A design method for large-size cone casing-end gear connection structure of aircraft engines

Abstract

This invention discloses a design method for a large-scale conical shell-end tooth connection structure for aircraft engines, belonging to the field of aircraft engine design. This method addresses the arc-end tooth-short bolt connection structure, a key part of a large-scale aircraft engine rotor. By clarifying its structural characteristic parameters, conducting load environment and force analysis, and clarifying optimization design objectives and four constraints (design interface deformation coordination, interface contact damage, preload loss, and axial stiffness characteristics), the design objectives are integrated into an objective function and an appropriate constraint optimization method is selected to achieve a design method that optimizes the objective function. This method provides technical support for improving aircraft engine performance and ensuring reliability.

Description

Technical Field

[0001] The present invention belongs to the field of aero-engine design, and in particular relates to a design method for a large-size cone casing-end gear connection structure of an aero-engine. Background Art

[0002] As the core power unit of modern aircraft, the structural design of aircraft engines directly impacts their performance, reliability, and lifespan. The rotor, a key component of an aircraft engine, is particularly crucial for its connection structure, as it bears complex operating conditions such as aerodynamic, centrifugal, bending, and thermal loads. The circular arc end tooth connection is a highly efficient mechanical connection method widely used to connect the rotor disc and shaft segments of aircraft engines. It primarily consists of circular arc end teeth, flanges, and preload bolts. The preload bolts apply an axial preload, enabling reliable engagement and load transfer between the end teeth under load. In large-scale aircraft engines, the cone-shell end tooth connection, due to its unique geometry and mechanical properties, has become a crucial structural form for efficient torque transmission. Typically, the cone-shell end tooth connection consists of cone-shell end teeth and short preload bolts. The cone-shell geometry optimizes radial and axial stiffness, while leveraging the high load-bearing capacity of the end tooth structure to achieve precise positioning and reliable torque transmission between connected components. Compared with traditional connection methods, the cone shell-end tooth connection has the characteristics of compact structure, light weight, high automatic centering accuracy, and strong torque transmission capability. It can effectively withstand various complex working conditions such as aerodynamic axial force, aerodynamic torque, bending load, and maneuvering flight inertia load.

[0003] However, large-scale cone shell-end tooth connection structures face many challenges in practical applications. First, the increase in the geometric size of the cone shell will lead to poor deformation coordination of the connection interface under complex loads. In particular, under the action of centrifugal loads and bending loads, the end tooth interface may open, directly affecting the contact state and transmission performance of the end tooth surface. Secondly, when the semi-cone angles of the cone shell vary greatly, the axial load will cause the bolts to bear additional bending loads, increasing the risk of stress concentration in the connection structure. In addition, uneven wall thickness of the cone shell may cause insufficient local stiffness, further adversely affecting the interface reliability and overall stiffness of the end tooth connection structure.

[0004] The existing design methods for large-size cone shell-end tooth connection structures have the following main deficiencies:

[0005] 1) Insufficient interface deformation coordination: Under centrifugal loads and bending loads, the end tooth interface is prone to opening or separation, affecting the torque transmission performance and connection stiffness. 2) Severe preload loss: Under high temperature and complex loads, the bolt preload is easily attenuated due to interface deformation and thermal stress, resulting in deterioration of connection performance. 3) Uneven distribution of structural stiffness: Improper design of the cone shell wall thickness will lead to insufficient local stiffness, affecting the overall mechanical properties. 4) Rapid accumulation of interface damage: The tooth surface is prone to fatigue damage and sliding wear under complex loads, reducing the service life of the connection structure.

[0006] In practical applications, arc-end teeth-short bolt connections are often used in critical areas of large-scale aircraft engine rotors. The symmetrically distributed arc-end teeth achieve efficient torque transmission and load distribution. However, due to limitations in structural dimensions, the number of bolts, and preload control, further research is needed on issues such as interface deformation coordination, preload loss, and interface damage in the end-teeth connection.

[0007] In response to the above problems, there is an urgent need for a robust design method for large-size cone shell-end tooth connection structures that can achieve high reliability under complex load environments, so as to improve the interface coordination, preload retention capability and damage resistance of the connection structure, and provide technical support for the performance improvement and reliability assurance of aircraft engines. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a design method for a large-scale cone casing-end gear connection structure for an aircraft engine. To solve the problems in the prior art and achieve the above invention objectives, the technical solution adopted by the present invention is:

[0009] A design method for a large-size cone casing-end gear connection structure of an aircraft engine, comprising:

[0010] Step 1: Based on the design requirements, the structural characteristic parameters of the large-scale cone shell-end tooth connection structure are clarified. Based on the geometric characteristics of the cone shell-end tooth connection, the structural characteristic parameters that affect the connection performance are collected and clarified.

[0011] Step 2: Perform load environment and force analysis on the large-scale cone shell-end gear connection structure. Based on the load environment, establish a two-dimensional or three-dimensional mechanical analysis model to simulate the load effects under different working conditions.

[0012] Step 3: Clarify the optimization design objectives and constraints, and integrate the design objectives into an objective function;

[0013] Step 4: Select a constrained optimization method to obtain the structural characteristic parameters that optimize the objective function and meet the constraints.

[0014] The present invention has the following beneficial effects:

[0015] This technology effectively addresses issues such as inconsistent interface deformation, contact damage, preload loss, and insufficient stiffness under complex load conditions. Through optimized design, it improves the torque transmission capacity, rigidity, and reliability of the connection structure, providing technical support for the efficient operation of aircraft engines. It also offers technical support for the integrated design of advanced aircraft engine rotor structures and dynamics. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of the design method for the large-size cone casing-end gear connection structure of an aircraft engine proposed by the present invention;

[0017] Figure 2 Schematic diagram of the structural characteristic dimensions of the cone shell-end tooth connection structure in an embodiment of the present invention;

[0018] Figure 3 Schematic diagram of interface deformation differences of the connection structure in an embodiment of the present invention, including radial deformation difference, axial deformation difference and angular deformation difference. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other. To achieve the above-mentioned objectives, the present invention adopts the following technical solutions.

[0020] like Figure 1 A design method for a large-size cone casing-end gear connection structure of an aircraft engine, comprising:

[0021] Step 1: Based on the design requirements, the structural characteristic parameters of the large-scale cone shell-end tooth connection structure are clarified. Based on the geometric characteristics of the cone shell-end tooth connection, the structural characteristic parameters that affect the connection performance are collected and clarified.

[0022] Step 2: Perform load environment and force analysis on the large-scale cone shell-end gear connection structure. Based on the load environment, establish a two-dimensional or three-dimensional mechanical analysis model to simulate the load effects under different working conditions.

[0023] Step 3: Clarify the optimization design objectives and constraints, and integrate the design objectives into an objective function;

[0024] Step 4: Select a constrained optimization method to obtain the structural characteristic parameters that optimize the objective function and meet the constraints.

[0025] Furthermore, step 1 includes:

[0026] The structural characteristic parameters in step 1 are composed of geometric size parameters and material performance parameters. They are the main design parameters in the structural design process and directly determine the mechanical properties of the connection structure. Figure 2 、 3 As shown, Figure 2 、 Figure 3 Middle: 1st axis cone shell angle , the thickness of the first shaft end gear flange , angle of cone shell of 2nd axis , thickness of the second shaft end gear flange , and bolt parameters: screw diameter D, screw length L. is the radial deformation difference of the interface, is the axial deformation difference of the interface, is the interface angular deformation difference.

[0027] The geometric dimension parameters include: the first axis cone shell angle , the thickness of the first shaft end gear flange , angle of cone shell of 2nd axis , thickness of the second shaft end gear flange , and bolt parameters: number of bolts in a full circle K=24, screw diameter D=10.5mm, screw length L=41,5mm.

[0028] The material performance parameters are as follows: the material of the cone shell is TC17 (β forging), the processing method is integral CNC milling, and the material of the pre-tightening bolt is GH159.

[0029] Furthermore, step 2 includes:

[0030] The step 2 mainly analyzes the assembly load, temperature load, and bending load borne by the cone shell-end tooth connection structure. Where M is the tightening torque, F is the axial preload, D is the screw diameter, and k is the bolt tightening torque coefficient, assumed to be 0.15. Taking the maximum operational state as an example, the ambient temperature at the end-tooth connection is approximately 220°C. Based on the gyroscopic torque of the fan rotor during maneuvering flight (3.5 rad / s), the bending load on the end-tooth connection structure is determined to be 35,684 N·m.

[0031] Furthermore, in step 3, the optimization design objectives are to minimize the total weight of the cone shell-end gear connection structure and maximize the torque transmission capacity and interface contact stiffness of the end gear connection. The design constraints that the connection structure must meet are determined, primarily in the following four areas: interface deformation coordination, interface contact damage, preload loss, and axial stiffness characteristics.

[0032] In step 3: interface deformation coordination It mainly describes the interface deformation difference of the connection structure under centrifugal load and axial load, including radial deformation difference, axial deformation difference and angular deformation difference. The goal is to minimize the deformation difference, and the expression is as follows:

[0033] ,

[0034] in, is the radial deformation difference of the interface, is the axial deformation difference of the interface, is the interface angular deformation difference, is the allowable value of the radial deformation difference of the interface, is the allowable value of the interface axial deformation difference, is the allowable value of the interface angular deformation difference.

[0035] In this embodiment, the interface deformation coordination is required to be: the radial deformation difference of the interface does not exceed 0.05 mm, the axial deformation difference of the interface does not exceed 1.5 mm, and the angular deformation difference of the interface does not exceed 0.5°.

[0036] In step 3, the interface contact damage It is primarily determined by the contact stress distribution and the relative slip ratio. Excessive contact stress or excessive slip ratio can lead to fatigue damage or wear. The goal is to make the contact stress distribution uniform and reduce slip. The expression is as follows:

[0037] ,

[0038] in, is the maximum contact stress in the end tooth contact interface, is the yield limit of the end tooth material, and the stress shall not exceed the yield limit. is the ratio of the contact surface slip area, The allowable value of slip ratio.

[0039] In this embodiment, it is required that the contact normal stress is evenly distributed and the slip ratio does not exceed 15%.

[0040] In step 3, the preload loss It is mainly determined by the residual preload. The higher the residual preload, the more reliable the connection. The goal is to minimize the loss of preload. The relative expression is as follows:

[0041] ,

[0042] in, is the initial preload in the assembled state, It is the residual preload under working conditions.

[0043] In this embodiment, it is required that the residual preload force is not less than 60%.

[0044] The axial stiffness characteristics in step 3 The local axial stiffness of the connection structure is required to be no less than twice the axial stiffness of the rotor. Insufficient axial stiffness will lead to a decrease in dynamic performance. The goal is to maximize the axial stiffness, which is expressed as follows:

[0045] ,

[0046] in, is the rotor axial stiffness, is the local axial stiffness of the connection structure.

[0047] In this embodiment, it is required that the local stiffness of the connection structure is not less than twice the axial stiffness of the rotor.

[0048] The objective function needs to comprehensively consider the performance indicators of four aspects: interface coordination, interface contact damage, preload loss, and axial stiffness characteristics. The following is a complete objective function design, which uses the form of weighted multi-objective optimization to convert each indicator into a mathematical expression and integrate it into an overall objective function. The form of objective function J is as follows:

[0049] ,

[0050] This embodiment requires that the weight of each performance indicator is, .

[0051] Step 4: Select a constrained optimization method to find the design size that optimizes the objective function and meets the constraints.

[0052] In this embodiment, the particle swarm optimization algorithm is used to iteratively solve the optimization algorithm to obtain the optimal design size. The optimization results are substituted into the finite element model to verify whether the design meets all the constraints; if not, the optimization model is adjusted and iterated again. The schematic diagram of the final optimization solution is shown in the figure. Figure 2 As shown, the first axis cone shell angle , the thickness of the first shaft end gear flange , angle of cone shell of 2nd axis , thickness of the second shaft end gear flange , and bolt parameters: number of bolts in a full circle K=24, screw diameter D=10.5mm, screw length L=42mm.

[0053] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various deformations, modifications, and substitutions made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A design method for a large-size cone casing-end gear connection structure of an aircraft engine, characterized in that: The following steps are involved: Step 1: Based on the design requirements, the structural characteristic parameters of the large-scale cone shell-end tooth connection structure are clarified. Based on the geometric characteristics of the cone shell-end tooth connection, the structural characteristic parameters that affect the connection performance are collected and clarified. Step 2: Perform load environment and force analysis on the large-scale cone shell-end gear connection structure. Based on the load environment, establish a two-dimensional or three-dimensional mechanical analysis model to simulate the load effects under different working conditions. Step 3: Clarify the optimization design objectives and constraints, and integrate the design objectives into an objective function; Step 4: Select a constrained optimization method to find the structural characteristic parameters that optimize the objective function and meet the constraints. The structural characteristic parameters in step 1 are composed of geometric size parameters and material performance parameters, wherein the geometric size parameters include: the first axis cone shell angle , the thickness of the first shaft end gear flange , angle of cone shell of 2nd axis , thickness of the second shaft end gear flange ; And bolt parameters: number of full-circle bolts K, screw diameter D, screw length L; material performance parameters include: cone shell material, bolt material; In step 2, the assembly load, temperature load and bending load borne by the cone shell-end tooth connection structure are analyzed; In step 3, the optimization design objectives are to minimize the total weight of the cone shell-end tooth connection structure; maximize the torque transmission capacity and interface contact stiffness of the end tooth connection; and determine the design constraints satisfied by the cone shell-end tooth connection structure, including the following four aspects: interface deformation coordination, interface contact damage, preload loss, and axial stiffness characteristics; The objective function considers the performance indicators of four aspects: interface coordination, interface contact damage, preload loss and axial stiffness characteristics. It adopts the form of weighted multi-objective optimization to convert each indicator into a mathematical expression and integrate it into an overall objective function. The form of objective function J is as follows: ， in, is the interface deformation coordination, The interface contact damage is is the preload loss, is the axial stiffness characteristic, is the weight of each performance indicator.

2. The method for designing a large-size cone casing-end gear connection structure for an aircraft engine according to claim 1, characterized in that: Interface deformation coordination Describes the interface deformation difference of the connection structure under centrifugal load and axial load, including radial deformation difference and axial deformation difference. The goal is to minimize the deformation difference. The expression is as follows: ， in, is the radial deformation difference of the interface, is the axial deformation difference of the interface, is the interface angular deformation difference, is the allowable value of the radial deformation difference of the interface, is the allowable value of the interface axial deformation difference, is the allowable value of the interface angular deformation difference.

3. The design method of a large-size cone casing-end gear connection structure of an aircraft engine according to claim 1, characterized in that: Interface contact damage It is determined by the contact stress distribution and the relative slip ratio. The goal is to make the contact stress distribution uniform and reduce slip. The expression is as follows: ， in, is the maximum contact stress in the end tooth contact interface, The stress should not exceed the yield limit of the end gear material. is the ratio of the contact surface slip area, The allowable value of slip ratio.

4. The method for designing a large-size cone casing-end gear connection structure for an aircraft engine according to claim 1, characterized in that: Preload loss Determined by the residual preload, the goal is to minimize the loss of preload. The relative expression is as follows: ， in, is the initial preload in the assembled state, It is the residual preload under working conditions.

5. The method for designing a large-size cone casing-end gear connection structure for an aircraft engine according to claim 1, characterized in that: Axial stiffness characteristics The local axial stiffness of the connection structure is required to be no less than twice the axial stiffness of the rotor. The goal is to maximize the axial stiffness. The expression is as follows: ， in, is the rotor axial stiffness, is the local axial stiffness of the connection structure.

6. The method for designing a large-size cone casing-end gear connection structure for an aircraft engine according to claim 2, characterized in that: The radial deformation difference of the interface shall not exceed 0.05 mm, the axial deformation difference of the interface shall not exceed 1.5 mm, and the angular deformation difference of the interface shall not exceed 0.5°.

7. The method for designing a large-size cone casing-end gear connection structure for an aircraft engine according to claim 3, characterized in that: The contact normal stress is evenly distributed and the relative slip ratio does not exceed 15%.

8. The method for designing a large-size cone casing-end gear connection structure for an aircraft engine according to claim 4, characterized in that: The residual preload force shall not be less than 60%.

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