A method for designing assembly interface shape to improve manufacturability

Abstract

The application discloses a kind of assembly interface shape design methods for improving manufacturability, comprising the following steps: (1) according to the length, width and height of the assembly structure assembled by engine parts, the geometric model of engine assembly structure is established, and the fitting curve containing n undetermined coefficients is obtained;(2) the value of the initialized n undetermined coefficients is substituted into the fitting curve containing n undetermined coefficients;(3) according to the fitting curve, the assembly interface of the assembly structure is modeled using the finite element method, and a new finite element numerical analysis model of the assembly structure is obtained;(4) the finite element numerical analysis model of the new assembly structure is calculated, and if the objective function is less than or equal to the threshold value, the optimized design of the assembly interface shape fitting curve is obtained, so as to determine the shape of the assembly interface.The application can greatly improve the uniformity of contact stress distribution on the assembly interface, and the optimized design of the assembly interface shape is smooth and has good manufacturability.

Description

Technical Field

[0001] This invention relates to a technology for improving the manufacturability of the interface shape after optimization design of the assembly interface shape of mechanical equipment, specifically a method for designing the assembly interface shape to improve manufacturability. Background Technology

[0002] Assembly interfaces refer to the contact surfaces between assembled mechanical parts, components, and parts, and are widely present in mechanical equipment. The existence of assembly interfaces disrupts the continuity of mechanical structures, and contact stresses exhibit strong nonlinearity at these interfaces. The distribution of contact stress at assembly interfaces has a significant impact on the deformation, damping, stiffness, and vibration of mechanical equipment. Furthermore, the uniformity of contact stress distribution is a crucial indicator for evaluating the assembly accuracy and performance stability of precision electromechanical products. Effectively ensuring the uniformity of contact stress distribution at assembly interfaces has become a major obstacle to controlling high-cycle fatigue and achieving long-life, high-reliability service in domestically produced high-end equipment such as aero-engines. Therefore, improving the uniformity of contact stress distribution at assembly interfaces is of great significance.

[0003] The design of the assembly interface shape is an important means of controlling and improving the uniformity of contact stress distribution at the assembly interface. The basic idea is to design and manufacture the surfaces of the parts to be in contact with a specific shape before contact, thereby achieving a uniform distribution of contact stress on the assembly interface after contact. The development of finite element method (FEM) technology has made it simple and easy to analyze and optimize contact problems using numerical methods. When using the FEM method for assembly interface shape design, a typical solution is to transform the problem into a problem of modifying the coordinates of contact nodes on the contact interface during the calculation process. By modifying the coordinate positions of the contact nodes on the contact interface before contact, the contact deformation and contact stress on the contact interface after contact can be controlled. This method can effectively improve the uniformity of contact stress distribution on the assembly interface, but the final assembly interface shape is formed by connecting discrete contact nodes. This shape is non-smoothly transitioned, has poor manufacturability, and is directly related to the mesh generation method of the assembly interface, thus being greatly affected by the mesh generation method. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by proposing a method for designing assembly interface shapes to improve manufacturability. This method can significantly improve the uniformity of contact stress distribution at the assembly interface while simultaneously enhancing the manufacturability of the optimized interface shape design.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for designing assembly interface shapes to improve manufacturability includes the following steps:

[0007] (1) Based on the length, width and height of the assembly structure assembled from engine parts, establish a geometric model of the engine assembly structure, analyze the geometric model, and obtain a fitting curve containing n undetermined coefficients.

[0008] (2) Initialize the values ​​of n undetermined coefficients and substitute the initialized values ​​of the n undetermined coefficients into the fitted curve containing the n undetermined coefficients;

[0009] (3) The assembly interface of the assembly structure is modeled using the finite element method based on the fitted curve to obtain a new finite element numerical analysis model of the assembly structure.

[0010] (4) Perform finite element analysis on the finite element numerical analysis model of the new assembly structure to obtain the objective function of the assembly interface morphology optimization design. Determine whether the objective function is less than or equal to the threshold. If so, obtain the fitting curve of the optimized assembly interface shape to determine the assembly interface shape.

[0011] Furthermore, the geometric model is analyzed to obtain a fitting curve containing n undetermined coefficients, including the following steps:

[0012] The geometric model was processed using the finite element method to obtain the finite element numerical analysis model of the assembly structure;

[0013] Finite element analysis was performed on the finite element numerical analysis model of the assembly structure to obtain the initial contact stress distribution on the assembly interface. The distribution trend of the initial contact stress distribution was fitted to obtain a fitting curve containing n undetermined coefficients.

[0014] Furthermore, the geometric model is processed using the finite element method, including mesh generation, setting material properties, and applying loads and boundary conditions.

[0015] Furthermore, the assembly structure can be a bolted connection structure, a rivet connection structure, a pin connection structure, an adhesive bonding structure, or a key connection structure.

[0016] Furthermore, the specific process of step (3) is as follows: using the finite element method, based on the fitting curve in step (2), a geometric model of the assembly structure is established. The shape of the assembly interface in the geometric model of the assembly structure is the shape represented by the fitting curve. The geometric model of the assembly structure is meshed, and loads and boundary conditions are applied to obtain a new finite element numerical analysis model of the assembly structure.

[0017] Furthermore, the objective function is the maximum contact stress, the range of contact stress, the variance of contact stress, or the standard deviation of contact stress.

[0018] Furthermore, the maximum contact stress σ max The calculation formula is:

[0019] σ max =max{σ1σ2σ3…σ N}

[0020] Contact stress range σ Δ The calculation formula is:

[0021] σ Δ =σ max -σ min ,σ max =max{σ1σ2σ3…σ N},σ min =min{σ1σ2σ3…σ N}

[0022] Contact stress variance The calculation formula is:

[0023]

[0024] The formula for calculating the standard deviation of contact stress η is:

[0025]

[0026] Where, σ max The maximum contact stress value is σ. min The minimum contact stress value is σ. i Let σ be the contact stress value of the i-th contact node on the assembly interface of the assembly structure, N be the total number of contact nodes on the assembly interface of the assembly structure, and σ be the contact stress value of the i-th contact node on the assembly interface of the assembly structure. mean This represents the average contact stress value of N contact nodes on the assembly interface of the assembly structure.

[0027] Furthermore, if the objective function is greater than the threshold, then minimizing the objective function is taken as the optimization design objective, and an intelligent optimization algorithm is used to optimize the n undetermined coefficients to obtain a new set of n undetermined coefficient values;

[0028] Substitute the new n undetermined coefficient values ​​into the fitting curve, and then repeat steps (3)-(4) until the objective function δ is less than or equal to the threshold, so as to obtain the fitting curve of the optimized assembly interface shape and thus determine the assembly interface shape.

[0029] Furthermore, the intelligent optimization algorithm can be swarm intelligence optimization algorithm or artificial intelligence optimization algorithm.

[0030] Furthermore, swarm intelligence optimization algorithms include genetic algorithms, ant colony algorithms, or particle swarm optimization algorithms, while artificial intelligence optimization algorithms include artificial neural networks, convolutional neural networks, or generative adversarial networks.

[0031] This invention optimizes the design of assembly interface shapes by combining contact computational mechanics theory, data fitting methods, and intelligent optimization algorithms. This solves the manufacturability problem of the designed interface shape. Using this method, the uniformity of contact stress distribution on the assembly interface can be significantly improved. Furthermore, the optimized assembly interface shape is smooth and has good manufacturability. The optimized assembly interface shape fitting curve expression obtained in this invention can be directly input into a CNC center for interface shape processing. The proposed assembly interface shape design method is based on a numerical model and is applicable to various assembly connection methods such as bolting, riveting, and gluing, exhibiting good versatility. This invention achieves uniform contact stress distribution on the assembly interface while improving the manufacturability of the optimized interface shape. Attached Figure Description

[0032] Figure 1 This is a flowchart of the design method proposed in this invention;

[0033] Figure 2 This is a geometric model diagram of a single-bolt connection structure;

[0034] Figure 3 This is a finite element model diagram of a single-bolt connection structure;

[0035] Figure 4 It is a diagram showing the contact stress distribution and its fitting curve before the assembly interface shape design;

[0036] Figure 5 It is a comparison diagram of the contact stress distribution curves before and after the assembly interface shape design;

[0037] Figure 6 It is a comparison diagram of the outline shape of the assembly interface before and after the design of the assembly interface shape. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings.

[0039] This invention obtains the contact stress distribution at the assembly interface through finite element analysis, achieves accurate display and smooth transition of the assembly interface shape through curve fitting, and optimizes the assembly interface shape by optimizing the parameters in the fitted curve through an intelligent optimization algorithm. After the assembly interface shape is designed, the curve expression of the optimized assembly interface shape is obtained, which can be directly input into a CNC center for machining, thereby improving the manufacturability of the optimized assembly interface shape.

[0040] Specifically, the design process of the assembly interface shape design method for improving manufacturability proposed in this invention is described in [reference needed]. Figure 1 This includes the following steps:

[0041] (1) Based on the length, width, and height of the assembly structure assembled from engine parts, input the dimensional parameters in the 3D modeling software to establish the geometric model of the engine assembly structure. Use the finite element method to mesh the geometric model, set the material properties, apply loads and boundary conditions, and obtain the finite element numerical analysis model of the assembly structure. The assembly structure is a bolted connection structure, a rivet connection structure, a pin connection structure, a glued structure, or a keyed connection structure.

[0042] (2) Finite element analysis was performed on the finite element numerical analysis model of the assembly structure to obtain the initial contact stress distribution on the assembly interface. The distribution trend of the initial contact stress distribution was fitted to obtain n undetermined coefficients a1, a2, ... a n The fitted curve g(a1,a2,...a) (where n is an integer) n The resulting fitted curve g(a1,a2,...a...) is x); n x) can be either a straight line or a curve, and curves include various types of curves such as polynomial curves, logarithmic curves, and exponential curves.

[0043] (3) Initialize n undetermined coefficients a1, a2, ... a1 using either completely random initialization or random initialization following a certain probability distribution. n The values ​​of the n undetermined coefficients are then substituted into the fitted curve g(a1,a2,...a...) containing the n undetermined coefficients. n ,x).

[0044] (4) Based on the fitted curve g(a1,a2,...a1) obtained in step (3), n The assembly interface of the assembly structure is remodeled using the finite element method, and the new finite element numerical analysis model of the assembly structure is obtained. The specific process is as follows: using the finite element method, based on the fitting curve g(a1,a2,...a) in step (3), n To establish the geometric model of the assembly structure, the shape of the assembly interface in this geometric model is the fitted curve g(a1,a2,...a...). n The shape represented by x) is used to mesh the geometric model of the assembly structure, and loads and boundary conditions are applied to obtain a new finite element numerical analysis model of the assembly structure.

[0045] (5) Perform finite element analysis on the finite element numerical analysis model of the new assembly structure to obtain the objective function δ for the optimization design of the assembly interface morphology, and determine whether the objective function δ satisfies δ≤δ 指定 If satisfied, the optimized assembly interface shape fitting curve is obtained, thus determining the assembly interface shape; if not satisfied, proceed to step (6); where δ 指定is the threshold, and is a constant;

[0046] The objective function is an index reflecting the uniformity of contact stress distribution at the assembly interface, and can be any one of the following parameters: maximum contact stress, range of contact stress, variance of contact stress, and standard deviation of contact stress.

[0047] Maximum contact stress σ max The calculation formula is:

[0048] σ max =max{σ1σ2σ3…σ N}

[0049] Contact stress range σ Δ The calculation formula is:

[0050] σ Δ =σ max -σ min ,σ max =max{σ1σ2σ3…σ N},σ min =min{σ1σ2σ3…σ N}

[0051] Contact stress variance The calculation formula is:

[0052]

[0053] The formula for calculating the standard deviation of contact stress η is:

[0054]

[0055] Where, σ max The maximum contact stress value is σ. min The minimum contact stress value is σ. i Let σ be the contact stress value of the i-th contact node on the assembly interface of the assembly structure, N be the total number of contact nodes on the assembly interface of the assembly structure, and σ be the contact stress value of the i-th contact node on the assembly interface of the assembly structure. mean This represents the average contact stress value of N contact nodes on the assembly interface of the assembly structure.

[0056] (6) Taking minimizing the objective function δ as the optimization design objective, an intelligent optimization algorithm is used to optimize the n undetermined coefficients a1, a2, ... a n After optimization, a new set of a1, a2, ... a is obtained. n Values; among which, intelligent optimization algorithms include swarm intelligence optimization algorithms such as genetic algorithms, ant colony algorithms, and particle swarm algorithms, as well as artificial intelligence optimization algorithms such as artificial neural networks, convolutional neural networks, or generative adversarial networks.

[0057] (7) The new a1, a2, ... a1 from step (6) n Substitute the values ​​into the fitted curve g(a1,a2,...a) n Then return to steps (4)-(5) until the objective function δ satisfies δ≤δ 指定 The optimized assembly interface shape fitting curve is obtained, thereby determining the assembly interface shape.

[0058] Example 1

[0059] This invention relates to the assembly interface of the upper connector in a single-bolt connection structure (see...). Figure 2 Taking the shape design as an example, the shape of the assembly interface of the lower connector remains fixed.

[0060] In this invention, the assembly interface adopts a non-flat surface shape design, and the steps for designing this non-flat surface shape are as follows:

[0061] (1) See Figure 2 A geometric model of the single-bolt connection structure is established, including the upper and lower connectors connected by M6 bolts. (See...) Figure 3 Considering the axisymmetric properties of a single-bolt connection structure, an axisymmetric constraint is applied to the left side of the structure, i.e., the bolt axis, and a bolt preload (10kN) is applied at the middle position of the bolt. When establishing the finite element model, the mesh size of each component of the bolt connection structure is defined, the mesh is set to a quadrilateral mesh, and a free meshing method is used for mesh generation. The elastic modulus, Poisson's ratio, density, and other values ​​of the materials corresponding to each component of the bolt connection structure are input, and the material properties are set. A preload section is created at the middle position of the bolt, preload elements are inserted, and a bolt preload is applied to the preload elements. Nodes on the bolt axis are selected, and axisymmetric constraints are applied to all nodes on the bolt axis, resulting in the finite element numerical analysis model of the single-bolt connection structure.

[0062] (2) See Figure 4 Finite element contact analysis was performed on the finite element numerical analysis model of the single-bolt connection structure to obtain the initial contact stress distribution on the assembly interface. The trend of this contact stress distribution was fitted using a linear form to obtain a fitting curve g(a1,a2,x) containing two undetermined coefficients a1 and a2:

[0063] g(a1,a2,x)=a1x+a2

[0064] a1 is the first undetermined coefficient, a2 is the second undetermined system, and x is the horizontal direction of the assembly interface (i.e., Figure 4 The x-coordinate is indicated in the figure.

[0065] (3) Given the range of values ​​of the undetermined coefficients, the first undetermined coefficient a1 and the second undetermined system a2 are initialized in a completely random initialization manner within the range, and the initialized values ​​of the first undetermined coefficient a1 and the second undetermined system a2 are substituted into the fitted curve g(a1,a2,x).

[0066] (4) The assembly interface is remodeled based on the fitted curve g(a1,a2,x), the geometric model of the single bolt connection structure is re-established, the mesh is re-generated, and the load and boundary conditions are re-applied to obtain the finite element numerical analysis model of the single bolt connection structure with the shape of the assembly interface as the fitted curve g(a1,a2,x).

[0067] (5) Perform finite element analysis to obtain the objective function δ for the optimization design of the assembly interface morphology, and determine whether the objective function δ≤δ is satisfied. 指定 Or the number of iterations k = k max If any one of them is satisfied, the optimization process is terminated, and the fitting curve g(a1,a2,x) of the first undetermined coefficient a1 and the second undetermined system a2 values ​​and the optimized assembly interface shape is output; if neither is satisfied, then proceed to step (6).

[0068] (6) Taking minimizing the objective function δ as the optimization design objective, within the given range of values, the particle swarm algorithm is used to optimize the values ​​of the two undetermined coefficients a1 and the second undetermined system a2 to obtain a new set of values ​​of the first undetermined coefficients a1 and the second undetermined system a2.

[0069] (7) Substitute the new values ​​of the first undetermined coefficient a1 and the second undetermined system a2 from step (6) into the fitted curve g(a1,a2,x), and then return to step (4) to continue solving until the optimization process terminates.

[0070] The final values ​​of the undetermined coefficients obtained after the assembly interface shape design are as follows: a2 = 15.

[0071] Figure 5 The contact stress distribution curves before and after the assembly interface shape design are obtained from... Figure 5 It can be seen that after the assembly interface shape design, the maximum contact stress decreased from 56.74 MPa to 32.77 MPa, a reduction of 42.24%; the variance of the contact stress distribution decreased from 344.68 MPa. 2 It dropped to 89.13 MPa 2 This reduced the stress by 74.14%, significantly improving the uniformity of contact stress distribution at the assembly interface.

[0072] Figure 6 A comparison of the assembly interface outline shape before and after the assembly interface shape design, by Figure 6It can be seen that the assembly interface becomes a non-flat surface after shape design, with a smooth transition and simple processing; at the same time, the shape fitting curve is... It has a precise display and can be directly input into the CNC center for machining the shape of the assembly interface.

[0073] It is worth noting that, for Figure 5 and Figure 6 The contact stress distribution curve and assembly interface shape result shown in the figure after the assembly interface shape design will differ from the assembly interface contact stress distribution result after the assembly interface shape design if the contact stress distribution trend before the assembly interface shape design is not fitted by a straight line, but by a quadratic polynomial curve, logarithmic curve, or other curve forms.

[0074] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall also fall within the scope of protection of this invention. Technologies not covered in this invention can be implemented using existing technologies.

Claims

1. A method for designing assembly interface shapes to improve manufacturability, characterized in that, Includes the following steps: (1) Based on the length, width and height of the assembly structure assembled from engine parts, establish a geometric model of the engine assembly structure, and use the finite element method to mesh the geometric model, set material properties, apply loads and boundary conditions to obtain the finite element numerical analysis model of the assembly structure. (2) Perform finite element analysis on the finite element numerical analysis model of the assembly structure to obtain the initial contact stress distribution on the assembly interface. Fit the distribution trend of the initial contact stress distribution to obtain the result containing... undetermined coefficients Fitted curve where n is a positive integer; (3) Initialize the given information using either completely random initialization or random initialization following a probability distribution. undetermined coefficients The values ​​of the n undetermined coefficients after initialization are then substituted into the fitted curve. ; (4) Based on the fitted curve after substituting the values ​​of the undetermined coefficients The assembly interface of the assembly structure is modeled using the finite element method, so that the shape of the assembly interface in the geometric model of the assembly structure is the fitted curve. The shape represented is used to mesh the geometric model of the assembly structure, apply loads and boundary conditions, and obtain a new finite element numerical analysis model of the assembly structure. (5) Perform finite element analysis on the finite element numerical analysis model of the new assembly structure to obtain the objective function for the optimization design of the assembly interface morphology. Determine whether the objective function is less than or equal to the threshold. If so, obtain the fitting curve of the optimized assembly interface shape to determine the assembly interface shape and obtain the curve expression for inputting into the CNC center for assembly interface shape processing. If the objective function is greater than the threshold, minimize the objective function as the optimization design objective and use an intelligent optimization algorithm to optimize the assembly interface shape. undetermined coefficients Optimization is performed to obtain a new set of n undetermined coefficient values; (6) Substitute the values ​​of the new n undetermined coefficients into the fitted curve. Then repeat steps (4) and (5) until the objective function is less than or equal to the threshold, and obtain the fitting curve of the optimized assembly interface shape, thereby determining the assembly interface shape.

2. The assembly interface shape design method for improving manufacturability according to claim 1, characterized in that, The assembly structure can be a bolted connection, a riveted connection, a pin connection, an adhesive connection, or a keyed connection.

3. The assembly interface shape design method for improving manufacturability according to claim 1, characterized in that, The objective function is the maximum contact stress, the range of contact stress, the variance of contact stress, or the standard deviation of contact stress.

4. The assembly interface shape design method for improving manufacturability according to claim 3, characterized in that, Maximum contact stress The calculation formula is: Extremely poor contact stress The calculation formula is: Contact stress variance The calculation formula is: Standard deviation of contact stress The calculation formula is: in, This represents the maximum contact stress value. This represents the minimum contact stress value. For the assembly interface of the assembly structure, the first The contact stress value of each contact node. This represents the total number of contact nodes on the assembly interface of the assembly structure. For the assembly interface of the assembly structure The average value of the contact stress at each contact node.

5. The assembly interface shape design method for improving manufacturability according to claim 1, characterized in that, Intelligent optimization algorithms are collective intelligence optimization algorithms or artificial intelligence optimization algorithms.

6. The assembly interface shape design method for improving manufacturability according to claim 5, characterized in that, Swarm intelligence optimization algorithms include genetic algorithms, ant colony algorithms, or particle swarm optimization algorithms, while artificial intelligence optimization algorithms include artificial neural networks and convolutional neural networks.

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