A ceramic rivet suitable for connecting ceramic matrix composite laminates and a method of assembling the same

Abstract

The application relates to the field of ceramic matrix composite component manufacturing, and discloses a ceramic rivet suitable for connecting ceramic matrix composite laminates and an assembling method thereof. The rivet is designed as a split pin shaft and a mesh sleeve. The pin shaft is in a rod-shaped structure, the mesh sleeve is in a ring-shaped mesh structure in section, and the two side end heads are designed as reduced-diameter structures. The mesh sleeve is sleeved outside the pin shaft and located between the rivet hole and the pin shaft. During assembling, the mesh sleeve is extruded into the rivet hole so that the outer diameter of the mesh sleeve matches the inner diameter of the hole, and then the pin shaft is extruded into the mesh sleeve. The reduced-diameter end heads of the mesh sleeve are expanded and attached to the hole wall under the extrusion of the pin shaft, so that macro mechanical self-locking is formed. Meanwhile, through the flexible mesh sleeve as a buffer layer, collaborative locking is realized, and the problem that the existing rigid riveting is prone to stress concentration at the hole edge and causes great damage to the structural strength is avoided.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composite component manufacturing, and discloses a ceramic rivet suitable for connecting ceramic matrix composite laminates and its assembly method. Background Technology

[0002] The fabrication of fiber-reinforced ceramic matrix composite (FMC) components is limited by the inability to bend ceramic fibers in complex ways, and preforms typically cannot achieve the fabrication of intricate and complex structures. Therefore, connection technology has become a key technology restricting the current use of FMC. Connection technologies mainly include mechanical connections (screws and riveting) and adhesives. Existing mechanical connection technologies have significant shortcomings. Rigid connections are prone to stress concentration at the hole edges, and the processing cost of ceramic matrix composite bolts is high, and the processing damages continuous fibers, resulting in significant impairment to their structural strength. Summary of the Invention

[0003] The purpose of this invention is to provide a ceramic rivet and its assembly method suitable for connecting ceramic matrix composite laminates. By using a flexible mesh sleeve as a buffer layer, the pin is squeezed into the mesh sleeve to achieve coordinated locking, thus avoiding the problem that existing rigid riveting is prone to stress concentration at the hole edge, which causes significant damage to its structural strength.

[0004] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:

[0005] A ceramic rivet suitable for connecting ceramic matrix composite laminates, comprising: The pin is a rod-shaped structure, and the pin is used to be inserted into the rivet hole of the riveting structure; The mesh sleeve has a ring-shaped mesh structure in cross-section, and the two ends of the mesh sleeve are set with a reduced diameter structure. The mesh sleeve is disposed between the rivet hole and the pin.

[0006] Furthermore, the mesh sleeve has a fiber woven structure, and a filling and curing structure is also provided within the mesh-like porous structure of the mesh sleeve.

[0007] Furthermore, one end of the pin is configured as a tapered or frustum-shaped structure.

[0008] Furthermore, the pin has a necked section at the middle position.

[0009] To achieve the above-mentioned technical effects, the present invention also provides an assembly method for ceramic rivets suitable for connecting ceramic matrix composite laminates. This method, based on the aforementioned ceramic rivets suitable for connecting ceramic matrix composite laminates, includes: The mesh sleeve is squeezed into the rivet hole used to connect the two connectors; The pin is forced into the mesh sleeve so that the outer diameter of the pin matches the inner diameter of the mesh sleeve.

[0010] Furthermore, before or after inserting the pin into the mesh sleeve, a ceramic polymer precursor is injected into the rivet hole to cure and form the filled and cured structure.

[0011] Furthermore, the filled and cured structure includes at least one of ceramic particle reinforcement phase, ceramic short fiber reinforcement phase, or ceramic whisker reinforcement phase.

[0012] Furthermore, the rivet holes used to connect the two connectors have a smaller diameter in the middle and a larger diameter at both ends, forming a constricted shape.

[0013] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention designs the rivet as a separate pin and a mesh sleeve. The pin has a rod-like structure, and the mesh sleeve has a ring-shaped cross-section with tapered ends. The mesh sleeve is fitted outside the pin and located between the rivet hole and the pin. During assembly, the mesh sleeve is inserted into the rivet hole so that its outer diameter matches the inner diameter of the hole. Then, the pin is inserted into the mesh sleeve. The tapered ends of the mesh sleeve expand and conform to the hole wall under the pressure of the pin, forming a macroscopic mechanical self-locking mechanism. Simultaneously, the flexible mesh sleeve acts as a buffer layer, achieving coordinated locking and avoiding the problem of stress concentration at the hole edge, which significantly damages the structural strength of existing rigid riveting methods. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the mesh sleeve structure in the embodiment; Figure 2 This is a schematic diagram of the installation structure of the mesh sleeve and the pin shaft in the embodiment; Figure 3 This is a schematic diagram of the structure of the mesh sleeve and pin after they are inserted into the rivet holes in the embodiment. Figure 4 This is a schematic diagram showing the process after removing excess rivets from the surface of the laminate in the embodiment. Figure 5 This is a schematic diagram of the installation structure of the pin structure with the necked section in the rivet hole in the embodiment; Among them, 1. Pin; 2. Rivet hole; 3. Mesh sleeve; 4. Neck section. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0016] Example 1 See Figures 1 to 4 A ceramic rivet suitable for connecting ceramic matrix composite laminates, comprising: Pin 1 is a rod-shaped structure, and pin 1 is used to be inserted into the rivet hole 2 of the riveting structure; The mesh sleeve 3 has a ring-shaped mesh structure in cross-section. The two ends of the mesh sleeve 3 are set with a reduced diameter structure. The mesh sleeve 3 is disposed between the rivet hole 2 and the pin shaft 1.

[0017] In this embodiment, the rivet includes a pin 1 and a mesh sleeve 3. The pin 1 has a rod-shaped structure, and the mesh sleeve 3 has a ring-shaped mesh structure in cross-section, with both ends configured as a reduced-diameter structure. The mesh sleeve 3 is fitted outside the pin 1 and located between the rivet hole 2 and the pin 1. During assembly, the mesh sleeve 3 is squeezed into the rivet hole 2 so that its outer diameter matches the inner diameter of the hole. Then, the pin 1 is squeezed into the mesh sleeve 3. The reduced-diameter ends of the mesh sleeve 3 are squeezed by the pin 1 and expand to fit against the hole wall, forming a macroscopic mechanical self-locking. At the same time, the flexible mesh sleeve 3 acts as a buffer layer to achieve coordinated locking, avoiding the problem that existing rigid riveting is prone to stress concentration at the hole edge, which can cause significant damage to its structural strength.

[0018] Example 2 See Figures 1 to 4 This embodiment provides a ceramic rivet structure and its assembly method. The ceramic rivet includes two parts: a pin 1 and a mesh sleeve 3. The pin 1 is a dense fiber-reinforced ceramic matrix composite material, with continuous fibers in the axial direction, minimizing the impact of processing on the strength of the pin 1. The pin 1 has a rod-like structure with a uniform outer diameter cylindrical shape, and one end is tapered. The outer surface is appropriately roughened to increase adhesion. The mesh sleeve 3 is woven from ceramic fibers, with a ring-shaped mesh structure in the cross-section, possessing a certain degree of deformation capability. The woven mesh has numerous pores in the middle. The mesh sleeve 3 has a uniform outer diameter and a gradually decreasing inner diameter, meaning the ends of the mesh sleeve 3 are tapered, and the thickness gradually increases from the middle to both ends. The mesh sleeve 3 is fitted onto the outside of the pin 1, with the inner diameter of the mesh sleeve 3 matching the outer diameter of the pin 1.

[0019] During assembly, rivet holes 2 are first machined on the ceramic matrix composite (CMC) laminate to be riveted. The rivet holes 2 have a narrower diameter in the middle and wider diameters at both ends, forming a necked shape, and the surface of the holes is appropriately roughened to increase adhesion. A mesh sleeve 3 with an outer diameter between the maximum and minimum inner diameters of the rivet holes 2 is selected and inserted into the rivet holes 2, so that the outer diameter of the mesh sleeve 3 matches the inner diameter of the rivet holes 2.

[0020] Next, select a pin 1 with an outer diameter slightly smaller than the minimum inner diameter of the rivet hole 2, and insert the pin 1 into the mesh sleeve 3 so that the outer diameter of the pin 1 matches the inner diameter of the mesh sleeve 3. The tapered end of the pin 1 completely protrudes from the mesh sleeve 3. When the pin 1 is inserted, the tapered end of the mesh sleeve 3 is compressed and expands, tightly fitting against the wall of the rivet hole 2, forming a macroscopic mechanical self-locking effect.

[0021] To further enhance the riveting strength, a ceramic polymer precursor can be injected into the rivet hole 2 before or after the pin 1 is inserted into the mesh sleeve 3. Specifically, a suitable ceramic reinforcing phase, such as at least one of ceramic particle reinforcing phase, ceramic short fiber reinforcing phase, or ceramic whisker reinforcing phase, is selected and added to the ceramic polymer precursor solution to form a ceramic polymer precursor suspension containing the reinforcing phase. This ceramic polymer precursor solution is an organic polymer that undergoes pyrolysis at high temperature to generate a ceramic matrix. The suspension is then permeated into the mesh-like porous structure of the mesh sleeve 3.

[0022] The riveting structure, after being injected with the ceramic polymer precursor, is placed in a high-temperature pyrolysis furnace for high-temperature pyrolysis, causing the ceramic polymer precursor to decompose into a ceramic matrix. The resulting ceramic matrix contains reinforcing phases such as ceramic particles, short fibers, or whiskers. Simultaneously, the continuous ceramic fibers in the mesh sleeve 3 also reinforce the pyrolyzed ceramic matrix. The ceramic matrix solidifies within the pores of the mesh sleeve 3, forming a filled and solidified structure. This filled and solidified structure forms a microscopic interlock with the pin shaft 1 and the wall of the layer plate holes, further improving the riveting strength.

[0023] The ceramic polymer precursor injection and high-temperature pyrolysis steps were repeated multiple times until the ceramic matrix density met the preset requirements. Finally, the surface of the rivet holes 2 in the ceramic matrix composite laminate was finished to remove excess rivet portions from the laminate surface, such as... Figure 4 As shown, the rivets are flush with the surface of the shelf to meet the surface condition requirements.

[0024] This embodiment avoids direct connection between the rigid hole and the rivet by setting a flexible and deformable mesh sleeve 3 as an intermediate buffer layer between the rivet hole 2 and the pin 1. When the pin 1 is inserted, the reduced-diameter end of the mesh sleeve 3 expands and fills the rivet hole 2, forming a macroscopic mechanical self-locking. After the ceramic polymer precursor filling the pores of the mesh sleeve 3 solidifies, it forms a filled and solidified structure, creating a microscopic interlock with the pin 1 and the wall of the layer plate hole. The synergistic effect of macroscopic mechanical self-locking and microscopic interlocking forms a multi-layered, mutually reinforcing, and robust interface, effectively improving the pull-out strength of the riveted structure. Simultaneously, the rivet design avoids damage to continuous fibers caused by thread processing, reduces stress concentration, and solves the problems of high processing costs and damage to continuous fibers during the processing of ceramic matrix composite bolts, thus improving the strength of the riveted structure.

[0025] Example 3 like Figure 5As shown, this embodiment improves upon Embodiment 2 by modifying the structure of the pin 1. The pin 1 has a necked section 4 at its middle position, meaning the outer diameter of the middle part of the pin 1 is locally reduced. The remaining structure and assembly steps are the same as in Embodiment 2. The necked section 4 structure in the middle of the pin 1 creates a stress concentration area when the pin 1 is subjected to tensile force. However, since the pin 1 is made of fiber-reinforced ceramic matrix composite material and the fibers are continuous in the axial direction, the stress at the necked section 4 can be transmitted along the fiber direction, making it less prone to breakage. Simultaneously, the necked section 4 structure increases the mechanical interlocking effect between the pin 1 and the mesh sleeve 3, further enhancing the pull-out strength of the rivet.

[0026] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A ceramic rivet suitable for connecting ceramic matrix composite laminates, characterized in that, include: The pin is a rod-shaped structure, and the pin is used to be inserted into the rivet hole of the riveting structure; The mesh sleeve has a ring-shaped mesh structure in cross-section, and the two ends of the mesh sleeve are set with a reduced diameter structure. The mesh sleeve is disposed between the rivet hole and the pin.

2. The ceramic rivet for connecting ceramic matrix composite laminates according to claim 1, characterized in that, The mesh sleeve has a fiber woven structure, and a filling and curing structure is also provided inside the mesh pore structure of the mesh sleeve.

3. The ceramic rivet for connecting ceramic matrix composite laminates according to claim 1, characterized in that, One end of the pin is configured as a tapered or frustum structure.

4. The ceramic rivet for connecting ceramic matrix composite laminates according to claim 1, characterized in that, The pin has a necked section at the middle position.

5. A method for assembling ceramic rivets suitable for connecting ceramic matrix composite laminates, the method being based on the ceramic rivets for connecting ceramic matrix composite laminates as described in any one of claims 1 to 4, characterized in that, include: The mesh sleeve is squeezed into the rivet hole used to connect the two connectors; The pin is forced into the mesh sleeve so that the outer diameter of the pin matches the inner diameter of the mesh sleeve.

6. The assembly method of ceramic rivets for connecting ceramic matrix composite laminates according to claim 5, characterized in that, Before or after inserting the pin into the mesh sleeve, a ceramic polymer precursor is injected into the rivet hole to cure and form the filled and cured structure.

7. The assembly method of ceramic rivets for connecting ceramic matrix composite laminates according to claim 6, characterized in that, The filled and cured structure includes at least one of ceramic particle reinforcement phase, ceramic short fiber reinforcement phase, or ceramic whisker reinforcement phase.

8. The assembly method of ceramic rivets for connecting ceramic matrix composite laminates according to claim 5, characterized in that, The rivet holes used to connect two connectors have a smaller diameter in the middle and a larger diameter at both ends, forming a constricted shape.

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