CN113420346B - Nonreciprocal bending mechanical metamaterials and their design methods - Google Patents

Abstract

The present application discloses a nonreciprocal bending mechanics metamaterial and a design method thereof. The nonreciprocal bending mechanics metamaterial includes a plurality of periodically arranged and interconnected unit cell structures in a three-dimensional space; along a first direction , the unit cell structure includes a first subsection, a second subsection and a third subsection, and along the second direction, the unit cell structure also includes a fourth subsection and a fifth subsection arranged oppositely; The cell structure also includes a sixth sub-section and a seventh sub-section arranged oppositely; a non-reciprocal bending mechanics metamaterial provided by the present invention realizes the natural material by breaking the spatial inversion symmetry of the three-dimensional structure and introducing nonlinearity The lack of asymmetric forward and reverse bending stiffness properties provides a new paradigm for mechanically functional metamaterials.

Description

Nonreciprocal bending mechanical metamaterials and their design methods

technical field

The invention relates to the field of mechanical metamaterial structure design, in particular to a nonreciprocal bending mechanical metamaterial and a design method thereof.

Background technique

According to the Maxwell-Bettis reciprocity theorem in continuum mechanics, the forward and reverse bending deformations of most natural materials should maintain symmetry and reciprocity. Under the same magnitude of forward and reverse bending moment loads, the forward and reverse bending deflection and rotation angle responses of the material are symmetrical and consistent, with the same symmetrical forward and reverse bending stiffness.

If we can break through the limitation of Maxwell-Betis reciprocity theorem, prepare non-reciprocal bending materials with asymmetric forward and reverse bending stiffness characteristics, and obtain extraordinary mechanical properties that are not found in natural materials, which will provide mechanical system design. more degrees of freedom. However, non-reciprocal bending materials are still very scarce at present, and their development and design still face huge challenges.

SUMMARY OF THE INVENTION

The present invention aims to solve the above-mentioned problem of scarcity of non-reciprocal bending materials. To this end, the present invention discloses a nonreciprocal bending mechanics metamaterial and a design method thereof. The nonreciprocal bending mechanics metamaterial has asymmetric forward and reverse bending stiffness properties that natural materials do not have.

In one aspect, the present invention provides a non-reciprocal bending mechanical metamaterial, comprising a plurality of periodically arranged and interconnected unit cell structures in a three-dimensional space;

along the first direction, the unit cell structure includes a first subsection, a second subsection and a third subsection;

The first subsection includes four first connecting rods, which are the first A connecting rod, the first B connecting rod, the first C connecting rod and the first D connecting rod, and the No. 1 connecting rod of the four first connecting rods. One end is connected to the first end point, and the second ends of the four first connecting rods are all located in a first plane, and along the first direction, the first end points are located in the first plane and between the second subsections, and the first end point and the first plane have a first distance;

The second subsection includes four second connecting rods, which are respectively the second A connecting rod, the second B connecting rod, the second C connecting rod and the second T connecting rod, and the fourth connecting rod of the four second connecting rods. One end is connected to the second end point, and the second ends of the four second connecting rods are all located in a second plane, and along the first direction, the second end points are located in the second plane and the second plane. between the first subsections, and the second end point and the second plane have a second distance;

The third subsection includes four third connecting rods, which are the third connecting rod A, the third connecting rod B, the third connecting rod C and the third connecting rod D, and the fourth connecting rods of the four third connecting rods are One end is connected to the third end point, and the second ends of the four third connecting rods are all located in a third plane, and along the first direction, the third end points are located in the third plane away from the between the second subsections, and the third end point and the third plane have a third distance;

The orthographic projection of the first connecting rod on the second plane overlaps with the orthographic projection of the third connecting rod on the second plane, and the orthographic projection of the second connecting rod on the third plane is the same as the orthographic projection of the second connecting rod on the third plane. The first connecting rods are staggered in the orthographic projection of the third plane, and the orthographic projection of the first end point on the first plane, the orthographic projection of the second end point on the first plane and The orthographic projections of the third end point on the first plane overlap, and along the first direction, the first plane, the second plane and the third plane are parallel to each other;

Along the second direction, the unit cell structure further includes a fourth subsection and a fifth subsection disposed oppositely;

The fourth subsection includes four fourth connecting rods, which are the fourth A connecting rod, the fourth B connecting rod, the fourth C connecting rod and the fourth D connecting rod, and the fourth connecting rod of the four fourth connecting rods is the fourth connecting rod. One end is connected to the fourth end point, and the fourth node and the second ends of the four fourth connecting rods are all located in a fourth plane;

Wherein, the second end of the fourth A connecting rod and the second end of the first A connecting rod are connected to the first node, and the second end of the fourth B connecting rod is connected to the first B connecting rod. The second end of the connecting rod is connected to the second node, the second end of the fourth C connecting rod and the second end of the third B connecting rod are connected to the third node, and the second end of the fourth T connecting rod is connected to the third node. The second end of the third armor connecting rod is connected to the fourth node, and the second end of the second armor connecting rod is connected to the fourth end point;

The fifth subsection includes four fifth connecting rods, which are respectively the fifth connecting rod A, the fifth connecting rod B, the fifth connecting rod C and the fifth connecting rod D, the fourth connecting rod of the four fifth connecting rods. One end is connected to the fifth end point, and the fifth end point and the second ends of the four fifth connecting rods are all located in the fifth plane;

Wherein, the second end of the fifth A connecting rod and the second end of the first T connecting rod are connected to the fifth node, and the second end of the fifth B connecting rod and the first C connecting rod The second end of the C connecting rod is connected to the sixth node, the second end of the fifth C connecting rod and the second end of the third C connecting rod are connected to the seventh node, and the second end of the fifth C connecting rod and the second end of the third C connecting rod is connected to the eighth node, and the second end of the second C connecting rod is connected to the fifth end point;

The orthographic projection of the fourth connecting rod on the fourth plane overlaps with the orthographic projection of the fifth connecting rod on the fourth plane, and the orthographic projection of the fourth end point on the fourth plane is the same as the orthographic projection of the fourth connecting rod on the fourth plane. the orthographic projection of the fifth end point on the fourth plane overlaps, and along the second direction, the fourth plane and the fifth plane are parallel;

Along the third direction, the unit cell structure further includes a sixth subsection and a seventh subsection that are arranged oppositely;

The sixth subsection includes four sixth connecting rods, which are respectively the sixth A connecting rod, the sixth B connecting rod, the sixth C connecting rod and the sixth D connecting rod. One end is connected to the sixth end point, and the sixth end point and the second ends of the four sixth connecting rods are all located in the sixth plane;

The second end of the sixth A connecting rod is connected to the first node, the second end of the sixth B connecting rod is connected to the fifth node, and the second end of the sixth C connecting rod is connected to the eighth node, the second end of the sixth connecting rod is connected to the fourth node, and the second end of the second connecting rod is connected to the sixth end point;

The seventh subsection includes four seventh connecting rods, which are the seventh A connecting rod, the seventh B connecting rod, the seventh C connecting rod and the seventh D connecting rod. One end is connected to the seventh terminal, and the seventh terminal and the second ends of the four seventh connecting rods are all located in the seventh plane;

The second end of the seventh A connecting rod is connected to the second node, the second end of the seventh B connecting rod is connected to the sixth node, and the second end of the seventh C connecting rod is connected to the seventh node, the second end of the seventh fixed connecting rod is connected to the third node, and the second end of the second B connecting rod is connected to the seventh end point;

The orthographic projection of the sixth connecting rod on the sixth plane overlaps with the orthographic projection of the seventh connecting rod on the sixth plane, and the orthographic projection of the sixth end point on the sixth plane is the same as the orthographic projection of the sixth connecting rod on the sixth plane. The orthographic projection of the seventh end point on the sixth plane overlaps, and along the third direction, the sixth plane and the seventh plane are parallel;

Wherein, the first plane is perpendicular to the fourth plane, the sixth plane is perpendicular to the first plane, and the sixth plane is perpendicular to the fourth plane; and the first direction, the second plane The direction and the third direction intersect in pairs.

Preferably, the non-reciprocal bending mechanics metamaterial is a material with asymmetric forward and reverse bending stiffness properties.

Preferably, the first node, the second node, the third node, the fourth node, the fifth node, the sixth node, the seventh node and the eighth node are respectively eight vertices of a cuboid, and the second end point is the center of the cuboid.

Preferably, the first distance, the second distance and the third distance are all equal to δ.

Preferably, the height of the cuboid is the distance l between the first node and the fourth node, and 0<δ<0.5l.

Preferably, the unit cell structure is rotated by 180° with the connecting line of the first end point, the second end point and the third end point as the axis, and then overlaps with itself.

Preferably, along the first direction, adjacent unit cell structures share the first subsection or the third subsection;

Along the second direction, the adjacent unit cell structures share the fourth subsection or the fifth subsection;

And/or, along the third direction, adjacent unit cell structures share the sixth subsection or the seventh subsection.

Preferably, the first connecting rod, the second connecting rod, the third connecting rod, the fourth connecting rod, the fifth connecting rod, the sixth connecting rod and the seventh connecting rod The cross-sectional shape of the rod is circular, rectangular or annular.

Preferably, the non-reciprocal bending mechanics metamaterial is prepared by a three-dimensional additive manufacturing method;

Wherein, the preparation material of the non-reciprocal bending mechanics metamaterial is polymer or metal.

In yet another aspect, the present invention provides a method for designing any of the above-mentioned non-reciprocal bending mechanics metamaterials by breaking the spatial inversion symmetry of the three-dimensional structure and introducing non-reciprocal bending mechanics metamaterials. Linear to achieve asymmetric forward and reverse bending stiffness.

Compared with the prior art, a kind of non-reciprocal bending mechanics metamaterial and design method thereof provided by the present invention achieve the following beneficial effects:

The non-reciprocal bending mechanics metamaterial provided by the invention can break the limitation of Maxwell-Bettis reciprocity theorem, has asymmetric positive and reverse bending stiffness characteristics that natural materials do not have, and provides mechanical functional metamaterials. new paradigm.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The schematic embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation of the present application. In the attached image:

Fig. 1 is the front view of the non-reciprocal bending mechanics metamaterial provided by the present invention;

Fig. 2 is the top view of the non-reciprocal bending mechanics metamaterial provided by the present invention;

Fig. 3 is the side view of the non-reciprocal bending mechanics metamaterial provided by the present invention;

Fig. 4 is the structural representation of the unit cell structure in Fig. 1;

Fig. 5 is a schematic diagram of the cuboid space formed by eight nodes in the unit cell structure of Fig. 4;

Fig. 6 is the front view of the unit cell structure in Fig. 4;

Fig. 7 is the left side view of the unit cell structure in Fig. 4;

Fig. 8 is the top view of the unit cell structure in Fig. 4;

Figure 9 is a three-point bending load-deflection curve of the non-reciprocal bending mechanics metamaterial in Figure 1.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It should be noted that the described embodiments are in fact only some, not all, of the embodiments of the present invention, and are merely illustrative in fact and in no way intended to limit the present invention and its application or use. The scope of protection of this application should be determined by the appended claims.

1 to 9, FIG. 1 is a front view of the non-reciprocal bending mechanics metamaterial provided by the present invention, FIG. 2 is a top view of the non-reciprocal bending mechanics metamaterial provided by the present invention, and FIG. 3 is provided by the present invention. The side view of the non-reciprocal bending mechanical metamaterial, Figure 4 is a schematic structural diagram of the unit cell structure in Figure 1; Figure 5 is a schematic diagram of the cuboid space formed by eight nodes in the unit cell structure of Figure 4, and Figure 6 is a schematic diagram of the unit cell structure in Figure 4. The front view of the unit cell structure, Figure 7 is the left side view of the unit cell structure in Figure 4, Figure 8 is the top view of the unit cell structure in Figure 4, and Figure 9 is the three-point bending load of the non-reciprocal bending mechanics metamaterial in Figure 1 - Deflection curve. The non-reciprocal bending mechanics metamaterial 100 provided in this embodiment includes a plurality of periodically arranged and interconnected unit cell structures 200 in a three-dimensional space, and the unit cell structure 200 has the feature of breaking the symmetry of spatial inversion; Along the first direction X, the unit cell structure 200 includes a first subsection 10, a second subsection 20 and a third subsection 30; the first subsection 10 includes four first connecting rods 11, which are respectively the first connecting rods 11a, the first B connecting rod 11b, the first C connecting rod 11c and the first D connecting rod 11d, the first ends of the four first connecting rods 11 are connected to the first end Q1, and the four first connecting rods 11 The second ends are located in the first plane S1, along the first direction X, the first end Q1 is located between the first plane S1 and the second sub-section 20, and the first end Q1 and the first plane S1 have The first distance D1; the second subsection 20 includes four second connecting rods 21, which are the second connecting rod 21a, the second connecting rod 21b, the second connecting rod 21c and the second connecting rod 21d, respectively. The first ends of the second connecting rods 21 are connected to the second end Q2, and the second ends of the four second connecting rods 21 are all located in the second plane S2. Along the first direction X, the second end Q2 is located on the second plane S2. Between the two planes S2 and the first subsection 10, and the second end Q2 and the second plane S2 have a second distance D2; the third subsection 30 includes four third connecting rods 31, which are respectively the third connecting rods 31a , the third B connecting rod 31b, the third C connecting rod 31c and the third T connecting rod 31d, the first ends of the four third connecting rods 31 are connected to the third end Q3, and the first ends of the four third connecting rods 31 Both ends are located in the third plane S3, along the first direction X, the third end Q3 is located between the third plane S3 and the second sub-section 20, and the third end Q3 and the third plane S3 have a third distance D3 ; The orthographic projection of the first connecting rod 11 on the second plane S2 overlaps with the orthographic projection of the third connecting rod 31 on the second plane S2, and the orthographic projection of the second connecting rod 21 on the third plane S3 is overlapped with the orthographic projection of the first connecting rod 11 on the third plane S3. The orthographic projections of the third plane S3 are staggered, and the orthographic projection of the first endpoint Q1 on the first plane S1, the orthographic projection of the second endpoint Q2 on the first plane S1, and the orthographic projection of the third endpoint Q3 on the first plane S1 The projections overlap, and along the first direction X, the first plane S1, the second plane S2 and the third plane S3 are parallel to each other; along the second direction Y, the unit cell structure 200 further includes a fourth subsection 40 and a fifth Division 50; the fourth division 40 includes four fourth connecting rods 41, which are the fourth connecting rod 41a, the fourth connecting rod 41b, the fourth connecting rod 41c and the fourth connecting rod 41d, four The first end of the fourth connecting rod 41 is connected to the fourth terminal Q4, and the fourth terminal Q4 and the second ends of the four fourth connecting rods 41 are located in the fourth plane S4; wherein, the fourth connecting rod 41a The second end of the first A connecting rod 11a is connected to the first node P1, the second end of the fourth B connecting rod 41b and the second end of the first B connecting rod are connected to the second node At point P2, the second end of the fourth C connecting rod 41c and the second end of the third B connecting rod 31b are connected to the third node P3, and the second end of the fourth C connecting rod 41d is connected to the third node P3 of the third A connecting rod 31a. The two ends are connected to the fourth node P4, and the second end of the second connecting rod 21a is connected to the fourth end Q4; the fifth subsection 50 includes four fifth connecting rods 51, which are the fifth connecting rod 51a, Five B connecting rods 51b, fifth C connecting rods 51c, and fifth T connecting rods 51d, the first ends of the four fifth connecting rods 51 are connected to the fifth end Q5, and the fifth end Q5, and the four fifth connections The second ends of the rods 51 are all located in the fifth plane S5; wherein, the second end of the fifth A connecting rod 51a and the second end of the first T connecting rod 11d are connected to the fifth node P5, and the fifth B connecting rod 51b The second end of the first C connecting rod 11c is connected to the sixth node P6, the second end of the fifth C connecting rod 51c and the second end of the third C connecting rod 31c are connected to the seventh node P7, The second end of the fifth connecting rod 51d and the second end of the third connecting rod 31d are connected to the eighth node P8, the second end of the second connecting rod 21c is connected to the fifth end Q5; the fourth connecting rod 41 The orthographic projection of the fourth plane S4 overlaps with the orthographic projection of the fifth connecting rod 51 on the fourth plane S4, and the orthographic projection of the fourth endpoint Q4 on the fourth plane S4 and the orthographic projection of the fifth endpoint Q5 on the fourth plane S4 The projections overlap, and along the second direction Y, the fourth plane S4 and the fifth plane S5 are parallel; along the third direction Z, the unit cell structure 200 further includes a sixth subsection 60 and a seventh subsection 70 arranged oppositely; The subsection 60 includes four sixth connecting rods 61, which are respectively the sixth A connecting rod 61a, the sixth B connecting rod 61b, the sixth C connecting rod 61c and the sixth D connecting rod 61d. The first end is connected to the sixth end Q6, and the sixth end Q6 and the second ends of the four sixth connecting rods 61 are all located in the sixth plane S6; the second end of the sixth connecting rod 61a is connected to the first Node P1, the second end of the sixth B connecting rod 61b is connected to the fifth node P5, the second end of the sixth C connecting rod 61c is connected to the eighth node P8, and the second end of the sixth D connecting rod 61d is connected to the fifth node P8. Four nodes P4, the second end of the second connecting rod 21d is connected to the sixth end Q6; the seventh subsection 70 includes four seventh connecting rods 71, which are the seventh connecting rod 71a and the seventh connecting rod 71b respectively , the seventh C connecting rod 71c and the seventh T connecting rod 71d, the first ends of the four seventh connecting rods 71 are connected to the seventh end Q7, and the seventh end Q7, and the second of the four seventh connecting rods 71 The ends are all located in the seventh plane S7; the second end of the seventh A connecting rod 71a is connected to the second node P2, the second end of the seventh B connecting rod 71b is connected to the sixth node P6, and the seventh C connecting rod 71c is connected to the second node P6. The second end is connected to the seventh node P7, the second end of the seventh T connecting rod 71d is connected to the third node P3, and the second end of the second B connecting rod 21b is connected to the seventh terminal Q7; The orthographic projection of the sixth connecting rod 61 on the sixth plane S6 overlaps with the orthographic projection of the seventh connecting rod 71 on the sixth plane S6, and the orthographic projection of the sixth endpoint Q6 on the sixth plane S6 and the seventh endpoint Q7 on the sixth plane S6 overlap. The orthographic projections of the plane S6 overlap, and along the third direction Z, the sixth plane S6 and the seventh plane S7 are parallel; wherein, the first plane S1 and the fourth plane S4 are perpendicular, the sixth plane S6 is perpendicular to the first plane S1, and the sixth plane S6 is perpendicular to the first plane S1. The plane S6 is perpendicular to the fourth plane S4; and the first direction X, the second direction Y and the third direction Z intersect in pairs.

Optionally, the non-reciprocal bending mechanics metamaterial 100 is a material with asymmetric forward and reverse bending stiffness properties.

It is understandable that, when most natural materials undergo bending deformation, the forward and reverse bending deformation responses of the material are always symmetrical and consistent under the same magnitude and opposite bending loads. In other words, most natural materials have symmetrical forward and reverse bending stiffnesses. This law is related to the reciprocity referred to by the Maxwell-Betis reciprocity theorem in continuum mechanics. If the limitation of Maxwell-Bettis reciprocity theorem can be broken, non-reciprocal bending materials with asymmetric forward and reverse bending stiffness properties can be prepared, and the extraordinary mechanical properties that natural materials do not have can be obtained, which will provide the mechanical system design. more degrees of freedom. Based on this, the present invention provides a non-reciprocal bending mechanical metamaterial. The metamaterial is formed by periodic arrangement and connection of unit cell structures in three-dimensional space. The metamaterial exhibits extraordinary asymmetric forward and reverse bending stiffness properties when bent in the XZ plane or the XY plane. This nonreciprocal bending property originates from two physical conditions: the absence of mirror symmetry in the XZ plane of the metamaterial and the nonlinear deformation of the structure. At the same time, from the three-point bending load-deflection curve shown in Figure 9, it can be seen that under the same load, the forward bending deflection of the metamaterial is smaller than the reverse bending deflection. Therefore, the forward and reverse bending stiffnesses of the metamaterial are asymmetric, and when the load reaches 8 N, the forward bending stiffness is 1.8 times that of the reverse bending stiffness.

In some optional embodiments, continuing as shown in FIGS. 1 to 9 , in the non-reciprocal bending mechanics metamaterial 100 provided by this embodiment, the first node P1 , the second node P2 , the third node P3 , the first node P1 , the second node P2 , the third node The four nodes P4, the fifth node P5, the sixth node P6, the seventh node P7 and the eighth node P8 are the eight vertices of a rectangular parallelepiped W respectively; the second endpoint Q2 is the center of the rectangular parallelepiped W.

It can be understood that, in the unit cell structure 200 of the non-reciprocal bending mechanics metamaterial 100, the first node P1, the second node P2, the third node P3, the fourth node P4, the fifth node P5, the sixth node P6, The seventh node P7 and the eighth node P8 are respectively connected to the connected nodes to form a cuboid, and the second end Q2 is further set as the center of the cuboid W to determine the structure of the non-reciprocal bending mechanics metamaterial 100 .

Optionally, the first distance D1, the second distance D2, and the third distance D3 are all equal to δ, that is, D1=D2=D3=δ.

It can be understood that the first end Q1, the second end Q2 and the third end Q3 in the non-reciprocal bending mechanics metamaterial 100 are equivalent to the center of the first plane S1, the second plane S2 and the third plane S3 being upward or Move the displacement δ up and down to move out of the first plane S1, the second plane S2 and the third plane S3; optional, the fourth endpoint Q4, the fifth endpoint Q5, the sixth endpoint Q6 and the seventh endpoint Q7 are equivalent to the fourth plane The centers of S4, the fifth plane S5, the sixth plane S6 and the seventh plane S7 move up or down by the displacement amount δ, but due to the extension directions of the fourth plane S4, the fifth plane S5, the sixth plane S6 and the seventh plane S7 Parallel to the moving direction, the fourth endpoint Q4, the fifth endpoint Q5, the sixth endpoint Q6 and the seventh endpoint Q7 move in a plane.

Optionally, the height of the cuboid W is the distance l between the first node P1 and the fourth node P4, and 0<δ<0.5l. That is, the displacement δ of the first endpoint Q1, the second endpoint Q2, the third endpoint Q3, the fourth endpoint Q4, the fifth endpoint Q5, the sixth endpoint Q6 and the seventh endpoint Q7 and the height of the cuboid W are the first node P1 Related to the distance l between the fourth nodes P4, the structure of the non-reciprocal bending mechanics metamaterial 100 can be further defined, and at the same time 0<δ<0.5l, the present invention does not specifically limit the specific value of δ, as long as it is within the range It is enough, and will not be repeated below.

Optionally, the unit cell structure 200 is rotated by 180° around the connecting line of the first end Q1, the second end Q2 and the third end Q3, and then overlaps with itself, thereby ensuring that the non-reciprocal bending mechanics metamaterial is the metamaterial. The structure has double rotational symmetry in the YZ plane, but it is not limited to this. The distance between the first node P1 and the second node P2 can also be set, such as the distance between the first node P1 and the fifth node P5. The cell structure 200 is rotated by 90° with the connecting line of the first end Q1, the second end Q2 and the third end Q3 as the axis to coincide with itself, so as to ensure the non-reciprocal bending mechanics metamaterial. The metamaterial structure has four dimensions in the YZ plane. Re-rotational symmetry can also play a certain technical effect.

In some optional embodiments, continuing with reference to FIGS. 1 to 9 , in the non-reciprocal bending mechanics metamaterial 100 provided in this embodiment, the length of the fourth connecting rod 41a and the length of the fourth connecting rod 41b length, the length of the fifth A connecting rod 51a, the length of the fifth B connecting rod 51b, the length of the sixth A connecting rod 61a, the length of the sixth B connecting rod 61b, the length of the seventh A connecting rod 71a and the length of the seventh B connecting rod The lengths of the connecting rods 71b are all equal to e1; the length of the fourth C connecting rod 41c, the length of the fourth C connecting rod 41d, the length of the fifth C connecting rod 51c, the length of the fifth C connecting rod 51d, the sixth C connecting rod The length of the rod 61c, the length of the sixth C connecting rod 61d, the length of the seventh C connecting rod 71c, and the length of the seventh C connecting rod 71d are all equal to e2; e1>e2.

In some optional embodiments, continuing as shown in FIGS. 1 to 9 , in the non-reciprocal bending mechanics metamaterial 100 provided in this embodiment, along the first direction X, adjacent unit cell structures 200 share the first The subsection 10 or the third subsection 30; along the second direction Y, the adjacent unit cell structures 200 share the fourth subsection 40 or the fifth subsection 50; and/or along the third direction Z, the adjacent unit cells The structures 200 share either the sixth subsection 60 or the seventh subsection 70 . Furthermore, the non-reciprocal bending mechanics metamaterial 100 can be obtained by periodically arranging a plurality of adjacent unit cell structures 200 . 1 to 3 only illustrate that the adjacent unit cell structures 200 share the first subsection 10 or the third subsection 30 along the first direction X, but the present invention is not limited to this, the non-reciprocal bending mechanics exceed The material 100 may be provided with a plurality of unit cell structures 200 in at least one direction of the first direction X, the second direction Y and the third direction Z respectively, and the specific directions with a plurality of unit cell structures 200 may be based on the actual situation. settings, which will not be described in detail below.

Optionally, the cross-sectional shapes of the first connecting rod 11 , the second connecting rod 21 , the third connecting rod 31 , the fourth connecting rod 41 , the fifth connecting rod 51 , the sixth connecting rod 61 and the seventh connecting rod 71 are Round, rectangular or annular. The present invention does not make any changes to the cross-sectional shapes of the first connecting rod 11 , the second connecting rod 21 , the third connecting rod 31 , the fourth connecting rod 41 , the fifth connecting rod 51 , the sixth connecting rod 61 and the seventh connecting rod 71 . It is limited, as long as the non-reciprocal bending mechanics metamaterial 100 is guaranteed to be realized.

Optionally, the non-reciprocal bending mechanics metamaterial 100 is prepared by a three-dimensional additive manufacturing method, but it is not limited to this, and the non-reciprocal bending mechanics metamaterial 100 can be prepared in other ways, as long as the nonreciprocal bending mechanics metamaterial 100 has Asymmetric forward and reverse bending stiffness characteristics are sufficient, and other preparation methods that can realize non-reciprocal bending mechanics metamaterials also belong to the scope of protection. Wherein, the non-reciprocal bending mechanics metamaterial 100 can be prepared from resin, nylon, aluminum, copper, steel, aluminum alloy or titanium alloy, but not limited to this, other materials that can realize the nonreciprocal bending mechanics metamaterial 100 It also belongs to the protection scope of the present invention.

In some optional embodiments, the present invention also provides a method for non-reciprocal bending mechanics metamaterial, the non-reciprocal bending mechanics metamaterial is realized by breaking the spatial inversion symmetry of the three-dimensional structure and introducing nonlinearity Asymmetric forward and reverse bending stiffness. That is to say, based on the above method, non-reciprocal bending mechanics metamaterials with asymmetric forward and reverse bending stiffness properties can be obtained.

It can be known from the above embodiments that the beneficial effects of the present application are:

The non-reciprocal bending mechanics metamaterial provided by the invention can break the limitation of Maxwell-Bettis reciprocity theorem, has asymmetric positive and reverse bending stiffness characteristics that natural materials do not have, and provides mechanical functional metamaterials. new paradigm.

Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, not for limit the scope of the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention. The scope of the invention is defined by the appended claims.

Claims (8)

1. A non-reciprocal mechanical metamaterial with bending property is characterized by comprising a plurality of unit cell structures which are periodically arranged and connected with each other in a three-dimensional space;

along a first direction, the unit cell structure comprises a first subsection, a second subsection and a third subsection;

the first subsection comprises four first connecting rods which are respectively a first connecting rod A, a first connecting rod B, a first connecting rod C and a first connecting rod T, first ends of the four first connecting rods are connected to a first end point, second ends of the four first connecting rods are all located in a first plane, the first end point is located between the first plane and the second subsection along the first direction, and the first end point and the first plane are spaced by a first distance;

the second sub-part comprises four second connecting rods which are respectively a second connecting rod, a second connecting rod, a second third connecting rod and a second third connecting rod, first ends of the four second connecting rods are connected to a second end point, second ends of the four second connecting rods are all located in a second plane, the second end point is located between the second plane and the first sub-part along the first direction, and the second end point and the second plane are spaced at a second distance;

The third subsection comprises four third connecting rods which are respectively a third connecting rod, a third polypropylene connecting rod and a third T connecting rod, first ends of the four third connecting rods are connected to a third end point, second ends of the four third connecting rods are all located in a third plane, the third end point is located between the third plane and the second subsection along the first direction, and a third distance is reserved between the third end point and the third plane;

the orthographic projection of the first connecting rod on the second plane is overlapped with the orthographic projection of the third connecting rod on the second plane, the orthographic projection of the second connecting rod on the third plane is staggered with the orthographic projection of the first connecting rod on the third plane, the orthographic projection of the first end point on the first plane, the orthographic projection of the second end point on the first plane and the orthographic projection of the third end point on the first plane are overlapped, and the first plane, the second plane and the third plane are parallel to each other along the first direction;

in the second direction, the unit cell structure further comprises a fourth part and a fifth part which are oppositely arranged;

The fourth part comprises four fourth connecting rods which are respectively a fourth connecting rod, a fourth third connecting rod and a fourth connecting rod, the first ends of the four fourth connecting rods are connected to a fourth end point, and the fourth end point and the second ends of the four fourth connecting rods are all positioned in a fourth plane;

wherein the second end of the fourth connecting rod and the second end of the first A connecting rod are connected to a first node, the second end of the fourth connecting rod and the second end of the first B connecting rod are connected to a second node, the second end of the fourth C connecting rod and the second end of the third B connecting rod are connected to a third node, the second end of the fourth C connecting rod and the second end of the third B connecting rod are connected to a fourth node, and the second end of the second C connecting rod is connected to the fourth end point;

the fifth part comprises four fifth connecting rods, namely a fifth A connecting rod, a fifth B connecting rod, a fifth C connecting rod and a fifth T connecting rod, wherein the first ends of the four fifth connecting rods are connected to a fifth endpoint, and the fifth endpoint and the second ends of the four fifth connecting rods are positioned in a fifth plane;

Wherein the second ends of the fifth A connecting rod and the first T connecting rod are connected to a fifth node, the second ends of the fifth B connecting rod and the first C connecting rod are connected to a sixth node, the second ends of the fifth C connecting rod and the third C connecting rod are connected to a seventh node, the second ends of the fifth T connecting rod and the third T connecting rod are connected to an eighth node, and the second end of the second C connecting rod is connected to the fifth end point;

an orthographic projection of the fourth connecting rod on the fourth plane is overlapped with an orthographic projection of the fifth connecting rod on the fourth plane, an orthographic projection of the fourth endpoint on the fourth plane is overlapped with an orthographic projection of the fifth endpoint on the fourth plane, and the fourth plane and the fifth plane are parallel along the second direction;

along a third direction, the unit cell structure further comprises a sixth subsection and a seventh subsection which are oppositely arranged;

the sixth branch comprises four sixth connecting rods which are respectively a sixth connecting rod A, a sixth connecting rod B, a sixth connecting rod C and a sixth connecting rod D, first ends of the four sixth connecting rods are connected to a sixth end point, and the sixth end point and second ends of the four sixth connecting rods are located in a sixth plane;

A second end of the sixth A connecting rod is connected to the first node, a second end of the sixth B connecting rod is connected to the fifth node, a second end of the sixth C connecting rod is connected to the eighth node, a second end of the sixth D connecting rod is connected to the fourth node, and a second end of the second D connecting rod is connected to the sixth endpoint;

the seventh branch comprises four seventh connecting rods which are respectively a seventh first connecting rod, a seventh second connecting rod, a seventh third connecting rod and a seventh third connecting rod, first ends of the four seventh connecting rods are connected to a seventh end point, and the seventh end point and second ends of the four seventh connecting rods are all located in a seventh plane;

a second end of the seventh a connecting rod is connected to the second node, a second end of the seventh b connecting rod is connected to the sixth node, a second end of the seventh c connecting rod is connected to the seventh node, a second end of the seventh d connecting rod is connected to the third node, and a second end of the second d connecting rod is connected to the seventh end point;

an orthographic projection of the sixth connecting rod on the sixth plane is overlapped with an orthographic projection of the seventh connecting rod on the sixth plane, and an orthographic projection of the sixth end point on the sixth plane is overlapped with an orthographic projection of the seventh end point on the sixth plane, and the sixth plane and the seventh plane are parallel along the third direction;

Wherein the first plane and the fourth plane are perpendicular, the sixth plane is perpendicular to the first plane, and the sixth plane is perpendicular to the fourth plane; and the first direction, the second direction and the third direction intersect pairwise.

2. The non-reciprocal flexural mechanics metamaterial according to claim 1, wherein the non-reciprocal flexural mechanics metamaterial is a material having asymmetric positive and negative flexural stiffness characteristics.

3. The non-reciprocal flexural mechanical metamaterial according to claim 1, wherein the first node, the second node, the third node, the fourth node, the fifth node, the sixth node, the seventh node, and the eighth node are each eight vertices of a cuboid, and the second endpoint is a center of the cuboid.

4. The non-reciprocal flexural mechanical metamaterial according to claim 3, wherein the first end point, the second end point, and the third end point in the non-reciprocal flexural mechanical metamaterial are the centers of the first plane, the second plane, and the third plane by the displacement amount moving up or downδThe fourth end point, the fifth end point, the sixth end point and the seventh end point are the upward or upward and downward displacement of the centers of the fourth plane, the fifth plane, the sixth plane and the seventh plane δ；

The first, second and third pitches are all equal toδ；

The height of the cuboid is the distance between the first node and the fourth nodelAnd 0 <δ＜0.5l。

5. The non-reciprocal flexural mechanical metamaterial according to claim 3, wherein the unit cell structure is rotated 180 degrees around a connecting line of the first end point, the second end point and the third end point to coincide with itself.

6. The non-reciprocal flexural mechanical metamaterial according to claim 1, wherein adjacent unit cell structures share the first or third sections along the first direction;

along the second direction, adjacent unit cell structures share the fourth or fifth subsection;

and/or adjacent unit cell structures share the sixth or seventh division in the third direction.

7. The non-reciprocal, flexural mechanical metamaterial according to claim 1, wherein the cross-sectional shapes of the first, second, third, fourth, fifth, sixth, and seventh connecting rods are circular, rectangular, or annular.

8. The non-reciprocal flexural mechanics metamaterial according to claim 1, wherein the non-reciprocal flexural mechanics metamaterial is prepared by a three-dimensional additive manufacturing method;

the preparation material of the non-reciprocal bending mechanical metamaterial is polymer or metal.

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