Prismatic coplanar origami sandwich structure

Abstract

The prismatic coplanar origami sandwich structure comprises a columnar origami structure serving as a core layer, a large prismatic skin serving as an outer surface layer and a small prismatic skin serving as an inner surface layer, the columnar paper folding structure is characterized in that the columnar paper folding structure is formed by arranging a plurality of folding units around the Z axis in a multi-layer annular array mode; each folding unit is formed by splicing two folding subunits in a mirror image manner; each folded subunit has an outer plane coplanar with one cylindrical surface in the large prism skin and an inner plane coplanar with one cylindrical surface in the small prism skin. Configuration design capable of forming a coplanar platform is introduced into a paper folding core layer structure, more reliable connection between a surface and a core is achieved, a larger adjustable parameterized design space is provided, and excellent comprehensive mechanical properties and wide engineering application prospects are achieved.

Description

Technical Field

[0001] This invention relates to the field of sandwich structure design, specifically to a prism-shaped coplanar origami sandwich structure. Background Technology

[0002] Sandwich structures are widely used in engineering fields such as transportation and aerospace due to their excellent lightweight characteristics and outstanding energy absorption capabilities. In particular, columnar sandwich structures have significant application value in practical engineering due to their good axial load-bearing capacity and bending resistance.

[0003] Existing columnar sandwich structures offer a variety of core layer forms, with hexagonal honeycomb structures being a common example. As research into origami structures deepens, the flexibility of origami geometry and the unique mechanical properties exhibited at creases have provided new ideas and possibilities for core layer design. However, in most existing columnar origami sandwich structures, the connection between the core layer (such as Miura-Ori) and the inner and outer layers is limited by the origami structure itself. Typically, they can only rely on creases or vertices for point or line bonding with the inner and outer layers, resulting in a small effective contact area between the core and outer layers. Under axial compression or bending loads, the bonded area easily becomes fragile, leading to localized debonding and affecting the overall mechanical properties of the structure, thus limiting its full potential. Summary of the Invention

[0004] This invention provides a prism-shaped coplanar origami sandwich structure to achieve a more reliable connection between the core origami structure and the inner and outer layers, and to provide a larger adjustable parametric design space, thereby obtaining better and more adaptable overall mechanical properties.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A prismatic coplanar origami sandwich structure includes a columnar origami structure as the core layer, a large prismatic skin as the outer layer, and a small prismatic skin as the inner layer. The columnar origami structure is composed of multiple folding units arranged in a multi-layer circumferential array around the Z-axis. Each folding unit is formed by mirror-joining two folding sub-units. Each folding sub-unit is formed by folding 12 quadrilateral facets. The folding sub-unit is rectangular in its unfolded state, and five folding lines are provided within the rectangle to divide it into 12 facets. Of the five folding lines, two are arranged along the length of the rectangle, and three are arranged along the width of the rectangle. The two folding lines arranged along the length of the rectangle are respectively a first fold line formed by four first folds and a second fold line formed by four second folds. The four first folds of the first fold line are parallel to the four second folds of the second fold line. The folding directions of the first folds and the second folds are opposite. Three fold lines are arranged along the width of the rectangle. They are, in sequence, a third fold line formed by three mixed fold lines, a fourth fold line formed by three mixed fold lines, and a first straight line formed by three mixed fold lines. The third and fourth fold lines are symmetrical. The first broken line intersects the third broken line, the fourth broken line, and the first straight line at the first vertex, the second vertex, and the third vertex, respectively. The second broken line intersects the third broken line, the fourth broken line, and the first straight line at the fourth vertex, the fifth vertex, and the sixth vertex, respectively. The interior angles of the four adjacent faces at the first vertex, the second vertex, the fourth vertex, and the fifth vertex are 90° respectively. 90° and (180°- The interior angles of the four adjacent faces at the third and sixth vertices are 90°, 90°, (180°-), and (180°-) respectively. )and ,in These are adjustable parameters; The folding subunits are arranged according to the folding angle. After folding, an outer plane coplanar with one cylindrical face of the large prism skin and an inner plane coplanar with one cylindrical face of the small prism skin are obtained; folding angle Let be the angle between the normal vectors pointing to the same side of two adjacent faces with an interior angle of 90° at the sixth vertex, based on the number of sides of the prism. N and Sure.

[0006] After the folded subunit is folded, the acute angle formed by the projections of the plane normal of the outer plane and the plane normal of the inner plane onto the XY plane is: And satisfy the following relation:

[0007] The number of sides of the cross-sectional polygons of the large prism skin and the small prism skin. N =6, then the acute angle included =30°.

[0008] The internal angle of the plane =60°, then the folding angle =114.2°.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a prism-shaped coplanar origami core structure. Thanks to the outer and inner planes of the prism-shaped origami structure itself, which is the core layer, the origami core layer and the skin layer can achieve face-to-face contact connection. Compared with the method of connecting the core layer with the skin layer by relying only on creases or vertices, this structure significantly increases the face-core contact area, thereby improving the reliability of the face-core connection and effectively avoiding delamination or failure caused by weak local connection.

[0010] 2. The prism-shaped coplanar origami sandwich structure provided by the present invention, under axial compressive load, benefits from the orderly folding deformation guided by the creases of the core origami structure and the reliable connection between the face and the core, enabling the structure to undergo effective buckling and energy dissipation behavior, and exhibiting excellent axial bearing capacity and energy absorption capacity.

[0011] 3. The prism-shaped coplanar origami sandwich structure provided by the present invention has an overall structure whose shape, size and mechanical properties can be flexibly designed and adjusted according to requirements, has good parameter adjustability and has broad engineering application prospects. Attached Figure Description

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Figure 1 This is a three-dimensional schematic diagram of the hexagonal prism coplanar origami sandwich structure provided by the present invention; Figure 2 This is a schematic diagram of the structure of the folded subunit provided by the present invention; Figure 3 This is a schematic diagram of the Z-axis plane of the folded subunit provided by the present invention; Figure 4 This is a schematic diagram of two folding sub-units spliced ​​together to form a folding unit, provided by the present invention; Figure 5 This is a three-dimensional schematic diagram of the columnar origami structure provided by the present invention; Figure 6 This is a Z-axis planar schematic diagram of the columnar origami structure provided by the present invention; Figure 7 This is a three-dimensional schematic diagram of the large prism skin and the small prism skin provided by the present invention; Figure 8 This is a three-dimensional schematic diagram of the assembly of the hexagonal prism coplanar origami sandwich structure provided by the present invention; Figure 9 This is a schematic diagram of the Z-axis plane of the hexagonal prism coplanar origami sandwich structure provided by the present invention; Figure 10 The load-displacement curve of the hexagonal prism coplanar origami sandwich structure provided by this invention; Figure 11 This is a three-dimensional schematic diagram of the triangular prism coplanar origami sandwich structure provided by the present invention; Figure 12 This is a three-dimensional schematic diagram of the coplanar quadrangular prism origami sandwich structure provided by the present invention; In the diagram: 1 is a folding unit, 11 is a folding sub-unit, 101 is the third rectangular facet, 102 is the fourth rectangular facet, 103 is an isosceles trapezoidal facet, 104 is the fifth rectangular facet, 105 is the first right-angled trapezoidal facet, 106 is the second right-angled trapezoidal facet, 107 is the third right-angled trapezoidal facet, 108 is the fourth right-angled trapezoidal facet, 109 is the fifth right-angled trapezoidal facet, 110 is the sixth right-angled trapezoidal facet, 2 is a columnar origami structure, 3 is a large prism skin, 4 is a small prism skin, 51 is a complete external coplanar platform, 52 is a 1 / 2 external coplanar platform, 61 is a complete internal coplanar platform, and 62 is a 1 / 2 internal coplanar platform. Detailed Implementation

[0014] The present invention will now be described in further detail with reference to the accompanying drawings. It should be understood that the prism shape, Z-axis mirror symmetry number, dimensions of the folding sub-units, and the sizes of the in-plane angles and folding angles of the coplanar origami sandwich structure used in this embodiment are merely illustrative examples and do not limit the scope of protection of the present invention.

[0015] like Figure 1 As shown, taking a hexagonal prism coplanar origami sandwich structure as an example, the structure consists of a columnar origami structure 2 as the core layer, a large prism skin 3 as the outer layer, and a small prism skin 4 as the inner layer. The columnar origami structure 2 is formed by multiple folding units 1 arranged in an M-layer circumferential array around the Z-axis; the folding unit 1 is formed by two folding sub-units mirrored about the XY plane; the number of sides of the cross-sectional polygons of the large prism skin 3 and the small prism skin 4, as well as the number of folding units 1 arranged in a circumferential array around the Z-axis, are all the same. N In the picture N =6, M =4, but in practice only needs to satisfy N ≥3, M ≥1 is sufficient.

[0016] like Figure 2-3 As shown, the folding subunit 11 of folding unit 1 consists of 12 quadrilateral facets. Creases are provided at the facet connections. In its fully unfolded state, the outer contour is rectangular. Adjustable geometric dimensional parameters include a, b, c, d, e, and f. The unit contains two first-type vertices and four second-type vertices. Each vertex is composed of three mountain creases and one valley crease (or three valley creases and one mountain crease). In the figure, thick solid lines represent mountain creases, and thick dashed lines represent valley creases. The interior angles of the four adjacent facets at the first-type vertex are 90°, 90°, (180°-) respectively. )and The interior angles of the four adjacent faces at the second type of vertex are 90°, ... 90° and (180°- ),in As an adjustable parameter, the angle between the normal vectors pointing to the same side of two adjacent faces with an interior angle of 90° at the first type of vertex is the fold angle. A folding subunit 11 can be folded to form a 1 / 2 external coplanar platform 52 and a 1 / 2 internal coplanar platform 62.

[0017] After folding subunit 11, the normals at the centroids of four rectangular facets intersect the central rotation axis Z-axis of the circumferential array. The rectangular facet furthest from the Z-axis is the 1 / 2 outer coplanar platform 52, and the facet closest to the Z-axis is the 1 / 2 inner coplanar platform 62. Of the other two rectangular facets, the facet parallel to the 1 / 2 outer coplanar platform 52 is the third rectangular facet 101, and the facet parallel to the 1 / 2 inner coplanar platform 62 is the fourth rectangular facet 102. The 1 / 2 outer coplanar platform 52 and the third rectangular facet 101 are connected by an isosceles trapezoidal facet 103, and the 1 / 2 inner coplanar platform 62 and the fourth rectangular facet 102 are connected by a fifth rectangular facet 104. The 1 / 2 outer coplanar platform 52 and the fourth rectangular facet 62 are connected by... Plate 102 is connected by the first right trapezoidal plate 105. The 1 / 2 inner coplanar platform 62 is connected to the third rectangular plate 101 by the second right trapezoidal plate 106. The isosceles trapezoidal plate 103, the fifth rectangular plate 104, the first right trapezoidal plate 105 and the second right trapezoidal plate 106 are connected by the third right trapezoidal plate 107. The 1 / 2 outer coplanar platform 52, the isosceles trapezoidal plate 103 and the third rectangular plate 101 of the folded subunit 11 are connected to the fourth rectangular plate 102, the fifth rectangular plate 104 and the 1 / 2 inner coplanar platform 62 of the adjacent folded subunits arranged in a ring by the fourth right trapezoidal plate 108, the fifth right trapezoidal plate 109 and the sixth right trapezoidal plate 110 respectively. The first right-angled trapezoidal surface 105 and the fourth right-angled trapezoidal surface 108, the third right-angled trapezoidal surface 107 and the fifth right-angled trapezoidal surface 109, and the second right-angled trapezoidal surface 106 and the sixth right-angled trapezoidal surface 110 of folded subunit 11 are symmetrical about the plane containing the Z-axis and the normal at the centroid of the half-external coplanar platform 52. The acute angle formed by the projections of the normals of the half-external coplanar platform 52 and the half-internal coplanar platform 62 of folded subunit 1 onto the XY plane is... And satisfy the following relation:

[0018] when N and When determined, folding angle It can be uniquely determined.

[0019] like Figure 4-5As shown, folded sub-unit 11 is spliced ​​with adjacent folded sub-units that are mirror-symmetrical along the Z-axis to form folded unit 1. A folded unit 1 contains a complete inner coplanar platform 61 and two 1 / 2 outer coplanar platforms 52. In the Z-axis direction, adjacent layers of folded units can be spliced ​​to form a complete outer coplanar platform 51. Figure 4 The diagram shows how two folded sub-units 11 are spliced ​​together to form a folded unit 1, which in turn forms a complete internal coplanar platform 61.

[0020] like Figure 5-6 As shown, the columnar origami structure 2 is composed of 6×4 folding units 1. It should be noted that the columnar origami structure 2 is fabricated using integrated molding methods such as 3D printing, and there are no gaps between the folding units 1 after assembly. This columnar origami structure 2 includes several complete external coplanar platforms 51, several half-external coplanar platforms 52, and several complete internal coplanar platforms 61. For ease of description, all complete external coplanar platforms 51 and all half-external coplanar platforms 52 are collectively referred to as the external coplanar platform group, and all complete internal coplanar platforms 61 are collectively referred to as the internal coplanar platform group.

[0021] In this embodiment, the large prism skin 3 and the small prism skin 4 are respectively as follows: Figure 7 As shown in (a) and (b), their cross-sections are regular hexagons with different side lengths. The large prism skin 3 and the small prism skin 4 are respectively obtained by extending the outer coplanar platform group and the inner coplanar platform group of the columnar origami structure 2 in the plane until they intersect.

[0022] like Figure 8-9 As shown, the assembly method of the hexagonal prism-shaped coplanar origami sandwich structure is described in detail. The prism-shaped origami structure 2, which serves as the core layer, is connected face-to-face to the large prism skin 3 through its own outer coplanar platform group, and to the small prism skin 4 through its own inner coplanar platform group, thereby achieving a reliable connection between the surface and the core.

[0023] In a preferred embodiment, the geometric dimensions of the folding unit 1 are a=5.1mm, b=6.7mm, c=6.4mm, d=1mm, e=4.2mm, f=8.7mm, and the interior angles are... =60°, number of circumferential array elements N=6, number of layers M=4, plane normal angle =30°, folding angle =114.2°, and the thickness of all surfaces is 0.2mm.

[0024] In this embodiment, the following is established: Figure 1 The finite element model of the hexagonal prism coplanar origami sandwich structure shown is set to aluminum as the material, and numerical simulation calculations of its Z-axis mechanical compressive properties were performed, yielding the following results: Figure 10The load-displacement curve shown indicates that a high plateau segment is formed in the initial stage of compression, and the overall trend is a gradual and stable increase as compression progresses. The structure can buckle effectively, has good axial bearing capacity and excellent energy dissipation mechanism.

[0025] The prism-shaped coplanar origami sandwich structure provided by this invention can have any prism shape, and can be composed of regular polygonal cross-sections of large and small prism skins and a corresponding circumferential array of folding units. N To be determined together, for example, when N When the values ​​are 3 and 4 respectively, the corresponding triangular prism coplanar origami sandwich structures and quadrangular prism coplanar origami sandwich structures are as follows: Figure 11 and Figure 12 As shown.

[0026] The above description is merely an embodiment provided by the present invention. The present invention is not limited to this embodiment, and any simple modifications or substitutions that do not depart from the principles and basic characteristics of the present invention fall within the protection scope of the present invention.

Claims

1. A prismatic co-planar origami sandwich structure comprising a columnar origami structure as a core layer, a large prismatic skin as an outer face layer, and a small prismatic skin as an inner face layer; characterized in that, The cylindrical origami structure is arranged in a multi-layer annular array around a Z axis by a plurality of folded units; each folded unit is formed by mirror splicing of two folded sub-units; each folded sub-unit has an outer plane coplanar with a cylindrical surface of a large prism skin and an inner plane coplanar with a cylindrical surface of a small prism skin.

2. A prismatic co-planar origami sandwich structure according to claim 1, wherein, Each folded sub-unit is folded by 12 quadrilateral facets; the folded sub-unit is rectangular in a planar unfolded state, and 5 folding lines are arranged in the rectangular to divide the rectangular into 12 facets; of the 5 folding lines, 2 folding lines are arranged along a length direction of the rectangular, and 3 folding lines are arranged along a width direction of the rectangular; the 2 folding lines arranged along the length direction of the rectangular are a first folding line formed by 4 first creases and a second folding line formed by 4 second creases, respectively, and the 4 first creases of the first folding line are parallel to the 4 second creases of the second folding line; the folding directions of the first creases and the second creases are opposite; the 3 folding lines arranged along the width direction of the rectangular are, in sequence along the width direction, a third folding line formed by 3 mixed creases, a fourth folding line formed by 3 mixed creases, and a first straight line formed by 3 mixed creases; the third folding line and the fourth folding line are symmetrical; The first broken line intersects the third broken line, the fourth broken line, and the first straight line at the first vertex, the second vertex, and the third vertex, respectively. The second broken line intersects the third broken line, the fourth broken line, and the first straight line at the fourth vertex, the fifth vertex, and the sixth vertex, respectively. The interior angles of the four adjacent faces at the first vertex, the second vertex, the fourth vertex, and the fifth vertex are 90° respectively. 90° and (180°- The interior angles of the four adjacent faces at the third and sixth vertices are 90°, 90°, (180°-), and (180°-) respectively. )and ,in These are adjustable parameters; The folding sub-unit is folded according to a folding angle After folding, the outer plane is coplanar with one cylindrical surface of the large prism skin, and the inner plane is coplanar with one cylindrical surface of the small prism skin; the folding angle The sixth vertex is the included angle between the normal vectors of the two adjacent face patches with an in-face angle of 90° at the sixth vertex, and the normal vectors point to the same side, and the number of edges of the prism N And Determined.

3. A prismatic co-planar origami sandwich structure according to claim 1, wherein, The acute angle between the projection of the normal of the outer plane and the normal of the inner plane in the XY plane is and satisfies the relationship: 。 4. A prismatic co-planar origami sandwich structure according to claim 1, wherein, the number of sides of the cross-sectional polygon of the large prismatic skin and the small prismatic skin N = 6, the acute included angle = 30°.

5. A prismatic co-planar origami sandwich structure according to claim 1, wherein, the in-plane angle = 60°, the folding angle = 114.2°.

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