Component with optimized heat insulation and mechanical properties and node optimization method

Abstract

The invention belongs to the technical field of mechanical and thermal performance optimization, and particularly relates to a heat insulation and mechanical performance optimization component and a node optimization method, and the method is suitable for optimization of a lattice structure which is provided with connecting rods and has nodes generated by intersection of the connecting rods, and is particularly suitable for optimization of a lattice structure. Nodes need to be distributed on the six surfaces of the cubic unit cell, and when the positions of the nodes on the six surfaces of the cubic unit cell are changed, the positions of the connecting rods can be driven to change, so that the distribution mode and the specific surface area of the nodes and the connecting rods in the component are changed. In the aspect of mechanical properties, a lattice structure dominated by common deformation, tensile deformation or shear deformation is obtained; and in the aspect of thermal properties, the change of the specific surface area changes the change of heat convection and heat radiation quantity in the heat transfer process, so that a structure with better mechanical and heat-insulating properties can be obtained. Therefore, the mechanical property and the heat insulation property are adjustable, and the method has the advantages of being high in adjustability, free of development of a novel structure and convenient and fast to adjust.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical and thermal performance optimization, and in particular relates to a component and node optimization method for optimizing thermal insulation and mechanical performance. Background Art

[0002] In the field of aerospace, as the flight speed of new aircraft continues to increase, the performance requirements of the new generation of aerospace materials and structures are also constantly increasing, and they focus on indicators such as light weight, high efficiency, and long endurance. Therefore, higher requirements are placed on the material and structural design of aircraft. Taking the skin of hypersonic aircraft and space combat weapons as an example, when operating at ultra-high speeds (greater than Mach 5), they are required to be lightweight to reduce power consumption, high strength to resist impact, and excellent thermal insulation to avoid internal thermal damage or even spontaneous combustion. Therefore, there is an urgent need to develop and manufacture materials and structures that are both lightweight, high-strength and thermally insulating for use in hypersonic aircraft.

[0003] The development of new materials has the disadvantages of high cost and long time consumption, while the development and optimization of new structures have the advantages of easy lightness and adjustable performance. At present, there are many types of structures, and it is difficult to accurately select the structure according to the needs. Moreover, taking thermal insulation performance as an example, the mechanical properties of the structure are positively correlated with the relative density, while the thermal insulation performance is negatively correlated with the relative density. Therefore, there is a negative correlation between the mechanical properties and the thermal insulation performance, and it is difficult to improve both the mechanical properties and the thermal insulation performance at the same time by controlling the relative density. Summary of the invention

[0004] The purpose of the present invention is to provide a component with optimized thermal insulation and mechanical properties and a node optimization method, so that the component has both good thermal insulation and mechanical properties through node optimization.

[0005] To achieve the above-mentioned purpose, the present invention provides a node optimization method for the thermal insulation and mechanical properties of a component, wherein the component comprises m1 connected connecting rod units, each connecting rod unit comprises m2 connected connecting rods, and the connection nodes of each connecting rod in the same connecting rod unit are distributed on the surface of the same cubic unit cell, and there is at least one connection node on each of the six surfaces of each cubic unit cell, so as to regulate and optimize the thermal insulation and mechanical properties of the component; m1 is a positive integer greater than or equal to 1, and m2 is a positive integer greater than or equal to 12.

[0006] Furthermore, the connection nodes on each opposite face of the cubic unit cell are mirror-symmetric.

[0007] Furthermore, each of the connecting rod units is a centrally symmetrical polyhedron structure composed of the connecting rods;

[0008] The cubic unit cells where two adjacent connecting rod units are located have a common surface to ensure that the two adjacent connecting rod units are connected together.

[0009] Furthermore, the connection nodes of the connection rods are distributed at the center of the face, the center of the edge, or the midpoint of the line connecting the center of the face and the center of the edge of the cubic unit cell.

[0010] Furthermore, when the volume fraction of the connecting rods in the component is 8%, the connecting rods of the connecting rod unit form a regular octahedron.

[0011] Furthermore, the six connection nodes of the regular octahedron are distributed as follows: two connection nodes are distributed at the centers of two opposite faces of the cube unit cell, and the other four connection nodes are distributed at the centers of four edges of the other four faces, and the four edges are four edges perpendicular to the faces with the connection nodes distributed at the centers.

[0012] Furthermore, the side length of the cubic unit cell where the six connection nodes of the regular octahedron are located is 3-5 mm.

[0013] Furthermore, the connecting rod arrangement structure of each connecting rod unit is the same, and two adjacent connecting rod units are mirror-symmetrical; the cross section of the connecting rod is circular, elliptical or n-gonal, where n is a positive integer greater than 2;

[0014] The component is made of metal material and is formed by laser selective melting or casting.

[0015] Furthermore, according to the designed arrangement structure of the connecting rods, the diameter or side length of the connecting rods is adjusted so that the connecting rods in the component reach a target volume fraction; the target volume fraction is 5%-30%.

[0016] Furthermore, the component also includes heat bearing plates arranged on two opposite sides of the connecting rod unit.

[0017] The present invention also provides a component obtained by the above optimization method, which comprises a plurality of connected connecting rod units, each connecting rod unit comprises a plurality of connecting rods arranged and connected in a regular manner, and the connection nodes of each connecting rod in the same connecting rod unit are distributed on the surface of the same cubic unit cell.

[0018] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0019] 1. The node optimization method for thermal insulation and mechanical properties of components provided by the present invention utilizes a node optimization strategy and takes a cubic unit cell as a control reference so that each node is always distributed on the surface of the cubic unit cell. The connecting rod units and components obtained in this way can realize controllable changes in the structure, thereby changing the deformation mode and specific surface area of ​​the structure, realizing controllable changes in mechanical properties, thermal convection and thermal radiation, and thus facilitating the control and optimization of mechanical properties, thermal insulation and heat dissipation effects.

[0020] 2. The present invention can not only achieve simultaneous improvement of mechanical properties and heat dissipation properties, but also achieve simultaneous improvement of mechanical properties and thermal insulation properties. Since mechanical properties are positively correlated with relative density, and metal heat dissipation is also positively correlated with relative density, it is very easy to achieve simultaneous improvement of mechanical properties and heat dissipation properties by controlling relative density. However, thermal insulation performance is negatively correlated with relative density, and it is difficult to improve both mechanical properties and thermal insulation performance by controlling relative density. The present invention controls the deformation mode, heat convection amount and heat radiation amount of the component structure through node distribution, thereby obtaining a structure with mainly tensile deformation and low specific surface area, thereby achieving simultaneous improvement of mechanical properties and thermal insulation performance.

[0021] 3. The present invention obtains symmetrical connecting rod units by symmetrically distributing the nodes on the surface of the cubic unit cell, which makes it easier to obtain a structure with mainly tensile deformation and a low specific surface area. At the same time, according to a given volume fraction, the mechanical properties and thermal insulation properties can be simultaneously optimized through the node distribution to obtain a component with good mechanical properties and thermal insulation properties.

[0022] 4. The structural dimensions of the components produced by the node optimization method of the present invention can be in the range of micrometers to meters. Different sizes can be manufactured using different manufacturing schemes, ultimately satisfying the assembly requirements of the required components, and having the advantage of wide adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the grapefruit peel imitation structure of the embodiment of the present invention;

[0024] Figure 2 A schematic diagram of a node optimization strategy and a corresponding optimization structure according to an embodiment of the present invention;

[0025] Figure 3 This is a printed physical picture of the pomelo peel-like structure according to an embodiment of the present invention;

[0026] Figure 4 This is a printed physical image of a tetradecahedron structure according to an embodiment of the present invention;

[0027] Figure 5 A printed physical image of a regular octahedron structure of an embodiment of the invention;

[0028] Figure 6 The test results of the specific surface area of ​​the embodiments of the present invention are as follows;

[0029] Figure 7 The test results of the mechanical properties of the embodiments of the present invention are as follows;

[0030] Figure 8 The figures are test results of thermal performance of the embodiments of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] The present invention provides a node optimization method for the thermal insulation and mechanical properties of a component, wherein the component comprises m1 connected connecting rod units, each connecting rod unit comprises m2 connected connecting rods, and the thermal insulation and mechanical properties of the component are regulated and optimized by distributing the connection nodes of each connecting rod in the same connecting rod unit on the surface of the same cubic unit cell, and each cubic unit cell has at least one connection node on six surfaces; m1 is a positive integer greater than or equal to 1, and m2 is a positive integer greater than or equal to 12. The present invention has found that, with the cubic unit cell as the reference for node position regulation, when the nodes are distributed on the surface of the cubic unit cell, the component composed of the connecting rods between the nodes is easier to take into account both thermal insulation and mechanical properties, thus overcoming the problem that it is difficult to have both thermal insulation and mechanical properties.

[0033] The number of connecting rod units in the component is designed according to the actual size requirements. m1 connecting rod units are arranged and connected in an array to form a component of target size. The number m2 of connecting rods in each connecting rod unit is preferably 12 to 100, more preferably 12 to 40.

[0034] The node optimization method of the present invention is applicable to the optimization of lattice structures having connecting rods and whose connecting rods intersect to generate connecting nodes, and is particularly applicable to the optimization of lattice structures; the nodes must be distributed on the six surfaces of the cubic unit cell, and when the positions of the nodes on the six surfaces of the cubic unit cell change, the positions of the connecting rods can be driven to change, thereby changing the distribution mode and specific surface area of ​​the nodes and connecting rods in the component. In terms of mechanical properties, a lattice structure dominated by ordinary deformation, tensile deformation or shear deformation can be obtained; in terms of thermal properties, the change in specific surface area changes the changes in heat convection and heat radiation during the heat transfer process, and thus a structure with better mechanical and thermal insulation properties can be obtained. Therefore, the present invention realizes the adjustable mechanical properties and thermal insulation properties, and has the advantages of high adjustability, no need to develop new structures, and convenient adjustment.

[0035] Furthermore, by utilizing the adjustable performance, without changing the relative density of the connecting rod, changing the position and distribution of the connecting rod and the nodes can obtain a structure with tensile deformation and shear deformation as the main deformation. At the same time, since the length of the connecting rod changes due to the change in the position, a variable specific surface area can be obtained, thereby changing the heat convection and heat radiation, and thus controlling the heat insulation and heat dissipation effects. The present invention can easily achieve the adjustable mechanical properties and heat insulation properties, and thus optimize a structure with both high strength and excellent heat insulation properties.

[0036] Preferably, nodes are distributed on each face of the cubic unit cell, and the connection nodes on the opposite faces are mirror-symmetrical, with a total of three groups of opposite faces. The symmetrical distribution of nodes makes the resulting component more stable.

[0037] The movement of the connecting rod is symmetrical with adjacent unit cell surfaces, that is, the movement of the nodes of a certain unit cell surface will drive the movement of the nodes of other unit cell surfaces, and the moved nodes and the moved nodes of the adjacent unit cells are symmetrically distributed, and the symmetry plane is the central plane of the unit cell surface corresponding to the moved nodes and the moved nodes of the adjacent unit cells.

[0038] Preferably, each of the connecting rod units is a centrally symmetrical polyhedron structure composed of the connecting rods, and there are no connecting rods on the surface formed by each connecting rod of the connecting rod unit, and there are no connecting rods inside the polyhedron structure.

[0039] In particular, the cubic unit cells where two adjacent connecting rod units are located have a common surface, so that the two adjacent connecting rod units are connected to each other through a common connection node. In this way, the connecting rod units are connected and arranged in sequence to obtain the component.

[0040] Preferably, the connection nodes of the connecting rods are distributed at the center of the face, the center of the edge, or the midpoint of the line connecting the center of the face and the center of the edge of the cubic unit cell. Figure 1 and 2 The node position in .

[0041] Preferably, the connecting rod arrangement structure of each connecting rod unit is the same, and two adjacent connecting rod units are mirror-symmetrical, that is, the overall component is a symmetrical structure; the cross-section of the connecting rod is circular, elliptical or n-gonal, n>2.

[0042] The component is made of metal material and is formed by laser selective melting or casting. The structure after node optimization is made of low-density, high-temperature-resistant and high-strength materials. Small-sized structures can be formed by laser selective melting, and large-sized structures can be formed by casting.

[0043] Furthermore, according to the designed arrangement structure of the connecting rods, the diameter or side length of the connecting rods is adjusted so that the connecting rods in the component reach the target volume fraction; when the number and position of the nodes change, the volume fraction of the connecting rods will change. In order to ensure that the volume fraction remains unchanged, the diameter or side length of the connecting rods needs to be adjusted. Among them, the side length of the connecting rod can be changed by adjusting the side length of the cubic unit cell.

[0044] The target volume fraction is 5%-30%, for example, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 30% and the like.

[0045] Furthermore, the component also includes heat bearing plates arranged on two opposite sides of the connecting rod unit.

[0046] When the volume fraction of the connecting rod in the component is 8%, the connecting rods of the connecting rod unit form a regular octahedron, at which time, the thermal insulation and mechanical properties are optimal. The volume fraction of the connecting rod in the component refers to the percentage of the volume of the connecting rod to the total volume of the component.

[0047] Furthermore, the six connection nodes of the regular octahedron are distributed as follows: two connection nodes are distributed at the centers of two opposite faces of the cubic unit cell, and the other four connection nodes are distributed at the centers of four edges of the other four faces, and the four edges are four edges perpendicular to the faces where the connection nodes are distributed at the centers. The side length of the cubic unit cell where the six connection nodes of the regular octahedron are located is preferably 3-5 mm.

[0048] In practical applications, when the target volume fraction of the connecting rod is determined, the size of the cubic unit cell is first determined, and then the position of each node on its surface is determined. The position and number of the connecting rods are determined. According to the target volume fraction of the connecting rods, the diameter of the connecting rods is adjusted, and then printed layer by layer according to the designed node positions and sizes, and the components of the corresponding structure can be obtained. Then, by testing the mechanical and thermal insulation properties of the corresponding components, the node distribution structure with the best performance is selected. Since under the node distribution conditions specified in the present invention, the mechanical and thermal insulation properties basically show the same trend change, the amount of screening samples can be greatly reduced, and the mechanical and thermal insulation properties are guaranteed to be relatively excellent, so as to facilitate rapid optimization to obtain component structures with relatively excellent mechanical and thermal insulation properties. At the same time, the present invention also realizes the controllable design of mechanical and thermal insulation properties.

[0049] Example 1

[0050] A grapefruit peel-like polyhedron structure provided in Example 1 of the present invention is as follows: Figure 1As shown, including nodes on the six surfaces of the cubic unit cell, the side length of the corresponding cubic unit cell is 2a, there are four nodes on each surface, the distance between each node and the center of the surface is a / 2, and it is located on the line connecting the center of the face and the center of the edge. In Example 1, a is set to 1.5mm and 2.5mm, and the corresponding unit cell side length is 3mm and 5mm. The cubic unit cell with a side length of 3mm shows a 7×7×7 array in the Cartesian direction (that is, there are 7 cubic unit cells in each direction, and there are 7 connecting rod units), and finally the mechanical test structure of 21mm×21mm×21mm is arrayed. The unit cell with a side length of 5mm shows a 4×4×4 array in the Cartesian direction (that is, there are 4 cubic unit cells in each direction, and there are 4 connecting rod units), and finally the mechanical test structure of 20mm×20mm×20mm is arrayed. The thermal test structure consists of a sandwich material and upper and lower heat-bearing plates. The sandwich material is insulated by the arrangement of unit cells. The final array has a size of 60mm×60mm×30mm. The heat-bearing plate is 60mm×60mm×0.4mm for uniform heat flow. The final size of the thermal test structure is 60mm×60mm×30.8mm. Figure 3 In this embodiment, the volume fraction of the connecting rod is 8%, and according to the polyhedron structure imitating the grapefruit peel, the diameters of the connecting rods with the unit cell side lengths of 3 mm and 5 mm are 0.35 mm and 0.59 mm respectively.

[0051] The above structure is formed by laser selective melting of Ti600 high-temperature resistant titanium alloy. The corresponding material can serve for a long time under 600°C conditions, and its mechanical properties are not inferior to Ti-6Al-4V.

[0052] Figure 2 and Figure 4 and 5 The node optimization strategy and corresponding optimization results of the embodiment of the present invention are shown in FIG. 1 . The corresponding structures are a tetradecahedron and a regular octahedron. The node distribution of the tetradecahedron is as follows: there are 4 nodes on each of the two opposite faces, and they are located at the center of the four edges respectively. There is only one node on each of the other six faces, and it is located at the center of each face. Connecting each adjacent node obtains a connecting rod unit. The connecting rod unit array is printed to obtain Figure 4 The component structure shown in the figure has a volume fraction of 8%. According to the tetradecahedron structure, the diameters of the connecting rods with unit cell side lengths of 3 mm and 5 mm are 0.33 mm and 0.53 mm respectively.

[0053] The node distribution of the regular octahedron is as follows: two connection nodes are distributed at the centers of two opposite faces of the cube unit cell, and the other four connection nodes are distributed at the centers of the four edges of the other four faces, and the four edges are four edges perpendicular to the faces where the connection nodes are distributed at the centers. Connecting each adjacent node will obtain a connecting rod unit, and the connecting rod unit array is printed out. Figure 5The component structure shown in the figure. The volume fraction of the connecting rod is 8%. According to the regular octahedral structure, the diameters of the connecting rods with unit cell side lengths of 3 mm and 5 mm are 0.40 mm and 0.64 mm respectively.

[0054] Figure 6 The specific surface areas of the three structures when the side length of the unit cell is 3 mm and 5 mm (the specific surface area in the present invention refers to the ratio of the surface area to the volume of the unit cell). It can be seen that when the node distribution is the same, the specific surface area will also change when the side length of the cubic unit cell changes; when the side length of the cubic unit cell is fixed, the specific surface area can be changed by changing the node distribution.

[0055] Figure 7 The mechanical properties of the three structures with different unit cell sizes are shown. It can be seen that without changing the relative density (i.e. the volume fraction of the connecting rod), when the nodes change, the mechanical properties of the three structures are different, and the unit cell size will also affect the mechanical properties of the structure. Among them, the regular octahedron structure is a structure that is mainly tensile and has the strongest mechanical properties under the same unit cell size.

[0056] Figure 8 are the equivalent thermal conductivity of the three structures, where the experiment in the figure refers to the results obtained by the hotdisk thermal conductivity tester, and the simulation refers to thermal simulation, that is, a fixed heat flux is applied to the lower surface, and the upper and lower surface temperatures are simulated after steady state, and finally the equivalent thermal conductivity is calculated according to the formula. The equivalent thermal conductivity is different for different unit cell sizes. Under the same unit cell size, the equivalent thermal conductivity of the regular octahedron with the lowest specific surface area is the lowest, indicating that its thermal insulation performance is the best. Therefore, the present invention achieves the simultaneous improvement of mechanical properties and thermal insulation performance based on the node optimization strategy.

[0057] When the volume fraction is 8%, the component obtained by the connecting rod of the regular octahedron has better mechanical properties and thermal insulation properties. When the volume fraction changes, the optimal node and connecting rod size and distribution under the corresponding volume fraction can be determined according to the optimization method.

[0058] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A node optimization method for thermal insulation and mechanical properties of components, It is characterized in that The component includes m 1 connected connecting rod units, each connecting rod unit contains m 2 The thermal insulation and mechanical properties of the component are regulated and optimized by distributing the connection nodes of each connection rod in the same connection rod unit on the surface of the same cubic unit cell, and each cubic unit cell has at least one connection node on each of the six surfaces; m 1 is a positive integer greater than or equal to 1, m 2 is a positive integer greater than or equal to 12.

2. The node optimization method for thermal insulation and mechanical properties of a component according to claim 1, It is characterized in that The connection nodes on each opposite face of the cubic unit cell are mirror-symmetric.

3. The node optimization method for thermal insulation and mechanical properties of a component according to claim 2, It is characterized in that Each of the connecting rod units is a centrally symmetrical polyhedron structure formed by the connecting rods; The cubic unit cells where two adjacent connecting rod units are located have a common surface, so that the two adjacent connecting rod units are connected to each other through a common connection node.

4. The node optimization method for thermal insulation and mechanical properties of a component according to claim 3, It is characterized in that The connection nodes of the connection rods are distributed at the center of the face, the center of the edge, or the middle point of the line connecting the center of the face and the center of the edge of the cubic unit cell.

5. The node optimization method for thermal insulation and mechanical properties of a component according to claim 3, It is characterized in that When the volume fraction of the connecting rods in the component is 8%, the connecting rods of the connecting rod unit form a regular octahedron; the volume fraction refers to the percentage of the volume of the connecting rods to the total volume of the component.

6. The node optimization method for thermal insulation and mechanical properties of a component according to claim 5, It is characterized in that The six connection nodes of the regular octahedron are distributed as follows: two connection nodes are distributed at the centers of two opposite faces of the cube unit cell, and the other four connection nodes are distributed at the centers of four edges of the other four faces, and the four edges are four edges perpendicular to the faces with the connection nodes distributed at the centers.

7. The node optimization method for thermal insulation and mechanical properties of a component according to claim 6, It is characterized in that The side length of the cubic unit cell where the six connection nodes of the regular octahedron are located is 3-5 mm.

8. The node optimization method for thermal insulation and mechanical properties of a component according to claim 1, It is characterized in that The connecting rod arrangement structure of each connecting rod unit is the same, and two adjacent connecting rod units are mirror-symmetrical; the cross section of the connecting rod is circular, elliptical or n-gonal, where n is a positive integer greater than 2; The component is made of metal material and is formed by laser selective melting or casting.

9. A node optimization method for thermal insulation and mechanical properties of a component according to any one of claims 1 to 8, It is characterized in that According to the designed arrangement structure of the connecting rods, the diameter or side length of the connecting rods is adjusted so that the connecting rods in the component reach a target volume fraction; the target volume fraction is 5%-30%; the component preferably also includes a heat bearing plate arranged on two opposite surfaces of the connecting rod unit.

10. A component obtained by the node optimization method according to any one of claims 1 to 9.

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