A simulation modeling method for V-shaped folding wing umbrella fabric

Abstract

This invention discloses a simulation modeling method for a V-shaped folding parachute with a sliding sheet, belonging to the field of airdrop and airborne operations. The sliding sheet is an aerodynamic device for parachutes that can slow down the deployment speed of the parachute wings and reduce the dynamic load during opening. To simulate the aerodynamic characteristics of a parachute with a sliding sheet during inflation and deployment using numerical calculations, this invention establishes a geometric model of a rectangular sliding sheet with rings at four apex corners. The rectangular sliding sheet is then meshed, and freeform surface deformation technology is used to fold the sliding sheet into a "V" shape. Finally, the parachute lines are evenly distributed into four bundles, which are then passed through four iron rings for assembly. This method can be used for simulation calculations of the inflation and deployment of a parachute with a sliding sheet.

Description

Technical Field

[0001] This invention relates to the field of airborne equipment technology, specifically a simulation modeling method for the sliding fabric of a V-shaped folding wing parachute. Background Technology

[0002] Rammed parachutes, composed of flexible fabric, offer advantages such as small storage space, high glide ratio, and good maneuverability, playing a crucial role in space reentry. The parachute's sliding fabric, under the combined influence of air resistance and parachute lines, slides from the top to the bottom of the parachute, effectively slowing down the inflation and deployment speed, reducing the impact dynamic load during inflation and deployment, and preventing tearing of the parachute canopy. Because the parachute inflation and deployment process is very short, it is difficult to collect experimental data; therefore, numerical simulation has become a common method for studying this problem. Numerical simulation requires not only establishing a folded parachute model but also a folded sliding fabric model. How to create a computationally usable model of the folded sliding fabric has become a major challenge in the field of airdrop and airborne operations. Summary of the Invention

[0003] To address existing problems, this invention provides a simulation modeling method for V-shaped folding wing parachutes with sliding fabric. This method can be used for simulation calculations of wing parachutes with sliding fabric, solving the problem that the inflation and deployment process of existing wing parachutes without sliding fabric is very short, making it difficult to collect experimental data and thus impossible to perform simulation calculations.

[0004] The present invention discloses a simulation modeling method for V-shaped folding wing umbrella fabric, characterized by comprising the following steps:

[0005] 1) Establish a model of the entire rectangular sliding cloth;

[0006] 2) Mesh the rectangular sliding cloth model to obtain a rectangular sliding cloth shell mesh model;

[0007] 3) The rectangular sliding mesh model is folded and deformed using freeform surface deformation technology to finally obtain the V-shaped folding wing umbrella sliding mesh model.

[0008] Further optimization resulted in a rectangular sliding cloth model with a length of 0.78m and a width of 0.3m, and four apex corners equipped with rings with an inner radius of 8mm and an outer radius of 10mm.

[0009] Further optimization, step 2) specifically involves meshing the rectangular sliding cloth model using quadrilateral shell elements, with a mesh size of 10*10mm.

[0010] Further optimization, step 3) specifically involves:

[0011] Step 3.1 Use freeform surface deformation technology to embed a rectangular sliding shell mesh model into the deformation space;

[0012] Step 3.2 Then, by manipulating the deformation space, the embedded rectangular sliding shell mesh model is deformed, and finally the V-shaped folding wing umbrella sliding mesh model is obtained.

[0013] Further optimization, step 3.1) specifically involves: creating a parallelepiped for the rectangular sliding shell mesh model, and embedding the rectangular sliding shell mesh model into the parallelepiped.

[0014] Further optimization, step 3.2) specifically involves:

[0015] Step 3.21: Divide the hexahedron evenly into l, m, and n control nodes along the W, S, and H directions, totaling lmn;

[0016] Step 3.22: The local coordinates of each grid node in the rectangular sliding shell mesh model do not change relative to the control node in the hexahedron. Therefore, when the control node is moved, the global coordinates of each grid node are obtained again according to the Bernstein polynomial. The sliding fabric is folded and deformed by freeform surface deformation technology, and finally the V-shaped folding wing umbrella sliding fabric mesh model is obtained.

[0017] Further optimization involves step 3.22, which involves first translating the four rings upwards while keeping the horizontal direction unchanged, fixing one column of nodes in the middle of the rectangular sliding shell mesh model, and then deforming the rectangular sliding shell mesh model according to the movement of the rings to complete the first deformation; then translating the four rings horizontally towards the center while keeping the vertical direction unchanged, fixing one column of nodes in the middle of the rectangular sliding shell mesh model, and then deforming the rectangular sliding shell mesh model according to the movement of the rings to complete the second deformation, ultimately obtaining the V-shaped folding wing parachute sliding mesh model.

[0018] The beneficial effects of this invention are as follows:

[0019] When the sliding fabric of this invention is assembled with the parachute, the closure fabric is pulled to the bottom edge of the canopy during parachute closure. During opening, the bottom edge of the canopy inflates, causing the parachute lines to expand outwards. This results in pressure on multiple annular holes in the closure fabric, causing it to slide along the parachute lines towards the tether point. The resistance of the closure fabric and the friction between the annular holes and the parachute lines control the movement speed of the closure fabric, thereby controlling the opening speed of the parachute, reducing the dynamic load during the opening process, and preventing damage to the canopy. Furthermore, this invention solves the problem that the inflation and deployment process of existing parachutes without a sliding fabric is very short, making it difficult to collect experimental data. It enables simulation calculations of the parachute inflation and deployment process. Simulation results show that during the parachute inflation and deployment process, the peak dynamic load of a parachute without a sliding fabric is 32000N, while the peak dynamic load of a parachute with a sliding fabric is 24000N. This demonstrates that the sliding fabric structure can effectively reduce the dynamic load experienced by the parachute during inflation and deployment, preventing canopy breakage. Attached Figure Description

[0020] Figure 1This is a rectangular sliding cloth model diagram of the present invention;

[0021] Figure 2 This is a rectangular sliding shell mesh model diagram of the present invention;

[0022] Figure 3 This is a folded diagram of the first sliding shell mesh model of the present invention;

[0023] Figure 4 This is a folded diagram of the second sliding shell mesh model of the present invention;

[0024] Figure 5 This is a diagram of the crystal structure controlled by the freeform surface deformation technology of the present invention;

[0025] Figure 6 This is an assembly diagram of the slip fabric and paracord of the present invention;

[0026] Figure 7(a) shows the structural deformation of the parachute during the inflation and deployment process when the deployment time T=0s.

[0027] Figure 7(b) shows the structural deformation during the parachute inflation and deployment process of the present invention when the deployment time T=0.6s.

[0028] Figure 7(c) shows the structural deformation during the parachute inflation and deployment process of the present invention when the deployment time T=1.0s.

[0029] Figure 7(d) shows the structural deformation during the parachute inflation and deployment process of the present invention when the deployment time T=1.3s.

[0030] Figure 7(e) shows the structural deformation during the parachute inflation and deployment process of the present invention when the deployment time T=3.0s.

[0031] Figure 7(f) shows the structural deformation during the parachute inflation and deployment process of the present invention when the deployment time T=4.0s.

[0032] Figure 8(a) shows the flow field changes during the parachute inflation and deployment process of the present invention when the deployment time T=0s.

[0033] Figure 8(b) shows the flow field changes during the parachute inflation and deployment process of the present invention when the deployment time T=0.6s.

[0034] Figure 8(c) shows the flow field changes during the parachute inflation and deployment process of the present invention when the deployment time T=1.0s.

[0035] Figure 8(d) shows the flow field changes during the parachute inflation and deployment process of the present invention when the deployment time T=1.3s.

[0036] Figure 8(e) shows the flow field changes during the parachute inflation and deployment process of the present invention when the deployment time T=3.0s.

[0037] Figure 8(f) shows the flow field changes during the parachute inflation and deployment process of the present invention when the deployment time T=4.0s.

[0038] Figure 9 The graph shows the dynamic load variation curves for parachutes with and without slipped fabric. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] like Figure 1-5 As shown, this invention discloses a simulation modeling method for V-shaped folding wing umbrella fabric, comprising the following steps:

[0041] 1) Create a complete rectangular sliding cloth model, with circular rings at the four apex corners of the rectangular sliding cloth model;

[0042] 2) Mesh the rectangular sliding cloth model to obtain a rectangular sliding cloth mesh model;

[0043] Specifically, the rectangular sliding cloth model is meshed using quadrilateral shell elements, with a mesh size of 10*10mm.

[0044] 3) The rectangular sliding mesh model is folded and deformed using freeform surface deformation technology to obtain the V-shaped folding wing parachute sliding mesh model; specifically:

[0045] Step 3.1: Use freeform surface deformation technology to embed the rectangular sliding shell mesh model into the deformation space; specifically: for the rectangular sliding shell mesh model, create a parallelepiped, and embed the rectangular sliding shell mesh model into the parallelepiped.

[0046] Step 3.2: Then, by manipulating the deformation space, the embedded rectangular sliding shell mesh model is deformed, and finally the V-shaped folding wing umbrella sliding mesh model is obtained;

[0047] Specifically: Step 3.21: Divide the hexahedron evenly into l, m, and n control nodes along the W, S, and H directions, totaling lmn;

[0048] Step 3.22: The local coordinates of each grid node in the rectangular sliding shell mesh model do not change relative to the control node in the hexahedron. Therefore, when the control node is moved, the global coordinates of each grid node are obtained again according to the Bernstein polynomial. The sliding fabric is folded and deformed by freeform surface deformation technology, and finally the V-shaped folding wing umbrella sliding fabric mesh model is obtained.

[0049] Example:

[0050] like Figure 1-5As shown, first, a rectangular sliding cloth model is created using CATIA software. The rectangular sliding cloth model has a length of 0.78m and a width of 0.3m, with four apex rings having an inner radius of 8mm and an outer radius of 10mm.

[0051] Then, Hypermesh was used to mesh the rectangular sliding cloth model. The entire rectangular sliding cloth model was meshed using quadrilateral shell elements to obtain a rectangular sliding cloth shell mesh model with a mesh size of 10*10mm.

[0052] Then, for the rectangular sliding shell mesh model, a parallelepiped is created, and the sliding shell mesh model is embedded into the parallelepiped. The parallelepiped is evenly divided into l, m, and n control nodes in total lmn along three directions. The local coordinates of each mesh node of the rectangular sliding shell mesh model remain unchanged relative to the control nodes in the parallelepiped. First, the four rings are translated upwards by 0.25, while the horizontal direction remains unchanged. The middle column of nodes of the rectangular sliding shell mesh model is fixed. The rectangular sliding shell mesh model makes corresponding deformations according to the movement of the rings, completing the first deformation. Then, the four rings are moved horizontally towards the center, each translated by 0.09m, while the vertical direction remains unchanged. The middle column of nodes of the rectangular sliding shell mesh model is fixed. The rectangular sliding shell mesh model makes corresponding deformations according to the movement of the rings, completing the second deformation. Finally, the V-shaped folding wing parachute sliding shell mesh model is obtained.

[0053] like Figure 6 As shown, the parachute cords are then divided into four bundles of eight cords each. The four bundles of cords are then passed through the rings at the four corners of the folded "V"-shaped sliding fabric to complete the assembly with the parachute. This assembly is then used for simulation calculations of the parachute's inflation and deployment with the sliding fabric.

[0054] As shown in Figures 7(a)-7(f), the "V"-shaped sliding fabric will quickly unfold and slide downwards during the inflation of the parachute. When the parachute opens, the inflation of the bottom edge of the canopy causes the parachute lines to expand outwards, which in turn puts pressure on the multiple loops of the closing fabric. This causes the closing fabric to slide along the parachute lines toward the weight tether point. The resistance of the closing fabric and the friction between the loops and the parachute lines control the movement speed of the closing fabric, thereby controlling the opening speed of the parachute, reducing the dynamic load during the opening process of the parachute, and preventing the canopy from being damaged.

[0055] As shown in Figures 8(a)-8(f), during the inflation and deployment of the parachute with a sliding cloth, a significant flow separation phenomenon will appear on the upper surface of the parachute. The rear separation vortex will gradually dissipate, which solves the problem that the inflation and deployment process of the existing parachute without a sliding cloth is very short and it is difficult to collect experimental data. This enables the simulation calculation of the parachute inflation and deployment process.

[0056] Depend on Figure 9Simulation results show that during the parachute inflation and deployment process, the peak dynamic load of the parachute without a slip fabric is 32,000 N, while that of the parachute with a slip fabric is 24,000 N. This indicates that the slip fabric structure can effectively reduce the dynamic load on the parachute during inflation and deployment, preventing the canopy from breaking.

[0057] This invention has many specific applications. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A simulation modeling method for V-shaped folding wing umbrella fabric, characterized in that: Includes the following steps: 1) Establish a model of the entire rectangular sliding cloth; 2) Mesh the rectangular sliding cloth model to obtain a rectangular sliding cloth shell mesh model; 3) The rectangular sliding mesh model is folded and deformed using freeform surface deformation technology to finally obtain the V-shaped folding wing umbrella sliding mesh model; Step 3) specifically involves: Step 3.1 Use freeform surface deformation technology to embed a rectangular sliding shell mesh model into the deformation space; Specifically: For the rectangular sliding shell mesh model, create a parallelepiped and embed the rectangular sliding shell mesh model into the parallelepiped; Step 3.2 Then, by manipulating the deformation space, the embedded rectangular sliding shell mesh model is deformed, and finally the V-shaped folding wing umbrella sliding mesh model is obtained. Step 3.21: Divide the hexahedron evenly into l, m, and n control nodes along the W, S, and H directions, totaling lmn; Step 3.22: The local coordinates of each grid node in the rectangular sliding shell mesh model do not change relative to the control node in the hexahedron. Therefore, when the control node is moved, the global coordinates of each grid node are obtained again according to the Bernstein polynomial. The sliding fabric is folded and deformed by freeform surface deformation technology to finally obtain the V-shaped folding wing umbrella sliding fabric mesh model. Specifically, step 3.22 involves first translating the four rings upwards while keeping the horizontal direction unchanged, fixing one column of nodes in the middle of the rectangular sliding shell mesh model, and then deforming the rectangular sliding shell mesh model according to the movement of the rings to complete the first deformation; then translating the four rings horizontally towards the center while keeping the vertical direction unchanged, fixing one column of nodes in the middle of the rectangular sliding shell mesh model, and then deforming the rectangular sliding shell mesh model according to the movement of the rings to complete the second deformation, finally obtaining the V-shaped folding wing parachute sliding mesh model.

2. The simulation modeling method for V-shaped folding wing umbrella sliding fabric according to claim 1, characterized in that: The rectangular sliding cloth model has rings at its four apex corners.

3. The simulation modeling method for V-shaped folding wing umbrella sliding fabric according to claim 1, characterized in that: Step 2) Specifically, the rectangular sliding cloth model is meshed using quadrilateral shell elements to obtain a rectangular sliding cloth shell mesh model. The size of the mesh elements is set as required.

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