Complete machine recovery umbrella closing-up sliding cloth folding simulation modeling method

Abstract

The invention discloses a complete machine recovery umbrella closing-up sliding cloth folding simulation modeling method, which comprises the following steps of: establishing geometric models of triangular sewing parts and metal rings according to the structural geometric dimension of sliding cloth, performing Boolean operation, performing grid division, rotating and copying the models after grid division to obtain two triangular sewing parts, and carrying out V-shaped folding according to the size of the sliding cloth main part, carrying out modeling and grid division, rotating and copying the established two triangular sewing parts and metal rings and the sliding cloth main part, and carrying out connode elimination operation to obtain a final sliding cloth grid model. A parachute cord penetrates into a metal ring to obtain a whole machine recovery parachute grid model with closing-up sliding cloth, keyword setting operation is carried out based on simulation software, the shapes of the recovery parachute at some moments in the process are listed, and whether the recovery parachute can be normally opened or not is verified. According to the method, the small-size folding sliding cloth simulation model and the whole machine recovery umbrella can be assembled and combined, and the reliability of whole machine recovery simulation calculation is improved.

Description

Technical Field

[0001] The invention belongs to the field of airborne aviation equipment, and in particular relates to a simulation modeling method for folding sliding cloth of a complete recovery parachute. Background Art

[0002] The whole machine recovery parachute has the characteristics of large resistance characteristics and good stability. Its sliding cloth has two main functions in the whole machine recovery process. The first is to play the role of closing, which can effectively slow down the inflation speed of the whole machine recovery parachute and prevent the tearing of the canopy material due to excessive inflation speed. It can also greatly reduce the dynamic load impact during the inflation process of the whole machine recovery parachute. The second is that the sliding cloth slides down along the parachute rope under the action of air resistance and parachute rope extrusion, so that the whole machine recovery parachute restores its own resistance characteristics. The system descends steadily within the required speed range to achieve the recovery purpose.

[0003] At present, my country's research level on the core key principles of parachute aerodynamic characteristics is relatively backward, and it still adopts the "experience + simple engineering calculation + simulation" cycle design mode. A large number of tests must be carried out, and then multiple rounds of technical improvement and iterative design must be carried out to eliminate various problems and hidden dangers. The cycle of "test-problem-improvement-test" runs through the entire rectification and development process. The system design model has gradually matured and become reliable, but the airdrop test has increased the development cost, and the product development progress has been greatly affected. In addition, the testing methods are not accurate, the parachute test data has a large discreteness, and there are many invalid tests. The test phenomenon is difficult to reproduce, resulting in a large amount of tests, difficult test data analysis, and increased product design difficulty. Therefore, the whole machine recovery simulation has become an efficient and urgent research method. Among them, the folding problem of the small-size sliding cloth model has become the focus and difficulty of the simulation research, and it is also the key to whether the whole machine recovery simulation calculation is reliable, but there is currently no reference. Summary of the invention

[0004] In view of the current experimental problems caused by the whole machine recovery airdrop test, such as high development cost, slow product development progress, inaccurate testing methods, large discreteness of parachute test data, many invalid tests, and difficult reproduction of test phenomena, as well as the problem of difficulty in assembling and combining a small-size folding sliding cloth simulation model and a recovery parachute, the purpose of the present invention is to provide a whole machine recovery parachute closing sliding cloth folding simulation modeling method, which can assemble and combine a small-size folding sliding cloth simulation model with the whole machine recovery parachute, thereby improving the reliability of the whole machine recovery simulation calculation.

[0005] The technical solution adopted by the present invention is: A simulation modeling method for folding the closing sliding cloth of a whole-machine recycling umbrella adopts the following steps: S1) establishing a geometric model of the triangular suture part and the metal ring according to the structural geometric dimensions of the sliding cloth; S2) performing Boolean operation on the triangular suture part and the metal ring, and meshing the triangular suture part and the metal ring after the operation; S3) rotating and copying the meshed model, wherein the rotation angle is the spacing angle of the triangular stitching parts, and obtaining two triangular stitching parts; S4) performing V-shaped folding according to the size of the main part of the sliding cloth, and modeling and meshing the main part of the sliding cloth, so that the area and size of the main part of the sliding cloth after folding and unfolding correspond to the original structure; S5) rotating and copying the two triangular stitching parts and metal rings and the main part of the sliding cloth. The number of copies is the number of triangular stitching parts and metal rings. For the phenomenon of overlapping nodes in the sliding cloth mesh model, common nodes are eliminated to obtain the final sliding cloth mesh model. S6) inserting the parachute rope into the metal ring to obtain a grid model of the entire recovery parachute with a closing sliding cloth; S7) Perform keyword setting operations based on the simulation software, and after the calculation is completed, output the opening process of the recovery parachute with sliding cloth, list the shapes of the recovery parachute at some moments in this process, and verify whether the recovery parachute can be opened normally.

[0006] The sliding cloth comprises 12 sliding cloth main cloths and 12 triangular stitching parts which are arranged in a staggered manner, and comprises a bottom edge reinforcement belt, a reinforcement belt, a longitudinal reinforcement belt and a top edge reinforcement belt.

[0007] In step S3), the rotation angle is selected to be 30°, and the rotation center is selected to be the center of a circle with a radius of 0.1 m from the inner ring of the sliding cloth.

[0008] In step S5), the number of copies is selected as 12, and the rotation center is selected as the center of a circle with a radius of 0.1m from the inner ring of the sliding cloth.

[0009] In step S6), the parachute ropes are threaded into the metal rings in a "223" threading method to obtain a grid model of the entire recovery parachute with a closed sliding cloth. The "223" threading method means: 28 parachute ropes are threaded into 12 metal rings in sequence in a 2, 2, and 3 cycle mode.

[0010] In step S7), LS-DYNA software is used.

[0011] The beneficial effects of the present invention are: The method can combine the small-size folding sliding cloth simulation model with the whole machine recovery parachute assembly, thereby improving the reliability of the whole machine recovery simulation calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 11 is a schematic diagram of the structure of the sliding cloth in an embodiment of the present invention, in which: 1-main part of the sliding cloth; 2-bottom edge reinforcement belt; 3-reinforcement belt; 4-longitudinal reinforcement belt; 5-triangular stitching part; 6-top edge reinforcement belt.

[0013] Figure 2 It is a geometric model of a single sliding cloth stitching part and a metal ring in an embodiment of the present invention.

[0014] Figure 3 It is the geometric model of the sliding cloth sewing part after Boolean operation in the embodiment of the present invention.

[0015] Figure 4 It is the mesh division of the sliding cloth sewing part and the metal ring in the embodiment of the present invention.

[0016] Figure 5 This is the mesh division model after being rotated 30° and copied in the embodiment of the present invention.

[0017] Figure 6 This is the model mesh division with the main part of the sliding cloth added in the embodiment of the present invention.

[0018] Figure 7 It is a sliding cloth model in an embodiment of the present invention.

[0019] Figure 8 It is the final assembly of the simulation model of the umbrella system in the embodiment of the present invention.

[0020] Figure 9a This is the verification of the parachute opening process of the whole machine recovery parachute sliding cloth closing and parachute opening in the embodiment of the present invention, at 0s.

[0021] Figure 9b This is the verification of the parachute opening process of the whole machine recovery parachute sliding cloth closing in the embodiment of the present invention, at 0.5s.

[0022] Fig.9c This is the verification of the parachute opening process of the whole machine recovery parachute sliding cloth closing in the embodiment of the present invention, 1.5s.

[0023] Figure 9d This is the verification of the whole machine recovery parachute sliding cloth closing and parachute opening process in the embodiment of the present invention, 3s.

[0024] Fig.9e This is a verification of the whole machine recovery parachute sliding cloth closing and parachute opening process in the embodiment of the present invention, 4s.

[0025] Figure 9f This is the verification of the parachute opening process of the whole machine recovery parachute sliding cloth closing in the embodiment of the present invention, at 5.2s.

[0026] Figure 9g This is the verification of the parachute opening process of the whole machine recovery parachute sliding cloth closing in the embodiment of the present invention, 5.4s.

[0027] Figure 9h This is the verification of the parachute opening process of the whole machine recovery parachute sliding cloth closing in the embodiment of the present invention, 5.6s.

[0028] Figure 9i This is the verification of the parachute opening process of the whole machine recovery parachute sliding cloth closing in the embodiment of the present invention, 5.8s.

[0029] Figure 9j This is a verification of the whole machine recovery parachute sliding cloth closing and parachute opening process in the embodiment of the present invention, 6s.

[0030] Figure 9k This is the verification of the parachute opening process of the whole machine recovery parachute sliding cloth closing in the embodiment of the present invention, at 6.1s.

[0031] Figure 9l This is the verification of the parachute opening process of the whole machine recovery parachute sliding cloth closing in the embodiment of the present invention, at 6.15s. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0033] This embodiment discloses a method for folding a sliding cloth of a complete recovery umbrella. Figure 1 As shown, the sliding cloth has 12 pieces of staggered sliding cloth main cloth 1 and triangular stitching parts 5, and has a bottom edge reinforcement belt 2, a reinforcement belt 3, a longitudinal reinforcement belt 4 and a top edge reinforcement belt 6; the following steps are adopted: S1) Figure 2 As shown, according to Figure 1 The structural geometric dimensions of the middle sliding cloth establish the geometric model of the triangular stitching part 5 and the metal ring.

[0034] S2) Figure 3 As shown, the triangular suture portion 5 and the metal ring are subjected to Boolean operation, so that the two can be well assembled during subsequent mesh division, as shown in FIG. Figure 4 As shown, the triangular suture portion 5 and the metal ring after the operation are meshed.

[0035] S3) Figure 5 As shown, the meshed model is rotated and copied. Since there are 12 triangular stitching parts 5, the rotation angle is 30°, the rotation center is the center of a circle with a radius of 0.1m from the inner ring of the sliding cloth, and the number of copies is 1 to obtain two triangular stitching parts 5.

[0036] S4) Figure 6 As shown, according to Figure 1 The size of the middle sliding cloth main part 1 is V-folded, and the sliding cloth main part is modeled and meshed, so that the area and size of the sliding cloth main part 1 after folding and unfolding correspond to the original structure.

[0037] S5) Figure 7 As shown, the two triangular stitching parts 5 and the metal ring and the main part 5 of the sliding cloth are rotated and copied. The rotation center is also selected as the center of a circle with a radius of 0.1m from the inner ring of the sliding cloth. Since there are 12 pieces of the main sliding cloth 1 and the triangular stitching parts 5, the number of copies is selected as 12. As for the phenomenon of overlapping nodes in the sliding cloth mesh model, the common nodes are eliminated to obtain the final sliding cloth mesh model.

[0038] S6) Figure 8 As shown, the parachute ropes are threaded into the metal rings in a "223" threading method to obtain a grid model of the entire recovery parachute with a closed sliding cloth, wherein the sliding cloth is about 1.5m away from the bottom edge of the canopy; the so-called "223" threading method means that 28 parachute ropes are threaded into 12 metal rings in sequence in a 2, 2, and 3 cycle mode.

[0039] S7) Figures 9a to 9l As shown in the figure, the keyword setting operation is performed based on the LS-DYNA software. After the calculation is completed, the opening process of the recovery parachute with a sliding cloth is output, and the shapes of the recovery parachute at some moments in this process are listed to verify whether the recovery parachute can be opened normally. At the beginning of the opening process of the sliding cloth of the recovery parachute of the whole machine, the bottom edge of the canopy begins to inflate, and the air resistance and the force of the umbrella rope on the sliding cloth and the metal ring are not enough to make the sliding cloth slide down along the umbrella rope. At this time, the sliding cloth plays the role of closing, delaying the speed of the recovery parachute inflation, reducing the dynamic load impact during the opening process, and avoiding the rupture of the canopy. As the recovery parachute of the whole machine is inflated, the sliding cloth gradually slides down along the umbrella rope when the squeezing force of the umbrella rope on the metal ring reaches a certain critical value, and the recovery parachute of the whole machine continues to inflate until the system reaches a stable descent state and lands safely.

[0040] The method can combine the small-size folding sliding cloth simulation model with the whole machine recovery parachute assembly, improve the reliability of the whole machine recovery simulation calculation, and open up and lay a technical foundation for the subsequent independent research and development of the whole machine recovery parachute in my country. The above-described embodiments are part of the embodiments of this application, but not all of them.

[0041] The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

Claims

1. A simulation modeling method for folding the closing sliding cloth of a complete recovery umbrella, characterized in that: Use the following steps: S1) establishing a geometric model of the triangular suture part and the metal ring according to the structural geometric dimensions of the sliding cloth; S2) performing Boolean operation on the triangular suture part and the metal ring, and meshing the triangular suture part and the metal ring after the operation; S3) rotating and copying the meshed model, wherein the rotation angle is the spacing angle of the triangular stitching parts, and obtaining two triangular stitching parts; S4) performing V-shaped folding according to the size of the main part of the sliding cloth, and modeling and meshing the main part of the sliding cloth, so that the area and size of the main part of the sliding cloth after folding and unfolding correspond to the original structure; S5) rotating and copying the two triangular stitching parts and metal rings and the main part of the sliding cloth. The number of copies is the number of triangular stitching parts and metal rings. For the phenomenon of overlapping nodes in the sliding cloth mesh model, common nodes are eliminated to obtain the final sliding cloth mesh model. S6) inserting the parachute rope into the metal ring to obtain a grid model of the entire recovery parachute with a closing sliding cloth; S7) Perform keyword setting operations based on the simulation software, and after the calculation is completed, output the opening process of the recovery parachute with sliding cloth, list the shapes of the recovery parachute at some moments in this process, and verify whether the recovery parachute can be opened normally.

2. The whole machine recovery umbrella closing sliding cloth folding simulation modeling method according to claim 1 is characterized by: The sliding cloth comprises 12 sliding cloth main cloths and 12 triangular stitching parts which are arranged in a staggered manner, and comprises a bottom edge reinforcement belt, a reinforcement belt, a longitudinal reinforcement belt and a top edge reinforcement belt.

3. The whole machine recovery umbrella closing sliding cloth folding simulation modeling method according to claim 1 is characterized in that: In step S3), the rotation angle is selected to be 30°, and the rotation center is selected to be the center of a circle with a radius of 0.1 m from the inner ring of the sliding cloth.

4. The whole machine recovery umbrella closing sliding cloth folding simulation modeling method according to claim 1, characterized in that: In step S5), the number of copies is selected as 12, and the rotation center is selected as the center of a circle with a radius of 0.1m from the inner ring of the sliding cloth.

5. The whole machine recovery umbrella closing sliding cloth folding simulation modeling method according to claim 1, characterized in that: In step S6), the parachute ropes are threaded into the metal rings in a "223" threading method to obtain the entire recovery parachute grid model with a closed sliding cloth. The "223" threading method means: 28 parachute ropes are threaded into 12 metal rings in sequence in a 2-, 2-, and 3-rope cycle.

6. The whole machine recovery umbrella closing sliding cloth folding simulation modeling method according to claim 1, characterized in that: In step S7), LS-DYNA software is used.

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