阅读说明：本技术 连续纤维增强复合材料多层级轻质结构、设计及制造方法 (Continuous fiber reinforced composite multi-level lightweight structure, design and manufacturing method ) 是由 田小永 张学渊 李武丹 于 2021-08-16 设计创作，主要内容包括：连续纤维增强复合材料多层级轻质结构、设计及制造方法,包括具有方形几何图形的田字晶格胞元,由横梁与纵梁组成；胞元内部填充角度为±45的双对角线,其中每一组双对角线都关于它们之间横纵梁交点连线对称平行；双对角线以周期性平行分布,周期长度为沿横纵梁方向的胞元边长,且周期根据胞元数目选定；胞元结构为中心对称的图形,其中对角单元格中的结构形式相同,分别形成角度为±45双对角线互相交叉状结构,和由4条长度相等的横纵梁与单元格4角形成三角形,整体呈现八角蜂窝结构；通过几何参数调控结构分布,以及性能调控,实现连续纤维增强复合材料多层级轻质结构的一体化制造,多层级轻质结构具有更好的抗压缩、抗冲击性能力。(The continuous fiber reinforced composite material multi-level light structure, design and manufacture method comprises a grid cell with a square geometric figure, which consists of cross beams and longitudinal beams; filling dual diagonal lines with an angle of +/-45 in the cell element, wherein each set of dual diagonal lines are symmetrically parallel with respect to a connecting line of intersection points of the transverse beams and the longitudinal beams between the dual diagonal lines; the dual diagonal lines are distributed in a periodic parallel mode, the period length is the length of the side of the cell elements along the direction of the transverse beam and the longitudinal beam, and the period is selected according to the number of the cell elements; the cellular structure is a centrosymmetric figure, wherein the diagonal unit cells have the same structural form, a fork-shaped structure with an angle of +/-45 double diagonal lines and a triangle formed by 4 transverse longitudinal beams with the same length and 4 corners of the unit cells are respectively formed, and the whole cellular structure is in an octagonal honeycomb structure; the integrated manufacturing of the continuous fiber reinforced composite material multi-level light structure is realized by regulating and controlling the structural distribution and the performance through geometric parameters, and the multi-level light structure has better compression resistance and impact resistance.)

1. Continuous fibers reinforcing composite material multilayer light structure, its characterized in that: the lattice cell comprises a lattice cell shaped like a Chinese character 'tian' and provided with a square geometric figure, and consists of a cross beam and a longitudinal beam; filling double diagonals (oblique beams) with an angle of +/-45 in the cell element, wherein each group of the double diagonals (oblique beams) are symmetrically parallel to each other about a connecting line of crossing points of the transverse beams and the longitudinal beams between the two groups of the double diagonals (oblique beams); the dual diagonal lines (oblique beams) are distributed in parallel in a periodic manner, the period length is the length of the side of the cell elements along the direction of the transverse beam and the longitudinal beam, and the period is selected according to the number of the cell elements; the cell structure is a centrosymmetric figure, wherein the diagonal unit cells have the same structural form, and form a structure with an angle of +/-45 double diagonal lines (oblique beams) which are mutually crossed, and 4 longitudinal beams (short beams) with the same length and 4 corners of the unit cells form a triangle, so that the whole structure is in an octagonal honeycomb structure.

2. A method of designing a multi-level lightweight structure of continuous fiber reinforced composite as claimed in claim 1, comprising the steps of:

a) defining the beam period function and the dual diagonal (oblique beam) period function of the forming structure in the XOY plane:

beam function:

wherein m1 is a positive integer representing the number of the cross beams, and the number of the cross beams is not less than 3; l is the outline side length of the minimum square lattice in the cell element; x is the number of_m1The beam formed corresponding to each m1 when the side length of the profile is the same;

stringer function:

wherein m2 is a positive integer representing the number of the longitudinal beams, and the number of the longitudinal beams is not less than 3; y is_m2The longitudinal beams formed corresponding to each m2 when the side length of the profile is the same;

dual diagonal (oblique beam) function:

y＝-x+S+2m₃L

y＝-x+2L-S+2m₄L

y＝x+L+S-2m₅L

y＝x-L-S-2m₆L

wherein m3, m4, m5 and m6 are integers, different intercepts of the function are defined, the value range of the intercept is determined by the function of the cross beam and the longitudinal beam in the step a, and the intercept is calculated in the step c; s is defined as the minimum intercept of the function.

b) Designing and determining the outer contour dimension L of the cell element, wherein the value range of the internal partial parameter S is (0, L/2);

c) for coefficient m of period distribution_iCarrying out constraint value taking to obtain a geometrically parameterized light structure drawing-up contour and a filling structure of the multilayer continuous fiber composite material; and (3) solving the intersection point of the outer contour beam and the longitudinal beam in the XOY plane as a constraint boundary of an oblique beam constraint point and an inner transverse beam, and determining the distribution of the outer contour beam and the longitudinal beam in the contour by utilizing a transverse beam function and an oblique beam function, wherein the constraint conditions are as follows:

3. a method of making a multi-level lightweight structure of continuous fiber reinforced composite material designed according to claim 2, comprising the steps of:

1) respectively obtaining intersection point information of the transverse and longitudinal beams and the outer contour by programming through programming software, and traversing and sequencing the coordinate points from head to tail; obtaining the coordinates of intersection points of a dual diagonal line (oblique beam) and the outer contour, and traversing and sequencing the coordinate points from head to tail so as to obtain continuous coordinate points and continuous paths of the continuous fiber reinforced composite material multi-level light structure;

2) calculating process parameters according to the requirements of the 3D printing process of the continuous fiber reinforced composite material and the continuous path obtained in the step 1);

3) converting the continuous coordinate points and the continuous paths obtained in the step 1) and the process parameters obtained in the step 2) into a data format suitable for continuous fiber 3D printing equipment by using programming software, and outputting a data file;

4) importing the data file into a continuous fiber composite material 3D printing system, and preparing an integrally formed continuous fiber reinforced composite material multi-level light structure by adopting a continuous fiber 3D printing process and taking continuous fibers as reinforcements and thermoplastic materials as matrixes;

5) obtaining bionic multi-level structures with different structural forms and different compression and impact resistance by changing the structural parameter proportion value (S/L) in the step 3), and repeating the step 2), the step 3), the step 4) and the step 5) to obtain a series of multi-level light structures.

4. The continuous fiber reinforced composite multi-level lightweight structure according to claim 1, characterized in that: the transverse beams and the longitudinal beams respectively form a basic grid structure in a shape like Chinese character 'tian' at the same intervals; the double diagonal lines (oblique beams) are distributed in parallel and periodically to form a closed continuous fiber reinforced composite material multi-level light structure with the transverse beams and the longitudinal beams.

5. The method of designing a continuous fiber reinforced composite multi-level lightweight structure according to claim 2, wherein: the cell structure is formed by forming a part consisting of at least 4 cells in a geometric array.

6. The method of manufacturing a continuous fiber reinforced composite multi-level lightweight structure according to claim 3, wherein: the continuous fiber is carbon fiber, aramid fiber, polyethylene fiber or glass fiber.

7. The method of manufacturing a continuous fiber reinforced composite multi-level lightweight structure according to claim 3, wherein: the programming software in the step 3 is Matlab, C language, C + + or Python.

Technical Field

The invention relates to the technical field of continuous fiber reinforced composite materials, in particular to a continuous fiber reinforced composite material multi-level light structure, a design method and a manufacturing method.

Background

Fiber composite material structures exist in a plurality of organisms in the nature, and after the natural evolution of hundreds of millions of years, a multi-level composite material structure with self-adaptive local fiber content and fiber direction is obtained. The multi-level structure generally has different structural forms of macro-micro scale, organisms such as deep sea glass sponge, the macro structure of the organisms is in a spiral column shape, the organisms are unfolded in two dimensions to form a square lattice structure with double diagonal lines (oblique beams), and the diagonal lines and a transverse and longitudinal framework form a specific included angle; each skeleton in the microstructure has a bone core, and its surface forms a circumferential and axial envelope. Due to the coordination effect of macro and micro scales, the glass sponge can maintain the structural stability after bearing deep sea static pressure and fluctuation for a long time, which shows that the multi-level structure has excellent mechanical robustness and brings great inspiration for the design of the multi-level light structure of the continuous fiber reinforced composite material.

Compared with a single structure, the multi-level light structure has the structural characteristics of macro and micro scale, and the force transmission direction can be changed, so that the whole structure can absorb the damage energy when being subjected to compression and impact load, and the mechanical property of the structure is improved. The traditional manufacturing process of the continuous fiber composite material light structure mainly adopts hot-press forming, laying forming and the like to manufacture a structure with a simple shape, and cannot form a multi-layer light structure with excellent characteristics; the complex continuous fiber composite material structure is prepared by utilizing the processes of water jet, machining, assembly and the like, but the process cannot ensure the continuity of continuous fibers, so that the structural performance is greatly reduced. How to combine the properties of continuous fiber reinforced composites with the advantages of multi-level lightweight structures is a great difficulty faced by the current technology.

With the development of the 3D printing technology of the continuous fiber composite material, the manufacturing of the complex light structure of the continuous fiber composite material becomes possible. Chinese patent No. ZL201410325650.3, a continuous long fiber reinforced composite material 3D printer and a printing method thereof, solves the problem of fiber orientation; in a Chinese patent self-adaptive control method for resin content of 3D printing continuous fiber reinforced composite material, the content of fiber at any position is controlled by utilizing discrete point information, wherein the patent number is ZL201810681041.X; the Chinese patent ZL201710236473.5, a manufacturing method of a continuous fiber reinforced composite material light structure, utilizes model contour to extract structure information for manufacturing, and provides possibility for realizing a continuous fiber reinforced composite material multi-level light structure.

At present, the above patents still have the following disadvantages for continuous fiber reinforced composite multi-level light structure and 3D printing: a multi-level light structure design method based on biological structures is not formed; a manufacturing method of a multi-level lightweight structure based on a continuous fiber composite 3D printing process has not been formed.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a continuous fiber reinforced composite multi-level light structure, a design and a manufacturing method, which realize the integrated manufacturing of the continuous fiber reinforced composite multi-level light structure through regulating and controlling the structural distribution and the performance by geometric parameters, and the multi-level light structure has better compression resistance and impact resistance.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

the continuous fiber reinforced composite material multi-level light structure comprises a grid cell with a square geometric figure, and is composed of cross beams and longitudinal beams; filling double diagonals (oblique beams) with an angle of +/-45 in the cell element, wherein each group of the double diagonals (oblique beams) are symmetrically parallel to each other about a connecting line of crossing points of the transverse beams and the longitudinal beams between the two groups of the double diagonals (oblique beams); the dual diagonal lines (oblique beams) are distributed in parallel in a periodic manner, the period length is the length of the side of the cell elements along the direction of the transverse beam and the longitudinal beam, and the period is selected according to the number of the cell elements; the cell structure is a centrosymmetric figure, wherein the diagonal unit cells have the same structural form, and form a structure with an angle of +/-45 double diagonal lines (oblique beams) which are mutually crossed, and 4 longitudinal beams (short beams) with the same length and 4 corners of the unit cells form a triangle, so that the whole structure is in an octagonal honeycomb structure.

The design method of the continuous fiber reinforced composite material multi-layer light structure comprises the following steps:

a) defining the periodic function of the transverse longitudinal beam (short beam) and the periodic function of the dual diagonal (oblique beam) of the forming structure in the XOY plane:

beam function:

wherein m1 is a positive integer representing the number of the cross beams, and the number of the cross beams is not less than 3; l is the outline side length of the minimum square lattice in the cell element; x is the number of_m1The beam formed corresponding to each m1 when the side length of the profile is the same;

stringer function:

wherein m2 is a positive integer representing the number of the longitudinal beams, and the number of the longitudinal beams is not less than 3; y is_m2The longitudinal beams formed corresponding to each m2 when the side length of the profile is the same;

dual diagonal (oblique beam) function:

y＝-x+S+2m₃L

y＝-x+2L-S+2m₄L

y＝x+L+S-2m₅L

y＝x-L-S-2m₆L

wherein m3, m4, m5 and m6 are integers and are defined as different intercept coefficients of the function, and the value range of the intercept coefficients is determined by the function of the cross beam and the longitudinal beam in the step a and is obtained by calculation in the step c; s is defined as the minimum intercept of the function.

b) Designing and determining the outline side length L of the minimum square lattice of the cell element, wherein the value range of an internal distribution parameter S is (0, L/2);

c) for coefficient m of period distribution_iCarrying out constraint value taking to obtain a geometrically parameterized light structure drawing-up contour and a filling structure of the multilayer continuous fiber composite material; the intersection point of the outer contour cross beam and the longitudinal beam is obtained in the XOY plane to serve as a restraint boundary of the oblique beam restraint point and the inner transverse longitudinal beam, and a transverse longitudinal beam function is utilizedThe distribution of the digital and dual diagonal (oblique beam) functions in the contour is determined by the following constraint conditions:

a method of making a continuous fiber reinforced composite multi-level lightweight structure comprising the steps of:

1) respectively obtaining intersection point information of the transverse and longitudinal beams and the outer contour by programming through programming software, and traversing and sequencing the coordinate points from head to tail; obtaining the coordinates of intersection points of a dual diagonal line (oblique beam) and the outer contour, and traversing and sequencing the coordinate points from head to tail so as to obtain continuous coordinate points and continuous paths of the continuous fiber reinforced composite material multi-level light structure;

2) calculating process parameters according to the requirements of the 3D printing process of the continuous fiber reinforced composite material and the continuous path obtained in the step 1);

3) converting the continuous coordinate points and the continuous paths obtained in the step 1) and the process parameters obtained in the step 2) into a data format suitable for continuous fiber 3D printing equipment by using programming software, and outputting a data file;

4) importing the data file into a continuous fiber composite material 3D printing system, and preparing an integrally formed continuous fiber reinforced composite material multi-level light structure by adopting a continuous fiber 3D printing process and taking continuous fibers as reinforcements and thermoplastic materials as matrixes;

5) obtaining bionic multi-level structures with different structural forms and different compression and impact resistance by changing the structural parameter proportion value (S/L) in the step 3), and repeating the step 2), the step 3), the step 4) and the step 5) to obtain a series of multi-level light structures.

The transverse beams and the longitudinal beams respectively form a basic grid structure in a shape like Chinese character 'tian' at the same intervals; the double diagonal lines (oblique beams) are distributed in parallel and periodically to form a closed continuous fiber reinforced composite material multi-level light structure with the transverse beams and the longitudinal beams.

The cell structure is formed by forming a part consisting of at least 4 cells in a geometric array.

The continuous fiber is carbon fiber, aramid fiber, polyethylene fiber or glass fiber.

The programming software in the step 3 is Matlab, C language, C + + or Python.

The invention has the beneficial effects that: the invention introduces the continuous fiber 3D printing process into the composite material bionic structure for printing, provides a set of complete design and manufacturing method for manufacturing the multilayer continuous fiber composite material light structure, and realizes the self-adaptive variable structure parameter printing according to the requirement on the structure performance. The coordinate points are read by programming, and are sequenced according to the printing paths set in advance and then converted into the data file printed by the continuous fiber composite material 3D, the method solves the limitation of the multi-level structure of the traditional manufacturing method of the continuous fiber composite material, and the high-performance quick and low-cost integrated manufacturing of the multi-level light structure of the continuous fiber reinforced composite material based on the glass sponge structure is realized.

Drawings

FIG. 1 is a schematic view of the geometric parameter definition of a multi-level light structure of an embodiment continuous fiber reinforced composite.

FIG. 2 is a schematic view of a multi-level lightweight structural path of an example continuous fiber reinforced composite.

Fig. 3 is an example continuous fiber reinforced composite multi-layer lightweight structural sample 1.

Fig. 4 is an example continuous fiber reinforced composite multi-layer lightweight structural sample 2.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and examples.

As shown in fig. 1, in the present embodiment, taking an oblique beam with a slope of ± 1 in a glass sponge as an example, the continuous fiber reinforced composite material multi-level light structure includes a grid cell with a square geometry, and is composed of a cross beam and a longitudinal beam; filling double diagonals (oblique beams) with an angle of +/-45 in the cell element, wherein each group of the double diagonals (oblique beams) are symmetrically parallel to each other about a connecting line of crossing points of the transverse beams and the longitudinal beams between the two groups of the double diagonals (oblique beams); the dual diagonal lines (oblique beams) are distributed in parallel in a periodic manner, the period length is the length of the side of the cell elements along the direction of the transverse beam and the longitudinal beam, and the period is selected according to the number of the cell elements; the cell structure is a centrosymmetric figure, wherein the diagonal unit cells have the same structural form, and form a structure with an angle of +/-45 double diagonal lines (oblique beams) which are mutually crossed, and 4 longitudinal beams (short beams) with the same length and 4 corners of the unit cells form a triangle, so that the whole structure is in an octagonal honeycomb structure.

A design method of a continuous fiber reinforced composite material multi-layer light structure comprises the following steps:

a) defining an XOY plane, taking the starting point of a transverse beam and a longitudinal beam as an origin, defining transverse beams as being distributed at intervals L along a straight line in the positive X direction, and defining longitudinal beams as being distributed at intervals L along a straight line in the Y direction; the intercept of the oblique beam with the slope of 1 is S and (2X L-S) respectively, the intercept of the oblique beam with the slope of-1 is (L-S) and (S-L) respectively, and the intercept difference is 2X L; obtaining a multi-level light structure planned in a plane;

the following are the respective functions that determine the constituent units in the unit cell:

transverse longitudinal beams:double diagonal (oblique beam):

b) designing and determining the outer contour dimension L of the cell element, wherein the value range of the internal partial parameter S is (0, L/2);

c) according to the intersection points of the outermost circles of transverse longitudinal beams serving as the constraint points (X0, Y0) (X0, Y1) (X1, Y1) (X1, Y0) of the oblique beams, the distribution of the transverse longitudinal beams and the oblique beams in the contour is determined, and a multi-level light structure in a plane is obtained;

the function arrangement of the unit cell structure can be realized by the functions of all units in the regular structure formed by the unit cells under the coordinate system, and the functions are written as follows:

framework function:

dual diagonal (oblique beam) function:

the value of the coefficient influences whether the straight line and other straight lines enclose a required area or not, and then influences a formed structure, so that the coefficient is required to be restrained; how to judge whether the straight line is in the area, firstly, the periphery of the area is determined by the frame function, namely, the coordinates of 4 top points of the frame are determined as (x)₀,y₀)、(x₀,y_m2)、(x_m1,y_m2)、(x_m1,y₀) Namely (0,0), (0, m2L), (m1L, m2L), (m1L, 0); judging whether the straight line is in the area by using the 4 vertex coordinates, and obtaining the value range of the coefficient in the dual diagonal (oblique beam) function;

for (1) and (2): (x)_m1,y_m2) That is, (m1L, m2L) is a boundary constraint point, and the coordinate point is substituted into the original formula to obtain:

namely:

for ③ and fourthly: (x)₀,y_m2)、(x_m1,y₀) That is, (0, m2L), (m1L,0) are boundary constraint points, and the coordinate points are substituted into the original expression:

namely, it is

Namely, it is

In summary, the rule for selecting the coefficients of the regular structure with the unit cell as the structure is as follows:

the frame coefficient is a positive integer with m1, m2 being more than or equal to 3

Wherein L is the outline side length of the smallest square lattice in the cell; s is defined as the minimum intercept of the function; m1 is a positive integer, represents the number of the cross beams, and the number of the cross beams is not less than 3; m2 is a positive integer representing the number of the longitudinal beams, and the number of the longitudinal beams is not less than 3; and (c) defining different intercept coefficients of the functions as m3, m4, m5 and m6 are integers, determining the value range of the functions of the cross beam and the longitudinal beam in the step a, and calculating the values in the step c.

The manufacturing method of the continuous fiber reinforced composite material multi-layer light structure adopts continuous fiber composite material 3D printing equipment, and SolidWorks is modeling software, and comprises the following steps:

1) taking a plane two-dimensional structure consisting of 4 cells as a research object, as shown in fig. 1, utilizing programming software to firstly obtain intersection points of the inner transverse and longitudinal beams and the outer contour, and sequencing coordinates of the intersection points according to a head-to-tail traversal method along the beam direction, namely the outer contour 1-4 and the inner transverse and longitudinal beams 5-18; then, intersection points of the double diagonal lines (oblique beams) and the outer contour are obtained, and coordinates of the intersection points are sequenced to obtain 19-56 according to a method of traversing along the oblique beams from head to tail; thereby obtaining continuous coordinate points and continuous paths of the continuous fiber reinforced composite material multi-level light structure, as shown in fig. 2;

2) processing the continuous path obtained in the step 1) according to the requirements of the continuous fiber composite material 3D printing process, and calculating the resin feeding amount E; according to the known cross-sectional area R of continuous fiber and resin₁And R₂The print layer thickness H, the scan pitch C, and the shift distance d, then E ═ C-R is obtained₁)*d/R₂；

3) Converting the continuous coordinate points and the continuous paths obtained in the step 1) and the resin feeding amount obtained in the step 2) into a Gcode file format by using programming software, and outputting a data file;

4) the Gcode file is led into a continuous fiber composite material 3D printing system, continuous carbon fibers are used as reinforcement bodies and nylon materials are used as matrixes in a continuous fiber 3D printing process, and an integrally formed continuous fiber composite material multi-layer light structure based on glass sponge is prepared and shown in figure 3;

5) in the step 3, the structure is expressed by a parameterized function, so that the bionic multi-level light structure with different structural forms and different compression and impact resistance performances can be obtained by changing the structural parameter proportion value, namely S/L, and a series of continuous fiber reinforced composite multi-level light structures in other forms are obtained by repeating the steps 2), 3), 4) and 5), as shown in FIG. 4.