Ring axial notch distortion prediction method and model based on residual stress
By predicting the axial notch distortion of ring components through theoretical calculation methods, the problem of unstable ring component dimensions under the influence of residual stress in the existing technology is solved. It achieves efficient and accurate notch distortion prediction, supports process optimization and digital manufacturing, and is applicable to a variety of materials and complex structures.
Patent Information
- Application Number
- CN202510980339.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-16
- Publication Date
- 2025-11-21
AI Technical Summary
Existing technologies cannot effectively predict the relationship between residual stress and axial notch distortion of the ring, resulting in large differences in the size of the ring after cutting, making it impossible to complete assembly. Furthermore, multiple processing tests are required for verification, which consumes time and materials.
Using theoretical calculation methods, by detecting the residual stress on the inner and outer ring surfaces of the ring component and combining it with elastoplastic theory, the unloading bending moment and stress changes are calculated, and a prediction model for the axial notch distortion of the ring component is established. This model includes formulas for loading bending moment, unloading bending moment and stress changes, and predicts the notch distortion.
It enables accurate prediction of incision distortion in advance, reduces the number of tests, shortens the R&D cycle, reduces costs and resource waste, improves accuracy and reliability, supports process optimization and digital manufacturing, and is applicable to a variety of materials and complex structures.
Smart Images
Figure CN120995604A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of prediction technology for the split casing notch of aero-engines, and specifically to a method and model for predicting axial notch distortion of ring components based on residual stress. Background Technology
[0002] The split-ring casing, being the most structurally complex type of ring casing, involves manufacturing processes including ring blanking, punching, ring rolling, bulging, heat treatment, and machining. However, these processes generate residual stress within the material, which is transmitted and accumulates at each stage, ultimately remaining in the finished part. Furthermore, due to the thin wall thickness and poor rigidity of the ring components, dimensional distortion easily occurs after the entire ring is cut, influenced by residual stress. The axially cut ring has a large opening, resulting in significant dimensional differences between the two parts, making subsequent assembly impossible and leading to scrap. The primary reason for this problem is the unclear relationship between residual stress and the amount of cut distortion, making it impossible to predict the amount of cut distortion in advance.
[0003] In the actual use of mechanical components, various fractures and dimensional changes, besides being related to the strength of the material itself, are mostly caused by the influence of residual stress. The impact of residual stress on machining accuracy and dimensional stability is mainly manifested in the following ways: if a certain amount of residual stress exists in the material before machining, the dimensional accuracy and geometry of the component may change after machining. When unstable structures or unstable residual stresses exist in the component, the dimensions of the component will undergo slight plastic deformation under the action of time or working stress. For example, welding residual stress in structural steel and the slow transformation of retained austenite at room temperature can both change the accuracy and dimensions of the component.
[0004] At present, there is no similar scheme that can predict the relationship between residual stress and notch distortion. Summary of the Invention
[0005] To address the aforementioned problems, this invention provides a method and model for predicting axial cut distortion of ring components based on residual stress, which obtains the cut distortion variable through theoretical calculation and solves the problem that cut distortion detection can only be performed through processing tests.
[0006] This invention discloses a method for predicting axial notch distortion of ring components based on residual stress, comprising the following steps: (1) Residual stress was detected on the inner and outer ring surfaces of the ring component using blind hole method / ultrasonic method / contour method, etc. (2) Calculate the bending moment of the ring member Let the height of the ring be h (mm); the thickness be t (mm); the neutral layer be located at the centroid of the cross-section, and its radius before deformation be ρ (mm); the distance from the inner ring surface to the neutral layer be y1 (mm); and the circumferential stress distribution be σ. y1MPa; the distance from the neutral layer to the outer torus is y2 mm; the circumferential stress distribution is σ. y2 MPa; When the ring is not divided, it is a complete ring, with the two half-rings mutually constrained. Applying a constraint force to the half-rings at this time is equivalent to generating a loading bending moment M. The loading bending moment M can be obtained from the moment balance between the internal and external forces at the cross-section: After the segmentation, due to the disappearance of constraints, the semi-ring component is unloaded under the action of bending moment. This bending moment is called the unloading bending moment M′, which is comparable in magnitude to the loading bending moment but opposite in direction. Formula (2) M′=-M (3) Calculate the unloading bending moment After being cut, the unloading is elastic. According to the elastoplastic theory, the magnitude of the unloading bending moment is: In the formula, EI is the bending stiffness of the cross section. I is the moment of inertia of the cross section, in mm. 4 ; I=∫ A y 2 dA, where A is the cross-sectional area in mm² 2 ; (4) Calculate the stress change after unloading After the segmentation, elastic unloading occurs, and the stress change is as follows: In the formula, E is the elastic modulus, in MPa; M is the loading bending moment, N·mm; y is the distance from a point on the cross section to the neutral axis, in mm; (5) Calculate the angle change after unloading Under plane strain state From the definition of strain, we can obtain In the formula, ρ′ is the radius of the neutral layer after deformation and expansion, in mm; From formulas (5) and (6), we can obtain: In the formula, E′ is the elastic modulus during the plane strain process, in MPa; Since the length of the neutral layer remains unchanged before and after deformation: ρα=ρ′α′ Formula (8) In the formula, α is the angle before deformation, in °; α′ is the angle after deformation and expansion, in °; The angle change is then: Substituting formula (7) into formula (9) yields: (6) Calculate the distance change after unloading Based on the relationship between the distance and angle at both ends after deformation, and since the length of the neutral layer remains unchanged before and after deformation, the relationship between the maximum distance at both ends and Δα can be obtained: In the formula, ρ′ is the radius of the neutral layer after expansion, in mm; α is the distance between the neutral layer and the outer ring after expansion, in mm; L is the maximum distance between the two ends after the segmentation, in mm.
[0007] A prediction model for axial notch distortion of ring components based on residual stress is provided. The model is obtained using a method for predicting notch distortion of split-shell ring components based on residual stress. The model is as follows: In the formula, Δα represents the change in angle before and after deformation, in °; M is the loading bending moment, N·mm; ρ is the radius of the neutral layer before deformation, in mm; α is the angle before deformation, in degrees; E′ is the elastic modulus during the plane strain process, in MPa; I is the moment of inertia of the cross section, m 4 ; h is the height of the ring, in mm; y1 is the distance from the inner torus to the neutral layer, in mm; σ y1 For circumferential stress distribution, y is the distance from a point on the cross section to the neutral axis, in mm; y2 is the distance from the neutral layer to the outer torus, in mm; σ y2 This represents the circumferential stress distribution.
[0008] The incision distortion variable of this invention is obtained through theoretical calculation, which solves the problem that incision distortion can only be detected through processing tests.
[0009] This invention can accurately predict incision distortion in advance; improve efficiency, shorten the R&D cycle, and eliminate the need for repeated trial cuts: traditional methods require multiple processing tests to verify incision distortion, which consumes a lot of time and materials; this invention directly calculates through a theoretical model, which greatly reduces the cost of trial and error.
[0010] This invention can accelerate product iteration: it can predict abnormal variables during the design phase, optimize process parameters, and shorten the cycle from design to mass production.
[0011] This invention can reduce costs and resource waste; save on material and processing expenses; and avoid scrap losses due to test failures. It is especially suitable for high-value aerospace components, such as titanium alloy casings.
[0012] This invention can reduce reliance on testing: it reduces the frequent use of high-precision measuring equipment, such as coordinate measuring machines, thus saving testing costs.
[0013] This invention can improve accuracy and reliability, and quantitatively predict distorted variables: by taking into account comprehensive factors such as material properties, cutting force, and residual stress through theoretical models, the results are more accurate than empirical estimates.
[0014] Avoid human error: reduce interference caused by operational fluctuations (such as tool wear and clamping deviations) during machining tests.
[0015] This invention supports process optimization and forward-looking design. Parameter sensitivity analysis can simulate the impact of different cutting parameters on distortion, such as feed rate and rotational speed, to guide process optimization.
[0016] Structural improvements are based on: identifying high-distortion-risk areas in advance and strengthening the structural design accordingly, such as increasing local stiffness.
[0017] This invention promotes digital and intelligent manufacturing and CAE integration: it provides key inputs for Computer-Aided Engineering (CAE) and drives simulation-driven manufacturing processes.
[0018] Data accumulation and AI expansion: Long-term accumulated prediction data can be used to train AI models, further improving the level of prediction intelligence.
[0019] This invention has a wide range of applications, strong scalability, and multi-material compatibility: the model can be adapted to different materials, such as aluminum alloys and high-temperature alloys for distortion prediction.
[0020] Suitable for complex structures: Not only applicable to split-type casings, but also applicable to other precision ring-shaped components, such as turbine disks and bearing housings. Attached Figure Description
[0021] Figure 1 This is a schematic diagram showing the axial cut dimension distortion of the split-type casing ring.
[0022] Figure 2 This is a schematic diagram showing the location of the neutral layer in the cross-section.
[0023] Figure 3 This is a diagram showing the stress distribution across the cross section.
[0024] Figure 4 This is a schematic diagram showing the relationship between the distance and angle at both ends after deformation.
[0025] Figure 5This is a schematic diagram comparing the measured distortion of the ring component with the predicted distortion of the present invention. Detailed Implementation
[0026] The invention will be described below with reference to the accompanying drawings.
[0027] This invention discloses a method for predicting axial notch distortion of ring components based on residual stress, comprising the following steps: (1) Residual stress was detected on the inner and outer ring surfaces of the ring component using blind hole method / ultrasonic method / contour method, etc. (2) Calculate the bending moment of the ring member Let the height of the ring be h (mm); the thickness be t (mm); the neutral layer be located at the centroid of the cross-section, and its radius before deformation be ρ (mm); the distance from the inner ring surface to the neutral layer be y1 (mm); and the circumferential stress distribution be σ. y1 MPa; the distance from the neutral layer to the outer torus is y2 mm; the circumferential stress distribution is σ. y2 MPa; When the ring is not divided, it is a complete ring with the two half-rings mutually constrained. Applying a constraint force to the half-rings at this time is equivalent to generating a loading bending moment M. From the equilibrium of internal and external moments of the cross section, the loading bending moment is M: After the segmentation, due to the disappearance of constraints, the semi-ring component is unloaded under the action of bending moment. This bending moment is called the unloading bending moment M′, which is comparable in magnitude to the loading bending moment but opposite in direction. Formula (2) M′=-M (3) Calculate the unloading bending moment After being cut, the unloading is elastic. According to the elastoplastic theory, the magnitude of the unloading bending moment is: In the formula, EI is the bending stiffness of the cross section. I is the moment of inertia of the cross section, in mm. 4 ; I=∫ A y 2 dA, where A is the cross-sectional area in mm² 2 ; (4) Calculate the stress change after unloading After the segmentation, elastic unloading occurs, and the stress change is as follows: In the formula, E is the elastic modulus, in MPa; M is the loading bending moment, N·mm; y is the distance from a point on the cross section to the neutral axis, in mm; (5) Calculate the angle change after unloading Under plane strain state From the definition of strain, we can obtain In the formula, ρ′ is the radius of the neutral layer after deformation and expansion, in mm; From formulas (5) and (6), we can obtain: In the formula, E′ is the elastic modulus during the plane strain process, in MPa; Since the length of the neutral layer remains unchanged before and after deformation: ρα=ρ′α′ Formula (8) In the formula, α is the angle before deformation, in °; α′ is the angle after deformation and expansion, in °; The angle change is then: Substituting formula (7) into formula (9) yields: (6) Calculate the distance change after unloading Based on the relationship between the distance and angle at both ends after deformation, and since the length of the neutral layer remains unchanged before and after deformation, the relationship between the maximum distance at both ends and Δα can be obtained: In the formula, ρ′ is the radius of the neutral layer after expansion, in mm; α is the distance between the neutral layer and the outer ring after expansion, in mm; L is the maximum distance between the two ends after the segmentation, in mm.
[0028] A prediction model for axial notch distortion of ring components based on residual stress is provided. The model is obtained using a method for predicting notch distortion of split-shell ring components based on residual stress. The model is as follows: In the formula, Δα represents the change in angle before and after deformation, in °; M is the loading bending moment, N·mm; ρ is the radius of the neutral layer before deformation, in mm; α is the angle before deformation, in degrees; E′ is the elastic modulus during the plane strain process, in MPa; I is the moment of inertia of the cross section, m 4 ; h is the height of the ring, in mm; y1 is the distance from the inner torus to the neutral layer, in mm; σ y1 For circumferential stress distribution, y is the distance from a point on the cross section to the neutral axis, in mm; y2 is the distance from the neutral layer to the outer torus, in mm; σ y2 This represents the circumferential stress distribution.
[0029] This invention establishes a predictive model for residual stress and notch tension. The residual stress in this invention can be obtained by various methods such as blind hole method, ultrasonic method, and contour method. This invention comprehensively considers the influencing factors such as ring material and cross-sectional size, effectively ensuring the accuracy of the prediction. Example
[0030] The present invention will be illustrated below using the prediction of axial cut distortion of GH4706 alloy ring as an example.
[0031] The elastic modulus of GH4706 alloy is E = 210000 MPa; Poisson's ratio ν = 0.3. (1) Residual stress was detected on the inner and outer ring surfaces of the ring component using blind hole method / ultrasonic method / contour method, etc. The stress σ on the inner annular surface was measured using the blind hole method. y1 =30 MPa; outer annular stress σ y2 = -150MPa (2) Calculate the bending moment of the ring member The ring height is h = 100 mm; the thickness is t = 60 mm; the neutral layer is located at the centroid of the cross section, and its radius before deformation is ρ = 1170 mm; the distance from the inner ring surface to the neutral layer is y1 = 30 mm; the circumferential stress distribution is σ. y1 =30 (MPa); the distance from the neutral layer to the outer annulus is y2 = 30 mm; the circumferential stress distribution is σ y2 = -150 (MPa); When the ring is not divided, it is a complete ring, with the two half-rings mutually constrained. Applying a constraint force to the half-rings at this time is equivalent to generating a loading bending moment M. The loading bending moment M can be obtained from the moment balance between the internal and external forces at the cross-section: After the segmentation, due to the disappearance of constraints, the semi-ring component is unloaded under the action of bending moment. This bending moment is called the unloading bending moment M′, which is comparable in magnitude to the loading bending moment but opposite in direction. Formula (2) M′=-M (3) Calculate the unloading bending moment After being cut, the unloading is elastic. According to the elastoplastic theory, the magnitude of the unloading bending moment is: In the formula, EI is the bending stiffness of the cross section. I is the moment of inertia of the cross section, in mm. 4 ; I=∫ A y2 dA, where A is the cross-sectional area in mm² 2 ; (4) Calculate the stress change after unloading After the segmentation, elastic unloading occurs, and the stress change is as follows: In the formula, E is the elastic modulus, in MPa; M is the loading bending moment, N·mm; y is the distance from a point on the cross section to the neutral axis, in mm; (5) Calculate the angle change after unloading Under plane strain state From the definition of strain, we can obtain In the formula, ρ′ is the radius of the neutral layer after deformation and expansion, in mm; From formulas (5) and (6), we can obtain: In the formula, E′ is the elastic modulus during the plane strain process, in MPa; Since the length of the neutral layer remains unchanged before and after deformation: Formula (8) is ρα=ρ′α′ In the formula, α is the angle before deformation, in °; α′ is the angle after deformation and expansion, in °; The angle change is then: Substituting formula (7) into formula (9) yields: (α = 180° = π rad) α′=α-Δα=180.87° (6) Calculate the distance change after unloading Based on the relationship between the distance and angle at both ends after deformation, and since the length of the neutral layer remains unchanged before and after deformation, the relationship between the maximum distance at both ends and Δα can be obtained: In the formula, ρ′ is the radius of the neutral layer after expansion, in mm; α is the distance between the neutral layer and the outer ring after expansion, in mm; L is the maximum distance between the two ends after the segmentation, in mm. Take α=ρ′-ρ+y2=0.4+30=30.4mm; ΔL=L-L0=2×(1170.4+30.4)×sin(90.435°)-2×(1170+30)×sin(90°) =2401.6×0.99998-2400×1 =1.55197mm The measured distortion of the segmented ring component is compared with the predicted distortion of this invention. Figure 5 As shown, point a is 2mm from the inner ring surface; point b is 9mm from the inner ring surface; point c is the center; point d is 9mm from the outer ring surface; and point e is 2mm from the outer ring surface. The measured distortions of the cut dimensions are +0.271mm, -0.215mm, -1.812mm, -2.25mm, and -2.576mm. The predicted distortions according to this invention are +0.264mm, -0.466mm, -1.552mm, -2.339mm, and -2.363mm. This invention demonstrates high overall prediction accuracy, especially in key areas such as near the inner and outer ring surfaces, where the predictions closely match the actual measurements. The predicted distortions and measured distortions show consistent trends: from the inner ring to the outer ring, the distortion changes from positive to negative and the absolute value increases, consistent with the deformation law of residual stress release. The error at point e, the location of the maximum distortion that determines assembly accuracy, is only 8.3%, proving the effectiveness of the model in predicting core issues. The high overlap between the predicted curves and the measured data further corroborates the reliability of the model. In summary, the prediction model of this invention is accurate and effective within the allowable range of engineering errors, with an error of <10% in key areas. It has significant application value, especially for the distortion prediction of high-value aerospace components, such as the GH4706 casing.
Claims
1. A method for predicting axial notch distortion of ring components based on residual stress, characterized in that, Includes the following steps: (1) Residual stress was detected on the inner and outer ring surfaces of the ring component using blind hole method / ultrasonic method / contour method, etc. (2) Calculate the bending moment of the ring member Let the height of the ring be h, mm; the thickness be t, mm; the neutral layer be located at the centroid of the cross section, and the radius of the neutral layer before deformation be ρ, mm; the distance from the inner ring surface to the neutral layer be y1, mm; The circumferential stress distribution is σ y1 , MPa; the distance from the neutral layer to the outer annulus is y2, mm; The circumferential stress distribution is σ y2 MPa; When the ring is not divided, it is a complete ring with the two half-rings mutually constrained. Applying a constraint force to the half-rings at this time is equivalent to generating a loading bending moment M. From the equilibrium of internal and external moments of the cross section, the loading bending moment is M: After the segmentation, due to the disappearance of constraints, the semi-ring component is unloaded under the action of bending moment. This bending moment is called the unloading bending moment M′, which is comparable in magnitude to the loading bending moment but opposite in direction. Formula (2) M′=-M (3) Calculate the unloading bending moment After being cut, the unloading is elastic. According to the elastoplastic theory, the magnitude of the unloading bending moment is: In the formula, EI is the bending stiffness of the cross section. I is the moment of inertia of the cross section, in mm. 4 ; I=∫ A y 2 dA, where A is the cross-sectional area in mm² 2 ; (4) Calculate the stress change after unloading After the segmentation, elastic unloading occurs, and the stress change is as follows: In the formula, E is the elastic modulus, in MPa; M is the loading bending moment, N·mm; y is the distance from a point on the cross section to the neutral axis, in mm; (5) Calculate the angle change after unloading Under plane strain state From the definition of strain, we can obtain In the formula, ρ′ is the radius of the neutral layer after deformation and expansion, in mm; From formulas (5) and (6), we can obtain: In the formula, E′ is the elastic modulus during the plane strain process, in MPa; Since the length of the neutral layer remains unchanged before and after deformation: ρα=ρ′α′ Formula (8) In the formula, α is the angle before deformation, in °; α′ is the angle after deformation and expansion, in °; The angle change is then: Substituting formula (7) into formula (9) yields: (6) Calculate the distance change after unloading Based on the relationship between the distance and angle at both ends after deformation, and since the length of the neutral layer remains unchanged before and after deformation, the relationship between the maximum distance at both ends and Δα can be obtained: In the formula, ρ′ is the radius of the neutral layer after expansion, in mm; α is the distance between the neutral layer and the outer ring after expansion, in mm; L is the maximum distance between the two ends after the segmentation, in mm.
2. A prediction model for axial notch distortion of ring components based on residual stress, characterized in that, The model is obtained using the residual stress-based method for predicting the notch distortion of the split casing ring as described in claim 1. The model is as follows: In the formula, Δα represents the change in angle before and after deformation, in °; M is the loading bending moment, N·mm; ρ is the radius of the neutral layer before deformation, in mm; α is the angle before deformation, in degrees; E′ is the elastic modulus during plane strain, in MPa; I is the moment of inertia of the cross section, in meters. 4 ; h is the height of the ring, in mm; y1 is the distance from the inner torus to the neutral layer, in mm; σ y1 For circumferential stress distribution, y is the distance from a point on the cross section to the neutral axis, in mm; y2 is the distance from the neutral layer to the outer torus, in mm; σ y2 This represents the circumferential stress distribution.