A strength design method for elastic ring of aero-engine considering assembly tightness

Abstract

The present application belongs to the field of aircraft engine strength design, and particularly relates to an aircraft engine elastic ring strength design method considering assembly tightness. The aircraft engine elastic ring strength design method considering assembly tightness of the present application can design the strength of the aircraft engine elastic ring, which can greatly reduce the iteration cycle of the elastic ring design and improve the design efficiency; it comprehensively considers the influence of the elastic ring stiffness and assembly tightness, can realize the engineering design requirements, and can also meet the engineering assemblability; it considers the strength reserve design, and can meet the engineering elastic ring long life working requirements.

Description

Technical Field

[0001] The present application belongs to the field of aircraft engine strength design, and in particular relates to an aircraft engine elastic ring strength design method taking assembly tightness into consideration. Background Art

[0002] The most basic requirement for the vibration characteristics of the whole aircraft engine is to ensure that the rotor-support system has no harmful vibration within the operating speed range. Good rotor dynamic characteristics are the fundamental basis for achieving no harmful vibration within the rotor operating speed range. The rotor dynamics design criteria for aircraft engines require "ensuring that the operating speed and critical speed have sufficient margin". For modern advanced low bypass ratio engines, the operating speed range of the low-pressure rotor is 3000-9000r / min, and the operating speed range of the high-pressure rotor is 7000-15000r / min. To achieve the control of the rotor critical speed margin in such a wide operating speed range, it poses a challenge to the optimal design of the critical speed of the aircraft engine rotor. At present, elastic supports are widely used in aircraft engines for the optimization design of rotor critical speed. As an elastic support with simple structure, small space occupation and high reliability, elastic rings are widely used in aircraft engines. In the design process, the required flexibility is obtained by adjusting the parameters of the elastic ring to achieve the purpose of adjusting the critical speed of the rotor.

[0003] There are still many difficulties in the design and application of elastic rings in engineering. For example, in addition to achieving the design goal of lateral flexibility, the fatigue stress and strength reserve of the elastic ring must also be considered. On the other hand, elastic rings in engineering are mostly pre-tightened and installed. While adjusting the supporting stiffness, they also have a certain centering effect. Therefore, the radial flexibility must also be taken into account in the design to achieve an assemblable design.

[0004] In the prior art, the dynamic characteristics and design methods of the elastic ring structure itself have been studied, but most studies only consider the influence of the elastic ring parameters on its stiffness, and do not provide a specific process for engineering design of elastic rings, which is insufficient for the design guidance of specific parameters of elastic rings in engineering. Most analyses do not take into account the fatigue strength reserve requirements of elastic ring engineering structures, and rarely consider the strength reserve impact caused by the actual installation tightness of the elastic ring. At the same time, the radial flexibility of the elastic ring is not considered in the design process, and the engineering assemblability design is not achieved.

[0005] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned defects of the prior art. Summary of the invention

[0006] The purpose of the present application is to provide a method for designing the strength of an aero-engine elastic ring taking into account assembly tightness, so as to solve at least one problem existing in the prior art.

[0007] The technical solution of this application is:

[0008] A strength design method for an aero-engine elastic ring considering assembly tightness, comprising:

[0009] Step 1: Obtain the design stiffness K of the elastic ring d ;

[0010] Step 2: Determine the structural parameters and material selection of the elastic ring;

[0011] Step 3, calculating the stiffness K of the elastic ring according to the structural parameters of the elastic ring;

[0012] Step 4: Calculate the stiffness K and design stiffness K of the elastic ring d Deviation, judge whether the stiffness K of the elastic ring meets the requirements, if yes, proceed to the next step, if not, return to step 2 to re-determine the structural parameters and material selection of the elastic ring;

[0013] Step 5: Establish a UG three-dimensional model of the elastic ring according to the structural parameters of the elastic ring;

[0014] Step 6: Establish a finite element model of the elastic ring based on the UG three-dimensional model, and calculate the stiffness K of the elastic ring through finite element method. s ;

[0015] Step 7: Calculate the stiffness K of the elastic ring s and design stiffness K d Deviation, determine the stiffness K of the elastic ring s Whether the requirements are met, if yes, proceed to the next step, if not, return to step 2 to re-determine the structural parameters and material selection of the elastic ring;

[0016] Step 8: Check the strength of the elastic ring to determine whether the strength of the elastic ring meets the requirements. If so, determine the final structural parameters and material selection of the elastic ring. If not, return to step 2 to redetermine the structural parameters and material selection of the elastic ring.

[0017] In at least one embodiment of the present application, in step three, calculating the stiffness K of the elastic ring according to the structural parameters of the elastic ring includes:

[0018]

[0019] Among them, m is the number of bosses of the elastic ring, k is the stiffness of the elastic section of the elastic ring, E is the elastic modulus of the elastic ring material, l is the effective length of the elastic section arc, D1 is the inner diameter of the elastic ring, D2 is the outer diameter of the elastic ring, b is the boss width, L is the axial length of the elastic ring, and h is the thickness of the elastic section.

[0020] In at least one embodiment of the present application, in step 4, when |KK d |<0.2K dWhen , it is considered that the stiffness K of the elastic ring meets the requirements.

[0021] In at least one embodiment of the present application, in step seven, when |K s -K d |<0.1K d When the elastic ring stiffness K s Meet the requirements.

[0022] In at least one embodiment of the present application, in step eight, the elastic ring strength check to determine whether the elastic ring strength meets the requirements includes:

[0023] Obtain the working load of the elastic ring, calculate the static stress and dynamic stress of the elastic ring, calculate the strength reserve coefficient of the elastic ring according to the material properties of the elastic ring, and determine whether the strength reserve coefficient of the elastic ring meets the requirements.

[0024] In at least one embodiment of the present application, when the elastic ring strength reserve coefficient is not less than 1.5, it is considered that the elastic ring strength meets the requirement.

[0025] The invention has at least the following beneficial technical effects:

[0026] The aircraft engine elastic ring strength design method considering assembly tightness of the present application can design the strength of the aircraft engine elastic ring, which can greatly reduce the iteration cycle of the elastic ring design and improve the design efficiency; it comprehensively considers the influence of the elastic ring stiffness and assembly tightness, can realize the engineering design requirements, and can also meet the engineering assemblability; it takes into account the strength reserve design, and can meet the long-life working requirements of the elastic ring in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a method for designing the strength of an aero-engine elastic ring taking assembly tightness into consideration according to an embodiment of the present application;

[0028] Figure 2 It is a schematic diagram of the elastic ring structure of an embodiment of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0030] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.

[0031] The following is combined with Figure 1 to Figure 2 This application is described in further detail.

[0032] The present application provides a method for designing the strength of an aero-engine elastic ring taking into account assembly tightness, such as Figure 1 As shown, including:

[0033] Step 1: Obtain the design stiffness K of the elastic ring d ;

[0034] According to the rotor dynamics optimization, the design stiffness value of the elastic ring needs to be determined. Usually, this value is within a certain range.

[0035] Step 2: Determine the structural parameters and material selection of the elastic ring;

[0036] Given the preliminary design structural parameters and material selection of the elastic ring; because the elastic ring is located between the bearing and the bearing seat, the structural parameters of the elastic ring are limited by the engine structure space. For example, the value of the inner diameter D1 of the elastic ring depends on the outer diameter of the bearing where it is located; the thickness h of the elastic section is also affected by the size of the bearing seat, and the design of the boss height s also needs to comprehensively consider the strength design, etc. The structural parameters of the elastic ring are as follows Figure 2 As shown; at the same time, the elastic ring material is selected;

[0037] Step 3, calculating the stiffness K of the elastic ring according to the structural parameters of the elastic ring;

[0038] The stiffness K of the elastic ring is calculated according to the theoretical formula:

[0039]

[0040] Wherein, m is the number of bosses of the elastic ring, k is the stiffness of the elastic segment of the elastic ring, E is the elastic modulus of the elastic ring material, l is the effective length of the elastic segment arc, D1 is the inner diameter of the elastic ring, D2 is the outer diameter of the elastic ring, b is the boss width, L is the axial length of the elastic ring, and h is the thickness of the elastic segment;

[0041] When the elastic ring is assembled, it usually has a small interference fit with the bearing seat and the outer ring of the bearing, that is, the elastic ring is installed with pre-tightening deformation. The elastic section stiffness k can be regarded as the radial stiffness of the elastic ring, and its size can be used as a reference for the feasibility of assembly. At present, there is no clear requirement for this stiffness, but the smaller the stiffness, the higher the assemblability. The elastic ring stiffness K, which can be defined as the lateral stiffness of the elastic ring, is the most important design goal in the design of the elastic ring.

[0042] Step 4: Calculate the stiffness K and design stiffness K of the elastic ring d Deviation, determine whether the stiffness K of the elastic ring meets the requirements, if yes, proceed to the next step, if not, return to step 2 to re-determine the structural parameters and material selection of the elastic ring; Among them, when |KK d |<0.2K d When , it is considered that the stiffness K of the elastic ring meets the requirements;

[0043] In step 3, the elastic ring stiffness calculated by the empirical formula is simplified calculation, ignoring the influence of boss height and boss root rounding, etc., so the calculation result has a certain deviation; if the deviation exceeds 20%, it is necessary to redesign the elastic ring structural parameters; if the deviation does not exceed 20%, proceed to the next step of design;

[0044] Step 5: Establish a UG three-dimensional model of the elastic ring according to the structural parameters of the elastic ring;

[0045] Establish a detailed structural model based on structural design parameters;

[0046] Step 6: Establish a finite element model of the elastic ring based on the UG three-dimensional model, and calculate the stiffness K of the elastic ring through finite element calculation s ;

[0047] Using the detailed structural model established in step 5, a finite element model is established to accurately calculate the elastic ring stiffness;

[0048] Step 7: Calculate the stiffness K of the elastic ring s and design stiffness K d Deviation, determine the stiffness K of the elastic ring sDoes it meet the requirements? If yes, proceed to the next step. If not, return to step 2 to re-determine the structural parameters and material selection of the elastic ring. s -K d |<0.1K d When the elastic ring stiffness K s Meet the requirements.

[0049] When the deviation exceeds 10%, it is necessary to redesign the elastic ring structure parameters; if the deviation does not exceed 10%, proceed to the next step of design;

[0050] Step 8: Check the strength of the elastic ring to determine whether the strength of the elastic ring meets the requirements. If so, determine the final structural parameters and material selection of the elastic ring. If not, return to step 2 to redetermine the structural parameters and material selection of the elastic ring.

[0051] Obtain the working load of the elastic ring, calculate the static stress and dynamic stress of the elastic ring according to the load borne by the elastic ring, calculate the strength reserve coefficient of the elastic ring according to the material properties of the elastic ring, and judge whether the strength reserve coefficient of the elastic ring meets the requirements. When the strength reserve coefficient of the elastic ring is not less than 1.5, it is considered that the strength of the elastic ring meets the requirements.

[0052] The aircraft engine elastic ring strength design method considering assembly tightness of the present application can design the strength of the aircraft engine elastic ring, which can greatly reduce the iteration cycle of the elastic ring design and improve the design efficiency; it comprehensively considers the influence of the elastic ring stiffness and assembly tightness, can realize the engineering design requirements, and can also meet the engineering assemblability; it takes into account the strength reserve design, and can meet the long-life working requirements of the elastic ring in engineering.

[0053] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A strength design method for an aero-engine elastic ring taking assembly tightness into consideration, characterized in that: include: Step 1: Obtain the design stiffness K of the elastic ring d According to the rotor dynamics optimization, the design stiffness K of the elastic ring needs to be determined. d ; Step 2: Determine the structural parameters and material selection of the elastic ring; Step 3: Calculate the stiffness K of the elastic ring according to the structural parameters of the elastic ring, and calculate the stiffness K of the elastic ring according to the theoretical formula; Step 4: Calculate the stiffness K and design stiffness K of the elastic ring d Deviation, judge whether the stiffness K of the elastic ring meets the requirements, if yes, proceed to the next step, if not, return to step 2 to re-determine the structural parameters and material selection of the elastic ring; Step 5: Establish a UG three-dimensional model of the elastic ring according to the structural parameters of the elastic ring; Step 6: Establish a finite element model of the elastic ring based on the UG three-dimensional model, and calculate the stiffness K of the elastic ring by finite element method. s ; Step 7: Calculate the stiffness K of the elastic ring s and design stiffness K d Deviation, determine the stiffness K of the elastic ring s Whether the requirements are met, if yes, proceed to the next step, if not, return to step 2 to re-determine the structural parameters and material selection of the elastic ring; Step 8: Check the strength of the elastic ring to determine whether the strength of the elastic ring meets the requirements. If so, determine the final structural parameters and material selection of the elastic ring. If not, return to step 2 to redetermine the structural parameters and material selection of the elastic ring.

2. The method for designing the strength of an aircraft engine elastic ring taking assembly tightness into consideration according to claim 1, characterized in that: In step three, the stiffness K of the elastic ring is calculated according to the structural parameters of the elastic ring, including: Among them, m is the number of bosses of the elastic ring, k is the stiffness of the elastic section of the elastic ring, E is the elastic modulus of the elastic ring material, l is the effective length of the elastic section arc, D1 is the inner diameter of the elastic ring, D2 is the outer diameter of the elastic ring, b is the boss width, L is the axial length of the elastic ring, and h is the thickness of the elastic section.

3. The method for designing the strength of an aircraft engine elastic ring taking assembly tightness into consideration according to claim 2, characterized in that: In step 4, when |KK d |<0.2K d When , it is considered that the stiffness K of the elastic ring meets the requirements.

4. The method for designing the strength of an aircraft engine elastic ring taking assembly tightness into consideration according to claim 3 is characterized in that: In step 7, when |K s -K d |<0.1K d When the elastic ring stiffness K s Meet the requirements.

5. The method for designing the strength of an aircraft engine elastic ring taking assembly tightness into consideration according to claim 4, characterized in that: In step eight, the elastic ring strength check is performed to determine whether the elastic ring strength meets the requirements, including: Obtain the working load of the elastic ring, calculate the static stress and dynamic stress of the elastic ring, calculate the strength reserve coefficient of the elastic ring according to the material properties of the elastic ring, and determine whether the strength reserve coefficient of the elastic ring meets the requirements.

6. The method for designing the strength of an aircraft engine elastic ring taking assembly tightness into consideration according to claim 5, characterized in that: When the elastic ring strength reserve coefficient is not less than 1.5, it is considered that the elastic ring strength meets the requirements.

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