Explosive bolt collection device and its design method suitable for compact axial space

Abstract

This invention belongs to the field of aircraft separation structure design technology, specifically relating to an explosive bolt collection device and its design method suitable for compact axial space. The method includes: Step 1, determining the initial velocity and initial kinetic energy of the explosive bolt remnant; Step 2, selecting buffer structure connecting fasteners based on the initial kinetic energy of the explosive bolt remnant calculated in Step 1; Step 3, designing the collection structure based on the initial kinetic energy of the explosive bolt remnant calculated in Step 1 and the buffer structure connecting fasteners selected in Step 2; Step 4, conducting numerical simulation analysis and ground tests on the bolt collection device designed in Steps 2 and 3 to verify the feasibility of the design method for an explosive bolt collection device suitable for compact axial space. This invention can solve the problems of complex structure, high axial space requirements, and the risk of rebound in explosive bolt collection devices.

Description

Technical Field

[0001] This invention belongs to the field of aircraft separation structure design technology, specifically relating to an explosive bolt collection device and its design method suitable for compact axial space. Background Technology

[0002] In aircraft separation systems, explosive bolts, as a core connection and unlocking unit, have long held a dominant position due to their high technological maturity, strong reliability, and low cost. Their working principle is based on the precise detonation of an internal explosive charge; the instantaneous high energy generated reliably shears or separates predetermined structures, achieving millisecond-level precise unlocking and separation of aircraft sections (such as interstages, boosters, and fairings). This instantaneous separation capability, high predictability, and relatively simple system integration requirements make explosive bolts the preferred solution for many aircraft separation mechanisms, accumulating rich application experience in engineering practice.

[0003] However, the high-speed debris generated after the explosive bolts are released poses a serious safety threat to the still-operating aircraft body after separation. These metal fragments, possessing extremely high kinetic energy, are crucial for ensuring the overall safety of the separation process and the success of the aircraft mission. Therefore, designing an efficient and reliable explosive bolt debris collection device is an indispensable key element in ensuring the overall safety of the separation process and the success of the aircraft mission.

[0004] To address this need, current mainstream explosive bolt collection technologies mainly focus on energy dissipation and capture mechanisms, and currently rely primarily on two technical approaches:

[0005] One type is the honeycomb energy-absorbing structure, which utilizes the large plastic deformation of porous materials to absorb impact kinetic energy. Although the honeycomb structure has a relatively high energy absorption efficiency, in order to effectively dissipate the impact of high-energy debris, its structural thickness usually reaches tens of millimeters or more. In addition, to prevent the debris from rebounding, it is necessary to use additional mechanisms (such as spring grippers, conical teeth, etc.), which not only makes the manufacturing process complex but also adds additional local mass.

[0006] The second type is the conical bore energy-absorbing structure, which dissipates energy by using the friction and compression deformation between the debris and the inner wall of the conical cavity. Although this technical solution can solve the problem of debris rebound through friction self-locking, it requires a sufficiently long axial buffer stroke, which greatly occupies the valuable space inside the aircraft and seriously restricts the layout of equipment around the separation mechanism.

[0007] The core flaw of these two mainstream technical solutions lies in the fact that, to achieve effective kinetic energy absorption and capture, either the thickness (mass) of the buffer material must be increased and additional anti-rebound mechanisms added to enhance energy absorption and collection capabilities, or the buffer distance must be provided by extending the axial dimension (space). For example, invention patent application CN 109703793 A discloses an explosive bolt buffer energy absorption and recovery device, which uses a high-temperature alloy honeycomb buffer to reduce the impact force of explosive bolt fragments and recover high-speed separated explosive bolt fragments. This technical solution uses a single high-temperature alloy honeycomb buffer to achieve the buffer energy absorption and recovery function, but the thickness of the buffer still occupies a certain axial space, and the thickness of the buffer is positively correlated with the unlocking impulse of the explosive bolt. In addition, this technical solution does not consider the rebound process of the explosive bolt fragments; if the explosive bolt fragments rebound into the explosive bolt mounting hole, there is a risk of interfering with the separation process. Patent application CN 119953594 A discloses an explosive bolt collection device for a spacecraft separation system. After the explosive bolt detonates, the high-speed ejected broken chain connector moves along the bolt's axial direction within the collection hole of the device. This deformation causes compression on the inner wall of the collection hole, absorbing the kinetic energy of the high-speed moving broken connector. The friction between the broken connector and the inner wall of the collection hole creates a self-locking mechanism, thus suppressing the rebound of the broken connector. To achieve this frictional self-locking, the collection device has a conical hole with a semi-cone angle of 3.5° to 7°, which requires significant axial space and is detrimental to the internal structural space layout.

[0008] With the trend of modern aircraft design pursuing highly integrated structures, optimized quality, and maximized space utilization, there is an urgent need for a new type of explosive bolt collection device technology that can significantly reduce axial space requirements and reduce structural weight while meeting strict safety constraints (reliable energy absorption, effective capture, and prevention of rebound), thus achieving a synergistic optimization design of safety, lightweight, and compactness. Summary of the Invention

[0009] (a) Technical problems to be solved

[0010] The technical problem to be solved by the present invention is: how to provide an explosive bolt collection device and its design method suitable for a compact axial space, which can solve the technical problems of existing explosive bolt collection devices such as complex structure, high axial space requirements, and risk of springback.

[0011] (II) Technical Solution

[0012] To address the aforementioned technical problems, this invention provides a design method for an explosive bolt collection device suitable for compact axial spaces, characterized in that the design method includes:

[0013] Step 1: Determine the initial velocity and initial kinetic energy of the explosive bolt fragments based on the unlocking impulse of the explosive bolts used and the mass of the explosive bolt fragments after unlocking.

[0014] Step 2: Based on the initial kinetic energy of the explosive bolt remnant calculated in Step 1, select the fasteners for the buffer structure connection;

[0015] Step 3: Based on the initial kinetic energy of the explosive bolt remnant calculated in Step 1 and the buffer structure connecting fasteners selected in Step 2, carry out the design of the collection structure;

[0016] Step 4: Numerical simulation analysis and ground tests are conducted on the bolt collection devices designed in Steps 2 and 3 to verify the feasibility of the design method for explosive bolt collection devices suitable for compact axial spaces.

[0017] In step one, the initial velocity and initial kinetic energy of the exploded bolt remnant are calculated using a formula. Initial flight kinetic energy Where I is the impulse when the explosive bolt is unlocked, and m1 is the mass of the remaining explosive bolt.

[0018] In step two, the size and quantity of the fasteners connecting the buffer structure are determined based on the space. The strength grades of the symmetrically installed fasteners are different, providing initial lateral disturbance for the explosive bolt remnants.

[0019] In step two, the strength grades of the fasteners connecting the buffer structure differ. After determining the fasteners connecting the buffer structure, based on the ideal plasticity model and the formula... Estimate the energy dissipated by the fracture of each fastener, where U i Let A represent the energy dissipated when the i-th fastener breaks. i E represents the cross-sectional area of ​​the i-th connecting fastener. i Let σ represent the elastic modulus of the i-th fastener. si σ represents the yield strength of the i-th fastener. bi Represent the tensile strength of the i-th fastener; and calculate the total energy dissipated upon fracture of all fasteners. Furthermore, the total energy U dissipated by the fracture of all connecting fasteners should satisfy U≤0.2E0, where E0 represents the initial kinetic energy of the explosive bolt remnant.

[0020] In step three, the thickness of the collected structure satisfies Where τ represents the shear strength of the collecting structure material, d represents the diameter of the explosive bolt, and K represents the correction factor, typically ranging from 0.1 to 0.3, depending on boundary constraints and material plasticity; the axial length L of the collecting structure satisfies Where D represents the diameter of the through hole for installing the explosive bolt, l represents the axial length of the explosive bolt remnant, and 13-20mm is the reserved space for installing the buffer pad;

[0021] The slope angle α of the buffer pad satisfies The thickness of the cushioning pad should not be less than 8mm.

[0022] In step four, numerical simulation analysis is performed on the explosive bolt collection device designed in steps two and three for compact axial space. Based on the obtained running trajectory, speed curve of the explosive bolt remnant and stress condition of the collection device, the feasibility and reliability of the designed explosive bolt collection device are verified.

[0023] In step four, when conducting a ground verification test on the designed explosive bolt collection device suitable for compact axial space, the explosive bolt collection device is installed on the test fixture in conjunction with the explosive bolt, and the explosive bolt is detonated to verify the function and performance of the explosive bolt collection device.

[0024] Furthermore, the present invention also provides an explosive bolt collection device suitable for compact axial spaces, the collection device comprising a buffer structure and a collection structure;

[0025] The buffer structure includes: a threaded steel sleeve (003), a first threaded steel sleeve fastening screw (008), and a second threaded steel sleeve fastening screw (009);

[0026] The collection structure includes: a collection box (002), a collection box cover (007), and a buffer pad (006). The explosive bolt collection device is designed using the explosive bolt collection device design method suitable for compact axial space as described in any one of claims 1 to 6.

[0027] The collection box (002) has an inner opening structure and is designed as an integral part of the cabin body. It serves as part of the metal cabin body structure or as an end face reinforcement structure of the non-metal cabin body. The front end face and the outer side wall have mounting holes and are connected to the cabin body by screws and nuts.

[0028] The collection box (002) has a large through hole in the middle of its front end face for passing through an explosive bolt. Threaded holes are provided on both sides of the large through hole. A threaded hole is provided at the rear end face of the collection box (002) at the coaxial position with the large through hole for installing a buffer pad (006). Threaded holes are provided on the inner side wall of the collection box (002) for installing a collection box cover plate (007).

[0029] The threaded steel sleeve (003) has a threaded hole in the middle, which is connected to the explosion bolt through thread engagement; the threaded steel sleeve (003) has lugs on both sides, and a through hole is opened in the middle of the lugs. The first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009) pass through the through hole on the threaded steel sleeve lug and are connected to the threaded holes on both sides of the large through hole on the front face of the collection box.

[0030] The buffer pad (006) is a wedge-shaped structure with one inclined side and one flat side. A countersunk hole is opened on one side of the inclined side, and it is connected to the threaded hole on the rear end face of the collection box (002) by screws.

[0031] The collection box cover (007) is a thin plate structure that conforms to the inner wall of the collection box. It has through holes at its four corners and is connected to the threaded holes on the inner wall of the collection box by screws, forming a closed space together with the collection box (002).

[0032] The threaded steel sleeve (003) has different strength grades through the first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009), which are used to absorb the kinetic energy of the explosive bolt remnants and provide lateral disturbance.

[0033] (III) Beneficial Effects

[0034] Compared with existing technologies, the design method for an explosive bolt collection device suitable for compact axial space provided by this invention has a clear process and is simple to calculate. The explosive bolt collection device designed according to the above method has a simple structure and good manufacturability; it has low requirements for axial installation space, which is beneficial to the internal structural layout of the aircraft; it solves the problem of explosive bolt fragment rebound in a compact axial space, improving the reliability of aircraft separation; it is easy to install, and all components can be installed during the aircraft segment assembly stage. When the segments are docked, only the explosive bolts need to be screwed in, improving assembly efficiency. Attached Figure Description

[0035] Figure 1 A flowchart of a design method for a compact axial spatial explosive bolt collection device proposed in this invention is shown;

[0036] Figure 2 A front sectional view of the structure of an explosive bolt collecting device according to a specific embodiment of the present invention is shown;

[0037] Figure 3 A top sectional view of the explosive bolt collecting device provided according to a specific embodiment of the present invention is shown;

[0038] Figure 4 The diagram shows a schematic representation of the explosive bolt collecting device and the structure after the explosive bolts are installed, according to a specific embodiment of the present invention.

[0039] Figure 5 A schematic diagram of the buffering process in the initial stage after the explosive bolts are unlocked, according to a specific embodiment of the present invention;

[0040] Figure 6 A schematic diagram of the collection process at the end of the period after the explosive bolts are unlocked, according to a specific embodiment of the present invention;

[0041] Figure 7 Numerical simulation and ground verification test results of specific embodiments of the present invention are shown.

[0042] The above figures include the following reference numerals:

[0043] 001-Forward compartment hull; 002-Collection box; 003-Threaded steel sleeve; 004-Nut; 005-Screw; 006-Buffer pad; 007-Collection box cover; 008-First threaded steel sleeve fastening screw; 009-Second threaded steel sleeve fastening screw; 010-Rear compartment hull; 011-Explosive bolt; 012-Explosive bolt remnant; 013-Hole edge area. Detailed Implementation

[0044] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0045] To address the aforementioned technical problems, this invention provides a design method for an explosive bolt collection device suitable for compact axial spaces, characterized in that the design method includes:

[0046] Step 1: Determine the initial velocity and initial kinetic energy of the explosive bolt fragments based on the unlocking impulse of the explosive bolts used and the mass of the explosive bolt fragments after unlocking.

[0047] Step 2: Based on the initial kinetic energy of the explosive bolt remnant calculated in Step 1, select the fasteners for the buffer structure connection;

[0048] Step 3: Based on the initial kinetic energy of the explosive bolt remnant calculated in Step 1 and the buffer structure connecting fasteners selected in Step 2, carry out the design of the collection structure;

[0049] Step 4: Numerical simulation analysis and ground tests are conducted on the bolt collection devices designed in Steps 2 and 3 to verify the feasibility of the design method for explosive bolt collection devices suitable for compact axial spaces.

[0050] In step one, the initial velocity and initial kinetic energy of the exploded bolt remnant are calculated using a formula. Initial flight kinetic energy Where I is the impulse when the explosive bolt is unlocked, and m1 is the mass of the remaining explosive bolt.

[0051] In step two, the size and quantity of the fasteners connecting the buffer structure are determined based on the space. The strength grades of the symmetrically installed fasteners are different, providing initial lateral disturbance for the explosive bolt remnants.

[0052] In step two, the strength grades of the fasteners connecting the buffer structure differ. After determining the fasteners connecting the buffer structure, based on the ideal plasticity model and the formula... Estimate the energy dissipated by the fracture of each fastener, where U i Let A represent the energy dissipated when the i-th fastener breaks. i E represents the cross-sectional area of ​​the i-th connecting fastener. i Let σ represent the elastic modulus of the i-th fastener. si σ represents the yield strength of the i-th fastener. bi Represent the tensile strength of the i-th fastener; and calculate the total energy dissipated upon fracture of all fasteners. Furthermore, the total energy U dissipated by the fracture of all connecting fasteners should satisfy U≤0.2E0, where E0 represents the initial kinetic energy of the explosive bolt remnant.

[0053] In step three, the thickness of the collected structure satisfies Where τ represents the shear strength of the collecting structure material, d represents the diameter of the explosive bolt, and K represents the correction factor, typically ranging from 0.1 to 0.3, depending on boundary constraints and material plasticity; the axial length L of the collecting structure satisfies Where D represents the diameter of the through hole for installing the explosive bolt, l represents the axial length of the explosive bolt remnant, and 13-20mm is the reserved space for installing the buffer pad;

[0054] The slope angle α of the buffer pad satisfies The thickness of the cushioning pad should not be less than 8mm.

[0055] In step four, numerical simulation analysis is performed on the explosive bolt collection device designed in steps two and three for compact axial space. Based on the obtained running trajectory, speed curve of the explosive bolt remnant and stress condition of the collection device, the feasibility and reliability of the designed explosive bolt collection device are verified.

[0056] In step four, when conducting a ground verification test on the designed explosive bolt collection device suitable for compact axial space, the explosive bolt collection device is installed on the test fixture in conjunction with the explosive bolt, and the explosive bolt is detonated to verify the function and performance of the explosive bolt collection device.

[0057] Furthermore, the present invention also provides an explosive bolt collection device suitable for compact axial spaces, the collection device comprising a buffer structure and a collection structure;

[0058] The buffer structure includes: a threaded steel sleeve (003), a first threaded steel sleeve fastening screw (008), and a second threaded steel sleeve fastening screw (009);

[0059] The collection structure includes: a collection box (002), a collection box cover (007), and a buffer pad (006). The explosive bolt collection device is designed using the explosive bolt collection device design method suitable for compact axial space as described in any one of claims 1 to 6.

[0060] The collection box (002) has an inner opening structure and is designed as an integral part of the cabin body. It serves as part of the metal cabin body structure or as an end face reinforcement structure of the non-metal cabin body. The front end face and the outer side wall have mounting holes and are connected to the cabin body by screws and nuts.

[0061] The collection box (002) has a large through hole in the middle of its front end face for passing through an explosive bolt. Threaded holes are provided on both sides of the large through hole. A threaded hole is provided at the rear end face of the collection box (002) at the coaxial position with the large through hole for installing a buffer pad (006). Threaded holes are provided on the inner side wall of the collection box (002) for installing a collection box cover plate (007).

[0062] The threaded steel sleeve (003) has a threaded hole in the middle, which is connected to the explosion bolt through thread engagement; the threaded steel sleeve (003) has lugs on both sides, and a through hole is opened in the middle of the lugs. The first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009) pass through the through hole on the threaded steel sleeve lug and are connected to the threaded holes on both sides of the large through hole on the front face of the collection box.

[0063] The buffer pad (006) is a wedge-shaped structure with one inclined side and one flat side. A countersunk hole is opened on one side of the inclined side, and it is connected to the threaded hole on the rear end face of the collection box (002) by screws.

[0064] The collection box cover (007) is a thin plate structure that conforms to the inner wall of the collection box. It has through holes at its four corners and is connected to the threaded holes on the inner wall of the collection box by screws, forming a closed space together with the collection box (002).

[0065] The threaded steel sleeve (003) has different strength grades through the first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009), which are used to absorb the kinetic energy of the explosive bolt remnants and provide lateral disturbance.

[0066] Example 1

[0067] like Figure 1 As shown, this invention provides a design method for an explosive bolt collection device suitable for compact axial spaces. The design method includes: Step 1, determining the initial velocity and initial kinetic energy of the explosive bolt fragment based on the unlocking impulse of the used explosive bolt and the mass of the bolt fragment after unlocking; Step 2, selecting buffer structure connecting fasteners based on the initial kinetic energy of the explosive bolt fragment calculated in Step 1; Step 3, designing a collection structure based on the initial kinetic energy of the explosive bolt fragment calculated in Step 1 and the buffer structure connecting fasteners selected in Step 2; Step 4, conducting numerical simulation analysis and ground tests on the bolt collection device designed in Steps 2 and 3 to verify the feasibility of the explosive bolt collection device design method suitable for compact axial spaces.

[0068] In step 1, the unlocking impulse and the mass of the remaining explosive bolt are first determined based on the selected explosive bolt. Specifically, in this embodiment of the invention, an explosive bolt with a size of M24, an unlocking impulse of I = 10.6 N·m, a mass of the remaining explosive bolt of m1 = 190 g, and an axial length of l = 68 mm is selected. The initial flight velocity of the remaining explosive bolt after unlocking is then calculated. Initial flight kinetic energy

[0069] In step 2, two M5 screws are selected as the fasteners for the buffer structure according to the installation space. The strength grades of the two screws are 8.8 and 10.9, respectively, using a formula based on the ideal plasticity model. The energy dissipated by the fracture of each fastener is estimated to be 20.6J and 33.2J respectively, and the total energy dissipated is U = 53.8J, which satisfies U ≤ 0.2E0.

[0070] In step 3, this embodiment of the invention selects aluminum alloy 7075-T6 as the collecting structure material, with a shear strength τ = 330 MPa. The thickness of the collecting structure is determined according to empirical formulas. The correction factor is taken as the median of 0.2, resulting in a collection structure thickness h greater than or equal to 8.05 mm. Therefore, in this embodiment of the invention, the thickness is rounded to 8 mm.

[0071] Furthermore, in step 3, according to the formula The axial length L of the collecting structure is determined. In this embodiment of the invention, the diameter of the through hole for installing the explosion bolt is D = 26 mm, and the lower limit of the reserved space length is taken as 13 mm. The axial length of the collecting structure is calculated to be 87 mm.

[0072] Furthermore, in step 3, silicone rubber is selected as the cushioning pad material, and the inclination angle α of the cushioning pad slope satisfies... The calculated slope angle α is ≥ 5°, and in this invention example, it is 5°.

[0073] Applying the aforementioned design method for explosive bolt collection devices suitable for compact axial spaces, an embodiment of an explosive bolt collection device suitable for compact axial spaces is provided, such as... Figure 2 and Figure 3 As shown. The explosive bolt collecting device includes a buffer structure and a collecting structure, wherein the buffer structure includes a threaded steel sleeve, a first threaded steel sleeve fastening screw (008), and a second threaded steel sleeve fastening screw (009); the collecting structure includes a collecting box (002), a collecting box cover plate (007), and a buffer pad (006).

[0074] Furthermore, the collection box (002) has an internally open structure and is integrated with the cabin body, serving as part of the metal cabin structure or as an end face reinforcement structure of the non-metallic cabin body; its front end face and outer side wall have mounting through holes, which are connected to the front cabin body (001) by screws (005) and nuts (004); a large-sized through hole is opened in the middle of the front end face of the collection box (002), which is used to pass through the explosive bolt (011), and threaded holes are opened on both sides of the large-sized through hole; a threaded hole is provided at the rear end face of the collection box (002) coaxial with the large-sized through hole, which is used to install the buffer pad (016); the buffer pad (016) is a wedge-shaped structure with one inclined side and one flat side, and a countersunk hole is opened on the inclined side, which is connected to the threaded hole on the rear end face of the collection box (002) by screws (005);

[0075] Furthermore, the inner wall of the collection box (002) has threaded holes, and the collection box cover (007) is a thin plate structure that conforms to the inner wall of the collection box (002). The four corners of the collection box cover (007) have through holes, which are connected to the threaded holes of the inner wall of the collection box (002) by screws (005) to form a closed space together with the collection box (002).

[0076] Furthermore, the threaded steel sleeve (003) has a threaded hole in the middle, which is connected to the explosion bolt (011) through threaded engagement; the threaded steel sleeve (003) has lugs on both sides, and a through hole is opened in the middle of the lugs. The first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009) pass through the through hole on the threaded steel sleeve lug and are connected to the threaded holes on both sides of the large through hole on the front face of the collection box (002);

[0077] Combination Figures 4-6 The principle and process of collecting explosive bolts are further explained in the embodiments provided by the present invention.

[0078] The collection box (002) is installed on the front cabin body (001) in the manner described above, and the threaded steel sleeve (003) and the buffer pad (006) are installed inside through the inner opening of the collection box (002). Finally, the collection box cover plate (007) is installed.

[0079] Furthermore, during the docking of the compartments, the rear compartment body (010) is attached to the front compartment body (001) and aligned with the mounting holes. The explosive bolts (011) are screwed into the threaded steel sleeve (003) through the mounting holes from inside the rear compartment body, and a tightening torque is applied to complete the compartment connection.

[0080] When the aircraft reaches the target position and separates, the explosive bolt (001) receives an ignition signal. The internal pyrotechnics shear (pull) the bolt body, breaking it at the separation surface and forming an explosive bolt remnant (012) with initial kinetic energy. The initial kinetic energy of the explosive bolt remnant (012) is transferred through the threaded steel sleeve (003) to the first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009), causing plastic deformation and fracture of the first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009), thereby... The initial kinetic energy of the explosive bolt remnant (012) is dissipated. Furthermore, since the strength grades of the first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009) are different, their plastic deformation and fracture processes are not synchronized. This provides a certain lateral disturbance to the explosive bolt remnant (012), causing its velocity direction to deviate from the hole axis. As the explosive bolt remnant (012) flies toward the buffer pad (006), it will collide with the hole edge area (013), dissipating kinetic energy and further reducing the axial velocity of the explosive bolt remnant (012).

[0081] Furthermore, when the explosive bolt remnant (012) continues to fly until it comes into contact with the buffer pad (006), the buffer pad (006) deforms and collapses, absorbing the remaining kinetic energy of the explosive bolt remnant (012). When the axial velocity of the explosive bolt remnant (012) decreases to 0, the elastic potential energy stored in the buffer pad (006) begins to be released, pushing the explosive bolt remnant (012) to bounce back in the opposite direction. At the same time, the inclined surface design of the buffer pad (006) will disturb its motion posture, causing the axis of the explosive bolt remnant (012) to deviate further from the hole axis. During the rebound process, the explosive bolt remnant (012) collides in the hole edge area (013) and is stuck by the hole edge, preventing the explosive bolt remnant (012) from rebounding back into its mounting hole, thus completing the collection process.

[0082] After completing the structural design of a specific embodiment of the explosive bolt collection device of the present invention, the ANSYS Workbench display dynamics calculation module is used to perform numerical simulation analysis on the explosive bolt collection device, establish a numerical model of the explosive bolt collection device, set the material properties, contact relationships, boundary conditions and initial states of each component, and perform the solution. Simulation calculations show that both the first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009) undergo plastic deformation and fracture, significantly reducing the flight speed of the explosive bolt remnant (012). The first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009) have different strength grades, providing lateral disturbance to the explosive bolt remnant (012). During flight, the explosive bolt remnant (012) collides multiple times with the hole edge area (013), causing its flight speed to continuously decrease. The buffer pad (006) effectively prolongs the impact time of the explosive bolt remnant (012), reducing the impact load, and the structural stress fed back to the collection box (002) is much less than the material yield strength. The inclined surface design of the buffer pad (006) significantly changes the posture of the explosive bolt remnant (012) during rebound, causing it to collide and jam with the hole edge area (013) during rebound, thus achieving reliable collection.

[0083] After completing the simulation verification of the explosive bolt collection device embodiment proposed in this invention, a ground verification test was conducted. According to... Figure 4 As shown, the explosive bolt collecting device was installed on the tooling of the simulated front cabin (001), and the front and rear cabin toolings were connected using explosive bolts (011). The tooling was then fixed on the test bench. Ground tests verified that after the explosive bolts (011) were unlocked, both the first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009) underwent plastic deformation and fracture, effectively dissipating the initial kinetic energy of the explosive bolt remnant (012). The collecting box (002) did not undergo plastic deformation, meeting the structural strength requirements. The trajectory of the explosive bolt remnant (012) was consistent with the simulation results, meeting expectations. Finally, it was reliably collected by the collecting device without rebounding into the mounting hole.

[0084] In summary, this invention provides a design method for an explosive bolt collection device suitable for compact axial spaces. Based on design inputs, the method verifies its feasibility and reliability through theoretical analysis, numerical simulation, and ground-based testing. Compared to existing technologies, this invention dissipates the initial kinetic energy of the explosive bolt through plastic deformation and fracture of the connecting screw, as well as by applying lateral disturbances. This effectively addresses the disadvantages of existing explosive bolt collection devices, such as complex structures, high axial space requirements, and the risk of springback. This invention provides significant guidance for the design of explosive bolt collection devices.

[0085] In summary, this invention belongs to the field of aircraft separation structure design technology, specifically relating to an explosive bolt collection device and its design method suitable for compact axial space. The method includes: Step 1, determining the initial velocity and initial kinetic energy of the explosive bolt fragment based on the unlocking impulse of the used explosive bolt and the mass of the explosive bolt fragment after unlocking; Step 2, selecting buffer structure connecting fasteners based on the initial kinetic energy of the explosive bolt fragment calculated in Step 1; Step 3, designing a collection structure based on the initial kinetic energy of the explosive bolt fragment calculated in Step 1 and the buffer structure connecting fasteners selected in Step 2; Step 4, conducting numerical simulation analysis and ground tests on the bolt collection device designed in Steps 2 and 3 to verify the feasibility of the design method for an explosive bolt collection device suitable for compact axial space. The collection device is designed using the aforementioned method and includes a threaded steel sleeve, a first threaded steel sleeve fastening screw, a second threaded steel sleeve fastening screw, a collection box, a collection box cover, and a buffer pad. The collection box has an internally open structure and is integrated with the cabin body, serving as part of the metal cabin structure or as an end-face reinforcement structure for non-metallic cabins. The threaded steel sleeve has a circular lug structure and is installed inside the collection box by a first threaded steel sleeve fastening screw and a second threaded steel sleeve fastening screw. The first threaded steel sleeve fastening screw and the second threaded steel sleeve fastening screw have different strength grades, dissipating the initial kinetic energy of the explosive bolt remnants through plastic deformation, fracture, and providing lateral disturbance. The buffer pad is a wedge-shaped structure with one inclined surface and one flat surface. The collection box cover is a thin plate structure that conforms to the inner wall of the collection box, forming a closed space together with the collection box. Applying the technical solution of this invention can solve the technical problems of existing explosive bolt collection devices, such as complex structure, high axial space requirements, and the risk of springback.

[0086] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A design method for an explosive bolt collection device suitable for compact axial spaces, characterized in that, The design method for the explosive bolt collection device includes: Step 1: Determine the initial velocity and initial kinetic energy of the explosive bolt fragments based on the unlocking impulse of the explosive bolts used and the mass of the explosive bolt fragments after unlocking. Step 2: Based on the initial kinetic energy of the explosive bolt remnant calculated in Step 1, select the fasteners for the buffer structure connection; Step 3: Based on the initial kinetic energy of the explosive bolt remnant calculated in Step 1 and the buffer structure connecting fasteners selected in Step 2, carry out the design of the collection structure; Step 4: Numerical simulation analysis and ground tests are conducted on the bolt collection devices designed in Steps 2 and 3 to verify the feasibility of the design method for explosive bolt collection devices suitable for compact axial spaces.

2. The design method for an explosive bolt collection device suitable for compact axial space as described in claim 1, characterized in that, In step one, the initial velocity and initial kinetic energy of the exploded bolt remnant are calculated using formulas. Initial flight kinetic energy Where I is the impulse when the explosive bolt is unlocked, and m1 is the mass of the remaining explosive bolt.

3. The design method for an explosive bolt collection device suitable for compact axial space as described in claim 2, characterized in that, In step two, the size and quantity of the fasteners connecting the buffer structure are determined based on the space. The strength grades of the symmetrically installed fasteners are different, providing initial lateral disturbance for the explosive bolt remnants.

4. The design method for an explosive bolt collection device suitable for compact axial space as described in claim 3, characterized in that, In step two, the strength grades of the fasteners connecting the buffer structure differ, based on the formula... Estimate the energy dissipated by the fracture of each fastener, where U i Let A represent the energy dissipated when the i-th fastener breaks. i E represents the cross-sectional area of ​​the i-th connecting fastener. i Let σ represent the elastic modulus of the i-th fastener. si σ represents the yield strength of the i-th fastener. bi Represent the tensile strength of the i-th fastener; and calculate the total energy dissipated upon fracture of all fasteners. Furthermore, the total energy U dissipated by the fracture of all connecting fasteners should satisfy U≤0.2E0, where E0 represents the initial kinetic energy of the explosive bolt remnant.

5. The design method for an explosive bolt collection device suitable for compact axial space as described in claim 4, characterized in that, In step three, the thickness of the collected structure meets the following requirements. Where τ represents the shear strength of the collecting structure material, d represents the diameter of the explosive bolt, and K represents a correction factor that depends on boundary constraints and material plasticity; the axial length L of the collecting structure satisfies... Where D represents the diameter of the through hole for installing the explosive bolt, l represents the axial length of the explosive bolt remnant, and 13-20mm is the reserved space for installing the buffer pad; The slope angle α of the buffer pad satisfies 6. The design method of the explosive bolt collecting device suitable for compact axial space as described in claim 5, characterized in that, In step four, numerical simulation analysis is performed on the explosive bolt collection device designed in steps two and three for use in compact axial space. Based on the obtained running trajectory, velocity curve of the explosive bolt remnant and stress condition of the collection device, the feasibility and reliability of the designed explosive bolt collection device are verified. In step four, when conducting a ground verification test on the designed explosive bolt collection device suitable for compact axial space, the explosive bolt collection device is installed on the test fixture in conjunction with the explosive bolt, and the explosive bolt is detonated to verify the function and performance of the explosive bolt collection device.

7. A device for collecting explosive bolts suitable for compact axial spaces, characterized in that, The collection device includes a buffer structure and a collection structure; The buffer structure includes: a threaded steel sleeve (003), a first threaded steel sleeve fastening screw (008), and a second threaded steel sleeve fastening screw (009); The collection structure includes: a collection box (002), a collection box cover (007), and a buffer pad (006). The explosive bolt collection device is designed using the explosive bolt collection device design method suitable for compact axial space as described in any one of claims 1 to 6.

8. The explosive bolt collecting device suitable for compact axial space as described in claim 7, characterized in that, The collection box (002) has an inner opening structure and is designed as an integral part of the cabin body. It serves as part of the metal cabin body structure or as an end face reinforcement structure of the non-metal cabin body. The front end face and the outer side wall have mounting holes and are connected to the cabin body by screws and nuts. The collection box (002) has a large through hole in the middle of its front end face for passing through an explosive bolt. Threaded holes are provided on both sides of the large through hole. A threaded hole is provided at the rear end face of the collection box (002) at the coaxial position with the large through hole for installing a buffer pad (006). Threaded holes are provided on the inner side wall of the collection box (002) for installing a collection box cover plate (007). The threaded steel sleeve (003) has a threaded hole in the middle, which is connected to the explosion bolt through thread engagement; the threaded steel sleeve (003) has lugs on both sides, and a through hole is opened in the middle of the lugs. The first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009) pass through the through hole on the threaded steel sleeve lug and are connected to the threaded holes on both sides of the large through hole on the front face of the collection box.

9. The explosive bolt collecting device suitable for compact axial space as described in claim 8, characterized in that, The buffer pad (006) is a wedge-shaped structure with one side inclined and one side flat. A countersunk hole is opened on one side of the inclined surface, which is connected to the threaded hole on the rear end face of the collection box (002) by screws. The collection box cover (007) is a thin plate structure that conforms to the inner wall of the collection box. It has through holes at its four corners and is connected to the threaded holes on the inner wall of the collection box by screws, forming a closed space together with the collection box (002).

10. The explosive bolt collecting device suitable for compact axial space as described in claim 8, characterized in that, The threaded steel sleeve (003) has different strength grades through the first threaded steel sleeve fastening screw (008) and the second threaded steel sleeve fastening screw (009), which are used to absorb the kinetic energy of the explosive bolt remnants and provide lateral disturbance.

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