Bevel combined corrugated core sandwich structure and preparation method thereof

Abstract

The invention discloses a folded angle combined corrugated core sandwich structure and a preparation method thereof. The structure consists of an upper surface layer panel, a folded angle combined corrugated core and a lower surface layer panel in sequence. Aiming at the problems of stress concentration and local crushing caused by a single core layer load transmission path of a traditional triangular corrugated sandwich structure, the break angle combined corrugated core gives consideration to the transmission of longitudinal and transverse forces; and the sawtooth-shaped part of the vertical bevel supporting face is inserted, flattened and bonded to the local opening of the triangular corrugated core. Compared with a traditional triangular corrugated sandwich structure under the same mass and the same explosion load, the pressure peak value at the central unit of the back panel of the bevel combined corrugated core sandwich structure is reduced by 20.6%, and the specific energy absorption is improved by 4.6 times. By optimizing the force transmission path of the core layer, transformation from two-dimensional bending deformation to three-dimensional buckling deformation of a traditional triangular corrugated sandwich structure under the explosion load is achieved, and the energy absorption efficiency of the structure is greatly improved.

Description

Technical Field

[0001] This invention belongs to the technical field of sandwich structure materials, specifically relating to a folded combined corrugated core sandwich structure and its preparation method. Background Technology

[0002] With the increasing demand for explosion-proof structures in aerospace, shipbuilding, vehicle engineering, and construction, a variety of protective structures have emerged, such as single-layer protective structures, multi-layer protective structures, and sandwich structures.

[0003] Lightweight sandwich structures are energy-absorbing protective structures with significant advantages in the field of impact and blast load protection, but their performance still has certain limitations. Taking the traditional triangular corrugated sandwich structure as an example, under the action of blast load, the structure can only absorb energy through the plastic deformation of the material in local areas. The deformation mode is a two-dimensional bending deformation mode, with a significant stress concentration effect. This leads to the problem of rapid failure of the overall structure due to premature and severe local damage.

[0004] Therefore, it is essential to provide a sandwich structure with an improved core layer to enhance the energy absorption efficiency of the traditional triangular corrugated sandwich structure, improve its deformation mode, and overcome the problem of significant stress concentration effect, thereby improving the structure's explosion resistance. Summary of the Invention

[0005] To address the stress concentration and localized crushing problems caused by the single load transmission path of the core layer in traditional triangular corrugated sandwich structures under explosive loads, this invention provides a folded composite corrugated core sandwich structure and its fabrication method. This invention transforms the two-dimensional bending deformation mode of the traditional triangular corrugated sandwich structure under explosive loads into a three-dimensional buckling deformation mode, optimizes the force transmission between core layers, promotes synergistic deformation of the core layers, greatly improves the energy absorption efficiency of the structure, enhances its blocking and buffering effect against explosive shock waves, and significantly improves its blast resistance.

[0006] The specific technical solution is as follows:

[0007] A folded corrugated core sandwich structure and its fabrication method are disclosed. The folded corrugated core sandwich structure consists of three layers arranged sequentially: an upper surface panel, a folded corrugated core, and a lower surface panel.

[0008] Furthermore, the aforementioned angled corrugated core takes into account the propagation of both lateral and longitudinal forces. Based on the concept of mortise and tenon interlocking, it is obtained by inserting, flattening, and bonding the serrated part of the vertical angled support surface to the local opening of the triangular corrugated core.

[0009] The method for preparing the angled corrugated core sandwich structure of the present invention includes the following steps:

[0010] Step 1: Select a malleable and deformable sheet material and cut it according to the design dimensions of the folded corner corrugated core to obtain a triangular corrugated core mother plate with partial openings and a vertical folded corner support surface mother plate with serrated sides.

[0011] Step 2: Send the triangular corrugated core mother plate into the triangular corrugated forming roller, and press the flat mother plate to form a triangular corrugated panel.

[0012] Step 3: The vertical corner support plate is fed into the corner forming roller. The flat plate is formed into a corner panel by stamping. The serrated part of the corner panel is coated with a two-component epoxy structural adhesive with a long working time.

[0013] Step 4: Using the interlocking concept of mortise and tenon joints, assemble the triangular corrugated panel and the angled panel to form the angled corrugated core motherboard.

[0014] Step 5: Send the corner-folded corrugated core motherboard to the corner-folded corrugated core forming roller. Press the serrated part of the corner panel protruding from the triangular corrugated panel to flatten it by stamping. At the same time, apply pressure to make the serrated part bond firmly to the triangular corrugated panel. Heat the roller to promote the curing of the two-component epoxy structural adhesive to form the structural unit of the corner-folded corrugated core.

[0015] Step 6: Adhere the upper surface panel, the corner corrugated core, and the lower surface panel to form a corner corrugated core sandwich structure.

[0016] Furthermore, in step one, the local opening position, length dimension, and width dimension of the triangular corrugated core mother plate correspond to the protruding position, length dimension, and thickness dimension of the serrated portion of the vertical angled support surface mother plate, respectively.

[0017] Furthermore, in step one, the local opening positions of the triangular corrugated core mother plate and the protruding positions of the serrated portion of the vertical angled support surface mother plate are all equidistantly distributed.

[0018] Furthermore, the partially open triangular corrugated core mother plate in step one is obtained by intermittently cutting the triangular corrugated core mother plate at the required opening using a laser cutting device.

[0019] Furthermore, step five also includes: arranging the structural units along the x-axis and y-axis to form a folded corrugated core.

[0020] The beneficial effects achieved by this invention are as follows:

[0021] 1. The aforementioned angled corrugated core sandwich structure reduces the peak pressure at the center unit of the back panel by 20.6% compared to the traditional triangular corrugated core sandwich structure of the same mass under the same explosive load. The specific energy absorption of the aforementioned angled corrugated core sandwich structure under the same explosive load is 4.6 times that of the traditional triangular corrugated core sandwich structure. This invention, by reconstructing the core unit connection method, achieves the transformation of the two-dimensional bending deformation mode of the traditional triangular corrugated core sandwich structure under explosive load to a three-dimensional buckling deformation mode. This allows the structure to deform collaboratively over a wider range, effectively overcoming the stress concentration and localized crushing problems caused by the single load transmission path of the core layer in the traditional triangular corrugated core sandwich structure under explosive load. This significantly improves the energy absorption efficiency of the structure, enhances its blocking and buffering effect against explosive shock waves, and significantly improves its blast resistance.

[0022] 2. The method for preparing the angled corrugated core sandwich structure proposed in this invention cleverly utilizes the interlocking concept of mortise and tenon joints, effectively solving the problem of difficult connection between the triangular corrugated core and the vertical angled support surface. By applying a two-component epoxy structural adhesive with a long working time to the serrated part of the vertical angled support surface, the connection between the triangular corrugated surface and the vertical angled support surface is made more solid, enhancing the integrity of the angled corrugated core and giving it better mechanical properties. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the construction of the angled combined corrugated core sandwich structure provided in this application;

[0024] Figure 2 A schematic diagram of the structure of the angled corrugated core provided in this application;

[0025] Figure 3 A flowchart illustrating a manufacturing method for a folded corrugated core sandwich structure provided by the present invention;

[0026] Figure 4 A comparison of the pressure-time history curves at the center unit of the back panel of a folded-angle corrugated core sandwich structure and a traditional triangular corrugated core sandwich structure of the same mass under the same explosive load.

[0027] Figure 5 A comparison of the internal energy time history curves of a folded corrugated core sandwich structure of the same mass and a traditional triangular corrugated core sandwich structure under the same explosive load.

[0028] In the attached diagram: 1. Upper surface panel; 2. Structural unit of the angled corrugated core; 201. Triangular corrugated surface; 202. Vertical angled support surface; 3. Lower surface panel; 4. Triangular corrugated core mother plate; 5. Vertical angled support surface mother plate; 6. Triangular corrugated panel; 7. Angle-shaped panel; 701. Serrated portion of the angle-shaped panel. Detailed Implementation

[0029] To further understand the present invention, the present invention will be described below with reference to specific embodiments and accompanying drawings. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0030] The upper surface panel, the corner-trimmed corrugated core, and the lower surface panel in this invention are made of 304 stainless steel. The mechanical properties of 304 stainless steel are shown in Table 1.

[0031] Table 1 Mechanical properties of 304 stainless steel

[0032] <![CDATA[Density ρ ( kg / m 3 )]]> Young's modulus (MPa) Shear moudulus(MPa) <![CDATA[Yield stress σ y (MPa)]]> Poisson's ratio 7900 200 77 275 0.3

[0033] The technical solution of the present invention will now be described in conjunction with the embodiments. Example 1

[0034] As attached Figure 1 Appendix Figure 2 As shown, a sandwich structure with a folded corrugated core includes an upper surface panel 1, a folded corrugated core, and a lower surface panel 3. The folded corrugated core is formed by an array of structural units 2 of the folded corrugated core along the x-axis and y-axis directions.

[0035] The structural unit 2 of the angled corrugated core is formed by connecting the triangular corrugated surface 201 and the vertical angled support surface 202.

[0036] As attached Figure 3 As shown, the present invention also provides a method for preparing a folded corrugated core sandwich structure, comprising the following steps:

[0037] Step 1: Select a malleable sheet material and cut it according to the design dimensions of the angled corrugated core to obtain a partially open triangular corrugated core mother plate 4 and a vertical angled support surface mother plate 5 with serrated sides. The partial opening positions of the triangular corrugated core mother plate and the protruding positions of the serrated parts of the vertical angled support surface mother plate are equidistantly distributed. The partial opening positions, length dimensions, and width dimensions of the triangular corrugated core mother plate correspond to the protruding positions, length dimensions, and thickness dimensions of the serrated parts of the vertical angled support surface mother plate, respectively. The partially open triangular corrugated core mother plate is obtained by intermittently cutting the triangular corrugated core mother plate at the required opening points using a laser cutting device.

[0038] Step 2: The triangular corrugated core motherboard is fed into the triangular corrugated forming roller by a feeder, and the flat motherboard is formed into a triangular corrugated panel 6 by stamping.

[0039] Step 3: The vertical corner support plate is fed into the corner forming roller by the feeder. The flat plate is formed into a corner panel 7 by stamping. The serrated part of the corner panel is coated with a two-component epoxy structural adhesive with a long working time.

[0040] Step 4: Using the interlocking concept of mortise and tenon joints, insert the serrated part 701 of the angled panel 7 into the opening of the triangular corrugated panel 6, thereby assembling the triangular corrugated panel and the angled panel to form an angled corrugated core motherboard.

[0041] Step 5: The corner-folded corrugated core motherboard is sent to the corner-folded corrugated core forming roller. The serrated portion 701 of the corner-folded panel 7 protruding from the triangular corrugated panel 6 is flattened by stamping. At the same time, pressure is applied to firmly bond the serrated portion 701 to the triangular corrugated panel 6. Heating is used to promote the curing of the two-component epoxy structural adhesive to form the structural unit 2 of the corner-folded corrugated core. The structural unit is arrayed along the x-axis and y-axis to form the corner-folded corrugated core.

[0042] Step 6: Adhere the upper surface panel 1, the corner corrugated core, and the lower surface panel 2 to form a corner corrugated core sandwich structure.

[0043] Tables 2 and 3 show the full model dimensions of each component of the angled corrugated core sandwich structure built using LS-DYNA, and Tables 4 and 5 show the full model dimensions of each component of the traditional triangular corrugated core sandwich structure built using LS-DYNA.

[0044] Table 2 Geometric Dimensions of the Angle-Folded Corrugated Core Unit

[0045] Core layer height (mm) Core web thickness (mm) Sidewall length (mm) Unit length (mm) Unit width (mm) Vertical plane height (mm) 14 0.547 19.8 50 28 14

[0046] Table 3. Geometric dimensions of the upper and lower surface panels of the angled corrugated core sandwich structure.

[0047] Length (mm) Width (mm) Front panel thickness (mm) Back panel thickness (mm) 300 288 1.4 1.4

[0048] Table 4. Geometric dimensions of traditional triangular corrugated core units.

[0049] Core layer height (mm) Core web thickness (mm) Sidewall length (mm) Unit length (mm) Unit width (mm) Vertical plane height (mm) 14 0.7 19.8 50 28 14

[0050] Table 5. Geometric dimensions of the upper and lower surface panels of a traditional triangular corrugated sandwich structure.

[0051] Length (mm) Width (mm) Front panel thickness (mm) Back panel thickness (mm) 300 288 1.4 1.4

[0052] Appendix Figures 4-5 The results are obtained from numerical simulation of the explosive performance of the angled corrugated core sandwich structure.

[0053] Appendix Figure 4Table 6 compares the pressure time history curves at the center unit of the back panel of the improved corrugation sandwich structure and the traditional triangular corrugation sandwich structure of the same mass under the same explosive load. The peak pressure at the center unit of the back panel of the improved corrugation sandwich structure and the traditional triangular corrugation sandwich structure are shown in Table 6.

[0054] Table 6. Peak pressure at the center unit of the back panel for both structures

[0055] Improved corrugation Traditional corrugation 355 MPa 447 MPa

[0056] From Table 6 and Figure 4 It can be seen that the peak pressure at the center unit of the back panel of the angled corrugated core sandwich structure is 20.6% lower than that of the traditional triangular corrugated core sandwich structure. This indicates that by improving the connection method of the core unit, it effectively disperses the energy generated by the explosion, improves the problem of significant stress concentration effect, enhances the blocking and buffering effect of explosion energy, and significantly improves the explosion resistance performance of the structure without changing the mass.

[0057] Appendix Figure 5 A comparison of the internal energy time history curves of a folded-angle corrugated core sandwich structure and a traditional triangular corrugated core sandwich structure of the same mass under the same explosive load is shown. Figure 5 As shown, the internal energy of the angled corrugated core sandwich structure is significantly higher than that of the traditional triangular corrugated core sandwich structure. Calculations show that the specific energy absorption of the angled corrugated core sandwich structure is 4.6 times that of the traditional triangular corrugated core sandwich structure. This indicates that the introduction of the vertical angled support surface promotes the coordinated deformation of the core layer, significantly improving the energy absorption efficiency of the structure and providing a more reliable safety guarantee for the protected target.

Claims

1. A kind of angle combination corrugated core sandwich structure, characterized by, It is composed of three layers of upper surface layer panel, angle combination corrugated core and lower surface layer panel arranged in sequence; The angle combination corrugated core is based on the mortise and tenon joint interlocking idea, and the sawtooth part of the vertical angle support surface is inserted, flattened and bonded at the local opening of the triangular corrugated core to give.

2. The method of making a mitered combination-corrugated core sandwich structure of claim 1, wherein, It includes the following steps: Step one, select the plastic deformation plate, according to the design size of the angle combination corrugated core, obtain the local opening triangular corrugated core mother plate and the vertical angle support surface mother plate with sawtooth side. Step two, send the triangular corrugated core mother plate to the triangular corrugated forming roller, and form the triangular corrugated panel by stamping the flat mother plate. Step three, send the vertical angle support surface mother plate to the angle forming roller, form the angle panel by stamping the flat mother plate, and the sawtooth part of the angle panel is coated with a long-operable two-component epoxy structural adhesive. Step four, use the mortise and tenon joint interlocking idea to assemble the triangular corrugated panel and the angle panel to form the angle combination corrugated core mother plate. Step five, send the angle combination corrugated core mother plate to the angle combination corrugated core forming roller, flatten the sawtooth part of the angle panel protruding from the triangular corrugated panel by stamping, and at the same time, apply pressure to make the sawtooth part and the triangular corrugated panel firmly bonded, and heat to promote the curing of the two-component epoxy structural adhesive, forming the structural unit of the angle combination corrugated core. Step six, bond the upper surface layer panel, angle combination corrugated core and lower surface layer panel to form the angle combination corrugated core sandwich structure. 3.The preparation method of the angle combination corrugated core sandwich structure according to claim 2, characterized by, The local opening position, length direction size and width direction size of the triangular corrugated core mother plate in step one correspond to the protruding position, length direction size and thickness direction size of the sawtooth part of the vertical angle support surface mother plate respectively. 4.The preparation method of the angle combination corrugated core sandwich structure according to claim 2, characterized by, The local opening position of the triangular corrugated core mother plate and the protruding position of the sawtooth part of the vertical angle support surface mother plate in step one are both equidistantly distributed. 5.The preparation method of the angle combination corrugated core sandwich structure according to claim 2, characterized by, The local opening triangular corrugated core mother plate in step one is obtained by intermittent dot cutting at the opening position of the triangular corrugated core mother plate by a laser cutting device. 6.The preparation method of the angle combination corrugated core sandwich structure according to any one of claims 2-5, characterized by, The step five further includes: arraying the structural unit along the x-axis direction and the y-axis direction to form the angle combination corrugated core.

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