A free-form surface design method for rubber elastic elements

Abstract

The present invention belongs to the field of rubber elastic element product design, and proposes a method for designing free-form surfaces of rubber elastic elements. According to the requirements of the surface load of the rubber elastic element, combined with the reverse simulation analysis method, a free-form surface that can achieve a preset deformation state under a large load is designed, so that the free-form surface does not have wrinkles when deformed under a large load; it can be applied to products including ball joints, rubber piles, and conical springs. The existing design scheme is combined with the reverse simulation analysis method to implement finite element analysis, which has universal applicability, especially for complex structures. The deformation state of the rubber can be effectively taken into account, and the geometric model of the rubber body after deformation can be adjusted in time. The method of the present invention can be used to quickly design a free-form surface that can achieve a preset deformation state under a large load, and does not have wrinkles when deformed under a large load, thereby meeting the high load and long life requirements of the rubber elastic element.

Description

Technical Field

[0001] The present invention relates to the field of rubber elastic element product design, and in particular to a method for designing a free-form surface of a rubber elastic element. Background Art

[0002] Rubber elastic elements can attenuate and absorb high-frequency vibrations and noise. They also offer numerous advantages, such as small size, light weight, and maintenance-free design. Consequently, they are increasingly being used in rail vehicles, automobiles, and engineering machinery. Rubber elastic elements have low stiffness, and their free-form surfaces often experience significant deformation under load, resulting in wrinkles. The stress and strain at the wrinkled areas can change abruptly, making them areas at risk of fatigue failure in rubber elastic elements. The structural design of rubber elastic elements requires consideration of the design of the free-form surface under high load conditions. A well-optimized free-form surface can significantly improve the product's load-bearing deformation capacity and fatigue performance. Simulation analysis methods can be used to calculate the load-bearing deformation of rubber elastic elements, providing insights into the optimization of the free-form surface. Generally speaking, the design of a rubber free-form surface requires multiple rounds of optimization, but even then, achieving an ideal free-form surface free of wrinkles after load deformation is difficult.

[0003] The design problem of rubber free surface is not only common in ball joints, rubber piles and conical springs, but also in other elastic components with large load deformation and high fatigue life requirements.

[0004] Patent 201520135330.1 discloses a ball-jointed rubber elastic element with a jacket that is longer than the rubber. The length of the rubber increases gradually from the jacket-jointed side to the mandrel-jointed side. The rubber's free profile adopts a close-fitting design. Under heavy radial loads, this profile design deforms the rubber profile on the jacket side parallel to and closely to the jacket, but it cannot guarantee that the rubber profile on the mandrel side will deform without wrinkling.

[0005] Patent 201810809134.6 discloses a double-spherical traction rubber joint and its manufacturing method. The thickness of the rubber layer in the middle is less than or equal to the thickness at both ends of the rubber layer, and the sum of the radius of the core shaft spherical segment and the thickness of the rubber layer in the middle is less than or equal to the radius of the outer sleeve spherical segment. The free-form surface of the rubber layer is designed as a three-segment arc surface with a rear-closed profile. After the extrusion process, the free-form surface of the rubber forms a close-fitting profile. This profile design has a certain degree of uncertainty and requires multiple adjustments to achieve a relatively ideal profile.

[0006] Patent 201910675943.7 discloses an axial tie rod rubber joint and a method for improving fatigue performance. The rubber layer's outer profile is a large, close-fitting surface composed of a concave arc and an inclined surface. After radial pre-compression of the axle box tie rod rubber joint, the concave arc partially overlaps with the inclined surface and becomes straight. This profile design has certain uncertainties and requires multiple adjustments to achieve a satisfactory profile.

[0007] Patent 201910753404.0 discloses a tapered rubber-section traction ball joint and a method for preventing rubber surface cracking. The rubber surface features an asymmetrical, concave arc structure, with the apex of the arc located within 2 mm of the intersection of the inner cone sleeve's straight and oblique segments and the outer cone sleeve's straight and oblique segments. This surface design does not guarantee that the rubber surface will not wrinkle under heavy radial loads.

[0008] The design of the rubber free-form surface described in the aforementioned patent has certain uncertainties, requiring multiple optimizations to achieve the ideal design. Furthermore, there is no guarantee that the rubber free-form surface will not wrinkle under heavy radial loads. Therefore, designing a wrinkle-free rubber free-form surface under heavy loads to meet the high fatigue life requirements of elastic elements has become a key technical issue that needs to be addressed. Summary of the Invention

[0009] To address the aforementioned issues with existing technologies, the present invention proposes a method for designing free-form surfaces for rubber components based on reverse simulation. Based on the initial design of a rubber elastic component, this method, through reverse simulation analysis, rapidly designs a free-form surface capable of achieving a predetermined deformation state under high loads. This free-form surface exhibits no wrinkles under high-load deformation, meeting the high-load and longevity requirements of the rubber elastic component. This method is applicable to the design of free-form surfaces for various rubber elastic components with high-load requirements, including ball joints, rubber stacks, and conical springs.

[0010] The technical solution of the present invention is achieved as follows:

[0011] The present invention provides a method for designing a free-form surface of a rubber elastic element. Based on the requirements for the surface load of the rubber elastic element and combined with a reverse simulation analysis method, a free-form surface capable of achieving a preset deformation state under a large load is designed, so that the free-form surface does not have wrinkles when deformed under large load.

[0012] Furthermore, the reverse simulation analysis method is to study the initial stress field distribution of the rubber body in a preset deformed state, apply reverse load to the simulation analysis model of the rubber body in the preset deformed state; use the reverse simulation analysis results to obtain a mesh model of the rubber elastic element after deformation, establish a geometric model of the rubber body after deformation, and obtain a fixed design structure of the free surface of the rubber elastic element.

[0013] Furthermore, the requirements for the profile bearing include the interface size of the rubber elastic element, the bearing capacity of the product, the stiffness performance and fatigue performance requirements of the product, and the initial design structure of the rubber elastic element is completed according to the requirements for the profile bearing.

[0014] Furthermore, the initial design structure of the rubber elastic element is simulated and analyzed to obtain stress distribution data based on the requirements of the rubber elastic element's profile load and the deformation of the initial design structure load. The stress distribution data is used as the initial input condition and mapped to the simulation analysis model of the rubber body in a preset deformation state.

[0015] Furthermore, the rubber elastic element is any one of a ball joint, a rubber pile or a conical spring.

[0016] Furthermore, the specific steps include:

[0017] S1. Establishing the Preliminary Structure of the Rubber Elastic Element: First, complete the initial design structure of the rubber elastic element based on the interface dimensions and stiffness performance requirements of the rubber elastic element and previous design experience;

[0018] S2. Establishing a geometric model of the rubber body in a predetermined deformed state: Simulating and analyzing the initial design structure of the rubber elastic element in step S1 to obtain load-bearing deformation and force data of the rubber free surface; then analyzing and establishing a geometric model of the rubber body after deformation, mapping the dimensions of the geometric model, and optimizing the free surface to a predetermined deformed state to form a geometric model of the rubber body in the predetermined deformed state;

[0019] S3 preset deformation state simulation analysis model of the rubber body: the preset deformation state of the rubber body geometric model is meshed to form a preset deformation state simulation analysis model of the rubber body;

[0020] S4. Reverse Simulation Analysis: Apply reverse load to the simulation analysis model of the rubber body in a preset deformed state and perform reverse simulation analysis.

[0021] S5. Geometric model of the deformed rubber body: A mesh model of the deformed rubber body is obtained using the reverse simulation analysis results. The mesh-to-geometry function is used to create the deformed geometric model of the rubber body.

[0022] S6. Finishing design: Based on the appropriate finishing of the free-form surface, the finalized design structure of the rubber free-form surface is obtained.

[0023] Furthermore, the dimensions are preliminarily determined according to the interface dimensions and stiffness performance requirements of the rubber elastic element. After determining the rubber shear modulus according to the stiffness performance requirements, the theoretical calculation formula of stiffness is applied, and the effective load-bearing dimensions of the rubber node that meet the stiffness performance requirements are obtained through numerical calculation methods. The design of the free surface adopts a design scheme of two oblique lines plus an arc transition.

[0024] Furthermore, the analysis in step S2 to establish the geometric model of the rubber body after deformation is as follows: a mesh model of the rubber body after deformation is obtained from the simulation results of the deformation of the initial design structure of the rubber body, and a function of generating a geometric body from a mesh is used to establish the geometric model of the rubber body after deformation.

[0025] Furthermore, step S4 specifically includes: using the stress distribution data of the initial design structure bearing deformation obtained by simulation analysis as initial input conditions, and mapping it to the simulation analysis model of the rubber body in a preset deformation state.

[0026] Furthermore, the result mapping function of the Abaqus analysis platform was used to obtain the initial stress field distribution of the rubber body in the preset deformation state.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present method for designing free-form surfaces for rubber elastic elements takes into account the structural and process characteristics of these surfaces. By combining existing design solutions with reverse simulation analysis methods, finite element analysis is achieved, making it particularly versatile for complex structures. This method effectively accounts for the deformation state of the rubber and allows for timely adjustments to the geometric model of the deformed rubber body. Using this method, a free-form surface capable of achieving a predetermined deformation state under high loads can be quickly designed, without wrinkles during high-load deformation, thus meeting the high-load and longevity requirements of rubber elastic elements.

[0029] Furthermore, the free-profile design method for rubber elastic elements of the present invention is applicable to the free-profile design of various rubber elastic elements with large load-bearing requirements, including products such as ball joints, rubber piles, and conical springs; it has a wide range of applications and is conducive to promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of the rubber elastic element (ball joint) of the present invention.

[0031] Figure 2 Schematic diagram of the initial design of the rubber body structure in an embodiment of the free-profile design method of the rubber elastic element (spherical joint) of the present invention.

[0032] Figure 3 This is the result of the load-bearing deformation simulation analysis of the initial design rubber body structure in the embodiment of the free-profile design method of the rubber elastic element of the present invention.

[0033] Figure 4 It is the geometric model of the initially designed rubber body structure after load deformation in the embodiment of the free-profile design method of the rubber elastic element of the present invention.

[0034] Figure 5 It is a geometric model of the rubber body structure in a preset deformation state in the embodiment of the method for designing the free profile surface of the rubber elastic element of the present invention.

[0035] Figure 6 It is a simulation analysis model of the rubber body structure in a preset deformation state in the embodiment of the free-profile design method of the rubber elastic element of the present invention.

[0036] Figure 7 It is the initial stress field distribution of the rubber body structure in a preset deformation state in the embodiment of the method for designing the free profile surface of the rubber elastic element of the present invention.

[0037] Figure 8 It is the reverse simulation analysis result of the rubber body structure in a preset deformation state in the embodiment of the free-profile design method of the rubber elastic element of the present invention.

[0038] Figure 9 It is a reverse deformation geometric model of the rubber body structure in a preset deformation state in the embodiment of the free-profile design method of the rubber elastic element of the present invention.

[0039] Figure 10 It is a free-profile design structure of a rubber body in a preset deformation state in the embodiment of the free-profile design method of a rubber elastic element of the present invention.

[0040] Figure 11 This is a partially enlarged cloud diagram of the load-bearing deformation analysis of the free surface of the rubber elastic element in the embodiment of the free surface design method of the present invention. DETAILED DESCRIPTION

[0041] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0042] The present invention's method for designing a free-form surface of a rubber elastic element can, based on the initial design of the rubber elastic element and in combination with an inverse simulation analysis method, design a free-form surface capable of achieving a preset deformation state under heavy load, thereby ensuring that the free-form surface remains wrinkle-free even under heavy load deformation. The method comprises the following steps: The initial design structure of the rubber elastic element is completed according to the interface dimensions and stiffness performance requirements of the rubber elastic element, based on previous design experience; then, a simulation analysis is performed on the initial design structure of the rubber elastic element, and the stress distribution data obtained from the load-bearing deformation of the initial design structure is used as the initial input condition and mapped to a simulation analysis model of the rubber body in a preset deformation state; then, a reverse load is applied to the simulation analysis model of the rubber body in the preset deformation state, and an inverse simulation analysis is performed; finally, a mesh model of the deformed rubber body is obtained using the inverse simulation analysis results, and a geometric model of the deformed rubber body is established to obtain the finalized design structure of the free-form surface of the rubber elastic element.

[0043] Example 1

[0044] The free-form surface design method of the rubber elastic element in this embodiment takes the ball joint product as an example. Figure 1 - Figure 2 As shown, the structural design dimensions R1 and R2 of the traction node core shaft 1 and outer sleeve 3 are determined based on the interface dimensions of the traction node. Based on the stiffness performance requirements, the effective load-bearing dimension L of the traction node rubber body 2 is calculated through analytical calculation. The initial design structure of the traction node, namely the initial design free profile, is then drawn. This free profile is composed of two oblique lines 1.3 connecting the rubber cover and an arc 1.4 transition. The arc is generally 5-10 mm. The rubber cover is generally less than 1 mm thick and less than 5 mm long. The angle of the oblique lines is between 30° and 50°. The arc between the two boundary contour lines 1.1 and the free profile contour line 1.2 between the rubber cover is generally 2-5 mm. The core shaft 1, rubber body 2, and outer sleeve are bonded together by vulcanization to form the traction node.

[0045] The method for designing a free-form surface of a rubber elastic element in this embodiment specifically includes the following steps:

[0046] S1. Figure 2 As shown in the figure, the initial design structure of the rubber elastic element was completed based on the interface dimensions and stiffness performance requirements of the rubber elastic element, based on previous design experience, namely the design proposal for surface optimization provided by the designer. The deformation state of the initial design structure is a bulging surface similar to three circular arcs, and the intended deformation state is a straight state without wrinkles.

[0047] According to previous design experience, it is necessary to select the appropriate surface design scheme from previous successful design cases based on the product's installation interface size, product load, product stiffness performance and fatigue performance requirements. The radial stiffness calculation formula is:

[0048]

[0049] Where, F: radial load, y: radial displacement, K: radial stiffness, L: length of the spherical joint, R1: inner diameter of the spherical joint, R2: outer diameter of the spherical joint, E: elastic model of the rubber material, G: shear modulus of the rubber material, M: shape coefficient M=1+4.67S;

[0050] .

[0051] Based on the required interface dimensions of the product, dimensions R1 and R2 can be preliminarily determined. Based on the stiffness performance requirements, after determining the hardness of the rubber material, that is, the rubber shear modulus G and E, the theoretical stiffness calculation formula is applied. Through numerical calculation methods, the effective load-bearing dimension L of the rubber node that meets the stiffness performance requirements can be obtained. The free surface design can adopt a design scheme of two oblique lines plus an arc transition. The initial design rubber body cross section is two boundary contour lines 1.1 and two free surface contour lines 1.2.

[0052] S2. Figure 3 As shown in the figure, the initial design structure of the rubber body is simulated and analyzed. For example, the load-bearing deformation of the rubber free surface is obtained by using the Abaqus analysis platform. Under the action of radial load, the rubber body at the squeezed end bulges toward the free surface. The rubber body in the transition area of ​​the arc 1.4 of the two oblique lines has a shorter rubber layer length than the two oblique lines 1.3 connecting the rubber layer near the outer sleeve 1 and the core shaft. As a result, the bulging degree of the two parts is inconsistent, forming a bulging surface approximately consisting of three arcs. The bulging of the rubber body in the outer sleeve 1 and the core shaft area is more serious than that in the arc transition area. According to the stress distribution data of the rubber body, the free surface of the rubber is folded at the surface fold 2.1 in Figure 3.

[0053] S3. Figure 4 As shown in FIG, the mesh model of the rubber body after deformation can be obtained from the simulation results of the initial design structure of the rubber body. The geometric model of the rubber body after deformation is established by using the function of generating a geometric body from a mesh.

[0054] S4. Figure 5As shown, the geometric model of the deformed rubber body is subjected to structural dimensional mapping, and the free-form surface is optimized to a predetermined deformation state, forming a geometric model 4 of the rubber body in the predetermined deformation state. The dashed line 4.1 represents the deformation state of the free-form surface of the initial design structure, and the solid line 4.2 represents the optimized predetermined deformation state. The predetermined deformation state represents the ideal state that the designer desires the free-form surface to achieve under load deformation. This state, in other words, represents the deformation state that optimizes fatigue life while satisfying stiffness requirements. Generally, the ideal load-bearing deformation state of the free-form surface is a flat surface without wrinkles. In this embodiment, under radial load, the rubber body at the squeezed end bulges toward the free-form surface. Because the rubber layer in the transition area between the two oblique arcs 1.4 is shorter than the two oblique lines 1.3 connecting the rubber layer near the core shaft, the bulging degree of the two sections is inconsistent, forming a bulging surface that approximates three arc segments. The bulging of the rubber body in the outer sleeve and core shaft regions is more severe than that in the arc transition region.

[0055] S5. Figure 6 As shown, the geometric model 4 of the rubber body in the preset deformation state is meshed using a hexahedral mesh with a mesh density that can accurately characterize the free surface of the rubber body and its deformation state; thus forming a simulation analysis model of the rubber body in the preset deformation state.

[0056] S6. Figure 7 As shown, the stress distribution data of the initial design structure bearing deformation obtained by simulation analysis is used as the initial input condition and mapped to the simulation analysis model of the rubber body in the preset deformation state. For example, the result mapping function (map solution) of the Abaqus analysis platform is used to obtain the initial stress field distribution of the rubber body in the preset deformation state. Subsequently, a reverse load is applied to the simulation analysis model of the rubber body in the preset deformation state, that is, a load equal to the initial design structure in size and opposite in direction is applied. For example, if the initial design structure applies a Y-axis load of 10kN, the reverse load is to apply a Y-axis load of -10kN; and a reverse simulation analysis is performed.

[0057] S7. Figure 8-Figure 9 As shown in the figure, the mesh model of the deformed rubber body is obtained by using the reverse simulation analysis results of a preset simulation analysis model of the deformed rubber body. The mesh generation geometry function is then used to establish the deformed geometric model of the rubber body. The meshing method is as follows: based on the product structure and the characteristics of the free-form surface, the free-form surface area and the internal rubber body area are divided. The free-form surface area is divided into several small areas so that the free-form surface area can be meshed using a hexahedron mesh. Then, the internal rubber body area is meshed using the hexahedron mesh layout, primarily based on the free-form surface mesh layout.

[0058] S8. Figure 9-10As shown, the free-form surface 8.1 of the deformed geometric model of the rubber body is an irregular curve, which is not suitable for manufacturing. The free-form surface is appropriately trimmed. The deformed geometric model of the rubber body is an irregular curve and cannot be dimensioned with clear dimensions, making it unsuitable for manufacturing. The deformed geometric model of the rubber body is input into the modeling software. Using the modeling software's drawing function, the irregular curves of the deformed free-form surface are replaced with dimensionable line segments and arcs. The trimming of the free-form surface completes the final design structure of the rubber free-form surface. The free-form surface consists of three arcs R3, R4, and R5. The surface formed by these three arcs R3, R4, and R5 should be as close as possible to the irregular curve free-form surface of the deformed rubber body obtained by inverse simulation.

[0059] like Figure 11 As shown, this embodiment can achieve smooth deformation under a large radial load, and the deformed rubber free surface is flat without wrinkles, which can meet the high load and long life requirements of the traction rubber elastic element.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for designing a free-form surface of a rubber elastic element, characterized in that: Based on the requirements of the surface load of the rubber elastic element and the reverse simulation analysis method, a free surface that can achieve a preset deformation state under large load is designed, so that there is no wrinkle on the free surface when it is deformed under large load; The rubber elastic element is any one of a ball joint, a rubber pile or a conical spring; The specific steps include: S1. Establishing the Preliminary Structure of the Rubber Elastic Element: First, complete the initial design structure of the rubber elastic element based on the interface dimensions and stiffness performance requirements of the rubber elastic element and previous design experience; S2. Establishing a geometric model of the rubber body in a predetermined deformed state: Simulating and analyzing the initial design structure of the rubber elastic element in step S1 to obtain load-bearing deformation and force data of the rubber free surface; then analyzing and establishing a geometric model of the rubber body after deformation, mapping the dimensions of the geometric model, and optimizing the free surface to a predetermined deformed state to form a geometric model of the rubber body in the predetermined deformed state; S3 preset deformation state simulation analysis model of the rubber body: the preset deformation state of the rubber body geometric model is meshed to form a preset deformation state simulation analysis model of the rubber body; S4. Reverse Simulation Analysis: Apply reverse load to the simulation analysis model of the rubber body in a preset deformed state and perform reverse simulation analysis. S5. Geometric model of the deformed rubber body: A mesh model of the deformed rubber body is obtained using the reverse simulation analysis results. The mesh-to-geometry function is used to create the deformed geometric model of the rubber body. S6. Finishing design: Based on the appropriate finishing of the free-form surface, the finalized design structure of the rubber free-form surface is obtained.

2. The method for designing a free-form surface of a rubber elastic element according to claim 1, wherein: The reverse simulation analysis method is to apply reverse load to the simulation analysis model of the rubber body in the preset deformation state by presetting the initial stress field distribution of the rubber body in the preset deformation state; The mesh model of the deformed rubber elastic element is obtained by using the reverse simulation analysis results, the geometric model of the deformed rubber body is established, and the finalized design structure of the free surface of the rubber elastic element is obtained.

3. The method for designing a free-form surface of a rubber elastic element according to claim 2, wherein: The requirements for the profile bearing include the interface size of the rubber elastic element, the bearing capacity of the product, the stiffness performance and fatigue performance requirements of the product. The initial design structure of the rubber elastic element is completed according to the requirements for the profile bearing.

4. The method for designing a free-form surface of a rubber elastic element according to claim 3, wherein: The initial design structure of the rubber elastic element is simulated and analyzed to obtain stress distribution data based on the load-bearing requirements of the rubber elastic element's profile and the load-bearing deformation of the initial design structure. The stress distribution data is used as the initial input condition and mapped to the simulation analysis model of the rubber body in a preset deformation state.

5. The method for designing a free-form surface of a rubber elastic element according to claim 1, wherein: The dimensions of the rubber elastic element are preliminarily determined according to its interface dimensions and stiffness performance requirements. After determining the rubber shear modulus based on the stiffness performance requirements, the theoretical calculation formula of stiffness is applied and numerical calculation methods are used to obtain the effective load-bearing dimensions of the rubber node that meets the stiffness performance requirements. The free surface is designed using a design scheme of two oblique lines plus an arc transition.

6. The method for designing a free-form surface of a rubber elastic element according to claim 1, wherein: The analysis and establishment of the geometric model of the deformed rubber body in step S2 is as follows: a mesh model of the deformed rubber body is obtained from the simulation results of the deformation of the initial design structure of the rubber body, and the geometric model of the deformed rubber body is established by using the function of generating a geometric body from a mesh.

7. The method for designing a free-form surface of a rubber elastic element according to claim 1, wherein: Step S4 specifically includes: using the stress distribution data of the initial design structure bearing deformation obtained by simulation analysis as initial input conditions, and mapping it to the simulation analysis model of the rubber body in a preset deformation state.

8. The method for designing a free-form surface of a rubber elastic element according to claim 1, wherein: The result mapping function of the Abaqus analysis platform is used to obtain the initial stress field distribution of the rubber body in the preset deformation state.

Images