Aero-engine titanium alloy hollow fan blade and strength evaluation method thereof

Abstract

The application provides a kind of aero-engine titanium alloy hollow fan blade strength evaluation method, comprising: making hollow fan blade and solid fan blade have the same blade shape, according to the mass of solid fan blade cover and hollow fan blade mass, the mass center circumferential coordinate of the hollow fan blade when the hollow fan blade has reasonable cover is calculated, and the hollow fan blade structure is obtained;The static stress and vibration stress distribution of hollow fan blade is obtained by static strength and vibration characteristic analysis, whether the maximum point position of static stress and vibration stress distribution meets the requirements is judged, if it does not meet the requirements, then adjust the structure parameters of hollow fan blade;Determine the cross-section strength checking position of hollow fan blade, according to stress amplitude-average stress life curve, the relationship between solid fan blade strength and hollow fan blade strength is established, based on the static strength reserve standard of solid fan blade is not lower than the checking strength of solid fan blade, the strength of hollow fan blade hollow welding area is obtained.

Description

Technical Field

[0001] This application belongs to the field of aero-engine technology, and specifically relates to an aero-engine titanium alloy hollow fan blade and its strength evaluation method. Background Technology

[0002] As the thrust-to-weight ratio and bypass ratio of modern aero engines continue to increase, the centrifugal and aerodynamic loads on fan rotor blades are also increasing, resulting in greater loads on the rotor disk. Traditional fan rotor blades typically use solid titanium alloy blades. However, when the thrust-to-weight ratio and bypass ratio are too high, solid titanium alloy fan blades suffer from problems such as high weight, large deformation, high stress, and significant vibration. Using hollow titanium alloy fan blades can effectively reduce the weight of the fan blades themselves. The hollowness of hollow fan blades must reach at least 20% to effectively reduce the centrifugal load on the blades and rotor disk, and effectively reduce the weight of the fan components.

[0003] However, since hollow fan blades use the same titanium alloy material as solid fan blades, the strength evaluation methods for solid titanium alloy fan blades are currently commonly used when assessing the strength of hollow fan blades. Figure 1 and Figure 2 The schematic diagrams of solid and hollow fan blades shown illustrate that, due to the multi-layer diffusion-welded high-speed forming structure of titanium alloy hollow fan blades, their structure and mechanical properties differ significantly from those of solid fan blades. If the methods used to evaluate the static strength and vibration characteristics of solid fan blades are applied, the evaluation process is relatively fragmented, leading to inaccurate evaluation results for hollow fan blades. Furthermore, traditional static strength assessments for solid fan blades primarily focus on the blade surface; applying the same methods to check the hollow welded cavities of hollow fan blades results in potentially risky assessments, which are detrimental to the durability and reliability design of hollow fan blades. Additionally, the methods for adjusting the cover weight of solid fan blades are not applicable to adjusting the cover weight of hollow fan blades. Summary of the Invention

[0004] The purpose of this application is to provide a hollow titanium alloy fan blade for an aero-engine and a method for evaluating its strength, in order to solve or mitigate at least one of the problems in the prior art.

[0005] The technical solution of this application is: a method for evaluating the strength of titanium alloy hollow fan blades for aero engines, the method comprising:

[0006] To make hollow fan blades have the same blade shape as solid fan blades, the circumferential coordinates of the centroid of the hollow fan blades are calculated based on the shroud amount of the solid fan blades and the mass of the hollow fan blades, so as to obtain the hollow fan blade structure that satisfies the reasonable shroud amount of the hollow fan blades.

[0007] The static stress distribution of the hollow fan blade is obtained through static strength analysis, and the vibration stress distribution of the hollow fan blade is obtained through vibration characteristic analysis. It is then determined whether the maximum point of the static stress distribution and vibration stress distribution of the hollow fan blade meets the requirements. If the requirements are not met, the structural parameters of the hollow fan blade are adjusted until the maximum point of the stress distribution and vibration stress distribution of the hollow fan blade meets the requirements.

[0008] The cross-sectional strength check location of the hollow fan blade is determined. Based on the stress amplitude-average stress and other life curves, the relationship between the strength of the solid fan blade and the strength of the hollow fan blade is established. Based on the static strength reserve standard of the solid fan blade being no less than the check strength of the solid fan blade, the strength of the hollow welded area of ​​the hollow fan blade is obtained.

[0009] Furthermore, the process of calculating the circumferential coordinates of the centroid of a hollow fan blade to achieve a reasonable shroud amount based on the solid fan blade shroud amount and the hollow fan blade mass includes:

[0010] The amount of material for a hollow fan blade is derived from the amount of material for a solid fan blade:

[0011]

[0012] In the formula, M xj,离 This refers to the centrifugal bending moment;

[0013] M xj,气 For aerodynamic bending moment;

[0014] M xj,合 For the combined bending moment;

[0015] m 空 Mass of the hollow blade;

[0016] ω is the rotational speed;

[0017] z i Let i be the radial coordinate of section i;

[0018] z j Let j be the radial coordinate of section j;

[0019] z k The radial coordinates of the 1, 2, ..., j sections when k = 1, 2, ..., j;

[0020] y j Let j be the circumferential coordinate of section j;

[0021] y i空 Here are the circumferential coordinates of section i of the hollow blade;

[0022] P yk The aerodynamic pressure on the blade surface at section 1, 2, ..., j when k = 1, 2, ..., j;

[0023] Mass relationship between solid fan blades and hollow fan blades m 空 =a·m 实 ;

[0024] In the formula, m 空 For the mass of the hollow blade, m 实 denoted as the mass of the solid blade, and 'a' as the hollowness ratio.

[0025] Based on the derived formula for the shroud volume of hollow fan blades and the mass relationship between solid and hollow fan blades, the circumferential centroid coordinates of the hollow fan blades are obtained:

[0026] Furthermore, the stress distribution area in the hollow region includes the hollow region ribs and wall plates, and the stress distribution area in the solid region includes the solid region blade surface.

[0027] Furthermore, the process for determining whether the locations of the maximum points of the static stress distribution and vibration stress distribution meet the requirements is as follows:

[0028] 1) When the point of maximum static stress is located in the hollow area of ​​the hollow fan blade and the point of maximum vibration stress is located in the solid area, increase the wall thickness or rib thickness near the point of maximum static stress.

[0029] 2) When the point of maximum static stress is located in the solid area of ​​the hollow fan blade and the point of maximum vibration stress is located in the hollow area, the bending or torsional nodal line position of the hollow fan blade is adjusted according to the dangerous vibration mode of the hollow fan blade in order to adjust the position of the point of maximum vibration stress.

[0030] 3) When the maximum static stress point and the maximum vibration stress point are both located in the hollow area of ​​the hollow fan blade, adjust the stiffness distribution of each surface of the hollow fan blade to enhance the cross-sectional stiffness of the hollow area.

[0031] The stress distribution of the hollow fan blade is satisfied when the maximum static and vibration stress points of the hollow fan blade are both located in the solid area of ​​the hollow fan blade.

[0032] Furthermore, the cross-sectional strength verification parts of the hollow fan blade include: the cavity diffusion welding part, the cavity inner wall plate, the cavity inner rib plate, the cavity hollow-solid transition part, the blade basin side surface, and the blade back side surface.

[0033] Furthermore, based on the stress amplitude-mean stress and other life curves, a relationship between solid fan blades and hollow fan blades is established. The process includes:

[0034] Establish formulas for calculating the static strength reserve of solid and hollow fan blades:

[0035]

[0036] In the formula, n b实 Reserve for the static strength of solid fan blades;

[0037] n b空 To provide static strength reserves for hollow fan blades;

[0038] σ b The ultimate strength of the blade material;

[0039] σ v实 Static stress of solid fan blades;

[0040] σ v空 Static stress in hollow fan blades;

[0041] Establish blade dynamic strength reserve n 动 Calculation formula:

[0042] In the formula, σ a For the allowable vibration stress, σ 动 This refers to the vibration stress of the blade;

[0043] Based on the assumption that the vibration stress of a solid fan blade is equal to that of a hollow fan blade, we obtain that the allowable vibration stress of a hollow fan blade is equal to that of a solid fan blade: σ a空 =σ a实 ;

[0044] The relationship is derived from the Goodman stress amplitude-mean stress isochronous life curve:

[0045]

[0046] Where b represents the degree of decrease in the fatigue limit of the hollow blade;

[0047] σ v空 The static stress is that of the hollow fan blades.

[0048] σ v实 The static stress of a solid fan blade;

[0049] σ -1空 The fatigue limit of the hollow fan blade;

[0050] σ -1实 The fatigue limit of solid fan blades;

[0051] Based on the strength verification formula, dynamic strength reserve formula, and relational formulas, the relationship between the strength of solid fan blades and the strength of hollow fan blades is obtained:

[0052] In addition, this application provides a hollow titanium alloy fan blade for an aero-engine, wherein the strength of the hollow fan blade is evaluated according to any of the above-described methods for evaluating the strength of hollow titanium alloy fan blades for aero-engines.

[0053] The hollow fan blade strength assessment method provided in this application can improve the design efficiency of hollow fan blade shroud. In the stress distribution assessment of blades that integrates static strength and vibration characteristics, the stress distribution assessment results are more reasonable and accurate, which can improve the durability and reliability of hollow fan blades. Attached Figure Description

[0054] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0055] Figure 1 Figure 1 shows a schematic diagram of a solid fan blade, where Figure 2a is a front view of the solid fan blade and Figure 3b is a top view of the solid fan blade.

[0056] Figure 2 Figure 1 shows a schematic diagram of a hollow fan blade, where Figure 2a is a front view of the hollow fan blade and Figure 3b is a top view of the hollow fan blade.

[0057] Figure 3 This is a flowchart of the strength evaluation method for titanium alloy fan blades of aero-engines according to this application.

[0058] Figure 4 This is a schematic diagram showing the adjustment of the shroud volume for a hollow fan blade.

[0059] Figure 5 This is a schematic diagram of the hollow and solid areas of a hollow fan blade.

[0060] Figure 6 This is a schematic diagram of the strength verification area for hollow fan blades.

[0061] Figure 7 This is a Goodman stress amplitude-mean stress diagram according to an embodiment of this application. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0063] like Figure 3 The flowchart shown illustrates the strength assessment method for hollow fan blades. The strength assessment method for titanium alloy hollow fan blades for aero-engines proposed in this application mainly comprises three parts:

[0064] Part 1: Assessment of the amount of hollow fan blade cover.

[0065] When rotor blades are operating, they are subjected to centrifugal bending moment caused by centrifugal force and aerodynamic bending moment caused by aerodynamic pressure. By designing a reasonable blade centrifugal center-of-mass coordinate system, the centrifugal bending moment can compensate for the aerodynamic bending moment, thereby reducing the bending stress of the blades and ensuring that the combined bending moment of the centrifugal and aerodynamic bending moments is within an acceptable adjustment range. The bending moment compensation is as follows: Figure 4 As shown in the figure. Section i is the section containing the blade's centroid, and section j is the section used for evaluating the blade shroud.

[0066] Hollow fan blades have the same blade shape as solid fan blades, but the difference lies in the mass change caused by the hollow interior of the hollow fan blade.

[0067] Based on the above principles, the circumferential (y-axis) coordinates of the centroid of a hollow fan blade that provides a reasonable (i.e., equivalent blade back-blade stress) shroud is calculated using the solid fan blade shroud amount and the hollow fan blade mass. The calculation process is as follows:

[0068] The formula for the amount of shroud for solid fan blades is used to derive the amount of shroud for hollow fan blades:

[0069]

[0070] In the formula, M xj,离 This refers to the centrifugal bending moment;

[0071] M xj,气 For aerodynamic bending moment;

[0072] M xj,合 For the combined bending moment;

[0073] m 空 Mass of the hollow blade;

[0074] ω is the rotational speed;

[0075] z i Let i be the radial coordinate of section i;

[0076] z j Let j be the radial coordinate of section j;

[0077] z k For k = 1, 2, ..., j, the radial coordinates of the sections 1, 2, ..., j;

[0078] y j Let j be the circumferential coordinate of section j;

[0079] y i空 Here are the circumferential coordinates of section i of the hollow blade;

[0080] P yk The aerodynamic pressure on the blade surface at sections 1, 2, ..., j when k = 1, 2, ..., j.

[0081] Relationship between the mass of solid and hollow fan blades: m 空 =a·m 实

[0082] In the formula, m 空 For the mass of the hollow fan blade, m 实 Let be the mass of the solid fan blade, and 'a' be the hollowness ratio.

[0083] The circumferential centroid coordinates of the hollow fan blades can be obtained from the above formula:

[0084] When designing hollow fan blades, the blade profile and solid fan blade structure are determined first. Then, a detailed hollow structure is designed according to the target hollowness ratio. Finally, after the hollow fan blade structure is finalized, strength calculations and shroud adjustments and optimizations are performed. The shroud amount for hollow blades cannot be designed during the performance and structural design phases; multiple rounds of shroud adjustments, optimizations, and evaluations must be conducted after the hollow blade design is complete.

[0085] Based on the mass relationship between solid and hollow fan blades in this application, the circumferential centroid coordinates y of the hollow fan blade can be obtained during the design of the hollow fan blade, according to the solid fan blade profile provided by the performance specialist and the target hollowness 'a' provided by the structural specialist. i空 This feedback is then relayed to the performance and structural professionals, allowing the hollow blade shroud design to be completed during the performance and structural design of the hollow fan blades, even if the shroud assessment is approved.

[0086] Part Two: Stress Distribution Assessment of Hollow Fan Blades Based on Integrated Static Strength and Vibration Characteristics

[0087] The inner cavity of hollow fan blades is formed by high-speed diffusion welding, which inevitably results in welding defects that affect the fatigue performance of the blades. The performance of the hollow region is worse than that of the solid region. When the maximum static or vibration stress is located in the hollow region, the weakest point of the hollow fan blade is also located there, which may manifest as insufficient dynamic strength reserve in the hollow region, thus weakening the overall durability and reliability of the hollow fan blade.

[0088] like Figure 5 The diagram shows the locations of the hollow region A1 and the solid region A2 of the hollow fan blade. The stress in the hollow region of the hollow fan blade is mainly distributed in the hollow region ribs and walls, while the stress in the solid region of the hollow fan blade is mainly distributed on the surface of the solid region.

[0089] The static stress distribution of the hollow fan blades was obtained through static strength analysis, and the vibration stress distribution was obtained through vibration characteristic analysis. When the point of maximum static stress or maximum vibration stress is located in the hollow region A1, the hollow fan blade is relatively dangerous; when the points of maximum static stress and maximum vibration stress coincide and are located in the hollow region A1, the hollow fan blade is at its most dangerous.

[0090] To address the above issues, this application provides corresponding optimization and improvement methods until the stress distribution assessment of the hollow fan blades is passed. The process includes:

[0091] 1) When the point of maximum static stress is located in the hollow region A1 and the point of maximum vibration stress is located in the solid region A2, increase the wall thickness or rib thickness near the point of maximum static stress to enhance local rigidity.

[0092] 2) When the point of maximum static stress is located in the solid region A2 and the point of maximum vibration stress is located in the hollow region A1, the position of the blade bending or torsional nodal line is adjusted according to the dangerous vibration mode of the hollow fan blade in order to adjust the position of the point of maximum vibration stress.

[0093] The adjustment process is as follows: Based on the position of the nodal line of the dangerous vibration mode, the thickness of the corresponding blade section is adjusted, either thickened or thinned, so that the position of the nodal line changes, that is, the vibration mode changes, and the corresponding maximum vibration stress point also moves accordingly, so that the maximum vibration stress point moves to the solid area.

[0094] 3) When both the maximum static stress point and the maximum vibration stress point are located in the hollow region A1, adjust the stiffness distribution of each surface of the hollow fan blade to enhance the cross-sectional stiffness of the hollow region.

[0095] The adjustment process involves increasing the overall thickness of the section at the point of maximum static and vibration stress, or increasing the thickness of the section wall and ribs, to enhance the stiffness of the weak section and thus optimize the overall stiffness distribution.

[0096] Through the above process of adjustment, until the maximum static stress and vibration stress points of the hollow fan blade are both located in the solid area A2, the stress distribution assessment of the hollow fan blade is passed.

[0097] Part Three: Blade Strength Verification Based on Comprehensive Blade Surface Stress Analysis and Cavity Internal Stress Analysis.

[0098] When verifying the strength of hollow fan blades, attention should be paid to the surface stress and internal stress of the cavity. Strength verification should be performed on all sections along the blade height. Figure 6 As shown, the cross-sectional strength check areas for hollow fan blades include:

[0099] 1) Cavity diffusion welding section 11;

[0100] 2) Internal wall panel 12 of the cavity;

[0101] 3) Internal ribs 13 of the cavity;

[0102] 4) Hollow-solid transition section 14 inside the cavity;

[0103] 5) Leaf side surface 15;

[0104] 6) The back surface of the blade 16.

[0105] Based on the test results of the diffusion welded test specimen of hollow fan blade, the strength of the diffusion welded part is close to that of the base material, and it is considered that the strength of the welded part is equal to that of the base material; in addition, the fatigue performance of the diffusion welded part is lower than that of the base material.

[0106] like Figure 7 As shown, this application proposes a strength verification method for the welded part of the cavity based on the blade Goodman stress amplitude-mean stress and other life curves. The aim is to control the strength and fatigue life of the welded part by controlling the static stress at the blade welded part. The process is as follows:

[0107] Static strength reserve formulas for solid and hollow fan blades:

[0108] In the formula, n b实 Reserve for the static strength of solid fan blades;

[0109] n b空 To provide static strength reserves for hollow fan blades;

[0110] σ b The ultimate strength of the blade material (the material is the same for both hollow and solid fan blades);

[0111] σ v实 The static stress of a solid fan blade;

[0112] σ v空 This represents the static stress of the hollow fan blade.

[0113] Blade dynamic strength reserve formula:

[0114] In the formula, σ a For the allowable vibration stress, σ 动 This represents the vibration stress of the blade.

[0115] To ensure that hollow fan blades and solid fan blades have the same reliability and durability, the dynamic strength reserve of hollow fan blades should be equal to that of solid fan blades. Based on the assumption that the vibration stress of solid fan blades is equal to that of hollow fan blades, the allowable vibration stress of hollow fan blades should be equal to that of solid fan blades, thus yielding: σ a空 =σ a实 ;

[0116] From the isolife curves of the Goodman stress amplitude-mean stress diagram, we can obtain:

[0117]

[0118] Where b represents the degree of decrease in the fatigue limit of the hollow blade, σ v空 For the static stress of the hollow fan blade, σ v实 For the static stress of a solid fan blade, σ -1空 For the fatigue limit of the hollow fan blade, σ -1实 This represents the fatigue limit of a solid fan blade.

[0119] From the above formula, we can obtain:

[0120] The static strength reserve standard for solid fan blades shall not be lower than the verification strength n of solid fan blades. b实 Therefore, the static stress reserve required for strength verification of the hollow welded area can be obtained to be no less than n. b空 .

[0121] The hollow fan blade strength assessment method provided in this application can improve the design efficiency of hollow fan blade shroud. In the stress distribution assessment of blades that integrates static strength and vibration characteristics, the stress distribution assessment results are more reasonable and accurate, which can improve the durability and reliability of hollow fan blades.

[0122] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for evaluating the strength of hollow titanium alloy fan blades for aero-engines, characterized in that, The method includes: To make hollow fan blades have the same blade shape as solid fan blades, the circumferential coordinates of the centroid of the hollow fan blades are calculated based on the shroud amount of the solid fan blades and the mass of the hollow fan blades, so as to obtain the hollow fan blade structure that satisfies the reasonable shroud amount of the hollow fan blades. The static stress distribution of the hollow fan blade is obtained through static strength analysis, and the vibration stress distribution of the hollow fan blade is obtained through vibration characteristic analysis. It is then determined whether the maximum point of the static stress distribution and vibration stress distribution of the hollow fan blade meets the requirements. If the requirements are not met, the structural parameters of the hollow fan blade are adjusted until the maximum point of the stress distribution and vibration stress distribution of the hollow fan blade meets the requirements. The cross-sectional strength check location of the hollow fan blade is determined. Based on the stress amplitude-mean stress isolife curve, a relationship is established between the strength of the solid fan blade and the strength reserve of the hollow fan blade. Based on the premise that the static strength reserve standard of the solid fan blade is not lower than the strength reserve of the solid fan blade, the strength reserve standard of the hollow welded area of ​​the hollow fan blade is obtained. The process of establishing the relationship between the strength of the solid fan blade and the strength reserve of the hollow fan blade based on the stress amplitude-mean stress isolife curve includes: Establish formulas for calculating the static strength reserve of solid and hollow fan blades: 、 ； In the formula, Reserve for the static strength of solid fan blades; To provide static strength reserves for hollow fan blades; The ultimate strength of the blade material; Static stress of solid fan blades; Static stress in hollow fan blades; Establish blade dynamic strength reserves Calculation formula: ; In the formula, For allowable vibration stress, This refers to the vibration stress of the blade; Based on the assumption that the vibration stress of a solid fan blade is equal to that of a hollow fan blade, we obtain that the allowable vibration stress of a hollow fan blade is equal to that of a solid fan blade: ; The relationship is derived from the Goodman stress amplitude-mean stress isochronous life curve: ； Where b represents the degree of decrease in the fatigue limit of the hollow blade; The fatigue limit of the hollow fan blade; The fatigue limit of solid fan blades; Based on the static strength reserve formula, the dynamic strength reserve formula, and the relationship obtained from the life curve of the Goodman stress amplitude-mean stress diagram, the relationship between the strength reserve of solid fan blades and the strength reserve of hollow fan blades is constructed as follows: .

2. The method for evaluating the strength of hollow titanium alloy fan blades for aero-engines as described in claim 1, characterized in that, The process of calculating the circumferential coordinates of the centroid of a hollow fan blade to achieve a reasonable shroud amount based on the solid fan blade cover and the hollow fan blade mass includes: The amount of material for a hollow fan blade is derived from the amount of material for a solid fan blade: ； In the formula, This refers to the centrifugal bending moment; For aerodynamic bending moment; For the combined bending moment; Mass of the hollow blade; Rotational speed; Let i be the radial coordinate of section i; Let j be the radial coordinate of section j; The radial coordinates of sections 1, 2, ..., j when k = 1, 2, ..., j; Let j be the circumferential coordinate of section j; Hollow blades Circumferential coordinates of the cross section; The aerodynamic pressure on the blade surface at section 1, 2, ..., j when k = 1, 2, ..., j; Mass relationship between solid fan blades and hollow fan blades ; In the formula, For solid blade quality, Hollow rate; Based on the derived formula for the shroud volume of hollow fan blades and the mass relationship between solid and hollow fan blades, the circumferential coordinates of the centroid of the hollow fan blade are obtained: .

3. The method for evaluating the strength of hollow titanium alloy fan blades for aero-engines as described in claim 2, characterized in that, The process for determining whether the locations of the maximum points of the static stress distribution and vibration stress distribution meet the requirements is as follows: 1) When the point of maximum static stress is located in the hollow area of ​​the hollow fan blade and the point of maximum vibration stress is located in the solid area, increase the wall thickness or rib thickness near the point of maximum static stress. 2) When the point of maximum static stress is located in the solid area of ​​the hollow fan blade and the point of maximum vibration stress is located in the hollow area, the bending or torsional nodal line position of the hollow fan blade is adjusted according to the dangerous vibration mode of the hollow fan blade in order to adjust the position of the point of maximum vibration stress. 3) When both the point of maximum static stress and the point of maximum vibration stress are located in the hollow region of the hollow fan blade, adjust the stiffness distribution of each surface of the hollow fan blade to enhance the cross-sectional stiffness of the hollow region. The stress distribution of the hollow fan blade is satisfied when the maximum static and vibration stress points of the hollow fan blade are both located in the solid area of ​​the hollow fan blade.

4. The method for evaluating the strength of hollow titanium alloy fan blades for aero-engines as described in claim 3, characterized in that, The hollow region stress distribution area of ​​the hollow fan blade includes the hollow region ribs and wall plates, and the solid region stress distribution area of ​​the hollow fan blade includes the solid region blade surface.

5. The method for evaluating the strength of hollow titanium alloy fan blades for aero-engines as described in claim 1, characterized in that, The cross-sectional strength verification areas of the hollow fan blades include: the cavity diffusion welding area, the cavity inner wall plate, the cavity inner rib plate, the cavity hollow-solid transition area, the blade basin side surface, and the blade back side surface.

6. A hollow titanium alloy fan blade for an aero-engine, characterized in that, The cross-sectional strength of the hollow fan blade is evaluated according to the strength evaluation method for titanium alloy hollow fan blades of aero-engines as described in any one of claims 1 to 5.

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