Composite material patching and repairing method based on priority number system

Abstract

The invention belongs to the technical field of wave-absorbing composite material repairing, and discloses a composite material patching repairing method based on a priority number system, which comprises the following steps: S1, determining a priority number of a standard accessory based on a composite material damage range and the priority number system; s2, after the damage and repair area of the composite material is determined, the repair area is machined into a circular truncated cone hole, materials of the same model and the same batch are machined into a circular truncated cone plate matched with the circular truncated cone hole, and the diameters of the large ends of the circular truncated cone hole and the circular truncated cone plate refer to the priority number of the standard accessory in S1; s3, the machined circular truncated cone plate is repaired to the circular truncated cone hole part through a glue joint technology, and then the glue joint part is polished to be flat, so that complete repairing is achieved; according to the invention, the composite material can be conveniently and quickly repaired through the design of the preferential number series standardized accessories.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave absorbing composite material repair, and in particular to a method for patching and repairing composite materials based on the preferred number system. Background Art

[0002] Microwave absorbing composite materials are functional composite materials that can effectively absorb and attenuate the energy of incident electromagnetic waves and convert it into heat energy or other forms of energy for dissipation. It combines the characteristics of multiple materials and has functions such as microwave absorbing ability and structural support, and is widely used in the fields of electronic information and the like. Microwave absorbing composite materials include coated microwave absorbing composite materials, structural microwave absorbing composite materials, intelligent microwave absorbing composite materials, etc. Structural microwave absorbing composite materials are widely used, which have both load-bearing and microwave absorbing functions, and achieve "material as structure" by uniformly dispersing microwave absorbing agents in the matrix or designing multi-layer composite structures (such as honeycomb sandwich, laminate).

[0003] Microwave absorbing composite materials are inevitably damaged by various external forces during use, and small damage to microwave absorbing composite materials may cause a sharp decline in microwave absorbing performance. Therefore, timely repair must be carried out. Considering that the damaged parts of microwave absorbing composite materials vary in size, traditional repair processes face the problems of adapting the size of the replacement parts and the size matching, resulting in low repair efficiency. Summary of the Invention

[0004] The present invention aims to provide a method for patching and repairing composite materials based on the preferred number system, and realizes convenient and rapid repair of composite materials through standardizing the design of replacement parts by the preferred number system.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for patching and repairing composite materials based on the preferred number system, comprising the following steps:

[0007] S1. Determine the preferred number of the standard replacement part based on the damage range of the composite material and the preferred number system;

[0008] S2. After determining the damaged and repaired areas of the composite material, process the repaired area into a frustum-shaped hole, and process the same type and batch of materials into a frustum-shaped plate that fits the frustum-shaped hole. The large-end diameters of the frustum-shaped hole and the frustum-shaped plate refer to the preferred number of the standard replacement part in S1;

[0009] S3. Patch the pre-processed frustum-shaped plate to the frustum-shaped hole part through an adhesive bonding process, and then polish the adhesive bonding part to be flat to achieve complete repair.

[0010] Further, in S1, the preferred numbers include 40mm, 50mm, 62.5mm, 80mm, 100mm, 125mm, 160mm, 200mm.

[0011] Further, in S2, the angle between the generatrix of the frustum-shaped hole and the top surface or the bottom surface of the frustum-shaped hole is 30° to 60°; the angle between the generatrix of the frustum-shaped plate and the top surface or the bottom surface of the frustum-shaped plate is 30° to 60°.

[0012] Further, in S2, the large end diameter dimension of the frustum-shaped hole has a negative tolerance of 1 mm to 3 mm.

[0013] The beneficial effects of the technical solution are as follows:

[0014] A composite material patch repair method based on the preferred number system provided by the present invention, based on the basic theory of the preferred number system and the analysis and investigation of the damage size of the composite material, uses a composite series composed of the three series of R5, R10, and R10 / 3 to determine the preferred numbers (40 mm, 50 mm, 62.5 mm, 80 mm, 100 mm, 125 mm, 160 mm, 200 mm) of the standard fittings. This sequence takes into account both the size and the accessibility of the maintenance tools, realizes the interchangeability of maintenance, reduces the maintenance cost, can adapt to the emergency repair environment of the future battlefield, and realizes the economical, rapid, and effective repair of local damage of composite material components. And the plate patch is designed in a frustum shape, that is, the edge of the circular plate should be designed as a wedge with a taper of 30° to 60°, which can avoid the sudden change of the edge structure stiffness and generate stress concentration in the adhesive layer. Description of the Drawings

[0015] Figure 1 It is a schematic diagram of the frustum-shaped hole in a composite material patch repair method based on the preferred number system of the present invention;

[0016] Figure 2 It is a schematic diagram before and after cleaning and blowing ash of the square plate with a frustum-shaped hole processed by the present invention;

[0017] In the figure, (a) is the schematic diagram before cleaning and blowing ash; (b) is the schematic diagram after cleaning and blowing ash;

[0018] Figure 3 It is a schematic diagram before and after cleaning and blowing ash of the frustum-shaped plate processed by the present invention;

[0019] In the figure, (a) is the schematic diagram before cleaning and blowing ash; (b) is the schematic diagram after cleaning and blowing ash;

[0020] Figure 4 It is a schematic diagram of the fitting of the frustum-shaped plate and the frustum-shaped hole after processing by the present invention;

[0021] Figure 5 It is a schematic diagram of the repaired structural plate after equal-thickness treatment by a grinding machine and a partial enlarged schematic diagram;

[0022] In the figure, (a) is a schematic diagram of a structural board; (b) is a partially enlarged schematic diagram of (a). Detailed implementation mode

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and the implementation mode:

[0024] In the use of the wave-absorbing composite material, various external force damages are inevitably suffered. A small damage to the wave-absorbing composite material may cause a sharp decline in the wave-absorbing performance. Therefore, it must be repaired in time. Considering that the damaged parts of the wave-absorbing composite material are large and small, the traditional repair process faces the problems of adapting the size of the replacement parts and the size matching. For the method of repairing local damage of the composite material based on the standardized parts of the preferred number system, the standardized sizes of the parts and holes are the premise of its work. There are many preferred number systems in the related technologies. In the actual application process, it is a large workload to find the standardized sizes of the suitable parts and holes, resulting in a cumbersome repair process and low repair efficiency. Therefore, finding a suitable preferred number system is the core to improve its interchangeability. In order to better achieve the interchangeability of maintenance and reduce the maintenance cost, the present invention will provide a method for patching and repairing the composite material based on the preferred number system according to the basic theory of the preferred number system and analyzing the damage size range of the composite material.

[0025] A method for patching and repairing the composite material based on the preferred number system includes the following steps:

[0026] S1. Determine the preferred number of the standard parts based on the damage range of the composite material and the preferred number system;

[0027] Among them, the preferred number and the preferred number system were proposed by Charles Renard. After that, in order to commemorate him, the preferred number system was called the Rr number system. The national standard GB / T 321-2005 "Preferred numbers and preferred number systems" stipulates that the preferred number system consists of a series of decimal geometric progressions and stipulates 5 common series, with the code names Rr (r = 5, 10, 20, 40, 80). Among them, the 4 common series of R5, R10, R20, and R40 are basic series, and R80 is a supplementary series, which is only used in special occasions with very fine grading.

[0028] The common ratio of the preferred number system is shown in Table 1;

[0029] Table 1 Common ratio of the preferred coefficient

[0030]

[0031] Each of the preferred number systems is a preferred number. However, if calculated completely according to the common ratio of the preferred number, (except for the integer power of 10) they are all irrational numbers and generally cannot be directly used. Therefore, in practice, they are generally the common values after rounding. The common values that are often used are called preferred numbers, and generally five significant figures are taken.

[0032] Meanwhile, in production, the preferred number system also has two types: derivative series and composite series. Derivative series: In the Rr series, a derivative series can be formed by taking values at intervals with a certain term difference P, that is, the Rr / P series. For example, in the R10 series, by taking values with a term difference P = 3 (every other two terms), the R10 / 3 series can be formed, and its common ratio is. For example, 1, 2, 4, 8,...; 1.25, 2.5, 5, 10,... These all belong to this series, which is the commonly used multiple series. Composite series: It is a multi-common ratio series formed by mixing several common ratio series. For example, the series 10, 16, 25, 35.5, 50, 71, 100, 125, 160 is a composite series composed of three series: R5, R20 / 3, and R10.

[0033] Composite materials are very likely to be damaged during normal training and on the battlefield. During normal training, local damages such as scraping, impact, extrusion deformation, and debonding may occur. During wartime, in addition to the above damages, fragment damages caused by bullets, shells, etc. and shock damages caused by explosions will also occur. And the sizes of these damages are crucial for us to determine the preferred coefficient of the fittings.

[0034] Combined with the investigation of the damage sizes of composite materials, it can be known that the damage sizes of these devices to the surface generally do not exceed 400 mm, and the minimum is about 3 mm. At the same time, combined with the actual sizes of composite material components and the actual situation, when the damage size is greater than 200 mm, it is often accompanied by the damage of electronic devices, heat insulation layers, etc. in the internal structure. At this time, the possibility of relying on on-site repair is relatively small. Therefore, the upper limit of the diameter of the standardized repair fittings is set to d = 200 mm. Similarly, the setting of the lower limit of the radius of the fitting size also needs to consider its own conditions and repair conditions. For example: calculated according to the thickness of the composite material of 25 mm and the wedge angle (the angle between the bus and the top or bottom surface of the frustum) of 30° - 60°, as Figure 1 shown, when the radius of the upper surface size is 40 mm, the radius of the lower surface size is 19.5 mm - 28 mm. If the thickness is increased further, the lower surface size will be smaller, which is not conducive to the processing and on-site repair of the fittings. Therefore, within the current size range, the upper limit of the radius of the standardized repair fittings is set to r = 40 mm. Based on these upper and lower limits, the principle of the composite coefficient in the preferred number is used to determine the preferred number. After optimization, the composite series composed of the three series R5, R10, and R10 / 3 is finally used to determine the preferred number of the standard fittings. The specific values are shown in Table 2. This sequence takes into account both the size and the accessibility of the repair tools, can adapt to the emergency repair environment of the future battlefield, and realizes the economical, rapid, and effective repair of local damages of composite material components.

[0035] Table 2 Preferred numbers of fitting radii (unit: mm)

[0036] 40 50 62.5 80 100 125 160 200

[0037] S2. After determining the damaged and repaired areas of the composite material, use a portable cutting machine to process the repaired area into a frustum-shaped hole. The angle between the generatrix of the frustum-shaped hole and the top surface or the bottom surface of the frustum-shaped hole is 60°. Process the material of the same model and batch into a frustum-shaped plate that fits the frustum-shaped hole. The angle between the generatrix of the frustum-shaped plate and the top surface or the bottom surface of the frustum-shaped plate is 60°. The major end diameters of the frustum-shaped hole and the frustum-shaped plate refer to the preferred numbers of the standard fittings in S1. A number of frustum-shaped plates can be pre-processed. In actual applications, cut out the frustum-shaped hole according to the size of the damaged part and use it directly.

[0038] Among them, generally, the shape of the plate patch should not be too special, and there should be sufficient fillet transitions when it changes. The edge of the patch should be designed as a wedge with a certain taper to avoid sudden changes in the edge structural stiffness and generate stress concentration in the adhesive layer. Therefore, the edge of the patch is designed as a 60° wedge here. Considering the convenience of processing honeycomb structure composite materials, use a straight shank three-edge chamfering tool with the same angle to process the damaged part into a 60° wedge-shaped hole, as Figure 1 shown. The selection of the tool rotation speed and feed rate should be set in combination with the structural characteristics of the composite material to minimize the occurrence of problems such as edge damage, fiber pull-out, cracking, and burning. In addition, to make the frustum-shaped plate fit the cut of the frustum-shaped hole, the surface diameter size of the frustum-shaped hole should be set with a negative tolerance of 1 mm to 3 mm.

[0039] S3. Repair the pre-processed frustum-shaped plate to the frustum-shaped hole part through the bonding process, and then polish the bonded part to achieve a complete repair.

[0040] According to the above repair method steps, the following experiments were carried out:

[0041] Select a number of square plate products of the same batch and model with a size of 300 mm × 300 mm and a thickness ≤ 25 mm. First, fix the cutting machine on the plate, determine the cutting size and the center of the frustum according to the size and position of the damaged part, start the cutting machine, and cut out a 60° (oblique joint angle, that is, the angle between the surface and the conical surface) frustum-shaped hole, then repair the pre-processed frustum to the cutting part through the bonding process, and finally polish the bonded part to achieve a complete repair. The repair result diagram is as Figures 2 - 5 .

[0042] In summary, a composite material patch repair method based on the preferred number system provided by the present invention, based on the basic theory of the preferred number system and the analysis and investigation of the damage size of composite materials, uses a composite series composed of three series of R5, R10, and R10 / 3 to determine the preferred numbers of standard fittings (40mm, 50mm, 62.5mm, 80mm, 100mm, 125mm, 160mm, 200mm). This sequence takes into account both the size and the accessibility of maintenance tools, realizes the interchangeability of maintenance, reduces the maintenance cost, can adapt to the emergency repair environment of the future battlefield, and realizes the economical, rapid and effective repair of local damage of composite material components. And the plate patch is designed in a frustum shape, that is, the edge of the circular plate should be designed as a wedge with a taper of 30° to 60°, which can avoid the sudden change of the edge structural stiffness and generate stress concentration in the adhesive layer.

[0043] The above are only the embodiments of the present invention. Specific technical solutions or common knowledge such as characteristics well known in the art are not described in detail herein. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners and other records in the specification can be used to explain the content of the claims.

Claims

1. A composite material patch repair method based on the preferred number system, characterized in that It includes the following steps: S1. Determine the preferred numbers of standard fittings based on the damage range of the composite material and the preferred number series; S2. After determining the damaged and repaired areas of the composite material, process the repaired area into a frustum-shaped hole, process the same type and batch of materials into a frustum-shaped plate that fits the frustum-shaped hole, and the major diameters of the frustum-shaped hole and the frustum-shaped plate refer to the preferred numbers of the standard fittings in S1; S3. Patch the pre-processed frustum-shaped plate to the frustum-shaped hole part through the bonding process, and then polish the bonded part to achieve a complete repair.

2. A method for composite material patch repair based on the preferred number system according to claim 1, characterized in that: In S1, the preferred numbers include 40mm, 50mm, 62.5mm, 80mm, 100mm, 125mm, 160mm, 200mm.

3. A composite material patching and repairing method based on the preferred number system according to claim 1, characterized in that: In S2, the angle between the generatrix of the frustum-shaped hole and the top surface or the bottom surface of the frustum-shaped hole is 30° - 60°; the angle between the generatrix of the frustum-shaped plate and the top surface or the bottom surface of the frustum-shaped plate is 30° - 60°.

4. A composite material patching and repairing method based on the preferred number system according to claim 1, characterized in that: In S2, the major diameter dimension of the frustum-shaped hole has a negative tolerance of 1mm - 3mm.

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