A method of designing a netting connector and a netting connector

Abstract

The present application belongs to the design method of mechanical structure, and particularly relates to a design method of a net rope connecting piece and a net rope connecting piece. The present application provides a design method of a net rope connecting piece, which comprises the following steps: designing a curved surface model of the net rope connecting piece according to use details and using a curvature mode to obtain a preliminary structure of the net rope connecting piece; defining a clamp according to the preliminary structure of the net rope connecting piece, applying external load according to actual stress conditions, performing finite element analysis and obtaining analysis results; optimizing the design of the net rope connecting piece again according to the finite element analysis results; repeatedly performing finite element analysis and optimizing the design of the net rope connecting piece; and trial producing the optimized net rope connecting piece and performing a tension test. The net rope connecting piece optimized by the design method through finite element analysis is optimal in overall structure when use conditions are met; the structure designed through the finite element analysis of the present application can bear greater tension.

Description

Technical Field

[0001] This invention pertains to the design methods of mechanical structures, and particularly relates to a design method for a rope connector and a rope connector. Background Technology

[0002] Existing finite element analysis commonly uses single tetrahedral, hexahedral, or pyramidal meshing methods. When checking and analyzing malformed meshes, regardless of the meshing method used, there is an over-concentration of malformed meshes at the intersections of the part surfaces. This indicates that the mesh is difficult to accurately divide at these locations, requiring further processing and optimization of the malformed meshes. Existing technologies do not address malformed meshes, and existing mesh optimization methods are simplistic. This leads to inaccurate stress analysis of the parts and affects the actual performance evaluation of the product.

[0003] Currently, in the national amusement park industry, most rope-connected facilities use rigid metal components (such as...) for their connection and fixing ends. Figure 2 As shown, when children come into contact with the rope, it can easily cause skin abrasions, posing a safety hazard; the plastic parts used for connection and fixation at the ends are not strong enough and have very few applicable scenarios. Existing rigid metal rope connectors have fixed ends that are essentially immobile, making the rope prone to wear and tear and lacking cushioning function. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a design method for a rope connector. The rope connector optimized through finite element analysis using this method exhibits the best overall structure when meeting usage requirements. The finite element analysis of this invention can better analyze the stress state of the parts, thereby allowing for better optimization of the surface structure details, resulting in more uniform cell sizes, smoother joints, and a more rational load-bearing structure. The structure designed after finite element analysis using this invention can withstand greater tensile forces.

[0005] The specific technical solution of this invention is as follows:

[0006] This invention provides a design method for a rope connector, comprising: designing a curved surface model of the rope connector based on usage details and using a curvature pattern to obtain an initial structure of the rope connector; defining a fixture and applying an external load according to the actual stress conditions based on the initial structure of the rope connector, performing finite element analysis and obtaining the analysis results; further optimizing the design of the rope connector based on the finite element analysis results; repeating the finite element analysis to further optimize the design of the rope connector; and conducting trial production of the optimized rope connector and performing tensile tests.

[0007] Further improvements include a design mesh generation method, which involves: using an unstructured topology analysis method to divide the part into a finite number of hexahedral elements; after dividing the part into multiple elements, checking the local element morphology and isolating the distorted positions; dividing the distorted positions into tetrahedral elements; and at the contact positions between tetrahedral and hexahedral elements, combining the head and tail of two tetrahedral elements to form one side of a hexahedron.

[0008] Further improvements include checking and optimizing the mesh quality. Checking the mesh quality includes checking the mesh aspect ratio, Jacobian, and checking for small locations within the mesh. Optimizing the mesh involves making the mesh aspect ratio close to 1. For locations with small curvature, if the aspect ratio is large, the mesh needs to be finer to reduce the mesh aspect ratio.

[0009] A further improvement is that the optimized mesh also includes making the Jacobian ratio close to 1.0, the Jacobian ratio being proportional to the edge curvature.

[0010] Further improvements include checking minute locations of the mesh, such as rounded corners, included corners, and edge corners. After checking, mesh control is used to further optimize the mesh.

[0011] Further improvements require the use of a more precise incompatible combination method after mesh generation, employing the FFEPlus (iterative) solver and advanced matrix graph reordering techniques to perform calculations and optimize the mesh.

[0012] Further improvements include setting Jacobi points and dividing the mesh based on curvature. The Jacobi points are 4, and a finer mesh needs to be divided in the high curvature region to make the finite element calculation of the part more accurate.

[0013] This invention provides a net rope connector, which includes a fixed base and a ball-head fastener. The outer surface of the fixed base is petal-shaped and has a first stepped cylindrical hole in the center. The first stepped cylindrical hole is arranged from top to bottom as a first cylindrical hole, a spherical hole, and a second cylindrical hole, and the diameter of the first cylindrical hole is smaller than the diameter of the second cylindrical hole. The outer surface of the ball-head fastener is arranged from top to bottom as a cylindrical surface, a spherical surface, and a conical surface, and the cylindrical surface corresponds to the first cylindrical hole, the spherical surface corresponds to the spherical hole, and the ball-head fastener has a second stepped cylindrical hole in the center. The taper of the conical surface is 104°.

[0014] In a further improvement, the second stepped cylindrical hole is arranged from top to bottom as a third cylindrical hole and a fourth cylindrical hole. The diameter of the third cylindrical hole is 6mm smaller than that of the fourth cylindrical hole. The third cylindrical hole and the fourth cylindrical hole form a stepped surface, and the minimum thickness of the stepped surface is 6.8mm.

[0015] In a further improvement, both the fixing base and the ball head fastener are made of plastic, and the fixing base has a rope fixing hole on its side.

[0016] The beneficial effects achieved by this invention are as follows:

[0017] This invention provides a design method for a rope connector. The rope connector designed using this method through finite element analysis has the optimal overall structure when meeting usage requirements. The finite element analysis of this invention can better analyze the stress state of the parts, thereby optimizing the details of the curved surface structure, making the cells more uniform, the joints smoother, and the load-bearing structure more reasonable. The structure designed after the finite element analysis of this invention can withstand greater tensile forces.

[0018] This invention provides a novel net rope connector. The connector employs a ball-head structure where the net rope passes through a snap fastener. Through calculation and testing, it not only meets the strength requirements for securing net ropes in various scenarios, but also features a wider range of motion in the spherical structure at the rope's fixing end, providing a cushioning function. This makes the connector suitable for most amusement facilities. The net rope is protected within the snap fastener, preventing wear and tear. Furthermore, the connector has no sharp edges and is made of plastic, significantly reducing the risk of abrasions and scratches caused by accidental bumps during play, thus alleviating safety hazards. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating a design method for a rope connector according to an exemplary embodiment;

[0020] Figure 2 This is a structural schematic diagram of a rope connector in the prior art;

[0021] Figure 3 This is a structural schematic diagram of a rope connector according to an exemplary embodiment;

[0022] Figure 4 This is a schematic diagram of the structure of a fixed base according to an exemplary embodiment;

[0023] Figure 5 This is a top view of a fixed base according to an exemplary embodiment;

[0024] Figure 6 yes Figure 5 AA section view;

[0025] Figure 7 This is a schematic diagram of the structure of a ball-head fastener according to an exemplary embodiment;

[0026] Figure 8This is a schematic diagram of the structure of a ball-head fastener according to an exemplary embodiment;

[0027] Figure 9 This is a finite element analysis displacement cloud diagram of a preliminary fixed base shown according to an exemplary embodiment;

[0028] Figure 10 This is a finite element analysis displacement cloud diagram of the final version of the fixed base, as shown in an exemplary embodiment.

[0029] Figure 11 This is a finite element analysis stress cloud diagram of a preliminary fixed base shown according to an exemplary embodiment;

[0030] Figure 12 This is a finite element analysis stress cloud diagram of the final version of the fixed base, shown according to an exemplary embodiment;

[0031] Figure 13 This is a finite element analysis displacement cloud diagram of a preliminary ball joint fastener, shown according to an exemplary embodiment.

[0032] Figure 14 This is a finite element analysis displacement contour plot of the final version of the ball head fastener, shown according to an exemplary embodiment.

[0033] Figure 15 This is a finite element analysis stress cloud diagram of a preliminary ball joint fastener, shown according to an exemplary embodiment.

[0034] Figure 16 This is a finite element analysis stress contour plot of the final version of the ball head fastener, shown according to an exemplary embodiment.

[0035] Figure 17 This is a diagram of the first tensile test of a rope connector according to an exemplary embodiment;

[0036] Figure 18 This is a diagram of a second tensile test of a rope connector according to an exemplary embodiment.

[0037] The reference numerals in the attached figures are explained as follows:

[0038] 1. Fixed base; 11. First stepped cylindrical hole; 111. First cylindrical hole; 112. Second cylindrical hole; 12. Net rope fixing hole;

[0039] 2. Ball head fastener; 21. Second stepped cylindrical hole; 211. Third cylindrical hole; 212. Fourth cylindrical hole; 213. Step surface. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are only used to explain the invention and are not intended to limit the scope of protection of the present invention.

[0041] like Figures 9-16 As shown, the design method for the rope connector provided by the present invention includes: S1--designing a surface model of the rope connector based on usage details and using a curvature mode to obtain an initial structure of the rope connector; S2--defining a fixture based on the initial structure of the rope connector and applying an external load according to the actual stress conditions, performing finite element analysis and obtaining the analysis results; S3--optimizing the design of the rope connector again based on the finite element analysis results; S4--repeating the finite element analysis to further optimize the design of the rope connector; S5--trial production of the optimized rope connector and conducting tensile tests.

[0042] Finite element analysis (FEM) involves setting Jacobian points, creating a curvature-based mesh, and checking mesh quality. A Jacobian point of 4 is chosen for FEM, considering both computational difficulty and speed, as this is a reasonable value. A high-quality mesh is also selected. Due to the complex curved surface of the part, a curvature-based meshing method is used to create a more detailed mesh in high-curvature regions, ultimately leading to more accurate FEM calculations. After meshing, mesh quality is checked in two ways: first, the aspect ratio is checked; ideally, it should be close to 1. For areas with low curvature, a large aspect ratio requires mesh refinement to reduce the aspect ratio and improve the accuracy of the final calculation. Second, the Jacobian ratio is checked; ideally, the Jacobian ratio (with all mid-side nodes located exactly in the middle of the straight edge) should be close to 1.0. The Jacobian ratio increases with edge curvature. The Jacobian ratio at a point within an element can be used to measure the distortion at that location. The distance of the middle nodes of a high-quality mesh from the edge is checked; the cells should be non-distorted, as only under these conditions can the calculation results converge. After meshing, inspect minute locations, such as those with small fillet angles, and use mesh control to further optimize the mesh. Once meshing is complete, select a more precise incompatible combination method, use the FFEPlus (iterative) solver, and employ advanced matrix graph reordering techniques to perform calculations and optimize the mesh.

[0043] The finite element analysis also includes a design mesh generation method, which includes: using an unstructured topology analysis method to divide the part into a finite number of hexahedral elements; after dividing the part into multiple elements, checking the local element morphology and isolating the distorted positions separately; dividing the distorted positions into tetrahedral elements; and at the contact positions between tetrahedral and hexahedral elements, combining the head and tail of two tetrahedral elements to form one side of a hexahedron.

[0044] An unstructured topology analysis method is used to divide the part into a finite number of hexahedral elements. Adjacent faces of two elements form a double-sided contact structure, facilitating continuous mesh generation and subsequent stress calculations. After dividing the part into multiple elements, the local element morphology is examined. Areas with a high concentration of distorted elements require further optimization. These distorted areas are isolated and divided into tetrahedral elements. At the contact points between tetrahedrons and hexahedrons, the head-to-tail combination of two tetrahedrons forms one face of a hexahedron, with these three faces being the common plane. The Jacobian ratio of the elements and the aspect ratio of the element mesh are checked; the ideal shape has a value of 1. Based on this principle, the elements are further refined until there are no distorted elements and the Jacobian ratio and aspect ratio of the elements are close to 1.0. Using a combination of tetrahedrons and hexahedrons results in a more accurate mesh than using only tetrahedrons or hexahedrons.

[0045] Cell optimization allows for a more accurate analysis of the stress state of a part. It improves the cell division method and provides guidance for part design. Based on the initial design, it optimizes the details of the curved surface structure, making the cells more uniform, the joints smoother, and the load-bearing structure more reasonable. By analyzing the force direction between internal cells, it avoids stress concentration in the part under load and distributes the load to the whole part.

[0046] The above finite element analysis shows that the diameter of the third cylindrical hole of the second stepped cylindrical hole of the rope connector of the present invention is 6 mm smaller than the diameter of the fourth cylindrical hole, and the minimum thickness of the stepped surface of the ball head fastener is 6.8 mm. The outer surface of the ball head fastener is, from top to bottom, a cylindrical surface, a spherical surface, and a conical surface, and the taper of the conical surface is 104°.

[0047] By improving the finite element mesh generation, the parts are analyzed and calculated. Based on the mesh generation process and the analysis results, the part structure is gradually optimized before finalization and production. The finite element analysis results include the displacement, stress, and strain of the structure. Optimizing the design of the rope connector requires comprehensive consideration of the displacement, stress, and strain results of the structure, as well as ease of manufacturing. This leads to optimized design from aspects such as strengthening product strength, ensuring uniform stress distribution, reducing product weight while meeting usage requirements, minimizing product deformation, and facilitating manufacturing.

[0048] Tensile tests were conducted on the trial-produced rope connectors. Based on the test results described below (the maximum force (kN) and breaking strength (kN) of the existing rope connectors were 3.7 kN to 4.56 kN; the maximum force (kN) and breaking strength (kN) of the optimized rope connectors after improved finite element analysis were 6.81 kN to 7.69 kN), it can be seen that the structure designed based on the improved mesh generation finite element analysis can withstand greater tensile forces, proving the effectiveness and reliability of the aforementioned finite element analysis method. The rope connector optimized through the above finite element analysis exhibits the optimal overall structure when meeting the usage requirements.

[0049] like Figures 17-18 As shown, the optimized net rope connector was trial-produced and a tensile test was conducted.

[0050] First tensile test table of rope connector

[0051]

[0052] Second tensile test table of rope connector

[0053]

[0054] Experimental results: In both tests, the inner plastic buckle came off the outer plastic buckle. First test: Fm maximum force (kN) breaking strength (kN) = 7.69 kN; Second test: Fm maximum force (kN) breaking strength (kN) = 6.81 kN.

[0055] This invention provides a rope connector, such as... Figures 2-8 As shown, the rope connector includes a fixed base and a ball-head fastener. The fixed base 1 has a first stepped cylindrical hole 11 at its center. From top to bottom, the first stepped cylindrical hole 11 consists of a first cylindrical hole 111, a spherical hole, and a second cylindrical hole 112. The diameter of the first cylindrical hole 111 is smaller than the diameter of the second cylindrical hole 112. The outer surface of the ball-head fastener 2 consists of a cylindrical surface, a spherical surface, and a conical surface from top to bottom. The cylindrical surface corresponds to and is lower than the first cylindrical hole 111, and the spherical surface corresponds to the spherical hole. The total height of the spherical and conical surfaces is lower than the total height of the spherical hole and the second cylindrical hole 112. The ball-head fastener 2 has a second stepped cylindrical hole 21 at its center. Both the fixed base 1 and the ball-head fastener 2 are made of plastic. The outer surface of the fixed base 1 is petal-shaped. The taper of the conical surface is 104°. The second stepped cylindrical hole 21 consists of a third cylindrical hole 211 and a fourth cylindrical hole 212 from top to bottom. The diameter of the third cylindrical hole 211 is 6 mm smaller than that of the fourth cylindrical hole 212. The third cylindrical hole 211 and the fourth cylindrical hole 212 form a stepped surface 213, and the minimum thickness of the stepped surface 213 is 6.8 mm.

[0056] The method of using this rope connector is as follows: Pass the fixed end of the rope with the buckle through the first stepped cylindrical hole 11 of the fixing base 1. Then, use two ball-head fasteners 2 to fasten the rope buckle and tighten the two ball-head fasteners 2. Next, install the tightened two ball-head fasteners 2 into the first stepped cylindrical hole 11 of the fixing base 1. Then, pull the rope taut from the insertion end (the second stepped cylindrical hole 21 is used to prevent the rope from passing through the tightened two ball-head fasteners 2). Finally, fix the fixing base 1 in the desired position through the rope fixing hole 12. Preferably, the two ball-head fasteners 2 are tightened by interference fitting the mounting post into the mounting hole.

[0057] This rope connector features a ball-head structure where the rope passes through a snap fastener. Through calculation and testing, it not only meets the strength requirements for securing ropes in various scenarios, but also offers a wider range of motion for the spherical structure at the rope's fixing end, providing a cushioning function. This makes the connector suitable for most amusement facilities. The rope is protected within the snap fastener, preventing wear and tear. Furthermore, the connector has no sharp edges and is made of plastic, significantly reducing the risk of scratches and abrasions from accidental bumps during play, thus mitigating safety hazards.

[0058] This rope connector secures one end of the rope to the playground equipment. Through the connection and engagement of the ball-head fastener and the fixed base, the metal end of the rope is completely covered without gaps, preventing children from getting their hands pinched or bumping into it. The ball-head fastener structure, combined with the conical internal structure of the fixed base, ensures the rope tightens as it is pulled during play, preventing the fixed end from detaching. Compared to traditional metal rope end connectors, the ball-head structure allows the rope end to rotate freely 360° on a flat surface, making the rope on the playground equipment more flexible.

[0059] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A design method for a rope connector, characterized in that, include: Based on the usage details and using the curvature pattern to design the surface model of the rope connector, the initial structure of the rope connector was obtained. Based on the initial structure of the rope connector, the fixture is defined and an external load is applied according to the actual stress conditions. Finite element analysis is performed and the analysis results are obtained. Based on the finite element analysis results, the design of the rope connector was further optimized. Repeated finite element analysis was performed to optimize the design of the rope connectors. Trial production of the optimized net rope connectors and tensile testing were conducted. The finite element analysis includes a design mesh generation method, which includes: using an unstructured topology analysis method to divide the part into a finite number of hexahedral elements; after dividing the part into multiple elements, checking the local element morphology and isolating the distorted positions separately; dividing the distorted positions into tetrahedral elements; and at the contact positions between tetrahedral and hexahedral elements, combining the head and tail of two tetrahedral elements to form one side of a hexahedron.

2. The design method of the rope connector as described in claim 1, characterized in that, The finite element analysis also includes checking and optimizing the mesh quality. Checking the mesh quality includes checking the aspect ratio, Jacobian, and small locations of the mesh. Optimizing the mesh includes making the aspect ratio of the mesh close to 1. For locations with small curvature, if the aspect ratio is large, the mesh needs to be refined to reduce the aspect ratio of the mesh.

3. The design method of the rope connector as described in claim 2, characterized in that, The optimized mesh also includes making the Jacobian ratio close to 1.0, which is proportional to the edge curvature.

4. The design method of the rope connector as described in claim 2, characterized in that, The inspection of minute locations on the grid includes rounded corners, included corners, and edge corners. After inspection, grid control is used to further optimize the grid.

5. The design method of the rope connector as described in claim 1, characterized in that, After the mesh is generated, a more precise incompatible combination method should be selected. The FFEPlus solver should be used to perform calculations and optimize the mesh using advanced matrix graph reordering techniques.

6. The design method of the rope connector as described in claim 1, characterized in that, The finite element analysis also includes setting Jacobian points and dividing the grid based on curvature. The number of Jacobian points is 4, and a more detailed grid needs to be divided in the high curvature region to make the finite element calculation of the part more accurate.

7. A rope connector designed by the design method according to any one of claims 1-6, characterized in that, include: The fixed base (1) has a petal-shaped outer surface and a first stepped cylindrical hole (11) in the center. The first stepped cylindrical hole (11) consists of a first cylindrical hole (111), a spherical hole, and a second cylindrical hole (112) from top to bottom. The diameter of the first cylindrical hole (111) is smaller than the diameter of the second cylindrical hole (112). The ball head fastener (2) has an outer surface that is cylindrical, spherical and conical from top to bottom. The cylindrical surface corresponds to the first cylindrical hole (111), the spherical surface corresponds to the spherical hole, and the ball head fastener (2) has a second stepped cylindrical hole (21) at its center. The conical surface has a taper of 104°.

8. The rope connector as described in claim 7, characterized in that, The second stepped cylindrical hole (21) consists of a third cylindrical hole (211) and a fourth cylindrical hole (212) from top to bottom. The diameter of the third cylindrical hole (211) is 6 mm smaller than that of the fourth cylindrical hole (212). The third cylindrical hole (211) and the fourth cylindrical hole (212) form a stepped surface (213). The minimum thickness of the stepped surface (213) is 6.8 mm.

9. The rope connector as described in claim 7, characterized in that, The fixed base (1) and the ball head fastener (2) are both made of plastic, and the fixed base (1) has a rope fixing hole (12) on its side.

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