Turbine disc double-row arc end tooth connection structure simulator design method

Abstract

The invention relates to a turbine disc double-row arc end tooth connection structure simulation part design method, which comprises the steps of carrying out arc end tooth connection structure finite element analysis, calculating stress, strain, relative slippage conditions and the like of an end tooth local area, and determining a dangerous point corresponding to an actual failure mode; geometric parameters of the main structure of the arc end tooth are measured, and dangerous point stress, strain and relative slippage distance are extracted; concave teeth and convex teeth which are matched with each other serve as basic configurations, and the initial configuration of the arc end tooth simulation piece is designed by referring to the geometric situation of a real component; for an examined tooth, the tooth thickness is adjusted to change the actual rigidity, so that the relative error of a life control parameter in a local range of a dangerous point does not exceed 5% compared with a real component; the thickness of the examined tooth is optimized, the critical plane direction of the dangerous point is calculated to determine the crack propagation direction, and the critical crack propagation length of the simulation piece and the real component tend to be consistent in the crack propagation direction.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace engines, and in particular to a design method for a turbine disk double-row circular arc end teeth connection structure simulation component. Background Art

[0002] Arc end teeth are widely used to transmit torque between aircraft engine rotors due to their strong load-bearing capacity, automatic centering, and easy assembly. Aircraft engine turbine structures operate under complex service conditions of high temperature and high speed for a long time. The end teeth, which are subjected to high temperature, high speed, and high power loads, have become a weak point in aircraft engine fatigue failure, seriously affecting the safety and reliability of the engine. In order to study the fatigue performance of the arc end tooth connection structure, it is necessary to carry out end tooth fatigue test research. Due to the high cost of real component testing and the limited available data, it is urgent to carry out the design of simulation parts for the arc end tooth connection structure, simulate the service conditions in a laboratory environment, and study the fatigue performance of the arc end tooth connection structure.

[0003] The double-row arc-end tooth connection structure is press-fitted with high-strength bolts. It is subjected to certain loads immediately after assembly of the aircraft engine. After reaching the design speed, it is also subjected to high-temperature loads, centrifugal loads, and torsional loads. The tooth roots are susceptible to low-cycle fatigue failure due to stress concentration, while the tooth surfaces are susceptible to fretting fatigue failure due to relative slip. These two failure modes often exhibit a "competitive" relationship, meaning that the first location to fail will cause the entire disc to rupture and fail. Designing arc-end tooth simulations that accurately reflect the structural characteristics, stress-strain distribution, and contact state of different failure locations is a key issue.

[0004] In the prior art, a double-arc tooth root design method has been developed based on the stress concentration problem at the tooth root of an arc-end tooth structure. This research focuses on the stress concentration problem at the root of the arc-end tooth, ignoring the fretting fatigue failure of the tooth surface and is only applicable to failure assessment at a single location on the tooth root.

[0005] Some existing techniques have identified the critical point for fretting fatigue on the tooth surface through static analysis, extracted the tooth profile parameters at that location, simplified the arc-shaped end teeth into straight end teeth, and designed a matching concave tooth test piece and convex tooth fretting pad. This design method only addresses fretting fatigue failure on the end tooth surface, ignoring stress concentration at the end tooth root, and is therefore only applicable to failure assessment at a single location on the tooth surface.

[0006] In summary, existing arc-end tooth simulation designs simplify arc teeth into straight teeth, failing to fully reflect the load conditions of real components. Furthermore, during testing, they are often limited to assessing a single failure mode, failing to simultaneously address fatigue failure at both the tooth surface and tooth root. Consequently, the arc-end tooth simulation design cannot fully reflect fatigue performance under actual service conditions. Therefore, traditional arc-end tooth simulation design methods cannot accurately simulate service conditions and assess end tooth fatigue performance. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides a design method for a simulation part of a double-row circular arc end tooth connection structure of a turbine disk, which adopts an arc-shaped tooth surface as the basic configuration of the simulation part, fully reflecting the "competitive" behavior of the two failure modes of end tooth surface micro-fatigue and tooth root low-cycle fatigue under service load, and serves and supports the fatigue performance evaluation and strength design of the circular arc end tooth connection structure of the aircraft engine.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for designing a turbine disk double-row arc end tooth connection structure simulation component includes the following steps:

[0010] Step (1) Conduct finite element analysis of the arc end tooth connection structure, calculate the stress and strain state of the tooth root, the stress and relative slip distance of the tooth surface contact area, and use the critical plane method and the SWT life prediction model and the Ruiz life prediction model to determine the dangerous point corresponding to the actual failure mode;

[0011] Step (2) measuring the geometric parameters of the main structure of the arc end tooth, including the inner and outer diameters of the arc end tooth, the position of the bolt hole, the tooth profile parameters, etc., extracting the stress and strain state of the tooth root, the stress and relative slip of the tooth surface contact area;

[0012] Step (3) using the tensile form as the test form for the simulation part, taking the mutually matched concave and convex teeth as the basic configuration, and referring to the actual geometric status of the component, designing the initial configuration of the arc end tooth simulation part;

[0013] Step (4) For the tooth under test, adjust the tooth thickness to change its actual stiffness so that the relative error of the main damage parameters in the local range of the dangerous point between the simulated component and the real component does not exceed 5%, so as to ensure the consistency of the crack initiation life of the simulated component with that of the real component.

[0014] Step (5) For the tooth under test, calculate the critical plane direction of the dangerous point to determine the crack propagation direction. In the crack propagation direction, the stress intensity factor of the simulated component on the crack propagation path should change with the crack length, and the relative error with the real component should not exceed 5%, so as to ensure the consistency of the crack propagation life of the simulated component with that of the real component.

[0015] The advantages of the present invention compared with the prior art are:

[0016] (1) In the present invention, the tooth profile of the simulated component adopts an arc-shaped tooth surface, which fully restores the geometric structure of the real component and accurately controls the stress, strain and relative slip distance distribution at the failure risk point, providing a basis for accurately simulating the nonlinear behavior of the arc-end tooth under service load.

[0017] (2) The simulation component of the present invention takes into account the possible fretting fatigue failure of the tooth surface and low-cycle fatigue failure of the tooth root of the real component, and can simulate the "competitive" relationship between different failure modes of the real component under service conditions in a laboratory environment.

[0018] (3) The simulation part of the present invention is based on the general double-row arc end tooth configuration. It can change the stiffness of different areas of the end teeth according to the different peak load and amplitude load fatigue failure risk points under service conditions to meet the test and assessment requirements. The edge stiffness design method used is widely applicable.

[0019] (4) The simulation components of the present invention have fewer consumables and a simple test loading scheme. Compared with the test using real components, the present invention reduces the dependence on test equipment and saves the economic consumption of test materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of a method for designing a turbine disk double-row arc end teeth connection structure simulation component according to the present invention;

[0021] Figure 2 This is a stress and strain distribution diagram of the finite element analysis results of a real component of a turbine disk with double-row arc end teeth according to the present invention;

[0022] Figure 3 A schematic diagram of the assembly of two convex teeth and a test clamping structure supporting the simulation component of the present invention;

[0023] Figure 4 A comparison diagram of damage parameters of a designed example and a variable stiffness simulation part of a real component during the implementation of the design method of the present invention;

[0024] Figure 5 This is a design example diagram of a turbine disk double-row arc end tooth connection structure simulation component of the present invention. DETAILED DESCRIPTION

[0025] 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 embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining 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.

[0026] The following is a further description of the technical solution of the method for designing a turbine disk double-row arc end tooth connection structure simulation component in conjunction with the accompanying drawings. Figure 1 As shown, the following steps are included:

[0027] Step (1) Conduct finite element analysis of the arc end tooth connection structure, calculate the stress and strain state of the tooth root, the stress and relative slip distance of the tooth surface contact area, and use the critical plane method and the SWT life prediction model and the Ruiz life prediction model to determine the dangerous point corresponding to the actual failure mode;

[0028] Step (2) measuring the geometric parameters of the main structure of the arc end tooth, including the inner and outer diameters of the arc end tooth, the position of the bolt hole, the tooth profile parameters, etc., extracting the stress and strain state of the tooth root, the stress and relative slip of the tooth surface contact area;

[0029] Step (3) using the tensile form as the test form of the arc end tooth simulation component, using the mutually matched concave and convex teeth as the basic configuration of the arc end tooth, and referring to the actual geometric status of the component, designing the initial configuration of the arc end tooth simulation component;

[0030] Step (4) For the tooth under test, adjust the tooth thickness to change its actual stiffness so that the relative error of the main damage parameters in the local range of the dangerous point of the arc end tooth simulation component is no more than 5% compared with the real component, so as to ensure the consistency of the crack initiation life of the simulation component with that of the real component.

[0031] Step (5) For the tooth under test, calculate the critical plane direction of the danger point to determine the crack propagation direction. In the crack propagation direction, the stress intensity factor of the simulation component on the crack propagation path should change with the crack length, and the relative error with the real component should not exceed 5%, so as to ensure the consistency of the crack propagation life of the arc end tooth simulation component with the real component.

[0032] Furthermore, in the step (1), the stress and strain of the tooth root refer to the maximum normal stress and normal strain on the critical plane of the tooth root of the arc end tooth, and the low-cycle fatigue failure risk point at the tooth root is determined by calculating the SWT parameter value on the critical plane; the stress and relative slip conditions in the tooth surface contact area refer to the contact stress, surface shear stress and relative slip distance in the tooth surface contact area, and the fretting fatigue failure risk point on the tooth surface is determined by calculating the Ruiz parameter in this area.

[0033] Furthermore, in the step (2), the geometric parameters of the arc end teeth measured include the inner and outer diameters of the arc end teeth, which are used to determine the width of the end teeth of the simulation part; the inner and outer diameters of the middle tooth grooves, which are used to determine the slot spacing of the simulation part; the bolt hole position, which is used to determine the relative position of the bolt hole of the simulation part and the dangerous point of the end teeth; and the tooth profile parameters of the end teeth, which are used to determine the tooth shape parameters of the end teeth and the clearance amount of the end teeth matching.

[0034] Furthermore, in step (2), the arc end tooth geometric parameters also include the end tooth full height, tooth root height, tooth top height, tooth top chamfer height, tooth top clearance, mountain bottom height, tooth top chamfer angle, pressure angle, and mountain bottom angle.

[0035] Furthermore, in step (3), the concave and convex teeth that cooperate with each other are designed as the basic configuration, that is, a total of two tooth shapes are designed: the tested piece has two teeth for forming the tooth top gap and bearing the load, and the micro-matching tooth has only one tooth for applying the lateral load.

[0036] Furthermore, in step (4), the stiffness of the tooth under test is changed to adjust the position of the dangerous point on the tooth root and tooth surface and its damage parameters, and the fatigue life error is calculated according to the life model to be no more than 5%, so as to ensure the consistency of the crack initiation life of the simulated component with the real component.

[0037] Furthermore, in step (5), corresponding fatigue cracks are inserted according to different failure locations, and crack propagation calculations are carried out to ensure that the stress intensity factor of the simulated component on the crack propagation path changes with the crack length in the crack propagation direction, and the relative error with the real component does not exceed 5%, so as to ensure the consistency of the crack propagation life of the simulated component with that of the real component.

[0038] The present invention provides a more specific embodiment, which is specifically implemented as follows:

[0039] In the first step, the double-row arc-end tooth connection structure of a certain type of aircraft engine high-pressure rotor was used as the research object. Through finite element analysis, it was found that the stress concentration at the root fillet was obvious, and the first principal stress far exceeded the yield limit; the edge of the tooth surface contact area was squeezed, resulting in a large equivalent stress, such as Figure 2 As shown in the figure, the model mesh of the tooth root and tooth surface contact area is refined to calculate the local elastic-plastic stress-strain solution of the end tooth. By calculating the classic parameters SWT and Ruiz, the low-cycle fatigue failure danger points of the tooth root and the fretting fatigue failure danger points of the tooth surface can be determined. To ensure the accuracy of the calculated SWT and Ruiz parameters, the mesh size of the local root and tooth surface areas should be kept less than 0.05 mm.

[0040] The specific formula for calculating the SWT parameters is as follows:

[0041] ;

[0042] Where, is the maximum stress, is the strain amplitude, E is the elastic modulus, and They represent fatigue strength coefficient and fatigue ductility coefficient respectively, b and c are material fatigue strength index and fatigue ductility index, is the number of cycles to failure.

[0043] The specific formula for calculating the Ruiz parameter is as follows:

[0044] ;

[0045] Where, is the fretting coefficient, τ is the shear stress on the contact surface, δ is the relative slip distance, and σ is the contact normal stress.

[0046] The second step is to measure the geometric parameters of the main structure of the arc end teeth, including the inner and outer diameters of the arc end teeth, the position of the bolt holes, the tooth profile parameters, etc., and based on the finite element calculation results of the first step, extract the main damage parameters such as the tooth root stress and strain state, the stress in the tooth surface contact area, and the relative slip condition.

[0047] The third step is to use the tensile form as the test form for the simulation part. Based on the geometric configuration of the turbine comb disc end teeth, a flat simulation part is designed with arc end teeth distributed on both sides of the flat plate. However, the real arc end teeth mainly bear circumferential loads, and the tensile components can only be subjected to tensile loads. Therefore, with the diameter of the direct bolt holes of the inner and outer teeth as the symmetry axis, the basic configuration of the simulation part with inner teeth on both sides of the bolt holes is designed. In order to ensure the centering of the load during the test and assessment, the designed simulation part is used as the intermediate component, and the corresponding convex tooth simulation parts are assembled on the front and back sides respectively, such as Figure 3 shown.

[0048] The fourth step is to optimize the geometric configuration of the arc end tooth simulation component in order to achieve the design goal that the relative error of the main damage parameters in the local range of the dangerous point does not exceed 5% compared with the real component. Among them, for the critical plane normal stress or SWT damage parameter distribution of the tooth root dangerous point, this design adopts the variable stiffness method. Based on the principle that reducing the tooth thickness reduces the stiffness and increasing the tooth thickness increases the stiffness, the variable stiffness end tooth simulation component with unequal thickness is designed. Figure 4 As shown in the figure, the error of SWT damage parameters within 1 mm around the dangerous point of the tooth root is less than 3.48%, which meets the design criteria.

[0049] The fifth step involves performing crack growth analysis on various failure locations in the real component. Using 3D crack growth analysis software, semi-elliptical initial cracks are inserted at critical points on the tooth root and tooth surface. The crack growth length of the real component is calculated based on the fracture toughness. The substrate thickness of the simulated component is adjusted to ensure that the critical crack growth length of the simulated component and the real component are consistent in the crack growth direction.

[0050] This completes the design of a simulation component for the double-row circular-arc end teeth connection structure of an aircraft engine turbine. The simulation effectively simulates the geometry, stress and strain distribution, and failure modes of the actual end teeth, enabling verification of the fatigue performance of double-row circular-arc end teeth on turbine disks.

[0051] An example of a design is Figure 5 As shown: The tooth thicknesses of the arc-end variable stiffness structure are L1 = 1mm and L2 = 4mm. The tooth root fillet R = 1mm. The test specimen has a base thickness of L = 6mm, a length of L = 62mm, a width of L = 36cm, a tooth height of H = 7mm, a small bolt hole radius of r = 10.2mm, and a large bolt hole radius of r = 14mm. This example is similar to the actual component geometry, and the fatigue failure risk points are consistent with the actual component. The test section has been safety-verified to meet load-bearing requirements and effectively reflects the fatigue performance of the actual component.

[0052] The above embodiments are provided for the purpose of describing the present invention only and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principles of the present invention are intended to be within the scope of the present invention.

Claims

1. A method for designing a turbine disk double-row arc end tooth connection structure simulation component, characterized in that: The steps include: (1) Conduct finite element analysis of the arc end tooth connection structure, calculate the stress, strain and relative slip of the local area of the end tooth, and use the critical plane method, SWT life prediction model and Ruiz life prediction model to determine the dangerous point corresponding to the actual failure mode; (2) Measure the geometric parameters of the arc end teeth, including the inner and outer diameters of the arc end teeth, the position of the bolt holes, and the tooth profile parameters, and extract the stress and strain state of the tooth root, the stress in the tooth surface contact area, and the relative slip condition; (3) The tensile test form is used as the test form of the simulation part, and the concave and convex teeth that match each other are used as the arc end tooth connection structure configuration. Referring to the geometric status of the real component, the initial configuration of the arc end tooth simulation part is designed; (4) For the tooth under test, adjust the tooth thickness to change its actual stiffness so that the relative error of the damage parameters in the local range of the dangerous point of the arc end tooth simulation component is no more than 5% compared with the real component, so that the crack initiation life of the simulation component is consistent with that of the real component; (5) For the tooth under test, the critical plane direction of the dangerous point is calculated to determine the crack propagation direction. In the crack propagation direction, the stress intensity factor of the arc end tooth simulation piece on the crack propagation path varies with the crack length, and the relative error with the real component does not exceed 5%, so that the crack propagation life of the arc end tooth simulation piece is consistent with that of the real component.

2. The method for designing a turbine disk double-row arc end teeth connection structure simulation component according to claim 1, characterized in that: In the step (1), the stress, strain and relative slip conditions of the local area of the end teeth include the stress and strain state of the tooth root and the stress and relative slip of the tooth surface contact area.

3. The method for designing a turbine disk double-row arc end teeth connection structure simulation component according to claim 2, characterized in that: The stress and strain of the tooth root refer to the maximum normal stress and normal strain on the critical plane of the tooth root of the arc-end tooth, and the low-cycle fatigue failure risk point at the tooth root is determined by calculating the SWT parameter value on the critical plane; the stress and relative slip conditions in the tooth surface contact area refer to the contact stress, surface shear stress and relative slip distance in the tooth surface contact area, and the fretting fatigue failure risk point on the tooth surface is determined by calculating the Ruiz parameter in this area.

4. The method for designing a turbine disk double-row arc end teeth connection structure simulation component according to claim 1, characterized in that: In the step (2), the inner and outer diameters of the arc end teeth are used to determine the width of the end teeth of the simulation part; the inner and outer diameters of the middle tooth grooves are used to determine the slot spacing of the simulation part; the bolt hole position is used to determine the relative position of the bolt hole of the simulation part and the dangerous point of the end teeth; the tooth profile parameters of the end teeth are used to determine the tooth shape parameters of the end teeth and the clearance amount of the end teeth matching.

5. The method for designing a turbine disk double-row arc end teeth connection structure simulation component according to claim 1, characterized in that: In the step (2), the arc end tooth geometric parameters also include the end tooth full height, tooth root height, tooth top height, tooth top chamfer height, tooth top clearance, mountain bottom height, tooth top chamfer angle, pressure angle, and mountain bottom angle.

6. The method for designing a turbine disk double-row arc end teeth connection structure simulation component according to claim 1, characterized in that: In the step (3), the configuration of the arc end tooth simulation part is a mutually matching flat plate configuration, and the teeth to be tested are designed using a symmetrical structure method, that is, the front and back sides of the flat plate are simultaneously designed as the teeth to be tested; and double rows of arc end teeth inner teeth are designed on both sides of the bolt hole.

7. The method for designing a turbine disk double-row arc end teeth connection structure simulation component according to claim 1, characterized in that: In the step (4), the relative error of the life control parameter does not exceed 5%, which means that the SWT parameter error within 1 mm of the dangerous point of the arc end tooth simulation part is controlled to be no more than 5% compared with the real component.

8. The method for designing a turbine disk double-row arc end teeth connection structure simulation component according to claim 1, characterized in that: In the step (5), a semi-elliptical initial crack is inserted at the dangerous point using three-dimensional crack propagation analysis software, so that the critical crack propagation length of the simulated component is consistent with that of the real component in the crack propagation direction.

9. The method for designing a turbine disk double-row arc end teeth connection structure simulation component according to claim 3, characterized in that: The specific formula for calculating the SWT parameters is as follows: ； Where, is the maximum stress, is the strain amplitude, and They represent fatigue strength coefficient and fatigue ductility coefficient respectively, b and c are material fatigue strength index and fatigue ductility index, is the number of cycles to failure.

10. The method for designing a turbine disk double-row arc end teeth connection structure simulation component according to claim 3, wherein the Ruiz parameter is calculated using the following formula: ； Where τ is the shear stress on the contact surface, δ is the relative slip distance, σ is the contact normal stress, is the micro-motion coefficient.

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