WO2014025089A1 - Three-dimensional truss actuator composed of wires - Google Patents

Abstract

Disclosed is an actuator having a three-dimensional truss structure assembled by intersecting continuous wire groups in three or more directions, the wire groups each having spatially predetermined azimuth. The present invention provides an actuator having a three-dimensional truss structure assembled by intersecting continuous wire groups in three or more directions, the wire groups having spatially predetermined azimuth. The wire groups include a first wire group made of a material capable of reacting to an external physical or chemical change, and a second wire group made of a material that does not react. The three-dimensional truss actuator causes a change in the shape of the truss structure by the displacement of the first wire group resulting from the external physical or chemical change.

Description

3-D Truss Driver Made of Wire

The present invention relates to a driver, and more particularly, to a driver having a three-dimensional truss structure composed of a plurality of wires in three directions or more, and in which the entire structure changes shape due to a change in the surrounding environment.

The present invention is derived from a study conducted as part of a mid-sized researcher support project (challenge) supported by the Korea Research Foundation in 2012.

[Task control number: 2012R1A2A1A01003405, Assignment name: Manufacturing method of multi-scale ultra light metal]

Actuator is a device that constitutes a mechanical system, and is an element that causes the system to perform a desired motion by generating displacement by intention, and is classified into linear (or reciprocating) and rotating type according to the type of displacement, and according to the power source. Hydraulic, pneumatic, electric and the like can be classified. The conditions required for such a driver are listed as follows. First, frequent start-stops should be possible. That is, it should be easy to generate repetitive displacement. Second, it should be easy to control according to the command signal, and it should also have good response. Third, the force or torque generated while the inertia of the moving part is small should be large. Fourth, it should be as small and lightweight as possible and easy to repair.

Recently, actuators using smart materials instead of traditional hydraulic, pneumatic and electric motors have been in the spotlight. Smart material is a material that can react according to external environmental changes. Specifically, a material that can control displacement according to external environment such as stress, temperature, humidity, acidity (pH), electric field, magnetic field can be used as a driver. have. Typical examples include piezoelectric materials, magnetostrictive materials, shape memory alloys or polymers, pH-sensitive polymers, thermoelectric materials, electronic rheology Liquid (electrorheological (ER) fluid) and the like (Craig A, Rogers, "Intelligent Materials", Scientific American, Vol. 9, pp. 154-164 (1995)). Drivers using smart materials can be made compact and are advantageous to be intelligent in combination with sensors.

The actuator is often used in combination with the truss structure to achieve structural stability and to achieve the desired final motion through kinematic mechanisms. 1 shows an example of a device for generating a rotational movement by combining a linear actuator with a triangular truss.

Truss structures have traditionally been widely utilized as lightweight, high-strength structures for civil engineering, construction. In recent years, it has been reported that a structure having a greatly reduced size of the truss so that the length of the truss element is on the order of several micrometers to several millimeters has excellent characteristics as a kind of porous material. That is, although the conventional representative porous material is made of a large number of curved elements of irregular arches or circles, the new porous material having a truss shape has excellent mechanical strength and rigidity relative to weight. The truss structure may be classified according to the shape of the unit cell. FIG. 2 illustrates a single layer structure of a pyramid (a), an octet (b), and a kagome (c) truss and a kagome truss multi-layer structure (d). The method of manufacturing the material composed of the above truss is summarized in the paper by Wadley, Fleck, Evans (Fabrication and structural performance of periodic cellular metal sandwich structures, Composites Science and Technology Vol. 63, pp.2331-2343 (2003)). . Materials having a single layer truss structure can be produced through sheet metal forming or wire bending, while those having a multi layered truss structure can be produced only by investment casting. In other words, a truss structure is made of resin, and a mold is used to cast a metal (S. Chiras, DR Mumm, N. Wicks, AG Evans, JW Hutchinson, K. Dharmasena, HNG Wadley, S. Fichter, 2002, International Journal of Solids and Structures, Vol. 39, pp. 4093-4115).

In order to solve the problems of the above-described prior art, two of the inventors, including Kang Gi-joo, have a shape similar to that of an ideal kagome truss or octet truss by intersecting a group of continuous wires in six directions having an azimuth angle of 60 degrees or 120 degrees in space. Has developed a three-dimensional porous lightweight structure and its manufacturing method, the details of which are specifically disclosed in Patent No. 0708483 owned by the applicant.

In addition, two of the inventors, including Kang Gi-ju, can more effectively manufacture a three-dimensional porous lightweight structure, which is a three-dimensional woven wire made of spiral wires assembled by first forming a continuous wire spirally and then rotating and inserting it. A porous lightweight structure and a method of manufacturing the same have been proposed, and the details thereof are disclosed in detail in Korean Patent No. 1029183 owned by the present applicant.

FIG. 3 is a view illustrating a structure in which a shape similar to the three-dimensional kagome truss of FIG. 2 is assembled with a spiral wire in the Korean Patent No. 1029183. The three-dimensional multilayer truss structure composed of spiral wires having a shape similar to that of the kagome truss shown in FIG. 3 has various advantages over the prior art, such as excellent mechanical properties and mass production by a continuous process.

However, when the above-described three-dimensional multilayer truss structure is manufactured in the form of a generally used rectangular parallelepiped, the shape of the unit cell existing at the edge is not intact, which is not good in appearance and disadvantages in terms of mechanical strength. Interference has limitations in increasing the placement density of the wires.

Thus, three of the inventors, including Kang Gi-joo, proposed a method for manufacturing a new three-dimensional porous lightweight structure having a different shape from the kagome truss while being manufactured with a spiral wire in the patent application No. 10-2009-0080085. For reference, FIGS. 4 to 8 illustrate the structure disclosed in the patent application, and FIG. 9 illustrates a unit cell of the multilayer truss structure assembled with the spiral wires of FIGS. 3 and 4 to 8. Separately, three of the inventors, including Kang Gi-joo, have a structure in which only two wires meet at a wire crossing point while being able to assemble a spiral wire, and thus, a new three-dimensional that can be manufactured as a spiral wire having a smaller spiral radius. A grating truss structure and a method of manufacturing the same are proposed in Patent Application No. 10-2010-0059690. 10 shows a representative example thereof.

As described in FIG. 1, the driver is often used in combination with the truss structure because of the kinematic stability of the truss structure. 11 shows a driver having a kind of two-dimensional truss structure (T. J. Lu, J. W. Hutchinson, A. G. Evans, Optimal design of a flexural actuator, Journal of the Mechanics and Physics of Solids, 49 (2001) 2071-2093). Referring to FIG. 11, the upper and lower face plates and the core metal plates form a triangular truss structure, and one of the face plates is a shape memory alloy, and the entire structure can be bent upward as the temperature changes. Shows. The important point here is that even if the displacement occurs in the face, very little stress is applied to the middle or the other face. This ensures that the actuator is not only structurally stable, but also in terms of strength, even with repeated operation. This is because the structure is kinematically determinated and statically determinated according to Maxwell's law (Maxwell, JC, 1864. On the calculation of the equilibrium and stiffness of frames. Philos.Mag. 27, pp. 294-299).

More recently, it has been known that a driver can be manufactured using a three-dimensional truss. 12 shows an example (S.L. dos Santos e Lucato, J. Wang, P. Maxwell, R.M. McMeeking, A.G. Evans, International Journal of Solids and Structures, vol. 41 (2004) pp.3521-3543). Fig. 12 (a) shows that the upper face is composed of a simple thin plate, a two-dimensional kagome truss on the lower face, and a tetrahedral truss on the middle part, and Fig. 12 (b) shows a form of operation possible with such a truss driver. (c) shows a sample of actual truss elements of the lower two-dimensional kagome truss replaced by a linear motor. By adjusting the displacement of the linear motors, the upper face member may be changed into various shapes as shown in FIG. 12 (b). This drive system has received attention for its lightweight and rigid truss structure, which can generate complex three-dimensional deformations through the operation of multiple linear motors.

However, replacing only some truss elements with a linear motor constrains the truss cell to be small, complicated to manufacture, and expensive. Conventional actuators such as hydraulic, pneumatic, and electric motors, which are not trusses, have heavy disadvantages, and conventional smart material drivers have problems of low structural strength or small displacement. With the recent energy crisis and the development of advanced science, light and large displacements are required, and high-strength structural strength, rigidity and low-cost actuators are required.

The present invention was devised to solve the above-mentioned problems, and has a three-dimensional truss-like structure assembled by intersecting a continuous group of wires in three or more directions having a constant azimuth angle in space, and some wires due to external environmental changes. As the length of the field is changed, the entire structure is changed in shape, so that it is light and generates a large displacement, and is made of material having excellent structural strength and rigidity and low cost, thereby providing an advantageous driver in terms of economy.

As a means for solving the above technical problem, the present invention is a driver comprising a three-dimensional truss structure formed by intersecting a continuous wire group of three or more directions having a constant azimuth angle in space, the wire group is an external physical Or a first wire group made of a material capable of reacting with a chemical change and a second wire group made of a non-reacting material, to generate a displacement of the first wire group by an external physical or chemical change. Provided is a three-dimensional truss driver that causes a shape change of the truss structure.

In addition, the three-dimensional truss structure provides a three-dimensional truss driver, characterized in that any one selected from the group consisting of a pyramid truss structure, a kagome truss structure, an octet truss structure and a similar kagome truss structure.

In addition, the first wire group may include piezoelectric materials, magnetostrictive materials, shape memory alloys or polymers, pH-sensitive polymers, and thermoelectric materials. And a three-dimensional truss driver comprising one or more materials selected from the group consisting of an electrorheological (ER) fluid.

In addition, the physical or chemical change provides a three-dimensional truss driver, characterized in that one or more changes selected from the group consisting of stress, temperature, humidity, acidity (pH), electric field, magnetic field and electromagnetic field.

In addition, the shape change provides a three-dimensional truss driver, characterized in that one or more changes selected from the group consisting of structure height, shear, torsion and bending.

The present invention can provide a driver having a very high strength and rigidity relative to weight based on a three-dimensional truss structure having a stable structure.

In addition, since a part of the wire group constituting the three-dimensional truss structure is made of a smart material, the overall shape change of the structure occurs according to the displacement of the smart material wire penetrating the structure, it is possible to provide a driver capable of large deformation. .

In addition, when the truss structure is statically determinated and kinematically determinated, it is repetitive because only a very small level of deformation and stress occurs in other wires combined together that do not cause displacement. It is possible to provide a driver with excellent durability even for phosphorus driving.

In addition, various smart materials such as shape memory alloys can be manufactured in the form of wires, and there are various technologies for manufacturing trusses using wires. There is a very beneficial effect.

1 is a view showing a device for generating a rotational motion by combining a conventional linear actuator with a triangular truss,

FIG. 2 is a diagram illustrating a single layer structure of a pyramid, an octet, and a kagome truss and a kagome truss multi-layer structure;

3 is a view showing a structure in which a spiral wire is assembled in a form similar to the three-dimensional kagome truss of FIG.

4 to 8 show the structure disclosed in Patent Application No. 10-2009-0080085,

9 is a view illustrating a unit cell of a multi-layered truss structure assembled with the spiral wires of FIGS. 3 and 4 to 8;

10 is a view showing an example of a three-dimensional grating truss structure having a structure where only two wires meet at a wire intersection point assembled using a spiral wire proposed in Patent Application No. 10-2010-0059690;

11 illustrates a driver having a two-dimensional truss structure;

12 illustrates a driver fabricated using a three-dimensional truss;

13 is a view showing a Kagome truss unit cell,

14 to 16 are views illustrating a structure deformation process of the three-dimensional truss driver according to embodiments 1 to 3 of the present invention.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, throughout the specification, when a part is said to "include" a certain component, it means that it may further include other components, not to exclude other components, unless otherwise stated.

Based on the three-dimensional truss structure, the present inventors have intensively researched to provide a lightweight, weight-high strength and stiffness actuator. As a result, the three-dimensional truss using a common wire and a smart material wire in three or more directions is used. The entire truss structure is changed in height, shear, torsion and bending by manufacturing the structure in the form and applying the electric power to the smart material wire or changing the surrounding environment such as magnetic field, electromagnetic field, temperature, humidity, pH, etc. The present invention has been made in light of the fact that a new concept of a driver capable of changing the shape of the back can be manufactured.

Accordingly, the present invention is a driver comprising a three-dimensional truss structure assembled by intersecting a continuous group of wires in three or more directions having a constant azimuth angle in space, the wire group can react according to external physical or chemical changes A first wire group made of a material and a second wire group made of a non-reacting material are combined to generate a three-dimensional change of the truss structure by generating displacement of the first wire group by an external physical or chemical change. Start the truss driver.

In the present invention, the three-dimensional truss structure that is assembled by crossing three or more continuous wire groups may be various structures described above, for example, a pyramid truss structure, a kagome truss structure, an octet truss structure, or a structure similar thereto. The present invention is not limited thereto, and any one may be included as long as the wire is woven to form a structure similar to the truss structure. In this case, the wire may be first formed in a spiral shape and then rotated and inserted to assemble the structure to more effectively manufacture the porous structure.

In the present invention, the wire group is composed of a combination different from the conventional three-dimensional truss structure. That is, some of the wire group is composed of a first wire group, which is a material capable of reacting with external physical or chemical environmental changes in contact with or not contacting the wire, and the other wire group is a general material that does not react with the environmental change. And a second wire group. Here, the wire group means a collection of wires formed in the same direction.

The wire material constituting the first wire group is not limited as long as it is made of a so-called smart material having the above-described reaction properties. For example, piezoelectric materials, magnetostrictive materials, shape memory alloys or resins ( Materials such as shape memory alloys or polymers, pH-sensitive polymers, thermoelectric materials, and electrorheological (ER) fluids can be used. Further, the wire material constituting the second wire group may be a known general material, for example, a material such as metal, ceramic, synthetic resin, fiber reinforced synthetic resin, or the like.

Such a three-dimensional truss driver according to the present invention uses a common wire and a smart material wire together to create a three-dimensional kagome truss structure, for example, as specifically disclosed in Korean Patent No. 0708483, among which smart By inducing a displacement by applying electricity to a wire group made of material wires or by changing the surrounding environment, the shape change of the entire structure is induced, but deformation or stress is hardly applied to the ordinary wire group, which is not a smart material wire that causes driving. Does not have the characteristics. Thus, the truss structure has light weight, high strength, and high rigidity, and is durable in repetitive operation. Here, the common wire and the smart material wire are preformed in the form of a spiral as disclosed in Patent No. 1028183, Patent No. 1155267, and Patent Publication No. 10-2011-0139543, or as disclosed in Patent No. 1155262. As described above, a straight line and a spiral form may be mixed, or may be used in a straight line form as disclosed in Korean Patent No. 0566729 or in a flexible state as disclosed in Korean Patent No. 0944326.

Hereinafter, the present invention will be described in more detail with reference to specific examples. In the following embodiments, a three-dimensional kagome truss will be described for convenience, but the same principle can be applied to similar trusses made of wire or other types of truss structures. 13 shows a Kagome truss unit cell. As shown in FIG. 13, the Kagome unit cell is composed of parallel truss elements in six directions, of which ①, ②, and ③ directions are in-plane directions, and ④, ⑤, and ⑥ directions are out of plane. The out-of-plane direction is shown.

Example 1

FIG. 14 (a) shows that the entire truss structure is deformed by uniformly stretching the length by applying electricity or changing the environment when the wire group corresponding to the truss element in the out-of- plane ④, ⑤, ⑥ direction is made of smart material. The front and back shapes are shown. That is, it can be seen that the smart wires in three out-of-plane tensile strains are actuated to increase the height of the entire structure. On the other hand, Figure 14 (b) shows a smart wire that must be deformed for driving to increase the height of the structure when the woven spiral wire as a structure similar to the Kagome truss as disclosed in Patent No. 1029183 shows in black have.

Example 2

Figure 15 (a) is a wire group corresponding to the truss element in the ④, ⑤ direction by applying electricity or changing the environment when the wire group corresponding to the truss element in the out-of- plane ④, ⑤, ⑥ direction is made of a smart material. The length of the truss structure is deformed by stretching the length and shrinking the length of the group of wires in the? Direction. That is, it can be seen that the two directions of the smart wires in the out-of-plane three directions are the tensile deformation and the other one is the shrinkage deformation, thereby actuating the entire structure to shear sideways. On the other hand, Figure 15 (b) is a smart wire that must be stretched and contracted for shear driving as shown in Figure 15 (a) when weaving the spiral wire as disclosed in the Patent No. 1029183 to make a structure similar to the Kagome truss It is shown in black and gray.

Example 3

FIG. 16 (a) shows the wire group by applying electricity or changing the environment when the wire group corresponding to the truss element in one of the in- plane ①, ②, ③ directions shown in FIG. 16 (b) is made of smart material. The length of the truss structure is deformed by deforming or compressing the length differently according to the height. Specifically, it can be seen that the entire structure is bent and actuated by tensile strain or shrinkage of the wire in one of the three in-plane directions, depending on the height from the neutral surface of the cross section. In FIG. 16, a wire is drawn in the horizontal direction (① direction), which is drawn in a field of view rotated about 30 degrees in plane as compared with FIGS. 13 to 15 so that bending deformation is easily seen. On the other hand, Figure 16 (c) shows a smart wire that must be stretched or shrunk for shear driving of the structure when weaving a spiral wire as disclosed in the Patent No. 1029183 to make a structure similar to the Kagome truss in black .

Preferred embodiments of the present invention have been described in detail above with reference to the drawings. The description of the present invention is for illustrative purposes, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention.

Therefore, the scope of the present invention is shown by the claims below rather than the detailed description, and all changes or modifications derived from the meaning, scope, and equivalent concepts of the claims are included in the scope of the present invention. Should be interpreted.

Claims (5)

1. An actuator comprising a three-dimensional truss structure assembled by intersecting a group of three or more continuous wires each having a constant azimuth angle in space, wherein the wire group is formed of a material capable of reacting according to external physical or chemical changes. And a second wire group composed of a wire group and a non-reacting material to generate a displacement of the first wire group by an external physical or chemical change, thereby causing a shape change of the truss structure.
2. The method of claim 1,

   The three-dimensional truss structure is any one selected from the group consisting of a pyramid truss structure, a kagome truss structure, an octet truss structure and a similar kagome truss structure.
3. The method of claim 1,

   The first wire group includes piezoelectric materials, magnetostrictive materials, shape memory alloys or polymers, pH-sensitive polymers, thermoelectric materials and A three-dimensional truss driver comprising at least one material selected from the group consisting of an electrorheological (ER) fluid.
4. The method of claim 1,

   Wherein said physical or chemical change is one or more changes selected from the group consisting of stress, temperature, humidity, acidity (pH), electric field, magnetic field and electromagnetic field.
5. The method of claim 1,

   The shape change is a three-dimensional truss driver, characterized in that at least one change selected from the group consisting of structure height, shear, torsion and bending.

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