim 5, characterized in that: Preparing an embedding body (2), comprising: Connecting the second sub-embedded body (22) to one of the first sub-embedded bodies (21) by gluing; The two first sub-embedded bodies (21) are arranged opposite to each other, and the edges of the two first sub-embedded bodies (21) are glued together, and the second sub-embedded body (22) is located between the two first sub-embedded bodies (21), thereby obtaining the embedded body (2).

7. The method for preparing a layered comparison test block for nondestructive testing of composite materials according to claim 5, characterized in that: The embedding body (2) is subjected to a heat pressing process, comprising: Arrange auxiliary materials according to the requirements for the arrangement of layered comparison test blocks for non-destructive testing of composite materials during curing; The embedded body (2) is hot compacted according to the curing system requirements of the layered comparison test block for non-destructive testing of composite materials.

8. The method for preparing a layered comparison test block for nondestructive testing of composite materials according to claim 5, characterized in that: The hot-pressed embedded body (2) is embedded in the composite material layer, comprising: Laying the first paving layer (1), and performing a first vacuum hot compaction after the first paving layer (1) is laid; After the first vacuum hot compaction, the hot-pressed embedded body (2) is placed at a set position of the first layer (1), and a twist strip (3) is wrapped around the embedded body (2), and then the assembly formed by the first layer (1), the embedded body (2) and the twist strip (3) is subjected to a second vacuum hot compaction; After the second vacuum hot compaction, a second layer (4) is laid on top of the embedded body (2), and a third vacuum hot compaction is performed; After the third vacuum hot compaction, auxiliary materials are arranged and cured according to the production requirements of layered comparison test blocks for non-destructive testing of composite materials, so that the embedded body (2) after the hot pressing treatment is embedded in the composite material layer.

9. A layered comparison test block for nondestructive testing of composite materials, characterized in that: The layered comparison test block is made by the method for preparing a layered comparison test block for non-destructive testing of composite materials according to any one of claims 5 to 8.

10. The layered comparison test block for nondestructive testing of composite materials according to claim 9, characterized in that: A layered comparison test block for non-destructive testing of composite materials comprises: an embedded body (2), a first layer (1) located below the embedded body (2), a second layer (4) located above the embedded body (2), and a twist strip (3) wound around the embedded body (2).

Images