Connecting structure and connecting method of metal and composite material
By using connecting plates and composite plates with thermal expansion coefficient matching in the connection structure between metal and composite materials, and using fasteners and bushings to provide preload and uniform contact area, the failure and insufficient strength of the existing connecting structures in temperature changes and vibration environments is solved, and higher connection strength, stability and maintenance are achieved.
Patent Information
- Application Number
- CN202411781971.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-04
- Publication Date
- 2025-03-28
AI Technical Summary
The connecting structures of existing metals and composite materials are prone to failure and have poor strength, especially in temperature changes and vibration environments, which can easily lead to structural failure and poor maintenance properties of the connecting parts.
A metal-composite connection structure is adopted, including connecting plates, composite plates, bushings and fasteners. The thermal expansion coefficient of the connecting plate and the composite plate is small. Through the cooperation of the fasteners and bushings, a preload force and a uniform contact area are provided to enhance the strength and stability of the connection.
It effectively reduces strain differences caused by temperature changes, improves the load-bearing capacity and tensile fatigue resistance of the connection, avoids the problems of loosening and disengagement of composite plates under pressure or vibration environments, and improves maintenance and removability.
Smart Images
Figure CN119712674A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of heterogeneous material connection, and in particular to a connection structure and a connection method of metal and composite materials. Background Art
[0002] At present, the most commonly used method for connecting metal and composite materials on aircraft is still the traditional metal structure connection method, that is, the metal and composite materials are respectively connected to a metal connector through bolts to achieve force transmission. This method does not take into account the difference in thermal expansion properties between metal and composite materials, which can easily lead to structural failure of the connection part.
[0003] Although after continuous technological development, a more advanced HYPER (Hybrid penetrative reinforcement) connection joint was subsequently developed, that is, by processing multiple rows of tiny pins at the end of a titanium alloy connector, and then laying the composite material on the end and curing it together with the connector, so that the pins are embedded in the composite material, this connection method is easy to cause the composite material to split at the pins when the joint is tensile, forming a through crack, which leads to connection failure. At the same time, since the pins are embedded in the thickness direction of the composite material, the tensile performance of the laminated layer is greatly reduced, and since the pins are not constrained in the thickness direction of the composite material, when the composite material is compressed or vibrated, the connection is easy to break away from the pins, resulting in connection failure. That is, although the existing HYPER joint alleviates the problem of the difference in thermal expansion properties between metal and composite materials, its tensile and fatigue resistance is not high, and it is easy to produce strength problems, and it is difficult to apply to the main load-bearing structure with large loads. In addition, due to the matching method of curing after the pins are inserted into the composite material, if the connector fails, it can only be repaired together with the composite material, and it is not detachable and has poor maintainability. Summary of the invention
[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a connection structure and a connection method of metal and composite materials, so as to solve the problem that the connection structure of metal and composite materials in the prior art is prone to failure and has poor strength.
[0005] To achieve the above-mentioned purpose and other related purposes, one aspect of the present invention provides a connection structure between metal and composite materials, including: a connection plate, one end of which is provided with a connection portion, the connection portion is provided with a plurality of first connection holes, and the other end of the connection plate is used to connect with the metal member; a composite material plate, one end of which is provided with a plurality of second connection holes; a plurality of bushings, the number of the bushings corresponds to the number of the first connection holes, one end of the bushing is embedded in the first connection hole, and the other end of the bushing is embedded in the second connection hole; a fastener, the fastener includes a connecting rod, the connecting rod is sleeved in the bushing, one end of the connecting rod is provided with a positioning flange, the other end of the connecting rod is threadedly connected with a fastening flange, the positioning flange is in conflict with the connection plate or the composite material plate, and the fastening flange is in conflict with the composite material plate or the connection plate; wherein the thermal expansion coefficient of the connection plate is α 1 , the thermal expansion coefficient of the composite material plate is α 2 , 0.5α 2 ≤α 1 ≤4α 2 .
[0006] Furthermore, the connecting portion includes a plurality of first step portions, each of which is provided with a plurality of first connecting holes, and the thickness of the plurality of first step portions decreases successively from the end away from the composite material plate to the direction close to the composite material plate; a plurality of second step portions are provided at the end of the composite material plate connected to the connecting portion, each of which is provided with a plurality of second connecting holes, and the thickness of the plurality of second step portions decreases successively from the end away from the connecting plate to the direction close to the connecting plate; the plurality of second step portions on the composite material plate are fitted one-to-one with the plurality of first step portions on the connecting portion.
[0007] Furthermore, a connection point between two adjacent first step portions and a connection point between two adjacent second step portions are both inclined surfaces.
[0008] Furthermore, the material of the connecting plate is titanium alloy, and the material of the composite material plate is carbon fiber reinforced composite material or glass fiber reinforced composite material.
[0009] Furthermore, the bushing is made of aluminum alloy.
[0010] Furthermore, the fastener is a bolt.
[0011] Furthermore, one end of the bushing is flush with the surface of the connecting plate, and the other end of the bushing is flush with the surface of the composite material plate.
[0012] As described above, the connection structure of metal and composite materials of the present invention has the following beneficial effects: compared with the traditional mechanical connection method, in the present invention, since the difference in thermal expansion coefficients between the connecting plate and the composite material plate is small, the strain difference caused by temperature changes can be greatly reduced, thereby alleviating the problem of extrusion damage to the hole edges of the composite material plate. At the same time, compared with the existing HYPER joint, in the present invention, the fastener is inserted into the connecting plate and the composite material plate through the bushing, and the bushing and the composite material plate are consistent in the entire thickness direction, the contact area is increased, and the bearing capacity is stronger; secondly, because the fastener provides a pre-tightening force in the thickness direction of the composite material plate, the interlayer performance of the composite material plate at the connection part is greatly improved, thereby preventing the composite material plate from loosening and detaching under pressure or vibration environment; at the same time, due to the presence of the bushing, the stress gradient at the edge of the first connecting hole and the second connecting hole can be reduced, which can effectively improve the bearing capacity of the connection part; on the other hand, the connecting plate and the composite material plate are connected by a fastener, and one end of the fastener adopts a threaded connection fastening flange, so it is easy to disassemble. When the connecting plate needs to be replaced or repaired in the later stage, the fastener is removed and the bushing is pulled out, and the connecting plate can be disassembled separately, which is convenient for later maintenance and has good maintainability.
[0013] Another aspect of the present invention provides a method for connecting the above-mentioned metal and composite material connection structure, and the method for connecting the metal and composite material comprises the following steps:
[0014] S1. A connecting portion is provided at one end of the connecting plate, and a plurality of first connecting holes are provided on the connecting portion;
[0015] S2. Disposing a bushing in the first connecting hole, so that one end of the bushing is embedded in the first connecting hole and the other end of the bushing protrudes upward from the surface of the connecting portion;
[0016] S3, laying unidirectional tapes layer by layer at the connection part, and after laying each layer of unidirectional tape, applying downward pressure to the unidirectional tape through a punching die, so that the other end of the bushing is embedded in the unidirectional tape, and the two unidirectional tapes adjacent to each other are closely fitted, and multiple stacked unidirectional tapes form a composite material plate;
[0017] S4, placing the connecting plate and the composite material plate connected in step 3 into an autoclave for curing, so that the multiple stacked unidirectional tapes are solidified together;
[0018] S5. Connect a fastener in the bushing.
[0019] Furthermore, the material of the connecting plate is titanium alloy, and the material of the unidirectional tape is carbon fiber reinforced composite material or glass fiber reinforced composite material.
[0020] The beneficial effects of the method for connecting metal and composite materials of the present invention are the same as the beneficial effects of the above-mentioned structure for connecting metal and composite materials, so they will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic structural diagram of the connection structure of metal and composite material provided by the present invention (fasteners omitted).
[0022] Figure 2 An exploded view of the connection structure of metal and composite material provided by the present invention (fasteners omitted) is shown.
[0023] Figure 3 An exploded view of the connecting plate and bushing provided by the present invention relative to the composite material plate is shown.
[0024] Figure 4 It shows a schematic diagram of the operation of pressing the composite material plate and the bushing provided by the present invention.
[0025] Description of Reference Numerals
[0026] 10 Connecting plates
[0027] 11. Connection
[0028] 111 First step
[0029] 101 First connection hole
[0030] 20 Composite material board
[0031] 21 Second step
[0032] 201 Second connection hole
[0033] 30 Bushing
[0034] 200 Punching die DETAILED DESCRIPTION
[0035] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.
[0036] In the description of the present invention, it should be noted that, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used in the present invention to indicate the orientation or position relationship is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.
[0038] See also Figures 1 to 4 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.
[0039] A first aspect of the present invention provides a connection structure between metal and composite material, such as Figure 1 and Figure 2 As shown, the connection structure includes a connection plate 10, a composite material plate 20, a plurality of bushings 30 and a fastener (not shown in the figure), wherein one end of the connection plate 10 is provided with a connection portion 11, and the connection portion 11 is provided with a plurality of first connection holes 101, and the other end of the connection plate 10 is used to connect with the metal member; one end of the composite material plate 20 is provided with a plurality of second connection holes 201, and the number of the bushings 30 corresponds to the number of the first connection holes 101, one end of the bushing 30 is embedded in the first connection hole 101 on the connection plate 10, and the other end of the bushing 30 is embedded in the second connection hole 201 on the composite material plate 20; the thermal expansion coefficient of the connection plate 10 is defined as α 1 , the thermal expansion coefficient of the composite material plate 20 is α 2 , 0.5α 2 ≤α 1 ≤4α 2The fastener includes a connecting rod, which is inserted into a bushing, one end of the connecting rod is provided with a positioning flange, and the other end of the connecting rod is threadedly connected with a fastening flange, the positioning flange is in conflict with the connecting plate 10 or the composite material plate 20, and the fastening flange is in conflict with the composite material plate 20 or the connecting plate 10, that is, when the positioning flange is in conflict with the connecting plate 10, the fastening flange is in conflict with the composite material plate 20, and when the positioning flange is in conflict with the composite material plate 20, the fastening flange is in conflict with the connecting plate 10.
[0040] The beneficial effects of the connection structure of metal and composite materials of the present invention are as follows: compared with the traditional mechanical connection method, in the present invention, since the difference in thermal expansion coefficients between the connecting plate 10 and the composite material plate 20 is small, the strain difference caused by temperature changes can be greatly reduced, effectively alleviating the problem of extrusion damage to the hole edges of the composite material plate. At the same time, compared with the existing HYPER joint, in the present invention, the fastener is inserted into the connecting plate 10 and the composite material plate 20 through the bushing, and the bushing 30 and the composite material plate 20 are consistent in the entire thickness direction, the contact area is increased, and the bearing capacity is stronger; secondly, because the fastener provides a pre-tightening force in the thickness direction of the composite material plate 20, the interlayer performance of the composite material plate at the connection part is greatly improved, thereby preventing the composite material plate from loosening and detaching under pressure or vibration environment; at the same time, due to the presence of the bushing, the stress gradient at the edge of the first connecting hole and the second connecting hole can be reduced, which can effectively improve the bearing capacity of the connection part; on the other hand, the connecting plate and the composite material plate are connected by a fastener, and one end of the fastener adopts a threaded connection fastening flange, so it is easy to disassemble. When the connecting plate needs to be replaced or repaired in the later stage, the fastener is removed and the bushing is pulled out, and the connecting plate can be disassembled separately, which is convenient for later maintenance and has good maintainability.
[0041] Further, in this embodiment, one end of the bushing 30 is flush with the surface of the connecting plate 10, that is, one end of the bushing is on the same horizontal plane as the surface of the connecting plate 10, and the other end of the bushing 30 is flush with the dial of the composite material plate 20, that is, the other end of the bushing is on the same horizontal plane as the surface of the composite material plate 20. That is, in this embodiment, the height of the bushing 30 is equal to the sum of the thickness of the connecting plate 10 and the composite material plate 20. Through this structural design, the fastener can make the connecting plate 10 and the composite material plate 20 fit more tightly, so that the fastener can more effectively provide pre-tightening force in the thickness direction of the composite material plate 20.
[0042] Specifically, in this embodiment, the fastener is a bolt, which has a simple structure and low cost.
[0043] Further, such as Figure 2As shown, in this embodiment, the connection part 11 includes a plurality of first steps 111, each of which is provided with a plurality of first connection holes 101, and the thickness of the plurality of first steps 111 decreases from the end away from the composite material plate 20 to the direction close to the composite material plate 20. Correspondingly, the end of the composite material plate 20 connected to the connection part 11 is provided with a plurality of second steps 21, each of which is provided with a plurality of second connection holes 201, and the thickness of the plurality of second steps 21 decreases from the end away from the connection plate 10 to the direction close to the connection plate 10. The plurality of second steps 21 on the composite material plate 20 and the plurality of first steps 111 on the connection part 11 are fitted one by one. Through the design of this structure, the connection between the connection plate 10 and the composite material plate 20 is set to a gradual thickness change, so that the force transmission effect is better, no sudden force is generated, and the connection is stable.
[0044] Furthermore, in order to further improve the stability of the connection between the connecting plate 10 and the composite material plate 20, as a preferred embodiment, Figure 2 As shown, the connection between two adjacent first step portions 111 is in the shape of an inclined surface, i.e., a slope. Accordingly, the connection between two adjacent second step portions 21 on the composite material plate 20 is also in the shape of an inclined surface, i.e., a slope. When the first step portion and the second step portion are in contact with each other, the inclined surface at the connection between the two adjacent first step portions 111 is in contact with the inclined surface at the connection between the two adjacent second step portions 21. Through this structural design, the force transmission effect can be further improved, sudden force can be avoided, and the stability of the connection between the connecting plate 10 and the composite material plate 20 can be improved.
[0045] Furthermore, in this embodiment, the material of the connecting plate 10 is preferably titanium alloy, and the material of the composite material plate 20 is preferably carbon fiber.
[0046] Furthermore, in this embodiment, the bushing 30 is made of aluminum alloy, which is light in weight and high in structural strength, and is very suitable for use in aircraft.
[0047] Another aspect of the present invention also provides a connection method of the above-mentioned metal and composite material connection structure. Specifically, the metal and composite material connection method comprises the following steps:
[0048] S1. A connecting portion is provided at one end of the connecting plate, and a plurality of first connecting holes are provided on the connecting portion;
[0049] S2. Disposing a bushing in the first connecting hole, so that one end of the bushing is embedded in the first connecting hole and the other end of the bushing protrudes upward from the surface of the connecting portion;
[0050] S3, laying unidirectional tapes layer by layer at the connection part, and after laying each layer of unidirectional tape, applying downward pressure to the unidirectional tape through a punching die, so that the other end of the bushing is embedded in the unidirectional tape, and the two unidirectional tapes adjacent to each other are closely fitted, and multiple stacked unidirectional tapes form the composite material plate;
[0051] Specifically, in this step S3, it can be understood that in the field of composite materials, "Unidirectional Tape" (UD tape for short) is a special form of fabric, which is composed of unidirectionally arranged fibers, which are impregnated in resin and pressed into a strip material. Specifically, in this embodiment, the material of the unidirectional tape is preferably carbon fiber reinforced composite material, and the material of the connecting plate is preferably titanium alloy. Since the difference between the thermal expansion coefficient of the titanium alloy and the thermal expansion coefficient of the carbon fiber is small, the strain difference between the connecting plate and the composite plate caused by temperature change can be greatly reduced, and the hole edge extrusion damage problem of the composite plate can be alleviated. In other optional embodiments, the material of the unidirectional tape can also be other materials such as glass fiber reinforced composite materials, as long as the thermal expansion coefficient of the connecting plate is greater than or equal to 0.5 times the thermal expansion coefficient of the composite plate, and less than or equal to 4 times the thermal expansion coefficient of the composite plate. Such a preferred range is sufficient.
[0052] It can be understood that in this embodiment, the second connection hole on the unidirectional tape, i.e., the composite material plate, is a hole punched directly on the unidirectional tape by the bushing 30 when the unidirectional tape is pressed downward by the punching die 200. Preferably, a through hole matching the outer diameter of the bushing is provided on the pressing block module 200.
[0053] S4, placing the connecting plate and the composite material plate connected in step 3 into an autoclave for curing, so that the multiple stacked unidirectional tapes are solidified together;
[0054] By inserting the bushing into multiple stacked prepreg unidirectional tapes (impregnated with resin), and then placing the connecting plate and the composite board formed by the multiple stacked unidirectional tapes into an autoclave for high-temperature curing, the bushing can be bonded to the resin on the composite board, so that the bushing and the composite board fit better, and the hole edge defect problem caused by drilling holes in the composite board can be effectively eliminated.
[0055] S5. Connect a fastener in the bushing.
[0056] In summary, compared with the traditional mechanical connection method, the connection structure and connection method of metal and composite materials in the present invention can greatly reduce the strain difference caused by temperature change and alleviate the problem of extrusion damage of the hole edge of the composite material. The connection hole of the fastener, that is, the bolt hole, is made by inserting the bushing into the wet composite plate, and then high-temperature curing and integrally forming it, with good fit, eliminating the hole edge defect problem caused by making holes in the composite material plate; at the same time, compared with the existing HYPER joint, in the present invention, the fastener is inserted into the connecting plate 10 and the composite material plate 20 through the bushing, and the bushing 30 and the composite material plate 20 are consistently matched in the entire thickness direction, the contact area is increased, and the load-bearing capacity is improved. The force is stronger; secondly, because the fastener provides a pre-tightening force in the thickness direction of the composite material plate 20, the interlayer performance of the composite material plate at the connection part is greatly improved, thereby preventing the composite material plate from loosening and detaching under pressure or vibration; at the same time, due to the presence of the bushing, the stress gradient at the edge of the first connection hole and the second connection hole can be reduced, which can effectively improve the bearing capacity of the connection part; on the other hand, the connecting plate and the composite material plate are connected by bolts, so it is easy to disassemble. When the connecting plate needs to be replaced or repaired later, the bolts and bushings can be removed to realize the separate disassembly of the connecting plate, which is convenient for later maintenance and has good maintainability. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.
[0057] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.
Claims
1. A connection structure of metal and composite material, characterized in that: include: A connecting plate, one end of which is provided with a connecting portion, the connecting portion is provided with a plurality of first connecting holes, and the other end of the connecting plate is used to be connected to a metal member; A composite material plate, wherein one end of the composite material plate is provided with a plurality of second connection holes; A plurality of bushings, the number of the bushings corresponds to the number of the first connecting holes, one end of the bushing is embedded in the first connecting hole, and the other end of the bushing is embedded in the second connecting hole; A fastener, the fastener comprising a connecting rod, the connecting rod is sleeved in the bushing, one end of the connecting rod is provided with a positioning flange, the other end of the connecting rod is threadedly connected with a fastening flange, the positioning flange is in conflict with the connecting plate or the composite material plate, and the fastening flange is in conflict with the composite material plate or the connecting plate; The thermal expansion coefficient of the connecting plate is α1, the thermal expansion coefficient of the composite material plate is α2, and 0.5α2≤α1≤4α2.
2. A connection structure of metal and composite material according to claim 1, characterized in that: The connecting portion includes a plurality of first step portions, each of which is provided with a plurality of first connecting holes, and the thickness of the plurality of first step portions decreases successively from the end away from the composite material plate to the direction close to the composite material plate; a plurality of second step portions are provided at one end of the composite material plate connected to the connecting portion, each of which is provided with a plurality of second connecting holes, and the thickness of the plurality of second step portions decreases successively from the end away from the connecting plate to the direction close to the connecting plate; the plurality of second step portions on the composite material plate are fitted one-to-one with the plurality of first step portions on the connecting portion.
3. A connection structure of metal and composite material according to claim 2, characterized in that: The connection point of two adjacent first step portions and the connection point of two adjacent second step portions are both inclined surfaces.
4. The connection structure of metal and composite material according to claim 1, characterized in that: The material of the connecting plate is titanium alloy, and the material of the composite material plate is carbon fiber reinforced composite material or glass fiber reinforced composite material.
5. The connection structure of metal and composite material according to claim 1, characterized in that: The bushing is made of aluminum alloy.
6. The connection structure of metal and composite material according to claim 1, characterized in that: The fastener is a bolt.
7. The connection structure of metal and composite material according to claim 1, characterized in that: One end of the bushing is flush with the surface of the connecting plate, and the other end of the bushing is flush with the surface of the composite material plate.
8. A method for connecting a metal and composite material connection structure according to any one of claims 1 to 7, characterized in that: The method for connecting metal and composite material comprises the following steps: S1. A connecting portion is provided at one end of the connecting plate, and a plurality of first connecting holes are provided on the connecting portion; S2. Disposing a bushing in the first connecting hole, so that one end of the bushing is embedded in the first connecting hole and the other end of the bushing protrudes upward from the surface of the connecting portion; S3, laying unidirectional tapes layer by layer at the connection part, and after laying each layer of unidirectional tape, applying downward pressure to the unidirectional tape through a punching die, so that the other end of the bushing is embedded in the unidirectional tape, and the two unidirectional tapes adjacent to each other are closely fitted, and multiple stacked unidirectional tapes form a composite material plate; S4, placing the connecting plate and the composite material plate connected in step 3 into an autoclave for curing, so that the multiple stacked unidirectional tapes are solidified together; S5. Connect a fastener in the bushing.
9. A method for connecting metal and composite materials according to claim 8, characterized in that: The material of the connecting plate is titanium alloy, and the material of the unidirectional belt is carbon fiber reinforced composite material or glass fiber reinforced composite material.