An embedded circular tube honeycomb sandwich panel, its molding method, and its application

Abstract

This invention provides an embedded cylindrical tube honeycomb sandwich panel, its molding method, and its application. The embedded cylindrical tube honeycomb sandwich panel includes an upper panel and a lower panel. Multiple honeycomb cores are longitudinally arranged between the upper and lower panels. Each honeycomb core includes a honeycomb and a thin-walled cylinder. The top of the thin-walled cylinder is longitudinally positioned on the bottom surface of the upper panel, and the bottom of the honeycomb is longitudinally positioned on the top surface of the lower panel. The thin-walled cylinder is inserted into the honeycomb, and its outer wall is tangent to the inner wall of the honeycomb, reducing the gap between the thin-walled cylinder and the honeycomb to provide synergistic impact resistance. This invention also provides a molding method for the embedded cylindrical tube honeycomb sandwich panel and its application in a near-field explosion finite element simulation model. This invention uses the honeycomb embedded cylindrical tube structure in the core material design of the sandwich panel, combining the synergistic effect of the sandwich structure panels to improve the structure's protective characteristics under blast shock waves.

Description

Technical Field

[0001] This invention relates to the field of energy-absorbing materials technology, specifically to an embedded circular tube type honeycomb sandwich panel, its molding method, and its application. Background Technology

[0002] Metal honeycomb structures possess excellent mechanical properties such as lightweight, energy absorption, and controllable deformation modes, and are often used in the design of energy-absorbing protective structures under extreme loads such as collisions, explosions, and impacts. A typical example is the core layer design used in sandwich structures. The core material increases the distance between the upper and lower panels, thereby increasing the structure's cross-sectional moment of inertia, which significantly improves the structure's specific stiffness and specific strength.

[0003] Due to the geometric characteristics of the honeycomb structure, it exhibits typical orthogonal anisotropy. When loaded along the hexagonal lattice array direction (coplanar loading), its stress deformation mechanism is mainly the rotation of the plastic hinge at the cell vertices and the bending of the cell walls. The load-bearing capacity of the honeycomb structure in this direction is relatively weak. However, when loaded along the hexagonal lattice axis (opposite-plane loading), its stress deformation mechanism is mainly the orderly shrinkage of the cell walls. The load-bearing capacity of the honeycomb structure in this direction is relatively strong, and it is also the main direction for energy-absorbing structure design.

[0004] Due to the aforementioned orthotropic behavior, cellular structures suffer from insufficient resistance to eccentric loads when subjected to non-uniaxial loads, making them prone to unfavorable load-bearing behaviors such as buckling instability. Furthermore, limitations in mature manufacturing processes mean that the plateau strength and energy absorption capacity of achievable single cellular cells still fall short of expectations, necessitating the development of cellular energy-absorbing structures with higher energy absorption capabilities. Considering these two requirements, researchers have proposed a cellular composite structure design approach and put forward several composite cellular structure design schemes.

[0005] Currently, the mainstream honeycomb composite structures include three main categories. The first category is a series honeycomb structure formed by combining honeycomb blocks according to a certain strategy. Shenzhen Qianxingda Technology Co., Ltd. (authorization announcement number: CN205479075U) Luo Chang, Yu Wenze, Huang Ke, and Huang Jiangping disclosed a variable strength metal honeycomb energy-absorbing device, including two end sleeves and multiple axially arranged energy-absorbing blocks disposed between the two end sleeves; adjacent energy-absorbing blocks are connected by guide sleeves; guide sleeve grooves for accommodating the energy-absorbing blocks are provided on both the left and right sides of the guide sleeves; the energy-absorbing blocks are composed of multiple energy-absorbing units connected by welding or adhesive; each energy-absorbing unit is composed of an upper part and a lower part connected by welding or adhesive.

[0006] The second type is a composite structure that fills the interior of a thin-walled metal structure with honeycomb cells to enhance or improve the energy absorption performance of traditional thin-walled metal structures and pure honeycomb structures. Zhou Baojun et al. of Shenzhen Qianxingda Technology Co., Ltd. (Authorization Announcement No.: CN108146463B) provided a honeycomb energy absorption device, including honeycomb elements for absorbing the impact energy of a vehicle, and a compressible guide tube assembly inserted into the honeycomb elements to guide the stacking of the honeycomb elements. This invention uses a compressible guide tube assembly as the guiding structure of the honeycomb energy absorption device. When a vehicle experiences a frontal collision, the length of the guide tube assembly is shortened due to compression, eliminating the need to reserve a backward distance equivalent to the initial length of the guide tube assembly at the rear of the honeycomb energy absorption device. This effectively solves the technical problem of the large space occupied by the backward travel of the guide tubes in the honeycomb energy absorption device during a vehicle collision.

[0007] The two types of structures mentioned above are mainly designed to improve the axial energy absorption capacity and resistance to eccentric loads of the honeycomb structure. They have high requirements for the axial spatial design dimensions of the structure and are not suitable for the sandwich panel design scenario targeted by this invention.

[0008] The third category utilizes lower-density polymers to fill the pores of the honeycomb structure based on its porosity characteristics, thereby improving the overall compressive performance of the structure. Liu Qiang et al. (Study on the Influence of EPP Foam Filling on the Compressive Performance of Aluminum Honeycomb Structures, *Glass Reinforced Plastics / Composite Materials*, 2017, (Issue 3)) studied the influence of EPP foam (polypropylene foam material) filling on the compressive performance of aluminum honeycomb structures using a combination of quasi-static axial compression experiments and finite element simulation. The experiments found that, compared to empty aluminum honeycombs, the peak force, average compressive strength, and absorbed energy of EPP foam-filled aluminum honeycomb structures increased by 1.9%–43.33%, 46.59%–179.53%, and 46.26%–179.04%, respectively. Furthermore, compared to the sum of empty aluminum honeycombs and single EPP foam, the average compressive strength and total absorbed energy of the foam-filled structure increased by 2%–23.5% and 3.9%–23.3%, respectively. Furthermore, the failure process of EPP foam-filled aluminum honeycomb was simulated using Ls-dyna software. The results showed that EPP foam filling effectively resists honeycomb wall deformation, and the failure process and displacement curves obtained were in good agreement with experimental data. This study indicates that using EPP foam to fill aluminum honeycomb can effectively improve the axial compressive performance of aluminum honeycomb structures.

[0009] When facing high-intensity impact loads, the core materials of existing mainstream porous sandwich structures need to improve their strength and energy absorption capacity. However, their reinforcement designs often face problems such as insignificant reinforcement effects or complex reinforcement processes. Conventional honeycomb structure reinforcement designs usually adopt the form of increasing cell wall thickness, but this significantly affects the overall stiffness of the core material, resulting in insufficient equivalent bond strength between the panel and the core material. Under impact loads, the panel and core are prone to debonding failure, and the reinforcement effect cannot be effectively exerted. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide an embedded circular tube honeycomb sandwich panel, its molding method, and its application. This invention uses the honeycomb embedded circular tube structure for the core material design of the sandwich panel, and combines the sandwich structure panel with the panel to enhance the structure's protective characteristics under the action of an explosive shock wave.

[0011] To solve the above-mentioned technical problems, the present invention provides a first implementation solution: an embedded cylindrical honeycomb sandwich panel. Multiple honeycomb cores are longitudinally arranged between the upper panel and the lower panel. The tops of the multiple honeycomb cores are connected to the bottom of the upper panel, and the bottoms of the multiple honeycomb cores are connected to the top surface of the lower panel, so that the upper panel, the lower panel, and the multiple honeycomb cores form an integral structure. Each honeycomb core includes a honeycomb cell and a thin-walled cylinder. The top of the thin-walled cylinder is longitudinally disposed on the bottom surface of the upper panel, and the bottom of the honeycomb cell is longitudinally disposed on the top surface of the lower panel. The thin-walled cylinder is vertically inserted into the honeycomb cell, and the outer wall of the thin-walled cylinder is tangent to the inner wall of the honeycomb cell, thereby reducing the gap between the thin-walled cylinder and the honeycomb cell, so that the thin-walled cylinder and the honeycomb have synergistic impact resistance.

[0012] Preferably, the top of the thin-walled cylinder is longitudinally bonded to the bottom surface of the top plate, and the bottom of the honeycomb cell is longitudinally bonded to the top surface of the top plate, and the integral structure is heated and cured to form the shape.

[0013] Preferably, the honeycomb cells are divided into multiple rows, and the multiple rows of honeycomb cells are closely arranged on the top surface of the bottom plate. The centers of any three honeycomb cells in two adjacent rows form an equilateral triangle. Multiple thin-walled cylinders are divided into multiple rows, and each row of thin-walled cylinders corresponds one-to-one with each row of honeycomb cells and is inserted vertically into the honeycomb cells.

[0014] Preferably, both the honeycomb cells and the thin-walled cylinder are made of the same metal material.

[0015] Preferably, the metal material is aluminum.

[0016] Preferably, the top of the thin-walled cylinder is bonded to the bottom surface of the upper panel, and the bottom of the honeycomb cell is bonded to the top surface of the lower panel using epoxy resin adhesive.

[0017] Preferably, the upper panel and the lower panel are made of aluminum alloy.

[0018] The present invention provides a second implementation scheme, which is a method for forming an embedded circular tube honeycomb sandwich panel, comprising the following steps:

[0019] Multiple honeycomb cells and multiple thin-walled cylinders were prepared;

[0020] Apply epoxy resin adhesive to the bottom plate, attach multiple honeycomb cells to the bottom plate, and press them firmly.

[0021] Each honeycomb cell is inserted into each thin-walled cylinder, and the honeycomb cell and the thin-walled cylinder are compacted.

[0022] Apply epoxy resin adhesive to the top panel, then glue the top panel onto multiple thin-walled cylinders and press it firmly.

[0023] The prepared embedded circular tube honeycomb sandwich panel is then heated and cured.

[0024] Preferably, both the upper panel and the lower panel are metal plates, and the shear strength of the epoxy resin metal bonding surface between the upper panel and the multiple thin-walled cylinders and the shear strength of the epoxy resin metal bonding surface between the lower panel and the multiple honeycomb cells are both not less than 15 MPa. The heating and curing temperature is 120℃~140℃.

[0025] The present invention provides a third implementation scheme, which is to provide an application of an embedded circular tube honeycomb sandwich panel in a near-field explosion finite element simulation model.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. This invention utilizes a reinforcement method of filling the honeycomb cell with a thin-walled cylinder, which does not require changing the honeycomb thickness of the honeycomb core. The bonding strength between the honeycomb core and the top panel is improved by using the thin-walled cylinder to bond with the top panel, giving full play to the reinforcing effect of the core material. At the same time, the filling-type reinforcement scheme does not directly increase the overall stiffness of the honeycomb core, retains the plastic deformation capacity, and improves the energy absorption characteristics.

[0028] 2. The sandwich panel of the present invention is formed by bonding the upper panel, the lower panel and multiple honeycomb cores into a whole. The impact load is effectively transferred to the entire honeycomb core through the upper panel, the lower panel and the adhesive layer. Its energy absorption protection does not rely entirely on the axial buckling deformation of the honeycomb cells or thin-walled cylinders. It also relies on the bending strength of the upper panel to disperse the explosion or impact load, and then transfers it to the honeycomb core of the thin-walled cylinder through the adhesive layer with a certain shear strength. The impact load is resisted by the lateral stiffness of the thin-walled cylinder and the honeycomb cells themselves and the complex interaction. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the embedded honeycomb sandwich structure of the present invention, wherein... Figure 1 (a) Schematic diagram of the embedded honeycomb sandwich structure; Figure 1 (b) A schematic diagram of the honeycomb sandwich structure (W is the coordinate axis of the width direction of the sandwich structure; L is the coordinate axis of the length direction of the sandwich structure; T is the coordinate axis of the height direction of the sandwich structure; h is the side length of the honeycomb cell). Figure 1 (c) Refers to the geometric design parameters of the honeycomb sandwich core (d is the wall thickness of the thin-walled cylindrical tube, R is the radius of the thin-walled cylindrical tube, t is the wall thickness of the first honeycomb cell in two adjacent rows of honeycomb cells, and 2t is the wall thickness of the second honeycomb cell in two adjacent rows of honeycomb cells).

[0030] Figure 2 This is a schematic diagram of the near-field explosion finite element model of the present invention;

[0031] Figure 3 This is a schematic diagram comparing the stress cloud results of the upper panel of the conventional honeycomb sandwich and the filled honeycomb sandwich of the present invention, where GHP represents the conventional honeycomb sandwich and HFCT represents the filled honeycomb sandwich.

[0032] Figure 4 for Figure 3 A schematic diagram of the conventional honeycomb sandwich structure used in the process;

[0033] Figure 5 for Figure 3 Schematic diagram of the honeycomb sandwich structure used in the process

[0034] Figure 6 This is a schematic diagram showing the comparison of the displacement trends of the lower panel of the conventional honeycomb sandwich core and the filled honeycomb sandwich core of the present invention;

[0035] Figure 7 This is a schematic diagram of the overall structure of a conventional honeycomb sandwich core.

[0036] Figure 8 for Figure 7 A partial top view of a conventional honeycomb sandwich core.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Top panel; 2. Bottom panel; 3. Honeycomb clip; 31. Honeycomb cell; 32. Thin-walled cylinder. Detailed Implementation

[0039] To make the above-mentioned objects, features, and advantages of the embodiments of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The inventors discovered that existing mainstream porous sandwich structure core materials, such as metal foam, lattice structures, and corrugated sheets, require improved core strength and energy absorption capacity when facing high-intensity impact loads. However, their reinforcement designs often face problems such as insignificant reinforcement effects or complex reinforcement processes. For example, metal foam requires changes in foaming ratios or raw material proportions, demanding high process control; lattice structures require changes in the geometry of the core material cell scaffold, resulting in complex processes; and the foam filling scheme used in corrugated sheets has limited reinforcement effects. Conventional honeycomb structure reinforcement designs typically increase cell wall thickness, but this significantly affects the overall stiffness of the core material, leading to insufficient equivalent bond strength between the panel and the core material. Under impact loads, the panel and core are prone to debonding failure, failing to effectively exert the reinforcement effect.

[0041] In view of this, the present invention adopts a reinforcement method of filling the honeycomb cell with a thin-walled cylinder, which does not require changing the honeycomb thickness of the honeycomb core. The bonding strength between the honeycomb core and the top panel is improved by using the bonding between the thin-walled cylinder and the top panel, giving full play to the reinforcement effect of the core material. At the same time, the filling reinforcement scheme does not directly improve the overall stiffness of the honeycomb core, retains the plastic deformation capacity, and improves the energy absorption characteristics.

[0042] like Figures 1-6 As shown, the present invention provides an embedded cylindrical honeycomb sandwich panel, including an upper panel 1 and a lower panel 2, wherein a plurality of honeycomb sandwich cores 3 are arranged longitudinally between the upper panel 1 and the lower panel 2. The top of the plurality of honeycomb sandwich cores 3 is connected to the bottom of the upper panel 1, and the bottom of the plurality of honeycomb sandwich cores 3 is connected to the top surface of the lower panel 2, so that the upper panel 1, the lower panel 2 and the plurality of honeycomb sandwich cores 3 form an integral structure. Each honeycomb sandwich core includes a honeycomb cell 31 and a thin-walled cylinder 32. The top of the thin-walled cylinder 32 is arranged longitudinally on the bottom surface of the upper panel 1, and the bottom of the honeycomb cell 31 is arranged longitudinally on the top surface of the lower panel 2. The thin-walled cylinder 32 is inserted vertically into the honeycomb cell 31, and the outer wall of the thin-walled cylinder 32 is tangent to the inner wall of the honeycomb cell 31, so as to reduce the gap between the thin-walled cylinder 32 and the honeycomb cell 31, so that the thin-walled cylinder 32 and the honeycomb cell 31 have synergistic impact resistance.

[0043] The sandwich panel of the present invention is formed by bonding the upper panel 1, the lower panel 2, and multiple honeycomb cores 3 into a whole. Figure 1 As shown in (a), the impact load is effectively transferred to the entire honeycomb core 3 through the upper panel 1, the lower panel 2 and the adhesive layer. Its energy absorption protection does not rely entirely on the axial buckling deformation of the honeycomb cell 31 or the thin-walled cylinder 32, but rather on the bending strength of the upper panel 1 to disperse the explosion or impact load, and then transfer it to the honeycomb core 3 of the thin-walled cylinder 32 through the adhesive layer with a certain shear strength. The impact load is resisted by the lateral stiffness of the thin-walled cylinder 32 and the honeycomb cell 31 and their complex interactions.

[0044] Specifically, the top of the thin-walled cylinder 32 is longitudinally bonded to the bottom surface of the top plate 1, and the bottom of the honeycomb cell 31 is longitudinally bonded to the top surface of the top plate 1, and the integral structure is heated and cured to form the shape.

[0045] The integral structure is an embedded cylindrical honeycomb core material. Although there is a geometric constraint between the inner wall of the honeycomb cell 31 and the outer wall of the thin-walled cylinder 32, due to the limitation of molding precision, there is still a gap between the thin-walled cylinder 32 and the inner wall of the honeycomb cell 31, which affects the load transfer and bearing efficiency. By bonding the bottom of the honeycomb cell 31 longitudinally to the top surface of the lower plate 2, and bonding the top of the thin-walled cylinder 32 longitudinally to the bottom surface of the upper plate 1, the explosive load acting on the panel can be effectively transferred through the shear strength of the adhesive, giving full play to the joint bearing capacity of the thin-walled cylinder 32 and the honeycomb cell 31.

[0046] Specifically, as shown in the attached document Figure 1 As shown in (b), a schematic diagram of the honeycomb sandwich structure is given, with L as the width axis, W as the length axis, and T as the height axis. Figure 1 (b) It can be seen that the honeycomb cells 31 are divided into multiple rows, and the multiple rows of honeycomb cells 31 are closely arranged on the top surface of the bottom plate 2. The centers of any three honeycomb cells 31 in any two adjacent rows form an equilateral triangle. Multiple thin-walled cylinders 32 are divided into multiple rows, and each row of thin-walled cylinders 32 corresponds one-to-one with each row of honeycomb cells 31 and is inserted vertically into the honeycomb cells 31. Figure 1 As shown in (c) Where h is the side length of the honeycomb cell 31, d is the wall thickness of the thin-walled cylinder 32, and R is the radius of the thin-walled cylinder 32.

[0047] Specifically, both the honeycomb cell 31 and the thin-walled cylinder 32 are made of the same metal material to ensure the deformation coordination between the honeycomb cell 31 and the thin-walled cylinder 32.

[0048] Specifically, the metal material is aluminum. Both the honeycomb cell 31 and the thin-walled cylinder 32 are made of aluminum alloy. The reason for choosing aluminum alloy is that aluminum alloy has better plastic deformation capacity than steel, is less prone to cracking, can produce large plastic yield deformation, is lighter in weight, has higher energy absorption efficiency per unit mass than steel, and its cost is lower than that of titanium alloy.

[0049] Specifically, the top of the thin-walled cylinder 32 is bonded to the bottom surface of the upper panel 1, and the bottom of the honeycomb cell 31 is bonded to the top surface of the lower panel 2 using epoxy resin adhesive. Epoxy resin adhesive is chosen here because it has strong adhesion to metal interfaces, excellent mechanical properties of the bonded interface, a wide range of curing stability, and is easy to cure.

[0050] Specifically, the upper panel 1 and the lower panel 2 are made of AL5052 aluminum alloy. The reason for choosing aluminum alloy is that aluminum alloy has better plastic deformation capacity than steel, is less prone to cracking, can produce large plastic yield deformation, is lighter in weight, has higher energy absorption efficiency per unit mass than steel, and its cost is lower than that of titanium alloy.

[0051] A method for forming an embedded circular tube honeycomb sandwich panel includes the following steps:

[0052] Multiple honeycomb cells 31 and multiple thin-walled cylinders 32 were prepared;

[0053] Apply epoxy resin adhesive to the lower panel 2, attach multiple honeycomb cells 31 to the lower panel 2, and press them firmly.

[0054] Each honeycomb cell 31 is inserted into each thin-walled cylinder 32, and the honeycomb cell 31 and the thin-walled cylinder 32 are compacted.

[0055] Apply epoxy resin adhesive to the top panel 1, then attach the top panel 1 to multiple thin-walled cylinders 32 and press it firmly.

[0056] The prepared embedded circular tube honeycomb sandwich panel is then heated and cured.

[0057] Specifically, both the upper panel 1 and the lower panel 2 are metal plates. The shear strength of the epoxy resin metal bonding surface between the upper panel 1 and the multiple thin-walled cylinders 32, and the shear strength of the epoxy resin metal bonding surface between the lower panel 2 and the multiple honeycomb cells 31 are both not less than 15 MPa. The heating and curing temperature is 120℃~140℃.

[0058] The adhesive layer needs to play a role in connecting the panel and the core material during the load-bearing process. Its bonding strength during structural deformation should be guaranteed as much as possible. The shear strength of honeycomb structures is usually between 1 and 5 MPa, and the shear strength of thin-walled round tubes is between 0.5 and 1.5 MPa. Therefore, the shear strength of the bonding interface should not be lower than the sum of the two, while ensuring a certain safety margin. In addition, the shear strength of epoxy resin adhesive can usually be guaranteed to be above 20 MPa. Therefore, the design parameter of 15 MPa will not pose new difficulties to the process.

[0059] Furthermore, the shear strength of epoxy resin is related to the temperature and time during its curing process. For example, at a curing temperature of 80±2℃, it requires 2–3 hours; if the temperature is increased to 100±2℃, the time is shortened to 1–2 hours; and at a high temperature of 150±2℃, a certain shear strength can be achieved in just 1 hour (using LY12CZ material tested at 150±5℃ for 3 hours, the measured shear strength value was 23.5 MPa). This indicates that by adjusting the curing conditions, the performance of epoxy resin, including its shear strength, can be optimized. Setting the curing temperature to 120–140℃ comprehensively considers ensuring shear strength while avoiding affecting the mechanical properties of the panel and core material.

[0060] Specifically, an application of an embedded circular tube honeycomb sandwich panel in a near-field explosion finite element simulation model is given.

[0061] like Figures 7-8 As shown, a conventional honeycomb sandwich structure is presented, which includes an upper panel, a lower panel, and multiple honeycomb cells. The multiple honeycomb cells are closely arranged between the upper panel and the lower panel and are connected to the upper panel and the lower panel.

[0062] Results Analysis

[0063] (I) Finite Element Simulation Model Analysis under Near-Field Explosion

[0064] Figure 2 A finite element simulation model of the embedded circular tube honeycomb sandwich panel proposed in this invention under near-field explosion is presented. The impact resistance performance of conventional honeycomb sandwich panels and filled honeycomb sandwich panels under near-field explosion load is compared through finite element simulation analysis. It is worth noting that, in order to ensure lateral comparability, the conventional honeycomb sandwich panel has undergone cell wall thickening treatment to ensure that the total mass of the two is consistent.

[0065] (II) Stress cloud diagram analysis of the upper panel of the sandwich structure

[0066] Figures 3-5 The stress cloud diagrams of the front panel 1 of the honeycomb sandwich panel are compared. GHP represents conventional honeycomb sandwich panels, and HFCT represents infilled honeycomb sandwich panels. At the same response time, the conventional honeycomb sandwich panel GHP has a higher overall stiffness and more obvious stress concentration, with the main stress area in the pressure wave center region. In contrast, the stress distribution of the infilled honeycomb sandwich panel HFCT is more reasonable. Due to the better plastic deformation capacity of the core material, a clear stress wave propagation zone is generated between the center and the boundary region, which fully utilizes the overall load-bearing capacity of the structure.

[0067] (III) Analysis of the displacement-time history curves of the center points of the upper and lower panels of the sandwich structure

[0068] Figure 6The displacement-time history curves of the center point of the upper and lower panels of the honeycomb sandwich panel are given. GHP represents conventional honeycomb sandwich, HFCT represents infilled honeycomb sandwich, F represents the upper panel, and B represents the lower panel. The comparison shows that, whether it is the upper panel 1 or the lower panel 2, the deflection control of the honeycomb sandwich panel with infilled honeycomb sandwich is better than that of the conventional honeycomb sandwich panel, and it shows better impact resistance.

[0069] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A honeycomb sandwich panel with embedded circular tubes, comprising an upper panel (1) and a lower panel (2), characterized in that, Multiple honeycomb cores (3) are longitudinally arranged between the upper panel (1) and the lower panel (2). The top of the multiple honeycomb cores (3) is connected to the bottom of the upper panel (1), and the bottom of the multiple honeycomb cores (3) is connected to the top surface of the lower panel (2), so that the upper panel (1), the lower panel (2) and the multiple honeycomb cores (3) form an integral structure. Each honeycomb core includes a honeycomb cell (31) and a thin-walled cylinder (32). The top of the thin-walled cylinder (32) is longitudinally bonded to the bottom surface of the upper panel (1), and the bottom of the honeycomb cell (31) is longitudinally bonded to the top surface of the lower panel (2). The thin-walled cylinder (32) is vertically inserted into the honeycomb cell (31), and the outer wall of the thin-walled cylinder (32) is tangent to the inner wall of the honeycomb cell (31) to reduce the gap between the thin-walled cylinder (32) and the honeycomb cell (31). When the impact load passes through the upper panel (1) and the lower panel (2), the honeycomb cores (32) can be connected to the bottom surface of the upper panel (1) and the lower panel (2). The plate (2) effectively transmits energy to the entire honeycomb core (3). Its energy absorption and protection function does not rely entirely on the axial buckling deformation of the honeycomb cells (31) or thin-walled cylinders (32), but rather on the bending strength of the upper panel (1) to disperse the explosion or impact load. Then, it is transmitted to the honeycomb core (3) of the thin-walled cylinders (32) through the adhesive layer with a certain shear strength. It resists the impact load by relying on the lateral stiffness of the thin-walled cylinders (32) and the honeycomb cells (31) themselves and the complex interaction. The multiple honeycomb cells (31) are divided into multiple rows, and the multiple rows of honeycomb cells (31) are closely arranged on the top surface of the lower plate (2). The centers of any three honeycomb cells (31) in two adjacent rows form an equilateral triangle. The multiple thin-walled cylinders (32) are divided into multiple rows, and each row of thin-walled cylinders (32) corresponds to each row of honeycomb cells (31) and is inserted vertically into the honeycomb cells (31).

2. The embedded circular tube honeycomb sandwich panel according to claim 1, characterized in that, Both the honeycomb cells (31) and the thin-walled cylinders (32) are made of the same metal material.

3. The embedded circular tube honeycomb sandwich panel according to claim 2, characterized in that, The metal material is aluminum.

4. The embedded circular tube honeycomb sandwich panel according to claim 1, characterized in that, The top of the thin-walled cylinder (32) and the bottom surface of the upper panel (1), as well as the bottom of the honeycomb cell (31) and the top surface of the lower panel (2), are bonded together with epoxy resin adhesive.

5. The embedded circular tube honeycomb sandwich panel according to claim 1, characterized in that, The upper panel (1) and the lower panel (2) are made of aluminum alloy.

6. A method for forming an embedded circular tube honeycomb sandwich panel according to any one of claims 1 to 5, characterized in that, Includes the following steps: Prepare multiple honeycomb cells (31) and multiple thin-walled cylinders (32); Apply epoxy resin to the bottom panel (2), attach multiple honeycomb cells (31) to the bottom panel (2), and press them firmly. A thin-walled cylinder (32) is inserted into each cell (31), and the cell (31) and the thin-walled cylinder (32) are compacted. Apply epoxy resin adhesive to the top panel (1), then bond the top panel (1) to multiple thin-walled cylinders (32) and press it firmly. The prepared embedded circular tube honeycomb sandwich panel is then heated and cured.

7. The molding method of an embedded circular tube honeycomb sandwich panel according to claim 6, characterized in that, Both the upper panel (1) and the lower panel (2) are metal plates. The shear strength of the epoxy resin metal bonding surface between the upper panel (1) and multiple thin-walled cylinders (32) and the shear strength of the epoxy resin metal bonding surface between the lower panel (2) and multiple honeycomb cells (31) are not less than 15 MPa. The heating and curing temperature is 120℃~140℃.

8. The application of the embedded circular tube honeycomb sandwich panel according to claim 1 in a near-field explosion finite element simulation model.

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