Solar panel connecting frame structure in bionic spiral laying form

Abstract

The invention discloses a solar panel connecting frame structure in a bionic spiral laying form, which comprises a joint, a main beam, a secondary beam and a sleeve which are all made of a carbon fiber composite material, the joint is of a solid structure, and the main beam, the sleeve and the secondary beam are of square thin-wall structures. The main beams, the sleeves and the secondary beams are all formed by bionic spiral layers, and interlayer fibers have constant spiral angles; the invention provides a damage failure analysis and layering angle optimization method of a solar panel connecting frame structure in a bionic spiral layering form. The connecting frame structure is improved and designed in a bionic spiral laying mode, the impact resistance of the connecting frame structure is remarkably improved on the premise that the mass is not increased, and the reliability and safety of a spacecraft can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the technical field, specifically relating to a biomimetic spiral layup solar panel connecting frame structure. Background Technology

[0002] Composite materials are materials with novel properties composed of two or more components with different properties on a macroscopic scale. Among them, fiber-reinforced composite materials have been widely used in structural components of launch vehicles, missiles, spacecraft, and satellites due to their advantages such as lightweight, high strength, and high stiffness. Spacecraft face extreme mechanical load environments such as high stress and impact during launch, in-orbit flight, and landing. These factors can cause brittle fracture of fiber-reinforced composite materials, thereby threatening the safety of spacecraft.

[0003] After the spacecraft's solar panels deploy, they are connected to the cabin structure via a connecting frame. The connecting frame primarily serves to connect the solar panels to the spacecraft's main structure, while also transmitting torque from the drive mechanism to achieve solar orientation of the solar panels. Therefore, the reliability and safety of the connecting frame during on-orbit operation are crucial to ensuring the overall performance of the solar panels and even the spacecraft. During orbital or attitude maneuvers, the spacecraft experiences impact loads on the connecting frame, which can easily lead to fracture failure. Therefore, the connecting frame requires materials with high strength, stiffness, and toughness. To reduce the weight of the solar panel connecting frame, carbon fiber composite materials are typically chosen as the preferred material. While carbon fiber composite materials possess high strength and stiffness, their toughness is relatively poor, making them prone to fracture failure. Summary of the Invention

[0004] The purpose of this invention is to provide a biomimetic spiral layup solar panel connecting frame structure to solve the problem that carbon fiber composite materials have high strength and stiffness, but poor toughness and are prone to fracture failure.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a biomimetic spiral layup solar panel connecting frame structure, including a joint and a solar panel, wherein the joint is used for installation on the spacecraft body structure and is a connection unit with the body structure; it also includes: sleeves, disposed on both sides of the joint, wherein the joint and the main beam are fixedly connected to each other through the sleeves, the sleeves are used to connect the solar panel structure, mainly bear bending moment and torque, and are the main load-bearing structure for impact loads on the solar panel;

[0006] Side beams are used to connect the two sleeves and enhance the overall structural stability.

[0007] The main beam, sleeve, and side beams are all square thin-walled structures. The square thin-walled structures are composed of single-layer carbon fiber reinforced composite materials laid up along the thickness direction, with the interlayer fibers having the same helical angle, which is a biomimetic helical layup form.

[0008] Preferably, the joint is a solid structure, consisting of a single layer of carbon fiber reinforced composite material laid up along the thickness direction, with the fibers in each layer having the same direction.

[0009] Preferably, the four components—joint, main beam, sleeve, and side beam—are all made of carbon fiber reinforced composite material.

[0010] Preferably, in the square thin-walled structure of the main beam, sleeve and side beam, the helix angle of the interlayer fibers of the single-layer carbon fiber reinforced composite material in the square thin-walled structure is 30 degrees.

[0011] A method for determining the helix angle of a biomimetic helical layered solar panel connecting frame structure, characterized by the following specific steps:

[0012] S51, for the connecting frame structure, determine the structural parameters, specifically including the length of the main beam, the length of the side beam, the length of the sleeve, the length of the joint, the side length, thickness and number of layers of the main beam, sleeve and side beam, and the single layer thickness of the carbon fiber reinforced composite material (the above parameters are determined when determining the size of the solar panel model in the actual process).

[0013] S52, determine the relevant material parameters (that is, the parameters that can be directly determined after the selection of materials), specifically including the longitudinal elastic modulus, transverse elastic modulus, in-plane Poisson's ratio, shear modulus, longitudinal tensile strength, longitudinal compressive strength, transverse tensile strength, transverse compressive strength, and shear strength of carbon fiber reinforced composite materials.

[0014] S53, given the initial helical angle of the biomimetic helical solar panel connecting frame structure. ;

[0015] S54. Based on the above parameters, establish a finite element model of the biomimetic spiral layup solar panel connecting frame structure;

[0016] S55, apply an equivalent impact load to the solar panel connecting frame structure, and use the progressive damage analysis method to analyze the failure of the biomimetic spiral layup type solar panel connecting frame structure.

[0017] S56, Obtain the displacement at the end of the main beam from the damage analysis results, and calculate the helix angle as follows: Equivalent energy dissipation of the time connection frame structure ;

[0018] S57, if If so, proceed to step S58; otherwise, let Repeat steps S53 to S56;

[0019] S58, construct the vertical axis as equivalent energy consumption. The horizontal axis represents the helix angle. From the histogram, select the spiral angle corresponding to the maximum equivalent energy consumption. To achieve the optimal ply angle;

[0020] The progressive damage analysis method comprises the following specific steps:

[0021] S61, apply the initial load step to the finite element model;

[0022] S62, using the constitutive relation considering damage, solve for stress and strain;

[0023] S63, based on the Hashin failure criterion, determine whether the initial damage has occurred: if the damage failure criterion is not met, increase the load and execute S62; if the damage failure criterion is met, execute step S64.

[0024] S65, calculate the damage variable, perform a reduction and degradation process on its stiffness, and calculate the damage stiffness matrix;

[0025] S66, determine whether the material has completely failed. If it has completely failed, end the analysis. If it has not completely failed, increase the load and repeat step S62.

[0026] The constitutive relation considering damage in S62 is as follows:

[0027] ;

[0028] In the formula For stress tensor, For strain tensor, The damage stiffness matrix can be expressed as follows:

[0029] ;

[0030] In the formula, For longitudinal elastic modulus, It is the transverse elastic modulus. and Poisson's ratio, Shear modulus As a variable representing the state of fiber damage, As a variable representing the damage state of the matrix, Variables representing the state of shear damage;

[0031] The criteria for the Hashin failure criterion described in S63 for the four failure modes are as follows:

[0032] (1) Fiber tensile failure ): ;

[0033] (2) Fiber compression failure ): ;

[0034] (3) Matrix tensile failure ): ;

[0035] (4) Matrix compression failure ( ): ;

[0036] In the above formula, The in-plane normal stress is along the principal fiber direction. The in-plane normal stress is perpendicular to the principal direction of the fiber. It is an in-plane shear force. For longitudinal tensile strength, For longitudinal compressive strength, For transverse tensile strength, For transverse compressive strength, Shear strength;

[0037] The damage variables mentioned in S65 include the following:

[0038] Fiber damage variables : ;

[0039] matrix damage variables : ;

[0040] Shear damage variables : ;

[0041] In the formula, For fiber tensile damage variable, For fiber compression damage variable, For matrix tensile damage variable, For matrix compression damage variables;

[0042] The fiber tensile damage variable, fiber compressive damage variable, matrix tensile damage variable, and matrix compressive damage variable can be calculated using the following formula:

[0043] ;

[0044] In the formula, the subscript Indicates the type of damaged material, which can be fiber. Damage or matrix Damage; superscript Indicates the damage mode, which can be tensile. Damage or compression damage; It is the initial equivalent displacement corresponding to the damage at the onset of this failure mode. It is the displacement corresponding to complete damage of the material in this failure mode. The equivalent displacement for each failure mode can be calculated using the following formula:

[0045] (1) Fiber tensile failure ): ;

[0046] (2) Fiber compression failure ): ;

[0047] (3) Matrix tensile failure ): ;

[0048] (4) Matrix compression failure ( ): ;

[0049] In the above formula, , The strain is the in-plane normal strain along the fiber direction. The strain is the in-plane normal strain perpendicular to the fiber direction. For in-plane shear strain, It is the characteristic length of the unit.

[0050] The technical effects and advantages of this invention are as follows: the main beam, sleeve, and secondary beam are all formed by biomimetic helical layup, and the interlayer fibers have a constant helical angle; this invention provides a method for damage and failure analysis and layup angle optimization of the biomimetic helical layup solar panel connecting frame structure; this invention improves the design of the connecting frame structure by adopting a biomimetic helical layup form, which significantly enhances the impact resistance of the connecting frame structure without increasing the mass, and can effectively improve the reliability and safety of spacecraft. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the overall structure of the connecting frame of the present invention;

[0052] Figure 2 This is a schematic diagram of the square thin-walled structure layup of the present invention;

[0053] Figure 3 This is a schematic diagram of the biomimetic spiral layup of the present invention;

[0054] Figure 4 This is the finite element model of the connecting frame of the present invention;

[0055] Figure 5 This is a flowchart of the progressive damage analysis process for composite materials according to the present invention;

[0056] Figure 6This is a schematic diagram of the damaged area of ​​the connecting frame in the first layup of the present invention;

[0057] Figure 7 This is a schematic diagram of the damaged area of ​​the connecting frame in the second layup of the present invention;

[0058] Figure 8 This is a schematic diagram of the damaged area of ​​the connecting frame in the third ply of the present invention;

[0059] Figure 9 This is a schematic diagram of the damaged area of ​​the connecting frame in the fourth ply of the present invention;

[0060] Figure 10 This diagram shows the equivalent energy consumption results of the connecting frame with different layup schemes according to the present invention.

[0061] In the diagram: 1. Joint; 2. Sleeve; 3. Main beam; 4. Side beam. Detailed Implementation

[0062] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0063] This invention provides, for example Figures 1-8 The biomimetic spiral layup solar panel connection frame structure shown includes a joint 1 and a solar panel. The joint 1 is used to be installed on the spacecraft star structure and is the connection unit with the star structure. It also includes a sleeve 2, which is set on both sides of the joint 1. The joint 1 and the main beam 3 are fixedly connected to each other through the sleeve 2. The sleeve 2 is used to connect the solar panel structure and mainly bears bending moment and torque. It is the main load-bearing structure for impact load of the solar panel.

[0064] Side beam 4 is used to connect the two sleeves 2 to enhance the overall structural stability;

[0065] The main beam 3, sleeve 2 and side beam 4 are all square thin-walled structures. The square thin-walled structure is composed of single-layer carbon fiber reinforced composite material laid up along the thickness direction. The interlayer fibers have the same helical angle, which is a biomimetic helical layup form.

[0066] Specifically, joint 1 is a solid structure, consisting of a single layer of carbon fiber reinforced composite material laid up along the thickness direction, with the fiber orientation in each layer being the same.

[0067] Specifically, the four components—joint 1, main beam 3, sleeve 2, and side beam 4—are all made of carbon fiber reinforced composite materials.

[0068] Specifically, in the square thin-walled structure of the main beam 3, sleeve 2 and side beam 4, the helix angle of the interlayer fibers of the single-layer carbon fiber reinforced composite material in the square thin-walled structure is 30 degrees.

[0069] Verification 1: The main beam, sleeve, and secondary beams are square thin-walled structures with large dimensions. They are prone to fracture failure under the impact loads of the solar panels, making them weak points in the connecting frame. The cross-sections of the main beam, secondary beams, and sleeves are as follows: Figure 2 As shown, it is a square thin-walled structure. In this example, the side length is designed to be 30.0 mm, the total thickness is 2.4 mm, and it contains 12 layers, with a single layer thickness of 0.2 mm.

[0070] The main difference between the solar panel connection frame structure designed in this example and the traditional composite material connection frame structure is that the main beam, sleeve, and secondary beams all adopt a biomimetic helical layup form, such as... Figure 3 As shown. A ply coordinate system is defined on each of the four faces of the thin-walled beam. , The y-axis is along the beam's axial direction, the y-axis is along the in-ply direction, and the z-axis is along the ply thickness direction. The ply angle in each single-layer slab is defined as relative... The included angle of the axis.

[0071] This example establishes a finite element model of the connecting frame structure. The solid joint is meshed using hexahedral elements, while the connecting sleeve, main beam, and secondary beam are meshed using shell elements. Figure 4 As shown. The bolt holes at the joints are set as fixed boundary conditions, and a shear load Qz along the Z direction is applied to the ends of the two main beams, where Qz = 1400 N. This example uses T300 / epoxy resin composite material, with the following mechanical properties: longitudinal elastic modulus 125.0 GPa, transverse elastic modulus 10.0 GPa, in-plane Poisson's ratio 0.3, in-plane shear modulus 4.3 GPa, out-of-plane shear modulus 4.3 GPa, longitudinal tensile strength 1421.0 MPa, longitudinal compressive strength 980.0 MPa, transverse tensile strength 31.2 MPa, transverse compressive strength 105.0 MPa, and shear strength 80.0 MPa.

[0072] The helix angle of the biomimetic spiral layup solar panel connector is its main structural parameter, and it is used to design the main beam, secondary beam, and [other components]. , , , Four different helix angles, and the ply angles for the four schemes are as follows: Scheme 1 0 12Scheme 2 [0 / 15 / 30 / ... / 165], Scheme 3 [0 / 30 / 60 / ... / 150], and Scheme 4 [0 / 45 / 90 / 135 / 180] represent the reference point, design boundary, and characteristic range of the biomimetic structure, respectively. Represents the traditional unidirectional augmentation reference, while To balance the upper limit of engineering design for axial stiffness and shear resistance, the following selection is made. The interval can cover the main effective design domain of the solar panel connection frame under actual working conditions. and As an intermediate gradient variable, it is used to capture the influence of the crack deflection mechanism unique to biomimetic spiral structures on energy consumption.

[0073] This example uses the progressive damage analysis method for composite materials to analyze the failure energy dissipation of a connecting frame structure under different ply helix angles, and selects the optimal helix angle. The progressive damage analysis method for composite materials mainly includes three steps: stress solution, material property degradation, and failure analysis, such as... Figure 5 As shown. First, the stress of the laminate is calculated, and the Hashin failure criterion is used to determine whether the material has failed. If the material has not failed, the load is increased and the calculation is repeated; if the material meets the failure criterion, its stiffness is reduced.

[0074] The damage area analysis results for the connecting frame under schemes 1, 2, 3, and 4 are as follows: Figure 6-9 As shown in the diagram. In Scheme 1, the damage to the connecting frame mainly occurs at the connection between the main beam and the secondary beam, with the failure mode being matrix tensile failure and a maximum matrix tensile damage parameter value of 1.00. In Scheme 2, the damage to the connecting frame mainly occurs at the connection between the main beam and the secondary beam, with the failure mode also being matrix tensile failure and a maximum matrix tensile failure parameter value of 1.00, indicating partial complete failure. In Scheme 3, the damage to the connecting frame mainly occurs at the connection between the main beam and the secondary beam, with the primary failure mode being fiber compression failure and a maximum fiber compression failure parameter value of 0.06, indicating that failure is just beginning. In Scheme 4, the failure type is matrix tensile failure, with a maximum damage parameter value of 0.97, approaching complete failure.

[0075] To examine the impact resistance of the connecting frame structure, the equivalent energy dissipation of the connecting frame under shear load was also calculated. . ,in For equivalent shear load, The displacement at the ends of the main beam. The equivalent energy dissipation of the connecting frame for different ply configurations is as follows: Figure 8 As shown, the results indicate that using The equivalent energy dissipation of the biomimetic helical ply connector structure with a helix angle is greater than that of other ply angles. Calculation results show that as the helix angle increases from... Increase to The equivalent energy dissipation of the structure shows a significant upward trend; and when the angle further increases to At this time, due to the decrease in axial stiffness, energy consumption actually decreases. These four sets of discrete angles successfully constructed a 'stiffness-toughness' balance curve, proving... While ensuring structural integrity, the layup maximizes the activation of the helical toughening mechanism of the biomimetic structure, and therefore it is determined to be the optimal layup angle.

[0076] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present 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 make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biomimetic spiral layup solar panel connection frame structure, comprising a joint and solar panels, wherein the joint is used for installation on a spacecraft structure and is a connection unit with the spacecraft structure; characterized in that: Also includes: Sleeves are installed on both sides of the joint. The joint and the main beam are fixedly connected to each other through sleeves. Sleeves are used to connect the solar panel structure and mainly bear bending moment and torque. They are the main load-bearing structure for the impact load of the solar panel. Side beams are used to connect the two sleeves and enhance the overall structural stability. The main beam, sleeve, and side beams are all square thin-walled structures. The square thin-walled structures are composed of single-layer carbon fiber reinforced composite materials laid up along the thickness direction, with the interlayer fibers having the same helical angle, which is a biomimetic helical layup form.

2. The biomimetic spiral layup solar panel connecting frame structure according to claim 1, characterized in that: The joint is a solid structure, consisting of a single layer of carbon fiber reinforced composite material laid up along the thickness direction, with the fibers in each layer having the same direction.

3. The biomimetic spiral layup solar panel connecting frame structure according to claim 1, characterized in that: The four components—joint, main beam, sleeve, and side beam—are all made of carbon fiber reinforced composite material.

4. The biomimetic spiral layup solar panel connecting frame structure according to claim 1, characterized in that: In the square thin-walled structure of the main beam, sleeve and side beam, the helix angle of the interlayer fibers of the single-layer carbon fiber reinforced composite material in the square thin-walled structure is 30 degrees.

5. The method for determining the helix angle of a biomimetic helical layered solar panel connecting frame structure according to claim 1, characterized in that, The specific steps are as follows: S51, for the connecting frame structure, determine the structural parameters, specifically including the length of the main beam, the length of the side beam, the length of the sleeve, the length of the joint, the side length, thickness and number of layers of the main beam, sleeve and side beam, and the thickness of a single layer of carbon fiber reinforced composite material; S52, determine the relevant material parameters, specifically including the longitudinal elastic modulus, transverse elastic modulus, in-plane Poisson's ratio, shear modulus, longitudinal tensile strength, longitudinal compressive strength, transverse tensile strength, transverse compressive strength, and shear strength of carbon fiber reinforced composite materials; S53, given the initial helical angle of the biomimetic helical solar panel connecting frame structure. ; S54. Based on the above parameters, establish a finite element model of the biomimetic spiral layup solar panel connecting frame structure; S55, apply an equivalent impact load to the solar panel connecting frame structure, and use the progressive damage analysis method to analyze the failure of the biomimetic spiral layup type solar panel connecting frame structure. S56, Obtain the displacement at the end of the main beam from the damage analysis results, and calculate the helix angle as follows: Equivalent energy dissipation of the time connection frame structure ; S57, if If so, proceed to step S58; otherwise, let Repeat steps S53 to S56; S58, construct the vertical axis as equivalent energy consumption. The horizontal axis represents the helix angle. From the histogram, select the spiral angle corresponding to the maximum equivalent energy consumption. This is the optimal ply angle.

6. The biomimetic spiral layup solar panel connecting frame structure according to claim 1, characterized in that: The progressive damage analysis method comprises the following specific steps: S61, apply the initial load step to the finite element model; S62, using the constitutive relation considering damage, solve for stress and strain; S63, based on the Hashin failure criterion, determine whether the initial damage has occurred: if the damage failure criterion is not met, increase the load and execute S62; If the damage failure criterion is met, proceed to step S64; S65, calculate the damage variable, perform a reduction and degradation process on its stiffness, and calculate the damage stiffness matrix; S66, determine whether the material has completely failed. If it has completely failed, end the analysis. If it has not completely failed, increase the load and repeat step S62.

7. The biomimetic spiral layup solar panel connecting frame structure as described in claim 6, characterized in that, The constitutive relation considering damage in S62 is as follows: ； In the formula For stress tensor, For strain tensor, The damage stiffness matrix can be expressed as follows: ； In the formula, For longitudinal elastic modulus, It is the transverse elastic modulus. and Poisson's ratio, Shear modulus As a variable representing the state of fiber damage, As a variable representing the damage state of the matrix, Variables representing the state of shear damage.

8. The biomimetic spiral layup solar panel connecting frame structure as described in claim 7, characterized in that, The criteria for the Hashin failure criterion described in S63 for the four failure modes are as follows: (1) Fiber tensile failure ): ; (2) Fiber compression failure ): ; (3) Matrix tensile failure ): ; (4) Matrix compression failure ( ): ; In the above formula, The in-plane normal stress is along the principal fiber direction. The in-plane normal stress is perpendicular to the principal direction of the fiber. It is an in-plane shear force. For longitudinal tensile strength, For longitudinal compressive strength, For transverse tensile strength, For transverse compressive strength, This represents the shear strength.

9. The biomimetic spiral layup solar panel connecting frame structure as described in claim 7, characterized in that, The damage variables mentioned in S65 include the following: Fiber damage variables : ; matrix damage variables : ; Shear damage variables : ; In the formula, For fiber tensile damage variable, For fiber compression damage variable, For matrix tensile damage variable, For matrix compression damage variables.

10. The biomimetic spiral layup solar panel connecting frame structure as described in claim 9, characterized in that, The fiber tensile damage variable, fiber compressive damage variable, matrix tensile damage variable, and matrix compressive damage variable can be calculated using the following formula: ； In the formula, the subscript Indicates the type of damaged material, which can be fiber. Damage or matrix Damage; superscript Indicates the damage mode, which can be tensile. Damage or compression damage; It is the initial equivalent displacement corresponding to the damage at the onset of this failure mode. It is the displacement corresponding to complete damage of the material in this failure mode. The equivalent displacement for each failure mode can be calculated using the following formula: (1) Fiber tensile failure ): ; (2) Fiber compression failure ): ; (3) Matrix tensile failure ): ; (4) Matrix compression failure ( ): ; In the above formula, , The strain is the in-plane normal strain along the fiber direction. The strain is the in-plane normal strain perpendicular to the fiber direction. For in-plane shear strain, It is the characteristic length of the unit.

Images