Numerical analysis method for processing deformation field considering intermediate geometric state and application thereof

Abstract

The application discloses a machining deformation field numerical analysis method considering intermediate geometric states and application, belongs to the machining deformation control and statics simulation technical field, and comprises the following steps: calculating the workpiece displacement field generated by the residual stress rebalancing caused by the current material removal based on numerical analysis; calculating the boundary corresponding to the material boundary removed in the initial configuration according to the displacement field; removing the material in the initial configuration according to the boundary, and then performing numerical analysis again to obtain the displacement field; and finally calculating the part deformation according to the displacement field. By using the method, the geometric and stress evolution in the machining process is dynamically simulated, the limitation of the traditional numerical analysis on the simulation of the intermediate state in the machining is broken through, the machining deformation prediction precision of the aerospace complex part is improved, and reliable numerical basis is provided for process optimization.

Description

Technical Field

[0001] This invention relates to the fields of machining deformation control and static simulation technology, and in particular to a numerical analysis method and application of machining deformation field considering intermediate geometric states. Background Technology

[0002] In the aerospace field, monolithic structural components are widely used to meet lightweight requirements. However, these components often experience severe deformation after machining due to residual stress. This deformation causes significant economic losses and severely impacts the development cycle of aerospace vehicles. Controlling machining deformation has become one of the most pressing issues in the aerospace manufacturing industry. To address this, existing researchers have proposed deformation control methods such as releasing part deformation during machining, applying pre-deformation, and adjusting the machining sequence. However, directly conducting machining experiments and optimizing the machining process through trial and error is costly and difficult to apply in engineering. Furthermore, during machining, the stress field of the part redistributes, causing deformation and dynamic changes in the material removal area. Existing numerical analysis methods struggle to simulate this process, making accurate simulation of deformation control effects difficult and hindering the simulation optimization of deformation control processes. Therefore, there is an urgent need to develop a simulation method that considers the geometric and residual stress evolution during machining to simulate the effects of different deformation control processes.

[0003] Inherent strain is one of the key techniques for analyzing residual stress and deformation, and it was first used to study welding residual stress. This refers to the permanent strain within a material that does not conform to the compatibility equations, which is related to the total strain. With elastic strain The relationship is as follows: Based on the theory of inherent strain, material removal does not affect the distribution of inherent strain. The deformation caused by material removal can be regarded as the result of the strain and displacement fields generated by material removal acting on the initial configuration and the boundary of the removed material. The problem of accurately predicting machining deformation can be transformed into the boundary of material removal on the initial configuration. The problem of finding the boundary on the boundary. Summary of the Invention

[0004] The purpose of this invention is to provide a numerical analysis method and application for machining deformation field considering intermediate geometric states. Based on the inherent strain theory, the problem of solving time-varying geometry and time-varying stress field during machining is transformed into solving the position of each machining feature within the initial blank geometry. This method can quickly and accurately simulate the influence of deformation control technology on machining deformation.

[0005] To achieve the above objectives, this invention provides a numerical analysis method for processing deformation fields considering intermediate geometric states, comprising the following steps:

[0006] S1. Obtain the initial configuration of the workpiece before machining, given a specific geometric state. and the corresponding residual stress field ;

[0007] S2. Perform machining simulation on the workpiece, remove material, and obtain the new configuration of the workpiece after stress redistribution. The current displacement field of the workpiece is obtained through calculation and analysis. ;

[0008] S3. Perform further machining simulation on the workpiece to obtain the material boundaries that need to be further processed and removed. And the configuration of the workpiece after stress redistribution following material removal is denoted as S4. Calculate the geometry of the material boundary to be removed in the initial model based on the displacement field; In the process, based on the geometry obtained in step S3, the material is removed. Numerical analysis was performed to obtain displacement field ;

[0009] S5. Determine if the processing has ended. If not, then use the result from S4. As in S2 , get S3 As in S2 Repeat steps S2-S4 until the machining is complete; if the machining is complete, calculate the part deformation.

[0010] Preferably, in step S3, the boundary is... According to the displacement field Mapping to the initial configuration yields the corresponding boundary in the initial configuration. At that time, by Discretize into point set The point set is obtained through finite element shape function interpolation. Corresponding displacement field .

[0011] Preferably, in step S3, when calculating the geometry of the material boundary to be removed in the initial model based on the displacement field, the discrete points corresponding to the calculated processing features in the initial configuration are... Reconstructing geometric surfaces using spline surfaces:

[0012] .

[0013] Preferably, after the machining simulation is completed in step S5, Corresponding processing deformation is The calculation formula is:

[0014] .

[0015] The application of a numerical analysis method for machining deformation field considering intermediate geometric states in machining deformation control technology includes machining sequence, timing of deformation release in machining process, and process reinforcement ribs.

[0016] Preferably, a geometric boundary set is generated based on the processing sequence of the geometric features of the parts according to different processing techniques, to simulate the control effect of the processing sequence and processing allowance on processing deformation during the material removal process.

[0017] Preferably, a geometric boundary set is generated according to the deformation release timing of different processing techniques to simulate the control effect of the deformation release timing on processing deformation during the material removal process.

[0018] Preferably, a geometric boundary set is generated based on the location and processing sequence of the process reinforcing ribs to simulate the control effect of the process reinforcing ribs on processing deformation.

[0019] Therefore, the present invention employs the above-mentioned numerical analysis method and application for processing deformation field considering intermediate geometric states, which has the following beneficial effects:

[0020] (1) The application of this method can significantly reduce the simulation error caused by residual stress mapping during the machining deformation simulation process;

[0021] (2) This method can be used to simulate the deformation control effect of machining deformation control processes such as machining allowance, machining sequence, and process reinforcement.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a flowchart of a numerical analysis method for processing deformation field considering intermediate geometric states according to the present invention;

[0024] Figure 2 This is a schematic diagram of the principle of a numerical analysis method for processing deformation field considering intermediate geometric states according to the present invention.

[0025] Figure 3 This is a simulation environment setup diagram of Embodiment 1 of the present invention;

[0026] Figure 4 This is a diagram showing the reconstruction result of the processing features in Embodiment 1 of the present invention;

[0027] Figure 5 This is a three-dimensional simulation part feature and boundary condition diagram of Embodiment 2 of the present invention, wherein (a) is a three-dimensional simulation part feature diagram and (b) is a simulation boundary condition setting diagram;

[0028] Figure 6 This is a residual stress diagram of Embodiment 2 of the present invention;

[0029] Figure 7 This is a reconstruction part drawing of Embodiment 2 of the present invention, wherein (a) is the reconstruction part geometry of processing sequence 1, and (b) is the reconstruction part geometry of processing sequence 2. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0032] like Figures 1-2 As shown, a numerical analysis method for processing deformation field considering intermediate geometric states includes the following steps:

[0033] S1. Obtain the initial configuration of the workpiece before machining, given a specific geometric state. and the corresponding residual stress field ;

[0034] S2. Perform machining simulation on the workpiece, remove material, and obtain the new configuration of the workpiece after stress redistribution. The current displacement field of the workpiece is obtained through calculation and analysis. ;

[0035] S3. Perform further machining simulation on the workpiece to obtain the material boundaries that need to be further processed and removed. And the configuration of the workpiece after stress redistribution following material removal is denoted as S4. Calculate the geometry of the material boundary to be removed in the initial model based on the displacement field; In the process, based on the geometry obtained in step S3, the material is removed. Numerical analysis was performed to obtain displacement field ;

[0036] S5. Determine if the processing has ended. If not, then use the result from S4. As in S2 , get S3 As in S2 Repeat steps S2-S4 until the machining is complete; if the machining is complete, calculate the part deformation.

[0037] Example 1

[0038] In this embodiment, the part is a 7075 aluminum alloy sheet. The dimensions, boundary conditions, and part machining features are as follows: Figure 3 As shown.

[0039] First, an unbalanced stress field is applied to the part. After simulation, the discrete point displacement field of the machined feature is extracted, the position of the machined feature within the initial part is calculated, and a reconstructed machined feature is generated. This is then simulated again using ABAQUS. The geometric position of the reconstructed feature after deformation is extracted and compared with the left side of the ideal machined feature. The error is compared between the reconstructed geometry and the theoretical dimensions of the machined feature directly. Figure 4 As shown. The average absolute error of the processing feature reconstruction method proposed in this embodiment is 0.008 mm, and the maximum absolute error is 0.002 mm. In contrast, the average absolute error obtained using the theoretical dimensions of the processing features is 0.01 mm, and the maximum absolute error is 0.02 mm, which reduces the average error by 20% and the maximum absolute error by 90%.

[0040] Example 2

[0041] This embodiment uses the method to simulate the machining deformation of 7075 frame-type structural parts, simulating the influence of machining allowance and machining sequence on machining deformation. The main mechanical properties of 7075 aluminum alloy are shown in Table 1.

[0042] Table 1 Mechanical properties of 7075 aluminum alloy

[0043] ;

[0044] Among them, the design includes, for example Figure 5 The structural component shown in (a) is 640mm long, 180mm wide, and 20mm high. Its wall thickness is 4mm and its web thickness is 5mm. The component has four groove features with a depth of 15mm. The simulation boundary conditions are set as follows: Figure 5In (b), the model is meshed using tetrahedral elements with a seed size of 2mm. The part clamping method positions the part through a small area in the middle, and deformation is controlled by releasing the part's deformation during machining intervals. Since multiple sets of fixtures restrict the part's deformation during machining, it is assumed that no local deformation occurs. During machining intervals, the part's deformation is released. The initial residual stress of the part is as follows: Figure 6 As shown, residual stress is applied via an ABAQUS subroutine.

[0045] The effects of three different machining processes on machining deformation were simulated. First, the machining deformation of the part under the traditional method was simulated. Since the deformation was not released, the simulation software simulated the machining deformation of the part under the fixed clamping method by removing all the material at once. Two machining sequences were then simulated for deformation control. The machining sequence and material removal amount for each step in Process 1 are as follows: ①(5mm)②(5mm)③(5mm)④(5mm)①(5mm)②(5mm)③(5mm)④(5mm)①(4.5mm)②(5.5mm)③(4.5mm)④(4.5mm)①(0.5mm)②(0.5mm)③(0.5mm)④(0.5mm). The machining sequence and material removal amount for each step in Process 2 are as follows: ①(5mm)①(5mm)①(4.5mm)①(0.5mm)②(5mm)②(5mm)②(4.5mm)②(0.5mm)③(5mm)③(5mm)③(4.5mm)③(0.5mm)④(5mm)④(5mm)④(4.5mm)④(0.5mm). The four machining features obtained by this method have the following shapes within the initial geometry of the initial part: Figure 7 The maximum deformation of the reconstructed part drawing is shown in Table 2 for the three machining processes.

[0046] Table 2 Maximum machining deformation for each machining process

[0047] ;

[0048] Therefore, this invention employs a numerical analysis method and application for machining deformation fields that considers intermediate geometric states. By constructing a numerical analysis framework that dynamically tracks the evolution of geometric states and stress fields during machining, it effectively solves the problem of insufficient accuracy caused by neglecting intermediate states in traditional machining deformation simulation methods. Simultaneously, this invention possesses the ability to accurately simulate various machining deformation control processes. By generating corresponding geometric boundary sets based on key factors such as machining sequence, allowance, deformation release timing, and the location of process reinforcing ribs, it can effectively simulate the control effect of different process parameters on machining deformation. It overcomes the limitations of existing numerical analyses in covering the coupling relationship between dynamic material removal boundaries and stress evolution, providing a reliable numerical tool for the optimization and iteration of machining deformation control processes for complex structural components in the aerospace field. This solves the engineering pain points of high cost, long cycle, and inaccurate simulation results associated with traditional trial-and-error methods.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A numerical analysis method for processing deformation fields considering intermediate geometric states, characterized in that, Includes the following steps: S1. Obtain the initial configuration of the workpiece before machining, given a specific geometric state. and the corresponding residual stress field ; S2. Perform machining simulation on the workpiece, remove material, and obtain the new configuration of the workpiece after stress redistribution. The current displacement field of the workpiece is obtained through calculation and analysis. ; S3. Perform further machining simulation on the workpiece to obtain the material boundaries that need to be further processed and removed. And the configuration of the workpiece after stress redistribution following material removal is denoted as The geometry of the material boundary to be removed is calculated in the initial model based on the displacement field. S4, in the initial configuration In the process, based on the geometry obtained in step S3, the material is removed. Numerical analysis was performed to obtain displacement field ; S5. Determine if the processing has ended. If not, then use the result from S4. As in S2 , get S3 As in S2 Repeat steps S2-S4 until the machining is complete; if the machining is complete, calculate the part deformation. In step S3, the boundary According to the displacement field Mapping to the initial configuration yields the corresponding boundary in the initial configuration. At that time, by Discretize into point set The point set is obtained through finite element shape function interpolation. Corresponding displacement field ; In step S3, when calculating the geometry of the material boundary to be removed in the initial model based on the displacement field, the discrete points corresponding to the calculated processing features in the initial configuration are... Reconstructing geometric surfaces using spline surfaces: 。 2. The numerical analysis method for machining deformation field considering intermediate geometric states according to claim 1, characterized in that, After step S5 completes the machining simulation, The corresponding processing deformation is The calculation formula is: 。 3. An application of the numerical analysis method for processing deformation field considering intermediate geometric states as described in any one of claims 1-2, characterized in that: Specifically, it is applied in the process of controlling deformation during machining, including machining sequence, timing of deformation release during machining, and process reinforcement ribs.

4. The application of the numerical analysis method for processing deformation field considering intermediate geometric states as described in claim 3, characterized in that: Based on the machining sequence of the geometric features of parts with different processing techniques, a geometric boundary set is generated to simulate the control effect of the machining sequence and machining allowance on machining deformation during the material removal process.

5. The application of the numerical analysis method for machining deformation field considering intermediate geometric states as described in claim 3, characterized in that: Geometric boundary sets are generated based on the deformation release timing of different processing techniques to simulate the control effect of deformation release timing on processing deformation during material removal.

6. The application of the numerical analysis method for machining deformation field considering intermediate geometric states according to claim 3, characterized in that: A geometric boundary set is generated based on the location and processing sequence of the process reinforcement ribs to simulate the control effect of the process reinforcement ribs on processing deformation.

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