A design method of thin-walled structure feature mockup considering load transmission path

Abstract

The application discloses a design method of a thin-walled structure feature simulation piece considering a load transmission path, and comprises the following steps: extracting geometric features and load transmission path features of a thin-walled structure, so as to facilitate subsequent construction of a preliminary simulation piece and provide a prerequisite for realizing mechanical equivalence of the feature simulation piece and the actual thin-walled structure at a fatigue key position; constructing a preliminary simulation piece based on the geometric features and the load transmission path features of the thin-walled structure; establishing a parameterized geometric model based on the preliminary simulation piece, so as to facilitate subsequent iteration; taking stress distribution at an examination position and original structure equivalence as a target, iteratively optimizing geometric parameters of the geometric model, so as to output a feature simulation piece, so that the stress distribution of the feature simulation piece is equivalent to the original structure and is closer to the stress state of the original structure.

Description

Technical Field

[0001] This invention relates to the field of structural strength assessment for aero-engines, and more specifically to a design method for a thin-walled structural feature simulation component that considers the load transfer path. Background Technology

[0002] The gas turbine backsplash is a key component of an aero-engine, primarily responsible for isolating high-temperature gas passages, guiding airflow, sealing chambers, and providing local support connections. During engine operation, the backsplash isolates the high-temperature mainstream gas from the outer support chambers, cooling chambers, or adjacent load-bearing structures, preventing direct thermal erosion of surrounding components. Furthermore, through its cooperation with sealing structures and related components, it controls the flow and leakage of the secondary air system, ensuring the aerodynamic efficiency of turbine components and the operational safety of the hot-end structure. In addition, the backsplash plays a crucial role in the installation, positioning, and assembly rigidity of related components at the turbine's rear. Structurally, the turbine backsplash is typically installed and fixed to the turbine casing, guide vane supports, turbine disk, and other structures using flanges, bolts, pins, or stop fittings. During engine operation, due to its proximity to the high-temperature gas passages and the simultaneous assembly constraints and multi-field coupling effects, the gas turbine backsplash bears complex mechanical and thermal loads. Its rounded corners, bolt holes, and other local geometric features often exhibit high stress concentration, making them critical areas for low-cycle fatigue failure. However, in actual whole-machine testing, the stress state in these critical areas is difficult to measure directly, and whole-machine testing is costly and time-consuming. Therefore, in engineering, characteristic simulation component testing is often used to replace whole-machine testing. By designing simulation components with stress distribution equivalent to that of key parts of the actual structure, fatigue life assessment can be carried out.

[0003] With the continuous development of structural strength design technology, some preliminary results have been achieved in the field of aero-engine feature simulation component design, but there are still shortcomings. Existing feature simulation component design methods are mostly based on stress gradient equivalence on the assessment path, but it is difficult to accurately reproduce the real stress gradient of the structure, resulting in a large deviation between the simulation component and the real structure in fatigue life assessment, which makes it difficult to meet the requirements of high-precision equivalent characterization. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned defects or problems existing in the prior art or to provide a material basis for overcoming the aforementioned defects or problems existing in the prior art, and to provide a design method for a thin-walled structural feature simulation component that considers the load transfer path.

[0005] To achieve the above objectives, the present invention and its preferred embodiments employ the following technical solutions, but the embodiments are not limited to the following solutions: Option 1: A design method for a thin-walled structural feature simulation component considering load transfer paths, comprising the following steps: Extract the geometric features and load transfer path features of the thin-walled structure, and construct a preliminary simulation based on the geometric features and load transfer path features of the thin-walled structure; A parametric geometric model is established based on the preliminary simulation component. The goal is to make the stress distribution at the test location equivalent to the original structure. The geometric parameters of the geometric model are iteratively optimized to output the characteristic simulation component.

[0006] Option 2, based on Option 1, includes geometric features such as the fillet radius R and local wall thickness t at the assessment location; the preliminary simulation component includes a side hole, a center hole, and a through hole, the center hole extending along a first direction, the side hole extending along a second direction perpendicular to the first direction, the side hole opening on the side of the preliminary simulation component, the side hole having an arc corner with a fillet radius R, the side hole being located in the second direction of the center hole, the centerline of the side hole parallel to the second direction being directly opposite the center of the center hole, and the distance between the side hole and the center hole being t; the through hole being parallel to the centerline of the first direction being directly opposite the center of the center hole, and located in the first direction of the center hole; The geometric parameters for iterative optimization include at least one or more of the following: the dimension a of the side hole along the first direction, the dimension c of the center hole along the first direction, the dimension d of the center hole along the second direction, and the dimension e of the side hole along the second direction.

[0007] Option 3, based on Option 2, involves symmetrically arranging the side holes on both sides of the central hole along the second direction, and symmetrically arranging the through holes on both sides of the central hole along the first direction.

[0008] Option 4, based on Option 2, involves constructing a preliminary simulation component, including the following steps: Based on a flat substrate, a first simulation component is provided. The first simulation component includes a first plate, a second plate, and a boss structure protruding from both sides of the first plate, wherein the boss structure has an arc angle with a radius R at the connection with the first plate. Add supporting ribs to connect the free end of the boss structure and the second plate to form a second simulated part with supporting ribs; A third simulation element is formed symmetrically along an axis of symmetry parallel to the second direction based on the second simulation element to form the side hole, wherein the axis of symmetry is located on the side of the arc angle opposite to the second plate; The second plate between the support ribs is removed based on the third simulation component to form the through hole, and the central hole is set to form the preliminary simulation component.

[0009] Option 5, based on Option 2, establishes a parametric geometric model and then imposes a time-fixed constraint on one end of the geometric model along the first direction, while applying a uniformly distributed tensile load to the other end, with the load direction parallel to the first direction; The geometric model is meshed using the finite element method, and the stress field distribution of the geometric model under a given load is solved. Based on the finite element calculation results, the maximum principal stress node on the surface of the side hole root is taken as the starting point of the assessment path. The path is defined as extending outward along the second direction with the starting point as the origin. The maximum principal stress value of each node is extracted at equal intervals along the assessment path. The maximum principal stress value of each point is divided by the maximum principal stress value at the starting point of the path to obtain the normalized stress gradient. The obtained normalized stress gradient is compared and analyzed with the original structural stress gradient within the critical distance to optimize the geometric parameters of the geometric model and output the final simulated part.

[0010] Option 6, based on Option 5, involves locally refining the mesh at the root of the side hole or other areas with large stress gradients when performing finite element mesh generation on the geometric model.

[0011] Scheme 7, based on Scheme 5, has the following iterative output conditions: The root mean square error of the normalized stress gradient within the critical distance is less than 5%; and the maximum principal stress value at the test position of the preliminary simulation part is equal to the maximum principal stress value at the test position of the original structure.

[0012] Option 8, based on Option 1, before the step of extracting the geometric features and load transfer path features of the thin-walled structure: For thin-walled structures, sector sub-models or overall finite element models are established. Boundary conditions and loads under service conditions are applied, and linear elastic finite element analysis is performed. Based on the calculation results, the maximum principal stress point and its region are identified as fatigue weak critical parts. Starting from the maximum principal stress point of the weak critical part, several stress gradient extraction paths are set along the critical plane, and the maximum principal stress distribution on each path is extracted. The path with the fastest stress decrease rate is selected as the assessment stress gradient path. The stress distribution on the assessment path is normalized, and the double slope method is used to perform linear fitting on the high-stress area and the low-stress area respectively. The intersection of the two fitted lines is taken as the critical distance endpoint, and the critical distance is calculated. Finally, the normalized stress gradient is fitted with a polynomial to establish a continuous and differentiable stress gradient characterization function.

[0013] As can be seen from the above description of the present invention and its preferred embodiments, compared with the prior art, the technical solution of the present invention and its preferred embodiments have the following beneficial effects due to the adoption of the following technical means: Through continuous observation, experimentation, and research, the applicant has learned that existing design methods for feature simulation components are mostly based on the equivalent stress gradient on the assessment path, but lack systematic extraction and equivalent mapping of geometric and load features. In thin-walled structures, the load transfer path can cause significant changes in stress distribution, making it difficult for traditional methods to accurately reproduce the true stress gradient of the structure.

[0014] A design method for a characteristic simulation component of a thin-walled structure considering load transfer paths includes the following steps: extracting the geometric features and load transfer path features of the thin-walled structure to facilitate the subsequent construction of a preliminary simulation component and to provide a prerequisite for achieving mechanical equivalence between the characteristic simulation component and the actual thin-walled structure at key fatigue locations; constructing a preliminary simulation component based on the geometric features and load transfer path features of the thin-walled structure; establishing a parametric geometric model based on the preliminary simulation component to facilitate subsequent iterations; and iteratively optimizing the geometric parameters of the geometric model with the goal of achieving stress distribution equivalence with the original structure at the test location to output the characteristic simulation component, thereby making the stress distribution of the characteristic simulation component equivalent to the original structure and closer to the stress state of the original structure. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments are briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the gas turbine rear baffle in Embodiment 1; Figure 2 This is a schematic diagram of the double slope method in Example 1; Figure 3 This is a schematic diagram illustrating the extraction of geometric features and load transfer path features of the thin-walled structure in Example 1; Figure 4 This is a schematic diagram of the geometric style of the preliminary feature simulation part designed in Example 1; Figure 5 This is a schematic diagram of the key geometric parameters in Example 1; Figure 6 This is a schematic diagram of a design method for a thin-walled structural feature simulation component that considers the load transfer path in Embodiment 1; Figure 7 This is a schematic diagram of the first simulated component in Example 1; Figure 8 This is a schematic diagram of the second simulated component in Example 1; Figure 9 This is a schematic diagram of the preliminary simulation component in Example 1; Figure 10 This is a schematic diagram of the danger plane in Example 1; Figure 11 This is a perspective view of the flat plate substrate in Example 1; Figure label: First plate 1; Second plate 2; Boss structure 3; Arc angle 31; Supporting rib 4; Through hole 5; Side hole 6; Center hole 7; First direction 8; Second direction 9; Detailed Implementation The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are preferred embodiments of the present invention and should not be considered as excluding other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] Unless otherwise expressly defined, the use of terms such as "first," "second," or "third" in the claims, description, and accompanying drawings of this invention is for distinguishing different objects and not for describing a specific order.

[0018] Unless otherwise expressly defined, in the claims, description, and accompanying drawings of this invention, the use of directional terms such as "center," "lateral," "longitudinal," "horizontal," "vertical," "top," "bottom," "inner," "outer," "upper," "lower," "front," "rear," "left," "right," "clockwise," and "counterclockwise" to indicate orientation or positional relationships is based on the orientation and positional relationships shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the specific scope of protection of this invention.

[0019] Unless otherwise expressly defined, the terms "fixed connection" or "fixed connection" used in the claims, description and drawings of this invention should be interpreted broadly to refer to any connection in which there is no displacement or relative rotation relationship between the two parties, including non-removable fixed connection, detachable fixed connection, integral connection and fixed connection by other means or components.

[0020] In the claims, description and accompanying drawings of this invention, the terms "comprising," "having," and variations thereof are used to mean "including but not limited to."

[0021] A design method for a simulation component of a thin-walled structure considering the load transfer path is proposed. The simulation component designed by this method can achieve high-precision equivalent characterization of the fatigue performance of key parts of the thin-walled structure, and can be used to replace the actual thin-walled structure for testing, thereby reducing testing costs.

[0022] Before preparing to design the simulation component, we must first analyze the corresponding performance of the actual thin-walled structure, specifically.

[0023] S1: Establish a finite element model of the thin-walled structure and identify weak and critical components. For practical thin-walled structures (such as gas turbine backsplashes, etc.) Figure 1 As shown in the figure, a sector sub-model or an overall finite element model is established, boundary conditions and loads under service conditions are applied, and linear elastic finite element analysis is carried out. Based on the calculation results, the maximum principal stress point and its region are identified as the fatigue weak key parts.

[0024] S2: Extract the stress gradient and critical distance at the assessment location (location of maximum stress). Starting from the point of maximum principal stress in the weakest and most critical part, along the critical plane (the plane where the load acts perpendicularly; in thin-walled structures, this specifically refers to the plane where centrifugal force acts), such as... Figure 10 As shown in the diagram. The red dots represent the points of maximum stress obtained from the finite element analysis. Several stress gradient extraction paths are set within the diagram, and the maximum principal stress distribution on each path is extracted. The path with the fastest stress decrease rate is selected as the stress gradient path for evaluation.

[0025] The stress distribution along the assessment path is normalized, and a double-slope method is used to perform linear fitting on the high-stress and low-stress areas respectively. The intersection of the two fitted lines is taken as the critical distance endpoint, and the critical distance L is calculated. The double-slope method is as follows: Figure 2 As shown, the horizontal axis represents the distance from the stress peak point on the stress gradient, in mm. Simultaneously, a polynomial fitting is performed on the normalized stress gradient to establish a continuously differentiable stress gradient characterization function. In step S2, the polynomial fitting form of the normalized stress gradient is:

[0026] in The stress value at node x. The maximum stress; For polynomial coefficients, Let i be the exponent. The polynomial is fitted using the `polyfit` function in MATLAB code. For example, assuming i=3, then the polynomial is a3x. 3 +a2x 2 +a1x+a0.

[0027] The simulation of the model will then proceed as follows: S3: Extract the geometric features and load transfer path features of thin-walled structures; To achieve mechanical equivalence between the simulated component and the actual thin-walled structure at critical fatigue locations, geometric features and load transfer path features that have a key impact on local stress distribution and fatigue life are extracted from the original structure, such as... Figure 3 As shown, it includes: (1) Fillet radius R: The geometric fillet radius of the fillet transition zone in the weak and critical part. This feature directly affects the stress concentration factor and local stress gradient; (2) Local wall thickness t: The minimum wall thickness at the weak and critical parts. This feature determines the local stiffness and bending resistance of the structure and has a significant impact on the stress response under bending moment. (3) Bending moment caused by wheel disk mating or connection boundary: Under actual service conditions, the rear baffle mats with the turbine disk through the boss structure 3, bolts or stop, etc. Due to the geometric constraints of the mating surface and the eccentricity of the load transfer path, additional bending moment will be generated at key locations such as the fillet. This bending moment effect is the key load characteristic that causes significant bending stress components at the fillet of the baffle, thus affecting fatigue life.

[0028] Specifically, the physical source of the bending moment effect is as follows: Under the action of axial force, radial force, or centrifugal load, the mating interface between the boss structure 3 and the turbine disk experiences force due to the eccentricity of the mating surface geometry or the asymmetry of the constraints, causing the force transmission path to deviate from the neutral axis. This results in the superposition of bending stress in areas of geometric abrupt changes such as fillets. This bending moment cannot be simulated by simple uniaxial tension or uniformly distributed load; it must be equivalently reproduced through the design of a reasonable load transfer path in the simulation component.

[0029] S4: Constructing a preliminary simulation based on the geometric features and load transfer path characteristics of thin-walled structures; Based on the geometric features (corner radius R, local wall thickness t) and load transfer path features (bending moment effect) extracted in step S3, a preliminary simulation component is constructed step by step according to the technical logic of "geometric reproduction—stability enhancement—load path decoupling—stress concentration and wall thickness control". The specific steps are as follows: The preliminary simulation component includes side holes 6, a central hole 7, and a through hole 5. The central hole 7 extends along a first direction 8, and the side holes 6 extend along a second direction 9 perpendicular to the first direction 8. The side holes 6 open onto the side of the preliminary simulation component, forming a U-shaped notch structure. The side holes 6 have an arc angle 31 with a radius of R. The side holes 6 are located on the second direction 9 of the central hole 7, with the center line of the side holes 6 parallel to the second direction 9 directly opposite the center of the central hole 7, and the distance between the side holes 6 and the central hole 7 is t. The through hole 5 is parallel to the center line of the first direction 8, directly opposite the center of the central hole 7, and located on the first direction 8 of the central hole 7 to reproduce the load transfer path characteristics. The side holes 6 are symmetrically arranged on both sides of the central hole 7 along the second direction 9, and the through holes 5 are symmetrically arranged on both sides of the central hole 7 along the first direction 8. Specifically... S4.1: Design a first simulated component with a boss feature to reproduce the fillet radius. With a flat substrate (such as Figure 11As shown in the figure, based on the basic configuration of the simulation component, a boss structure 3 is set in the test area (the area on the simulation component used to simulate the stress value of the actual thin-walled structure test position). The root of the boss structure 3 adopts the same fillet radius R as the original structure, thus setting the first simulation component. This step ensures that the geometry of the simulation component at the test position (i.e., the fillet transition) is consistent with the original structure. In addition, in order to prevent the simulation component from becoming unstable during the loading process (during the experimental loading process, the forces on both sides of the simulation component are uneven, which leads to violent fluctuations in the load-displacement curve and reduces the number of cycles that the simulation component can withstand), the boss structure 3 needs to be symmetrically treated.

[0030] Therefore, the structure of the first simulation component is as follows: the first simulation component includes a first plate 1 and a second plate 2 extending along the first direction 8, and a boss structure 3 protruding from both sides of the first plate 1 along the second direction 9 perpendicular to the first direction 8. The boss structure 3 has an arc angle 31 with a radius of R at the connection with the first plate 1. The dividing line between the first plate 1 and the second plate 2 is parallel to the second direction 9 and coincides with the side of the boss structure 3 that is away from the arc angle 31.

[0031] S4.2: Add 4 supporting ribs to enhance structural stability.

[0032] Add a support rib 4 to connect the free end of the boss structure 3 and the second plate 2 to form a second simulated component with the support rib 4; so that the boss structure 3 can bear tensile load, and the tensile load is transmitted to the root of the boss structure 3 through the support rib 4, causing the stress response in the test area to change.

[0033] S4.3: Symmetrical treatment to prevent loading instability The third simulation component is formed symmetrically along an axis of symmetry parallel to the second direction 9 based on the second simulation component to form the side hole 6. The axis of symmetry is located on the side of the arc angle 31 away from the second plate 2. The symmetrical design can eliminate the unexpected interference of the additional bending moment caused by eccentric loading on the stress distribution in the test area, and at the same time avoid the simulation component from undergoing overall bending or torsional instability during tensile loading, ensuring that the test area is in a controllable stress state.

[0034] S4.4: Remove the second plate 2 between the support ribs 4 to make the load transfer path closer to the actual working condition. Based on the third simulation, the second plate 2 between the support ribs 4 is removed to form a through hole 5. The through hole 5 consists of a boss structure 3, a first plate 1, support ribs 4, and the remaining second plate 2, roughly in the shape of a trapezoid. The side closest to the side hole 6 is the long side of the trapezoid. The transition angle at the connection of each hole wall of the through hole 5 can be gradually increased by increasing the radius of curvature according to the stress concentration in that area until the local stress concentration coefficient in that area is reduced to an acceptable level. This step connects the left and right parts only through the root of the boss structure 3 in the test area. This operation aims to decouple the load transfer path in the non-test area, so that the tensile load is mainly transferred through the root of the boss structure 3, thereby producing an "eccentric force transmission - local bending" effect similar to that of the real rear baffle in the test area, that is, realizing the equivalent reproduction of the bending moment effect described in step S3.

[0035] S4.5: Introducing the central hole 7 and forming a U-shaped notch structure simulation component, simultaneously achieving wall thickness control, opening simulation, and stress gradient adjustment: Finally, a central hole 7 is set to form the preliminary simulation part. A circular or elliptical central hole 7 is introduced at the center of the root of the boss structure 3 in the test area. By adjusting the distance between the central hole 7 and the notch test platform, the minimum cross-sectional width (dimension b) of the U-shaped notch root is precisely controlled, making it equal to the local wall thickness t of the original structure. Figure 3 (Dimension B in the diagram). This minimum cross-sectional width is a core geometric parameter that determines the stress level and stress gradient in the test area. The introduction of the central hole 7 causes the maximum principal stress to occur at the root of the notch; at the same time, by adjusting the size and position of the central hole 7, the stress gradient in the test area can be finely adjusted to meet the equivalent stress gradient requirements extracted in step S2.

[0036] Finally, after the above five sub-steps, such as Figure 4 As shown, the "U-shaped notch structure feature simulation component" was determined as the geometric style of the initial simulation component. This geometric style has the following characteristics: the radius R of the fillet at the root of the boss structure 3 is consistent with the original structure; the symmetrical structure ensures loading stability; the removal of the central beam structure achieves equivalent bending moment effect; and through the coordinated design of the central hole 7 and the U-shaped notch, the wall thickness t is accurately reproduced, the opening feature is simulated, and the stress gradient is controllably adjusted.

[0037] S5: Establishing a parametric model and finite element iterative optimization A parametric geometric model is established based on the preliminary simulation component; with the goal of making the stress distribution at the test location equivalent to the original structure, the geometric parameters of the geometric model are iteratively optimized to output the characteristic simulation component.

[0038] Specifically: S5.1: Establishing a parametric geometric model Establish a parametric geometric model of the preliminary simulation part. The key geometric parameters include at least one or more of the following: dimension a (arc spacing) of the side hole 6 along the first direction 8, dimension c (height of the center hole 7) of the center hole 7 along the first direction 8, dimension d (width of the center hole 7) of the center hole 7 along the second direction 9, and dimension e (depth of the side hole 6) of the side hole 6 along the second direction 9. The above geometric parameters can be used as variables during iterative optimization.

[0039] S5.2: Apply boundary conditions and loads The geometric model is subjected to a time-fixed constraint at one end along the first direction 8, constraining all translational and rotational degrees of freedom; a uniformly distributed tensile load is applied to the other end, with the load direction parallel to the first direction 8; during the iteration process, the magnitude of the tensile load can be adjusted so that the maximum principal stress at the test position of the simulated part is equal to the maximum principal stress value at the test position of the original structure.

[0040] S5.3: Finite Element Mesh Generation and Solution High-order elements were used to mesh the geometric model using finite element methods, with local meshing applied to the root of the side holes or other areas with large stress gradients to ensure computational accuracy. Linear elastic finite element analysis was then performed to solve for the stress field distribution of the geometric model under a given load. S5.4: Extract the stress gradient at the test location of the simulated part Based on the finite element calculation results, the maximum principal stress node on the root surface of the side hole 6 is taken as the starting point of the assessment path. The assessment path is defined as extending outward along the second direction 9 with the starting point as the origin. The maximum principal stress value of each node is extracted at equal intervals along the assessment path. The maximum principal stress value of each point is divided by the maximum principal stress value of the starting point of the path to obtain discrete stress gradient data. The normalized stress gradient is obtained by dividing the maximum principal stress value of each point by the maximum principal stress value of the starting point of the path. S5.5: Error Analysis and Iterative Optimization The obtained normalized stress gradient is compared with the original structural stress gradient within the critical distance to optimize the geometric parameters of the geometric model (a, c, d, e above) so that the simulated part meets the following two design criteria: Criterion 1: The root mean square error of the normalized stress gradient within the critical distance is less than 5%; Criterion 2: The maximum principal stress value at the test location of the preliminary simulation component is equal to the maximum principal stress value at the test location of the original structure (achieved by adjusting the tensile load, or by adjusting the geometric parameters to match the stress concentration factor).

[0041] S5.6: Output Results Based on the optimal combination of geometric parameters, complete the full geometric model of the feature simulation part and output the final simulation part.

[0042] S6: Determine the final feature simulation component design scheme Based on the iterative optimization results of step S5, the optimal combination of geometric parameters that satisfies the stress gradient equivalence and the consistency of the maximum principal stress is determined, engineering drawings of the feature simulation part are generated, and the processing requirements (such as smooth transition of rounded corners, surface roughness, shot peening state, etc.) are specified.

[0043] S7: Experimental Verification Stress-controlled fatigue tests were conducted on the designed characteristic simulation parts under service temperature, stress ratio, and frequency conditions. The fatigue life of the simulation parts was compared with the test life of the whole machine to verify the effectiveness of the design method.

[0044] (1) This invention is the first to systematically propose a feature simulation design method with triple equivalent of “geometric features-load transfer path-stress gradient”, which can reproduce the stress distribution and fatigue damage mechanism of key parts of thin-walled structures with high accuracy; (2) The present invention uses the critical distance theory and the double slope method to quantify the stress gradient, and combines it with parametric finite element iterative optimization to control the stress gradient error between the simulated part and the original structure within the critical distance to within 5%, which significantly improves the accuracy of fatigue life equivalent characterization. (3) The U-shaped notch feature simulation component designed in this invention can effectively simulate the bending moment and local wall thickness constraints in the original structure, overcoming the defect of traditional simulation component design ignoring the load transfer path; (4) The method of the present invention can be extended to the design of characteristic simulation parts of thin-walled structures of various aero-engines (such as turbine disks, baffles, casings, etc.), and has wide engineering applicability.

[0045] Compared with the prior art, this embodiment has the following beneficial effects: In one exemplary embodiment, a design method for a feature simulation component of a thin-walled structure considering load transfer paths includes the following steps: extracting the geometric features and load transfer path features of the thin-walled structure to facilitate the subsequent construction of a preliminary simulation component and to provide a prerequisite for achieving mechanical equivalence between the feature simulation component and the actual thin-walled structure at key fatigue locations; constructing a preliminary simulation component based on the geometric features and load transfer path features of the thin-walled structure; establishing a parametric geometric model based on the preliminary simulation component to facilitate subsequent iterations; and iteratively optimizing the geometric parameters of the geometric model with the goal of achieving stress distribution equivalence with the original structure at the test location to output the feature simulation component, thereby making the stress distribution of the feature simulation component equivalent to the original structure and closer to the stress state of the original structure.

[0046] In one exemplary embodiment, the geometric features include the fillet radius R and local wall thickness t at the assessment location; the preliminary simulation component includes a side hole 6, a central hole 7, and a through hole 5. The central hole 7 extends along a first direction 8, and the side hole 6 extends along a second direction 9 perpendicular to the first direction 8. The side hole 6 opens onto the side of the preliminary simulation component and has an arc angle 31 with a fillet radius of R. The side hole 6 is located on the second direction 9 of the central hole 7, and the center line of the side hole 6 parallel to the second direction 9 is directly opposite the center of the central hole 7, with a distance t between the side hole 6 and the central hole 7; the through hole 5 is parallel to the center line of the first direction 8, directly opposite the center of the central hole 7, and located on the first direction 8 of the central hole 7; the iteratively optimized geometric parameters include at least one or more of the following: the dimension a of the side hole 6 along the first direction 8, the dimension c of the central hole 7 along the first direction 8, the dimension d of the central hole 7 along the second direction 9, and the dimension e of the side hole 6 along the second direction 9, to form a corresponding preliminary simulation component capable of initially simulating the corresponding geometric features and load transfer path features of the thin-walled structure.

[0047] In one exemplary embodiment, the side holes 6 are symmetrically arranged on both sides of the central hole 7 along the second direction 9, and the through holes 5 are symmetrically arranged on both sides of the central hole 7 along the first direction 8. The symmetrical design can eliminate the unexpected interference of the additional bending moment caused by eccentric loading on the stress distribution in the test area, so as to avoid the simulation part from undergoing overall bending or torsional instability during tensile loading.

[0048] In one exemplary embodiment, constructing a preliminary simulation component includes the following steps: Based on a flat substrate, a first simulation component is constructed. The first simulation component includes a first plate 1 extending along a first direction 8, a second plate 2, and boss structures 3 protruding from both sides of the first plate 1. The boss structures 3 are symmetrically designed to prevent instability of the simulation component during loading. The connection between the boss structure 3 and the first plate 1 has an arc angle 31 with a radius R to simulate the arc angle 31 of a thin-walled structure. Supporting ribs 4 are added to connect the free end of the boss structure 3 and the second plate 2, forming a second simulation component with supporting ribs 4. This allows the boss to bear tensile loads, which are transmitted to the root of the boss structure 3 through the supporting structure, causing changes in the stress response of the test area and enhancing structural stability. The third simulation component is formed symmetrically along the axis of symmetry parallel to the second direction 9 based on the second simulation component to form the side hole 6. The axis of symmetry is located on the side of the arc angle 31 away from the second plate 2. The symmetrical design can eliminate the unexpected interference of the additional bending moment caused by eccentric loading on the stress distribution of the test area, and at the same time avoid the simulation component from undergoing overall bending or torsional instability during tensile loading, ensuring that the test area is in a controllable stress state.

[0049] Based on the removal of the second plate 2 between the support ribs 4 in the third simulation component, a through hole 5 is formed, so that the left and right parts are connected only through the root of the boss structure 3 in the test area. This operation aims to decouple the load transmission path in the non-test area, so that the tensile load is mainly transmitted through the root of the boss structure 3, thereby producing an "eccentric force transmission - local bending" effect similar to the real back baffle in the test area, and realizing the equivalent reproduction of the bending moment effect; and a central hole 7 is set to form a preliminary simulation component. By adjusting the distance between the central hole 7 and the side hole 6, it is made equal to the local wall thickness of the original structure.

[0050] In one exemplary embodiment, after establishing a parametric geometric model, one end of the geometric model along the first direction 8 is completely fixed in time, and a uniformly distributed tensile load is applied to the other end. The load direction is parallel to the first direction 8 to simulate the load on the actual thin-walled structure. During the iteration process, the magnitude of the tensile load can be adjusted so that the maximum principal stress at the test position of the simulated part is equal to the maximum principal stress value at the test position of the original structure.

[0051] The geometric model is meshed using the finite element method (FEM) and the stress field distribution under a given load is solved. Based on the FEM calculation results, the node with the maximum principal stress on the root surface of the side hole 6 is used as the starting point of the assessment path. The assessment path is defined as extending outward along the second direction 9 with the starting point as the origin. The maximum principal stress value of each node is extracted at equal intervals along the assessment path. The maximum principal stress value of each point is divided by the maximum principal stress value at the starting point of the path to obtain the normalized stress gradient. This gradient is compared with the original structure to determine whether the iteration has ended. The obtained normalized stress gradient is compared with the assessment stress gradient of the original structure within the critical distance to optimize the geometric parameters of the geometric model and output the final simulated part.

[0052] In one exemplary embodiment, when performing finite element mesh generation on the geometric model, local meshing is performed on the root of the side hole 6 or other areas with large stress gradients to ensure calculation accuracy.

[0053] In one exemplary embodiment, the iterative output conditions are: the root mean square error of the normalized stress gradient within the critical distance is less than 5%; and the maximum principal stress value at the preliminary simulated part's test position is equal to the maximum principal stress value at the original structure's test position, so as to match the actual situation as closely as possible.

[0054] In one exemplary embodiment, prior to the steps of extracting the geometric features and load transfer path features of the thin-walled structure: For thin-walled structures, sector sub-models or overall finite element models are established. Boundary conditions and loads under service conditions are applied, and linear elastic finite element analysis is performed. Based on the calculation results, the maximum principal stress point and its region are identified as fatigue weak critical parts. Starting from the maximum principal stress point of the weak critical part, several stress gradient extraction paths are set along the critical plane, and the maximum principal stress distribution on each path is extracted. The path with the fastest stress decrease rate is selected as the assessment stress gradient path. The stress distribution on the assessment path is normalized, and the high-stress area and low-stress area are linearly fitted using the double-slope method. The intersection of the two fitted lines is taken as the critical distance endpoint, and the critical distance is calculated. The normalized stress gradient is then fitted with a polynomial to establish a continuously differentiable stress gradient characterization function. Through preprocessing, the corresponding stress analysis of the actual thin-walled structure is formed for comparison when forming characteristic simulation parts later, thereby obtaining characteristic simulation parts that conform to the actual situation and making the simulation results more accurate.

[0055] The foregoing description of the specifications and embodiments is intended to explain the scope of protection of this invention, but does not constitute a limitation on the scope of protection of this invention. Modifications, equivalent substitutions, or other improvements to the embodiments of this invention or a portion thereof that can be obtained by those skilled in the art through logical analysis, reasoning, or limited experimentation, based on the teachings of this invention or the foregoing embodiments, in conjunction with common knowledge, general technical knowledge, and / or existing technology, should all be included within the scope of protection of this invention.

Claims

1. A design method for a thin-walled structural feature simulation component considering load transfer path, characterized in that: Includes the following steps, Extract the geometric features and load transfer path features of the thin-walled structure, and construct a preliminary simulation based on the geometric features and load transfer path features of the thin-walled structure; A parametric geometric model is established based on the preliminary simulation component. The goal is to make the stress distribution at the test location equivalent to the original structure. The geometric parameters of the geometric model are iteratively optimized to output the characteristic simulation component.

2. The design method for a thin-walled structural feature simulation component considering load transfer path as described in claim 1, characterized in that: The geometric features include the fillet radius R and local wall thickness t of the test position; the preliminary simulation part includes a side hole (6), a center hole (7) and a through hole (5), the center hole (7) extends along a first direction (8), the side hole (6) extends along a second direction (9) perpendicular to the first direction (8), the side hole (6) opens on the side of the preliminary simulation part, the side hole (6) is provided with an arc corner (31), the fillet radius of the arc corner (31) is R, the side hole (6) is located on the second direction (9) of the center hole (7), the center line of the side hole (6) parallel to the second direction (9) is directly opposite the center of the center hole (7), and the distance between the side hole (6) and the center hole (7) is t; the through hole (5) is parallel to the center line of the first direction (8) and is directly opposite the center of the center hole (7), and is located on the first direction (8) of the center hole (7); The geometric parameters for iterative optimization include at least one or more of the following: the dimension a of the side hole (6) along the first direction (8), the dimension c of the center hole (7) along the first direction (8), the dimension d of the center hole (7) along the second direction (9), and the dimension e of the side hole (6) along the second direction (9).

3. The design method for a thin-walled structural feature simulation component considering load transfer path as described in claim 2, characterized in that: The side holes (6) are symmetrically arranged on both sides of the central hole (7) along the second direction (9), and the through holes (5) are symmetrically arranged on both sides of the central hole (7) along the first direction (8).

4. The design method for a thin-walled structural feature simulation component considering load transfer path as described in claim 2, characterized in that: The construction of the initial simulation includes the following steps: Based on a flat substrate, a first simulation component is provided. The first simulation component includes a first plate (1) extending along a first direction (8), a second plate (2), and a boss structure (3) protruding from both sides of the first plate (1). The boss structure (3) has an arc angle (31) with a radius R at the connection between it and the first plate (1). Add a support rib (4) to connect the free end of the boss structure (3) and the second plate (2) to form a second simulation piece with a support rib (4); The third simulation element is formed symmetrically along an axis of symmetry parallel to the second direction (9) based on the second simulation element to form the side hole (6), the axis of symmetry being located on the side of the arc angle (31) away from the second plate (2); The second plate (2) between the supporting ribs (4) is removed based on the third simulation to form the through hole (5), and the center hole (7) is set to form the preliminary simulation.

5. The design method for a thin-walled structural feature simulation component considering load transfer path as described in claim 2, characterized in that: After establishing the parameterized geometric model, the time of one end of the geometric model along the first direction (8) is completely fixed and constrained, and a uniformly distributed tensile load is applied to the other end, with the load direction parallel to the first direction (8). The geometric model is meshed using the finite element method, and the stress field distribution of the geometric model under a given load is solved. Based on the finite element calculation results, the maximum principal stress node on the root surface of the side hole (6) is used as the starting point of the assessment path. The path is defined as extending outward along the second direction (9) with the starting point as the origin. The maximum principal stress value of each node is extracted at equal intervals along the assessment path. The maximum principal stress value of each point is divided by the maximum principal stress value at the starting point of the path to obtain the normalized stress gradient. The obtained normalized stress gradient is compared and analyzed with the original structural stress gradient within the critical distance to optimize the geometric parameters of the geometric model and output the final simulated part.

6. The design method for a thin-walled structural feature simulation component considering load transfer path as described in claim 5, characterized in that: When performing finite element mesh generation on the geometric model, local meshing is performed on the root of the side hole (6) or other areas with large stress gradients.

7. The design method for a thin-walled structural feature simulation component considering load transfer path as described in claim 5, characterized in that: The iterative output condition is: The root mean square error of the normalized stress gradient within the critical distance is less than 5%; and the maximum principal stress value at the test position of the preliminary simulation part is equal to the maximum principal stress value at the test position of the original structure.

8. The design method for a thin-walled structural feature simulation component considering load transfer path as described in claim 1, characterized in that: Before the steps of extracting geometric features and load transfer path features of thin-walled structures: For actual thin-walled structures, sector sub-models or overall finite element models are established, boundary conditions and loads under service conditions are applied, linear elastic finite element analysis is carried out, and based on the calculation results, the maximum principal stress point and its region are identified as the fatigue weak key parts. Starting from the point of maximum principal stress in the weak and critical part, several stress gradient extraction paths are set along the dangerous plane to extract the distribution of maximum principal stress on each path. The path with the fastest stress decrease rate is selected as the stress gradient path for assessment. The stress distribution on the assessment path is normalized, and the double slope method is used to perform linear fitting on the high stress area and the low stress area respectively. The intersection of the two fitted lines is taken as the critical distance endpoint, and the critical distance is calculated. The normalized stress gradient is then fitted with a polynomial to establish a continuous and differentiable stress gradient characterization function.

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