Whole machine recycling umbrella closing cloth folding simulation modeling method

Abstract

This invention discloses a simulation modeling method for the folding and closing of a complete recovery umbrella. Based on the structural geometry of the sliding fabric, a geometric model of the triangular seam and metal ring is established, Boolean operations are performed, and a mesh is generated. The meshed model is rotated and copied to obtain two triangular seam frames. A V-shaped fold is performed based on the dimensions of the main sliding fabric, followed by modeling and meshing. The two triangular seam frames, the metal ring, and one main sliding fabric frame are rotated and copied, and a common node elimination operation is performed to obtain the final sliding fabric mesh model. The umbrella ropes are threaded through the metal ring to obtain the entire mesh model of the complete recovery umbrella with the closing sliding fabric. Based on simulation software, keyword settings are performed to list the umbrella's shape at various moments during the process, verifying whether the umbrella can open normally. This method can assemble and combine a small-sized folding sliding fabric simulation model with the complete recovery umbrella, improving the reliability of the complete recovery simulation calculation.

Description

Technical Field

[0001] This invention belongs to the field of airborne aviation equipment, specifically relating to a simulation modeling method for the folding and sealing of the parachute opening of a whole aircraft. Background Technology

[0002] The whole-machine recovery umbrella is characterized by high resistance and good stability. Its sliding cloth plays two main roles in the whole-machine recovery process. First, it acts as a closing mechanism, which can effectively slow down the inflation speed of the whole-machine recovery umbrella, prevent the umbrella canopy material from being torn by excessive inflation speed, and also greatly reduce the dynamic load impact during the inflation process. Second, under the action of air resistance and the compression of the umbrella ropes, the sliding cloth slides down along the umbrella ropes, allowing the whole-machine recovery umbrella to restore its original resistance characteristics. The system descends steadily within the required speed range, thereby achieving the purpose of recovery.

[0003] Currently, my country's research on the core principles of parachute aerodynamics is relatively lagging, still employing a cyclical design model of "experience + simplified engineering calculations + simulation." This requires extensive testing and multiple rounds of iterative technical improvements to eliminate various problems and hidden dangers. The cycle of "experiment-problem-improvement-experiment" permeates the entire development process, gradually maturing and ensuring the system design model's reliability. However, airdrop testing increases development costs, significantly impacts product development progress, and suffers from inaccurate testing methods, large data dispersion, numerous invalid tests, and difficulty in reproducing experimental phenomena. This results in a large volume of tests, challenging data analysis, and increased product design complexity. Therefore, whole-system recovery simulation has become an efficient and urgent research method. The folding problem of small-sized sliding fabric models has become a key focus and challenge in simulation research, crucial to the reliability of whole-system recovery simulation calculations, but currently, there is no established reference. Summary of the Invention

[0004] To address the current challenges in whole-aircraft recovery and airdrop testing, such as high development costs, slow product development progress, inaccurate testing methods, large dispersion of parachute test data, numerous invalid test cases, and difficulty in reproducing test phenomena, as well as the difficulty in assembling small-sized folded sliding fabric simulation models and recovery parachutes, this invention aims to provide a simulation modeling method for the folding sliding fabric of a whole-aircraft recovery parachute. This method can assemble and combine small-sized folded sliding fabric simulation models with the whole-aircraft recovery parachute, improving the reliability of whole-aircraft recovery simulation calculations.

[0005] The technical solution adopted in this invention is:

[0006] A simulation modeling method for the folding and sealing of a whole-machine recycled umbrella includes the following steps:

[0007] S1) Establish the geometric model of the triangular seam and the metal ring based on the structural geometry of the fabric;

[0008] S2) Perform Boolean operations on the triangular seam and the metal ring, and then mesh the resulting triangular seam and the metal ring;

[0009] S3) Rotate and copy the meshed model, with the rotation angle being the spacing angle of the triangular stitching, to obtain two images of the triangular stitching.

[0010] S4) Perform a V-shaped fold according to the dimensions of the main part of the sliding fabric, and model and mesh the main part of the sliding fabric so that the area and dimensions of the main part of the sliding fabric after folding and unfolding correspond to the original structure;

[0011] S5) Rotate and copy the two triangular stitched parts and metal rings and one sliding cloth main part that have been established. The number of copies is selected according to the number of triangular stitched parts and metal rings. For the phenomenon of overlapping nodes in the sliding cloth mesh model, perform a common node elimination operation to obtain the final sliding cloth mesh model.

[0012] S6) Thread the paracord into the metal ring to obtain the whole machine recovery umbrella mesh model with the closing slip fabric;

[0013] S7) Based on the simulation software, set the keywords and output the opening process of the recovery parachute with the sliding cloth after the calculation is completed. List the shape of the recovery parachute at some moments in this process to verify whether the recovery parachute can open normally.

[0014] The fabric has 12 strips of fabric main body and 12 strips of triangular seam part arranged in an alternating manner, and has bottom edge reinforcement strip, reinforcement strip, longitudinal reinforcement strip and top edge reinforcement strip.

[0015] In step S3), the rotation angle is selected as 30°, 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.

[0016] 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.

[0017] In step S6), the paracords are threaded into the metal rings in a “223” threading method to obtain the whole machine recovery umbrella grid model with the closing slip fabric. The “223” threading method means that the 28 paracords are threaded into the 12 metal rings in a 2-2-3 loop pattern.

[0018] In step S7), LS-DYNA software is used.

[0019] The beneficial effects of this invention are:

[0020] This method can combine a small-sized folded fabric simulation model with the whole machine recovery umbrella assembly, improving the reliability of the whole machine recovery simulation calculation. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the sliding fabric in an embodiment of the present invention. In the figure: 1-main part of the sliding fabric; 2-bottom edge reinforcing band; 3-reinforcing band; 4-longitudinal reinforcing band; 5-triangular sewn part; 6-top edge reinforcing band.

[0022] Figure 2 This is a geometric model of a single fabric seam and a metal ring in an embodiment of the present invention.

[0023] Figure 3 This is the geometric model of the fabric seam after Boolean operation in this embodiment of the invention.

[0024] Figure 4 This refers to the fabric stitching section and the metal ring mesh division in this embodiment of the invention.

[0025] Figure 5 This is the mesh generation model after rotating by 30° and copying in the embodiment of the present invention.

[0026] Figure 6 This is the model mesh division for adding the main part of the sliding cloth in this embodiment of the invention.

[0027] Figure 7 This is the sliding cloth model in the embodiment of the present invention.

[0028] Figure 8 This is the assembly of the umbrella system simulation model in this embodiment of the invention.

[0029] Figure 9a This is a verification of the parachute recovery process in this embodiment of the invention, at 0s.

[0030] Figure 9b This is a verification of the parachute recovery process in this embodiment of the invention, at 0.5s.

[0031] Figure 9c This is a verification of the parachute recovery process in this embodiment of the invention, at 1.5 seconds.

[0032] Figure 9d This is a verification of the parachute recovery process in this embodiment of the invention, at 3 seconds.

[0033] Figure 9e This is a verification of the parachute recovery process in this embodiment of the invention, at 4 seconds.

[0034] Figure 9f This is a verification of the parachute recovery process in this embodiment of the invention, at 5.2 seconds.

[0035] Figure 9g This is a verification of the parachute recovery process in this embodiment of the invention, at 5.4 seconds.

[0036] Figure 9h This is a verification of the parachute recovery process in this embodiment of the invention, at 5.6 seconds.

[0037] Figure 9i This is a verification of the parachute recovery process in this embodiment of the invention, at 5.8 seconds.

[0038] Figure 9j This is a verification of the parachute recovery process in this embodiment of the invention, at 6 seconds.

[0039] Figure 9k This is a verification of the parachute recovery process in this embodiment of the invention, at 6.1 seconds.

[0040] Figure 9l This is a verification of the parachute recovery process in this embodiment of the invention, at 6.15s. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] This embodiment discloses a simulation modeling method for the folding and sealing of a whole-machine recycled umbrella, such as... Figure 1 As shown, the fabric has 12 alternating main fabric sections 1 and 12 triangular seam sections 5, and includes a bottom edge reinforcing band 2, a reinforcing band 3, a longitudinal reinforcing band 4, and a top edge reinforcing band 6; the following steps are employed:

[0043] S1) as Figure 2 As shown, according to Figure 1 The structural geometry of the medium-slip fabric is used to establish the geometric model of the triangular stitching part 5 and the metal ring.

[0044] S2) as Figure 3 As shown, Boolean operations are performed on the triangular seam 5 and the metal ring to ensure proper assembly during subsequent mesh generation. Figure 4 As shown, the triangular stitching part 5 and the metal ring after calculation are meshed.

[0045] S3) such as Figure 5 As shown, the model after meshing is rotated and copied. Since there are 12 triangular stitching parts 5, the rotation angle is 30°, 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, and the number of copies is selected as 1, resulting in two triangular stitching parts 5.

[0046] S4) as Figure 6 As shown, according to Figure 1The dimensions of the main sliding fabric 1 are folded in a V-shape, and the main sliding fabric is modeled and meshed so that the area and size of the main sliding fabric 1 after folding and unfolding correspond to the original structure.

[0047] S5) such as Figure 7 As shown, the two triangular stitched parts 5 and the metal ring, as well as the main sliding cloth part 1, 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 sliding cloth main parts 1 and 12 triangular stitched parts 5, the number of copies is selected as 12. For the phenomenon of overlapping nodes in the sliding cloth mesh model, the common node elimination operation is performed to obtain the final sliding cloth mesh model.

[0048] S6) as Figure 8 As shown, the entire mesh model of the whole-machine recovery umbrella with the closing sliding cloth is obtained by threading the paracords into the metal rings in a "223" threading method. The distance between the sliding cloth and the bottom edge of the umbrella canopy is approximately 1.5m. The so-called "223" threading method refers to threading 28 paracords into 12 metal rings in a cyclic pattern of 2, 2, and 3 cords.

[0049] S7) as Figures 9a to 9l As shown, keyword settings are performed using LS-DYNA software. After the calculation is completed, the opening process of the recovery parachute with the sliding cloth is output, listing the shape of the recovery parachute at some moments during this process to verify whether the recovery parachute can open normally. At the beginning of the opening process of the recovery parachute with the sliding cloth closed, the bottom edge of the canopy begins to inflate. The air resistance and the force of the parachute lines on the sliding cloth and metal ring are insufficient to make the sliding cloth slide down the parachute lines. At this time, the sliding cloth plays the role of closing, slowing down the inflation speed of the recovery parachute, reducing the dynamic load impact during the opening process, and preventing the canopy from breaking. As the recovery parachute inflates, when the squeezing force of the parachute lines on the metal ring reaches a certain critical value, the sliding cloth gradually slides down the parachute lines. The recovery parachute continues to inflate until the system reaches a stable descent state and lands safely.

[0050] This method enables the assembly and combination of a small-sized folded fabric simulation model with the complete recovery parachute, improving the reliability of the simulation calculation for complete recovery and laying a technological foundation for the subsequent independent development of complete recovery parachutes in my country. The embodiments described above are some, but not all, of the embodiments described in this application.

[0051] The detailed description of the embodiments in this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

Claims

1. A simulation modeling method for the folding and sealing of a whole-machine recycled umbrella, characterized in that, The following steps are adopted: S1) Establish the geometric model of the triangular seam and the metal ring based on the structural geometry of the fabric; S2) Perform Boolean operations on the triangular seam and the metal ring, and then mesh the resulting triangular seam and the metal ring; S3) Rotate and copy the meshed model, with the rotation angle being the spacing angle of the triangular stitching, to obtain two images of the triangular stitching. S4) Perform a V-shaped fold according to the dimensions of the main part of the sliding fabric, and model and mesh the main part of the sliding fabric so that the area and dimensions of the main part of the sliding fabric after folding and unfolding correspond to the original structure; S5) Rotate and copy the two triangular stitched parts and metal rings and one sliding cloth main part that have been established. The number of copies is selected according to the number of triangular stitched parts and metal rings. For the phenomenon of overlapping nodes in the sliding cloth mesh model, perform a common node elimination operation to obtain the final sliding cloth mesh model. S6) Thread the paracord into the metal ring to obtain the whole machine recovery umbrella mesh model with the tapered slip fabric; S7) Based on the simulation software, set the keywords and output the opening process of the recovery parachute with the sliding cloth after the calculation is completed. List the shape of the recovery parachute at some moments in this process to verify whether the recovery parachute can open normally.

2. The whole-machine recycling umbrella folding simulation modeling method as described in claim 1, characterized in that: The fabric has 12 strips of fabric main body and 12 strips of triangular seam part arranged in an alternating manner, and has bottom edge reinforcement strip, reinforcement strip, longitudinal reinforcement strip and top edge reinforcement strip.

3. The whole-machine recycling umbrella folding simulation modeling method as described in claim 1, characterized in that: In step S3), the rotation angle is selected as 30°, 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.

4. The whole-machine recycling umbrella folding simulation modeling method as described in 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 recycling umbrella folding simulation modeling method as described in claim 1, characterized in that: In step S6), the paracords are threaded into the metal rings in a "223" threading method to obtain the whole machine recovery umbrella grid model with the closing slip fabric. The "223" threading method means that the 28 paracords are threaded into the 12 metal rings in a 2-2-3 loop pattern.

6. The whole-machine recycling umbrella folding simulation modeling method as described in claim 1, characterized in that: In step S7), LS-DYNA software is used.

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