Bolt hole design method and system
By using segmented spline curves and parameter optimization models, the problems of time-consuming and labor-intensive bolt hole design with fixed curvature in existing technologies have been solved, and the continuous variable curvature design of bolt hole structures has been realized, meeting engineering requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- AECC HUNAN AVIATION POWERPLANT RES INST
- Filing Date
- 2026-01-13
- Publication Date
- 2026-05-12
AI Technical Summary
Existing bolt hole design methods are insufficient for designing structures that meet engineering requirements in high-speed rotating machinery. Furthermore, conventional curve description methods are time-consuming and labor-intensive, and cannot guarantee that the hole structure will achieve the required curvature at a specific location.
The bolt hole profile structure is described by using at least two even-numbered spline curves connected end to end, and the design variables are adjusted through a parameter optimization model to meet the engineering performance indicators, including using non-uniform rational B-spline curves and setting geometric constraints.
The continuous variable curvature design of the bolt hole structure was realized, which increased the design freedom and could meet the curvature requirements of specific positions under different conditions. The optimized bolt hole structure met the engineering performance indicators.
Smart Images
Figure CN122020885A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of aero-engine technology, and specifically relates to a bolt hole design method and system. Background Technology
[0002] Existing bolt hole designs typically use conventional curves to describe the bolt hole structure and rely on empirical parameter adjustments to obtain a final structure that meets engineering requirements. However, this design method is deterministic, and the empirical parameter adjustment method is time-consuming and labor-intensive, and may not be able to design a bolt hole structure that meets engineering requirements.
[0003] Current bolt hole design methods often use curves such as circles, straight lines combined with arcs, multi-segment arcs, ellipses, and hyperellipses to describe the structure. Then, the curve definition parameters are adjusted empirically to obtain a structure that meets engineering requirements. For example, the definition parameters of a circle are its center and radius. If a circle is used to describe the bolt hole structure, then when the radius is fixed, the curvature of the structure at any position is a constant value. While multi-segment arcs or a combination of straight lines and arcs can improve the constant curvature phenomenon to some extent, it is still a constant curvature design within the bolt hole location range. Although the curvature of ellipses and hyperellipses varies with parameters, the positions of maximum and minimum curvature are fixed, and the trend of change is also fixed, making it impossible to guarantee that the hole structure will obtain the required curvature at a specific position under all circumstances. Regardless of how the curve definition parameters are adjusted, the structure of the bolt hole is determined, and the design is carried out under a defined curve framework. In the design of hole structures for high-speed rotating machinery, it is difficult to design a structure that meets engineering requirements.
[0004] This invention provides a bolt hole design method that can design a bolt hole structure with continuous variable curvature, which increases the degree of freedom in hole structure design and enables the designed hole structure to meet engineering requirements. Summary of the Invention
[0005] To address the above problems, this invention provides a bolt hole design method, including bolt hole structure definition and bolt hole structure parameter optimization: The definition of bolt hole structure includes: The bolt hole profile structure is described by a spline curve consisting of at least two even-numbered segments connected end to end. The settings of each spline curve segment and control point satisfy the preset geometric constraints. The optimization of bolt hole structural parameters includes: A parameter optimization model is established using spline curve control parameters as design variables and at least one engineering performance index of bolt holes as the optimization objective. By adjusting the design variables through a parameter optimization model, bolt hole structure parameters that meet engineering performance indicators can be obtained.
[0006] Furthermore, the spline curve is a non-uniform rational B-spline curve.
[0007] Furthermore, the settings for each spline curve segment and control points satisfy preset geometric constraints, including: The number of control points for each spline curve segment is odd, and the intermediate control point is located on the radial axis of symmetry of the bolt hole; The control points of each spline curve segment are symmetrically distributed about the radial symmetry axis; The spline curves at adjacent ends are controlled to be collinear at the connection point; The bolt hole profile described by the spline curve has a gap between it and the bolt shaft that is not less than the radius of the bolt shaft.
[0008] Furthermore, the bolt hole profile structure is described using at least two spline curves connected end-to-end, including: A coordinate system is established with the center of the bolt shaft as the origin. The two spline curves are the upper part of the curves distributed in the first and second quadrants and the lower part of the curves distributed in the third and fourth quadrants, respectively. The connection point of the two spline curves and the control points at adjacent positions are on a straight line.
[0009] Furthermore, the engineering performance indicators include at least one of the following: the maximum equivalent stress at the bolt hole edge, the maximum circumferential stress, the maximum principal stress, the maximum radial displacement of the baffle, and the bolt clamping area.
[0010] Furthermore, the parameter optimization model includes an optimization mathematical model and an optimization physical model: parameter optimization is carried out based on the optimization mathematical model and the optimization physical model.
[0011] Furthermore, the optimization mathematical model takes the maximum equivalent stress at the edge of the bolt hole as the optimization objective, and the maximum circumferential stress, maximum principal stress, maximum radial displacement, and bolt clamping area as constraints.
[0012] Furthermore, the optimized physical model includes establishing a parametric model of the part containing bolt holes; Simulation is performed on the parametric model of the part.
[0013] Furthermore, the constraints include the maximum circumferential stress, the maximum principal stress, the maximum radial displacement, and the bolt clamping area: The maximum circumferential stress is not greater than the axial stress limit; the maximum principal stress is not greater than the principal stress limit; the maximum radial displacement is not greater than the radial displacement limit. The bolt clamping area is not less than the clamping area limit value.
[0014] This invention provides a bolt hole design system, comprising: Structural description module: Configured to describe the bolt hole outline structure using at least two even-numbered spline curves connected end to end; the setting of each spline curve and control point satisfies the preset geometric constraints. Parameter optimization module: Configured to use spline curve control parameters as design variables and at least one engineering performance index of bolt holes as optimization objectives to establish a parameter optimization model; adjust the design variables through the parameter optimization model to obtain bolt hole structural parameters that meet the engineering performance index.
[0015] Compared with the prior art, the present invention has the following advantages: 1. This invention describes bolt holes using segmented spline curves, which prevents abrupt changes in bolt hole adjustments and greatly increases the degree of freedom in bolt design. This allows bolt hole design to move beyond fixed structural forms and create bolt hole structures with arbitrary curvature and smooth, continuous curves. It also facilitates ensuring that bolt hole structures achieve the required curvature at specific locations under different conditions.
[0016] 2. This invention optimizes the parameters of the bolt hole structure based on mathematical modules and physical models, adjusts design variables to perform parametric modeling and simulation, and obtains a bolt hole structure form that meets engineering requirements.
[0017] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 A flowchart illustrating the method in an embodiment of the present invention is shown.
[0020] Figure 2 The diagram shows a description curve of the bolt hole in an embodiment of the present invention.
[0021] Figure 3 The structural definition of bolt holes in an embodiment of the present invention is shown.
[0022] Figure 4 A schematic diagram of the structural parameter optimization process in an embodiment of the present invention is shown.
[0023] Figure 5 A parametric model of the bolt hole in an embodiment of the present invention is shown. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0025] This invention provides a bolt hole design method, with reference to Figure 1 This includes defining the bolt hole structure and optimizing its parameters. The definition of bolt hole structure includes: The bolt hole profile structure is described by a spline curve consisting of at least two even-numbered segments connected end to end, and the setting of each spline curve and control point satisfies the preset geometric constraints. The optimization of bolt hole structural parameters includes: A parameter optimization model is established using spline curve control parameters as design variables and at least one engineering performance index of bolt holes as the optimization objective. By adjusting the design variables through a parameter optimization model, bolt hole structure parameters that meet engineering performance indicators can be obtained.
[0026] The spline curve is a non-uniform rational B-spline curve.
[0027] In one embodiment of the present invention, the setting of each spline curve segment and control point satisfies preset geometric constraints, including: The number of control points for each spline curve segment is odd, and the intermediate control point is located on the radial axis of symmetry of the bolt hole; The control points of each spline curve segment are symmetrically distributed about the radial symmetry axis; The spline curves at adjacent ends are controlled to be collinear at the connection point; The bolt hole profile described by the spline curve has a gap between it and the bolt shaft that is not less than the radius of the bolt shaft.
[0028] The bolt hole profile structure is described using at least two spline curves connected end-to-end, including: A coordinate system is established with the center of the bolt shaft as the origin. The two spline curves are the upper part of the curves distributed in the first and second quadrants and the lower part of the curves distributed in the third and fourth quadrants, respectively. The connection point of the two spline curves and the control points at adjacent positions are on a straight line.
[0029] The engineering performance indicators include at least one of the following: maximum equivalent stress at the bolt hole edge, maximum circumferential stress, maximum principal stress, maximum radial displacement of the baffle, and bolt clamping area.
[0030] Bolt hole structure definition method 1.1 Describing the curve The bolt hole structure is described by a spline curve controlled by a pole approach. This curve is a piecewise vector rational polynomial function, which can be expressed as: (1) In the formula Let be the coordinates of discrete points on the curve (the spatial representation of the curve), and u be a parameter. The first construction curve represents the... pole, The order of the curve, To control the poles, As a weighting factor, Let the parameter be u, the i-th pole, and the order of the curve be... The B-spline basis functions have the following number of control poles: The curve diagram is as follows Figure 2 The recursive formulas for the B-spline basis functions of each order of the curve in equation (1) above are defined as follows: (2) In the formula For a node, the node vector formed by it. for: (3) When the number of nodes is The order is The number of control poles is hour, , and The relationship between the three is as follows: When the minimum number of control poles is Sometimes, Therefore, the number of nodes is determined by both the order and the number of control poles. The node vector used is: (4) The spline curve has an order of 3-4 and a number of control poles of 5-9.
[0031] Specifically, in one case, the order is 3 and the number of control poles is 6, then k=3, n=5, m=3+5+1=9, so the number of nodes is 9+1=10. That is, U is a vector containing 10 numbers, the first 4 numbers are 0, the last 4 numbers are also 0, and the middle 2 numbers are 0.33333 and 0.6666. In another case, the order is 4 and the control pole is 5, so k=4, n=4, m=4+4+1=9, and the number of nodes is also 9+1=10. Similarly, U is a vector containing 10 numbers, but the first 5 numbers are 0 and the last 5 numbers are also 0. 1.2 Description method: refer to Figure 3 As shown, with the center of the bolt shaft as the origin (0,0), the radius of the bolt shaft is... The section perpendicular to the bolt axis is defined as the XY plane (X is circumferential and Y is radial in the section of a cylindrical section of revolution), and the middle circle is the bolt axis section. The bolt hole structure is described by two curves: the first curve is the upper part (mainly distributed in quadrants 1 and 2), described using control points 1-9; the second curve is the lower part (mainly distributed in quadrants 3 and 4), described using control points 10-18. The coordinates of the control points for the first curve are represented as follows: , , , , , , , , The coordinates of the control points for the second curve segment are: , , , , , , , , The two curve segments must satisfy the following seven constraints: 1) The number of control points in the first and second curve segments must be odd, and the intermediate control points (the 5th control point in the first curve segment and the 14th control point in the second curve segment) must be on the Y-axis, meaning the X-coordinate value of both intermediate control points is 0. and This is the basis for ensuring the circumferential symmetry of the bolt hole design.
[0032] 2) Both curves are symmetrical about the Y-axis (radial) and satisfy the following formula (5), that is, the X coordinate values of the control points are opposites and the Y coordinate values are equal. This design can ensure the uniformity and symmetry of the bolt hole structure in the circumferential direction, and at the same time ensure that the bolt hole and the bolt gap are consistent in the circumferential symmetrical position. (5) 3) The endpoint control points of the two curves are on the curves (other control points may not be on the curves) and are connected end to end, that is, the coordinates of control point 9 and control point 10 coincide. The coordinates of control point 1 and control point 18 coincide. This design ensures that the curve describing the bolt hole is closed.
[0033] 4) To ensure that the two curve segments are continuous and tangent at the intersection point and have a smooth structure, the coordinates of control points 8, 9, 10, and 11 must be on the same straight line, and the coordinates of control points 1, 2, 17, and 18 must be on the same straight line, which means satisfying the following equations (6) or (7): (6) (7) in, , where b is the intercept and a is a fixed value of the x-coordinate. If the line is perpendicular to the x-axis, it satisfies equation (7), otherwise it satisfies equation (6).
[0034] 5) The distance from the origin to the line defined by constraint 4 above is greater than the bolt shaft radius. And it meets the assembly requirements, that is, it meets the following equation (8). This design ensures that there is a gap in the circumferential direction and that the bolts can be installed into the bolt holes: (8) 6) The Y-intercept of the first curve segment and the Y-intercept of the second curve segment are equal and greater than the bolt shaft radius, i.e. This design ensures that the bolt hole and the bolt are aligned in the radial direction, and allows the bolt to be installed into the bolt hole.
[0035] 7) The order of both the first and second curve segments is taken as... All weight factors are taken Therefore, according to equation (1), the first segment of the curve and the second segment of the equation are both represented by the following equation (9): (9) The recursive formula for the B-spline basis function is defined as follows: (10) The node vector is: (11) This invention describes bolt holes using segmented spline curves, ensuring that bolt hole adjustments do not result in abrupt changes and greatly increasing the degree of freedom in bolt design. This allows bolt hole design to move beyond fixed structural forms and create bolt hole structures with arbitrary curvature and smooth, continuous curves. It also facilitates ensuring that bolt hole structures achieve the required curvature at specific locations under different conditions.
[0036] In one embodiment of the present invention, the parameter optimization model includes an optimization mathematical model and an optimization physical model: parameter optimization is carried out based on the optimization mathematical model and the optimization physical model.
[0037] The optimization mathematical model takes the maximum equivalent stress at the edge of the bolt hole as the optimization objective and the maximum circumferential stress, maximum principal stress, maximum radial displacement, and bolt clamping area as constraints.
[0038] The constraints include the maximum circumferential stress, maximum principal stress, maximum radial displacement, and bolt clamping area. The maximum circumferential stress is not greater than the axial stress limit; the maximum principal stress is not greater than the principal stress limit; the maximum radial displacement is not greater than the radial displacement limit. The bolt clamping area is not less than the clamping area limit value.
[0039] In one embodiment of the present invention, the optimized physical model includes establishing a parametric model of the part containing bolt holes; Simulation is performed on the parametric model of the part.
[0040] Bolt hole structure parameter optimization method Defining the bolt hole structure using the bolt hole structure definition method does not necessarily guarantee a structure that meets engineering design requirements immediately; optimization of the descriptive parameters is necessary. The optimization process mainly includes establishing an optimization mathematical model, establishing an optimization physical model, and performing parameter optimization based on the mathematical and physical models.
[0041] 2.1 Optimize the mathematical model Using the coordinates of the control points defining the bolt hole curve as the design variables of the optimization mathematical model, and taking the maximum equivalent stress of the bolt hole as the objective, and constraining the bolt clamping area, maximum circumferential stress, maximum principal stress, and maximum radial displacement, the following mathematical model is established: find:
[0042] st: (12) minimize:
[0043] in: For design variables, R d For a d-dimensional real space, To determine the number of design variables, Seqv(X), and These are the maximum equivalent stress, maximum circumferential stress, and maximum principal stress at the edge of the bolt hole, respectively. This represents the maximum radial displacement of the baffle. Bolt clamping area. , , and These are the circumferential stress limit, principal stress limit, maximum radial displacement limit, and clamping area limit, respectively.
[0044] 2.2 Optimize the physical model Optimizing the physical model includes modeling and simulation. The purpose of modeling is to establish a parametric model of the part containing bolt holes for simulation analysis, using CAD modeling software. The purpose of simulation is to obtain bolt hole evaluation indicators such as stress and displacement of the part containing bolt holes, using CAE simulation software.
[0045] Optimizing the physical model mainly involves two parts: one is the parametric model of the part, which is a UG model created using CAD software. This model includes parametric curves for the bolt holes, as shown in Figure 2. The bolt hole structure is adjusted primarily through the control points of these curves. Figure 5 As shown; the other is the simulation model, which mainly uses CAE software to conduct finite element simulation activities on the parametric model established by CAD software.
[0046] 2.3 Parameter Optimization Parameter optimization primarily employs optimization algorithms to automatically adjust design variables in the optimization mathematical model. The optimization process drives the automatic execution of parametric modeling and simulation calculations. Evaluation metrics are then fed back to the optimization algorithm. The algorithm determines whether to terminate the automatic iteration process based on constraint violations and objective convergence in the optimization mathematical model. If there are no constraints or convergence conditions, it iterates until a structural form meeting engineering requirements is obtained. The optimization process is as follows: Figure 4 As shown.
[0047] The coordinates after optimization and iteration are as follows: V1 (35.584, 3.72, 0); V2 (36.192, 3.68, 0); V3 (37.328, 3.52, 0); V4 (38.536, 2.68, 0); V5 (39.184, 0 , 0); V6 (38.536, -2.68, 0); V7 (37.328, -3.52, 0); V8 (36.192, -3.68, 0); V9 (35.584, -3.72, 0); V10 ( 35.584, -3.72, 0); V11 (33.752, -3.84, 0); V12 (33.344, -3.76, 0); V13 (32.76, -2.856, 0); V14 (32.4 72, 0, 0); V15 (32.76, 2.856, 0); V16 (33.344, 3.76, 0); V17 (33.752, 3.84, 0); V18 (35.584, 3.72, 0).
[0048] After optimization, the maximum equivalent stress decreased from 1754.2 MPa to 1420.1 MPa, a decrease of 19%; the clamping area decreased from 68 mm². 2 Increased to 68.312mm 2 The maximum principal stress decreased from 1800.4 MPa to 1427.4 MPa, a decrease of 20.7%; the maximum circumferential stress decreased from 1615.7 MPa to 1410.9 MPa, a decrease of 12.7%; and the maximum radial displacement decreased from 0.6968 mm to 0.6950 mm, a decrease of 0.3%.
[0049] The specific parameter optimization process is as follows: 1. Establishing an optimized mathematical model involves the three equations in Formula 12 above; 2. Bolt hole structure optimization employs intelligent optimization search-driven adjustment. Figure 3 Coordinates of control points V1~V18 in the middle; 3. Parametric modeling of the rear baffle consists of two parts: baffle modeling and bolt hole modeling. For baffle modeling, a sketch model of the baffle's revolved cross-section is first created using CAD software. After the cross-section sketch is completed, a revolve solid operation is used to rotate the sketch-built model 360 degrees to form the disc. Then, bolt hole modeling is performed using... Figure 3 In the middle method, the bolt holes are constructed by stretching and then subtracted from the disc body by Boolean subtraction to obtain the complete parametric model of the rear baffle; 4. Strength analysis and obtaining objective function and constraint values: The model is automatically read in by CAE software script and automatic calculation is performed. After the calculation is completed automatically, the extracted results are automatically output in text form.
[0050] This invention provides a bolt hole design system, comprising: Structural description module: Configured to describe the bolt hole outline structure using at least two even-numbered spline curves connected end to end; the setting of each spline curve and control point satisfies the preset geometric constraints. Parameter optimization module: Configured to use spline curve control parameters as design variables and at least one engineering performance index of bolt holes as optimization objectives to establish a parameter optimization model; adjust the design variables through the parameter optimization model to obtain bolt hole structural parameters that meet the engineering performance index.
[0051] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A bolt hole design method, characterized in that, include: Bolt hole structure definition and bolt hole structure parameter optimization: The definition of bolt hole structure includes: The bolt hole profile structure is described by a spline curve consisting of at least two even-numbered segments connected end to end. The settings of each spline curve segment and control point satisfy the preset geometric constraints. The optimization of bolt hole structural parameters includes: A parameter optimization model is established using spline curve control parameters as design variables and at least one engineering performance index of bolt holes as the optimization objective. By adjusting the design variables through a parameter optimization model, bolt hole structure parameters that meet engineering performance indicators can be obtained.
2. The bolt hole design method according to claim 1, characterized in that, The spline curve is a non-uniform rational B-spline curve.
3. The bolt hole design method according to claim 2, characterized in that, The settings for each spline curve segment and control points satisfy preset geometric constraints, including: The number of control points for each spline curve segment is odd, and the intermediate control point is located on the radial axis of symmetry of the bolt hole; The control points of each spline curve segment are symmetrically distributed about the radial symmetry axis; The spline curves at adjacent ends are controlled to be collinear at the connection point; The bolt hole profile described by the spline curve has a gap between it and the bolt shaft that is not less than the radius of the bolt shaft.
4. The bolt hole design method according to claim 3, characterized in that, The bolt hole profile structure is described using at least two spline curves connected end-to-end, including: A coordinate system is established with the center of the bolt shaft as the origin. The two spline curves are the upper part of the curves distributed in the first and second quadrants and the lower part of the curves distributed in the third and fourth quadrants, respectively. The connection point of the two spline curves and the control points at adjacent positions are on a straight line.
5. The bolt hole design method according to claim 1, characterized in that, The engineering performance indicators include at least one of the following: maximum equivalent stress at the bolt hole edge, maximum circumferential stress, maximum principal stress, maximum radial displacement of the baffle, and bolt clamping area.
6. The bolt hole design method according to claim 1, characterized in that, The parameter optimization model includes an optimization mathematical model and an optimization physical model: parameter optimization is carried out based on the optimization mathematical model and the optimization physical model.
7. The bolt hole design method according to claim 6, characterized in that, The optimization mathematical model takes the maximum equivalent stress at the edge of the bolt hole as the optimization objective and the maximum circumferential stress, maximum principal stress, maximum radial displacement, and bolt clamping area as constraints.
8. A bolt hole design method according to claim 6, characterized in that, The optimized physical model includes establishing a parametric model of the part containing bolt holes; Simulation is performed on the parametric model of the part.
9. A bolt hole design method according to claim 8, characterized in that, The constraints include the maximum circumferential stress, maximum principal stress, maximum radial displacement, and bolt clamping area. The maximum circumferential stress is not greater than the axial stress limit; the maximum principal stress is not greater than the principal stress limit; the maximum radial displacement is not greater than the radial displacement limit. The bolt clamping area is not less than the clamping area limit value.
10. A bolt hole design system, characterized in that, include: Structural description module: Configured to describe the bolt hole outline structure using at least two even-numbered spline curves connected end to end; the setting of each spline curve and control point satisfies the preset geometric constraints. Parameter optimization module: Configured to use spline curve control parameters as design variables and at least one engineering performance index of bolt holes as optimization objectives to establish a parameter optimization model; By adjusting the design variables through a parameter optimization model, bolt hole structure parameters that meet engineering performance indicators can be obtained.