A method for determining a forming tooling mold surface of a composite stiffened panel based on long stringer deformation capability

Abstract

The application belongs to the field of aircraft composite part manufacturing, and particularly relates to a method for determining a model surface of a composite stiffened panel forming tool based on the deformation capacity of a stringer. The method considers the deformation capacity of the stringer before tooling, effectively avoids the problems of scrapping, cycle, cost and the like caused by the mismatch between the stringer and the product skin after tooling, saves the development cycle, and is beneficial to the accurate manufacturing and iteration of the panel.

Description

Technical Field

[0001] This application belongs to the field of aircraft composite material parts manufacturing, specifically involving a method for determining the surface of a composite reinforced panel forming process based on the deformation capability of a stringer. Background Technology

[0002] The aerospace industry is increasingly demanding lightweight aircraft structures. For critical structures such as the vertical tail, rudder, and wings, composite material components are now almost always the preferred choice. These components are often large-sized panels, beams, and box-section ribs that require load-bearing capacity. For panel-type components, especially large ones, significant deformation occurs after curing due to factors such as differences in thermal expansion between the component and tooling during manufacturing, the anisotropy of the component itself, asynchronous curing within the component, and uneven curing pressure at the reinforcing stringers and skin. This deformation is often substantial, primarily spanwise, and can even reach decimeter levels, severely impacting assembly quality and efficiency. Simple process improvements cannot eliminate the curing deformation effects of stringer-reinforced panel-type components.

[0003] Due to the aforementioned panel structure, the deformation capacity of the stringer is a key factor affecting the determination of the repair model surface. Excessive repair amount will prevent the stringer from fitting snugly against the skin, while insufficient repair amount will have little effect on improving deformation. Summary of the Invention

[0004] Therefore, this application provides a method for determining the surface of a composite reinforced wall panel molding process based on the deformation capacity of a stringer. This method can pre-verify the feasibility of the molding method and the amount of modification, taking the deformation capacity of the stringer into account in determining the surface of the molding process, thus avoiding unnecessary waste of labor, material costs, and manufacturing cycle time.

[0005] According to one aspect of this application, a method for determining the surface of a composite reinforced wall panel forming process based on the deformation capacity of a stringer is provided. The composite reinforced wall panel is composed of a skin and stringers and is manufactured using a co-bonding process. The stringers are arranged along the length of the skin, and multiple stringers are parallel in the width of the skin. The stringers are first formed and cured, and then co-bonded together with the uncured skin. The ribs are then assembled onto the set positions.

[0006] After the wall panel described in this application is cured, the root and tip deform outwards towards the aerodynamic surface. Problems affecting assembly quality mainly occur at the root, which has better rigidity, such as... Figure 2However, simultaneously modifying the stringer and skin requires addressing significant coordination issues. This application describes a method where the stringer is not modified, but only the root of the large end of the panel is modified in the spanwise direction. Because the stringer's deformability is considered when determining the modification model surface, it avoids the stringer and panel failing to fit properly after modification, thus preventing wasted costs and time.

[0007] Specifically, this involves a vertical tail carbon fiber composite reinforced panel component. In the chord direction, the panel is reinforced by 10 "I"-shaped stringers, and in the span direction, several box-section rib positions are distributed.

[0008] Includes the following steps:

[0009] Determining the deformation capacity of the S1 girder: Place the girder on the inspection fixture and raise both ends of the girder at the same height to determine the actual maximum deformation capacity of the girder;

[0010] S2 Composite Reinforced Panel Shape Inspection and "Zero" Position Determination: Measure the shape of the composite reinforced panel, analyze the measurement data, determine the inflection point area of ​​the composite reinforced panel shape deformation, and determine the position of the "zero" position.

[0011] Determining the upper limit of S3 modification amount: Place the stringer on the inspection fixture, raise the large end of the stringer near the root of the skin until the "zero" position is just off the inspection fixture, record the height of the large end of each stringer raised, and take the smallest value among the recorded values ​​as the upper limit of modification amount.

[0012] S4 initially determines the surface of the composite reinforced wall panel forming fixture; in CATIA, based on the theoretical surface of the composite reinforced wall panel forming fixture, a composite reinforced wall panel forming fixture is generated with the selected deviation.

[0013] Verification of the deformation capacity of the S5 stringer; Based on S4, verify the deformation capacity of the stringer.

[0014] S6 physical verification.

[0015] Specifically;

[0016] Determination of the deformation capacity of the S1 stringer;

[0017] Determine the deformation capacity of the stringer to verify whether the resin can cover the gap between the stringer and the skin after the mold is repaired. Specifically, measure the deformation capacity of all the stringers in the wall panel.

[0018] Place the stringer on the inspection fixture, raise both ends of the stringer to the same height, and continuously increase the height until the stringer just detaches from the inspection fixture. The criterion is that a 0.2mm thick feeler gauge can just pass through it. The height at both ends raised at this point is H, which is the actual maximum deformation capacity of the stringer.

[0019] At the same time, record the position where the stringer just detaches from the tooling, that is, the distance from the large end of the stringer.

[0020] At this point, the girder can be approximated as a beam with simply supported ends and uniformly distributed gravity load, and the maximum deflection ω of the beam is the actual deformation capacity H of the girder.

[0021] According to the knowledge of mechanics of materials, ;

[0022] ω max This represents the maximum deflection of the stringer;

[0023] q is the self-weight load value (kN / m);

[0024] l represents the span (m) of the stringer.

[0025] E is the elastic modulus ( );

[0026] I is the moment of inertia of the cross section ( )

[0027] It can be seen that the maximum deformation capacity of a stringer is mainly limited by its length, and the deformation capacity of a shorter stringer is significantly reduced.

[0028] S2 composite reinforced wall panel shape inspection and "zero" position determination;

[0029] The composite reinforced wall panel is placed in the assembly position, the shape of the composite reinforced wall panel is measured, the measurement data is analyzed, the inflection point area of ​​the deformation of the composite reinforced wall panel is determined, and the "zero" position is set on the position of the rib near the inflection point area.

[0030] Under stable conditions in the panel manufacturing process, it is necessary to measure the surface deviation of the panel after curing in its unmodified state using a stable measurement method. During measurement, the panel should be aligned with the assembly posture, and the influence of external forces should be minimized to keep the panel in a near-free state. A laser tracker or scanner should be used to detect the panel's shape deviation. A minimum of three measurements are recommended.

[0031] Determination of the upper limit of S3 modification amount;

[0032] Select the stringer that passes through the "zero" position, place the stringer on the inspection fixture, and shim the large end of the stringer near the root of the skin until the "zero" position just detaches from the inspection fixture. Use the 0.2mm thick feeler gauge that just passes through as the judgment criterion, and record the height of the shim at the large end of each stringer. The smallest value among the recorded values ​​is taken as the upper limit of the modification amount.

[0033] S4 initially determined the surface of the composite reinforced wall panel molding and decoration model;

[0034] Based on the actual manufacturing process of composite reinforced wall panels, a modification amount is selected below the upper limit of the modification amount as the maximum modification amount at the root of the skin. The modification amount at the position of each rib from the root of the skin to the "zero" position is set in the form of an arithmetic sequence. In CATIA, this is used as the deviation amount. Based on the theoretical composite reinforced wall panel forming tooling surface, a composite reinforced wall panel forming tooling model surface is generated.

[0035] In CATIA, the deviation between the bottom surface of the selected stringer at the large end near the root of the skin and at the position of the upper rib of the stringer and the surface of the theoretical composite reinforced wall panel forming tooling and the composite reinforced wall panel forming tooling model is measured and recorded as the basis for verifying the deformation capacity of the stringer.

[0036] In CATIA, the maximum distance from the measuring station to the surface of the composite reinforced wall panel molding model, excluding the stringer at the "zero" position, must be below H. If it exceeds H, the shaping amount at the large end near the root of the skin and at the station of the upper rib of the stringer needs to be reduced, and adjusted sequentially until this height is below H.

[0037] Verification of the deformation capacity of the S5 stringer;

[0038] Place the stringer, positioned at the "zero" position, on the inspection fixture. Raise the large end of the stringer near the skin root by the amount recorded in S4 as the deviation at the large end near the skin root. Then measure the distance between the inspection fixture and the position pointing towards the first rib in the "zero" direction. If this distance is below the deviation recorded in S4 for the position of the first rib in the "zero" direction, the deformation capacity at this point is considered to meet the requirements. Continue raising the position of the first rib in the "zero" direction by the amount recorded in S4. Record the deviation at the position of the first rib pointing towards the "zero" position. Then measure the distance between the position of the second rib pointing towards the "zero" position and the inspection fixture. If this distance is below the deviation at the position of the second rib pointing towards the "zero" position recorded in S4, the deformation capacity at this point is considered to meet the requirements. This process continues until the deformation capacity at the position of each rib before the "zero" position meets the requirements, and the "zero" position is in close contact with the inspection fixture, and a 0.2mm thick feeler gauge cannot pass through. Then the deformation capacity of the stringer is considered to meet the requirements.

[0039] During the process, if the distance between any rib's position and the inspection fixture is greater than the deviation of the corresponding position recorded in S4, or if the gap between the "zero" position and the inspection fixture allows a 0.2mm thick feeler gauge to pass through, it is necessary to return to S4 and readjust the maximum trimming amount at the skin root and the trimming amount at each rib's position from the skin root to the "zero" position until the requirements are met. At this time, the trimming amount at each rib's position from the skin root to the "zero" position does not need to be set in the form of an arithmetic sequence.

[0040] S6 physical verification;

[0041] After determining the deviation amount that ensures each station passes through the "zero" position and meets the requirements, the surface of the composite reinforced wall panel forming tooling is considered to be the actual surface of the composite reinforced wall panel forming tooling. The composite reinforced wall panel forming tooling is repaired or newly manufactured according to this repaired surface. The repaired or newly manufactured composite reinforced wall panel forming tooling is used for actual production. The S2~S6 process is repeated on the newly produced composite reinforced wall panels until the newly produced composite reinforced wall panels meet the theoretical requirements.

[0042] The inspection fixture is a special inspection fixture for long stringers.

[0043] The advantages of this application are:

[0044] The large-size stiffened panel parts described in this application employ a co-bonding molding process. First, the stringers are pre-laid and cured. Then, the skin is manufactured, and the stringers are bonded together with an adhesive film. Finally, the cured stringers and the uncured skin are cured together to obtain the panel parts. To address the aforementioned deformation issues, the manufacturing process often involves modifying the part's forming tooling. By pre- inducing a reverse deformation in the part, the deviation from its theoretical shape after curing is reduced, thereby mitigating adverse effects on assembly and meeting manufacturing specifications and acceptance technical document requirements. This method considers the stringer's deformation capacity before tooling molding, effectively avoiding problems such as scrap, time constraints, and costs caused by mismatch between the stringers and the product skin after tooling molding. It saves development time and facilitates precise manufacturing and iteration of the panels. Attached Figure Description

[0045] Figure 1 This is a flowchart illustrating the method for determining the surface of a composite reinforced wall panel forming process based on the deformation capacity of a long girder.

[0046] Figure 2 This is an isometric schematic diagram of the entire wall panel.

[0047] Figure 3 This is a schematic diagram of the test for the deformation capacity of a stringer. Detailed Implementation

[0048] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0049] Example 1

[0050] This application discloses a method for determining the surface of a composite reinforced wall panel forming process based on the deformation capacity of a stringer. The following description is provided in conjunction with specific embodiments and accompanying drawings.

[0051] A method for determining the surface of a composite reinforced wall panel forming process based on the deformation capacity of a long girder includes the following steps:

[0052] Step 1: Determine the deformation capacity of the girder.

[0053] The deformation capacity of the stringers was determined to verify whether the resin could cover the gap between the stringers and the skin after mold repair. Specifically, the deformation capacity of all stringers in the panel was measured. Each stringer was placed on an inspection fixture, with both ends raised to the same height. The height was gradually increased until the entire stringer just detached from the inspection fixture. The criterion was that a 0.2mm feeler gauge (corresponding to the film thickness) could just pass through. The measured maximum deformation capacity H of the stringers is shown in Table 1.

[0054] Table 1 Actual Maximum Deformation Capacity of the Truss

[0055]

[0056] Step two: Inspect the shape of the wall panel, analyze the shape measurement data, and determine the "zero" position for shaping.

[0057] First, under stable panel manufacturing conditions, the surface deviation of the panel after curing, without modification of the tooling, needs to be measured. During measurement, the panel should be aligned with the assembly posture, and the influence of external forces should be minimized to keep the panel in a near-free state. A laser tracker or scanner should be used to detect the panel's shape deviation. At least three measurements are recommended.

[0058] After measuring the shape, the measurement data was analyzed, and the overall deformation of the wall panel remained stable at over 40mm.

[0059] The inflection point of the wall panel deformation was identified as rib #5. The "zero" position for the shaping was set near the inflection point rib #5.

[0060] Step 3: Determine the amount of trimming.

[0061] Based on the actual research and development progress and the remaining tooling allowance, the root trimming amount selected in this embodiment is 7mm, that is, the maximum trimming amount at the root position is 7mm.

[0062] Step 4: Preliminary determination of the model surface

[0063] Select rib #5 as the "zero" point for shaping. The shaping amount at the root of the wall panel is 7mm. The initial shaping amounts at rib #4, rib #3, rib #2, and rib #1 are 1.4mm, 2.8mm, 4.2mm, and 5.6mm, respectively.

[0064] Use the "Offset" command in CATIA software to create offset surfaces for the original part manufacturing surfaces, corresponding to five offset values ​​from 1.4 to 7 mm.

[0065] At position 4# rib, the four surfaces—the positioning surface of 4# rib, the positioning surface of 8# truss (because they are relatively centered in the chord direction), the positioning surfaces of the front and rear beams, etc.—intersect with the 1.4mm offset surface. This yields the intersection points on the axes of the front beam, rear beam, and 8# truss, corresponding to the 1.4mm offset from the prototype surface. These points are used to generate the input points for the reference spline curve of the model surface.

[0066] Similarly, the intersection points of rib #3, rib #2, rib #1, and the root section, respectively, with deviations from the prototype surface of 2.8mm, 4.2mm, 5.6mm, and 7mm on the axes of the front beam, rear beam, and truss #8, were obtained.

[0067] Select six intersection points on the front beam, rear beam, and No. 8 stringer axis respectively, and create three spline curves using the "spline curve" command.

[0068] Using the multi-section surface command, select 3 spline lines as guide lines, and select the edge lines at rib #5 and the root to generate the root repair model surface.

[0069] The generated root trimming model surface is joined with the top part of the original rib #5 after it has been divided to form an integral surface, which is used for verification and manufacturing.

[0070] The deviation of the girder's representative position was measured. On the generated surface, the representative positions of the girder were selected, mainly measuring the height of the support at the root of the large end of the corresponding wall panel, and also measuring the height of the support at the positions of ribs 1# to 5# of the girder. These measurements were recorded. This was used to verify the deformation capacity of the girder in practice. The measured values ​​are shown in Table 2.

[0071] Table 2 Height of the stringer at each rib position due to shaping

[0072]

[0073] Step 5: Verify the deformation capacity of the girder in practice.

[0074] Place the girder on the corresponding position on the inspection fixture. Raise the root of the large end of the girder to the corresponding height as measured in step four. Paper pads can be used. Taking girder #10 as an example, raise the root by 6.13mm. Measure the gap between the actual girder and the inspection fixture at position #1. If the gap is less than the measured gap of 5.56mm, then raise the girder at rib #1 by 5.56mm. Continue to verify positions #2, #3, #4, and #5 using the same method. Actual measurements show that the gaps between the girder and the fixture at positions #2, #3, and #4 are less than the theoretical gap recorded in step four. However, at position #5, there is a gap of 0.55~0.65mm, which is greater than 0.2mm.

[0075] Step 6: Correct the model surface based on the results of the physical verification of the stringer.

[0076] As described in step five, the gap at rib #5 is too large. The shaping height of the front rib should be reduced. Based on the measured data showing that the gap is too large, the original offset values ​​of the front ribs #4, #3, #2, and #1 should be adjusted from 1.4mm, 2.8mm, 4.2mm, and 5.6mm, respectively, by 0.5mm, 0.4mm, 0.3mm, and 0.2mm. The surface offset values ​​of the ribs #4, #3, #2, and #1 should be adjusted to 0.9mm, 2.4mm, 3.9mm, and 5.4mm, respectively.

[0077] Repeatedly verify and correct the model surface, adjust the surface offset values ​​of ribs #4, #3, #2, and #1 to 0.9mm, 2.4mm, 3.9mm, and 5.4mm respectively, and regenerate the corrected surface.

[0078] Repeated verification confirmed that the corrected model surface met the requirements. Meanwhile, since the maximum deformation capacity of the girder is primarily limited by its length, the shorter the girder, the weaker the deformation capacity. On the corrected new surface, it was verified that the theoretically raised distance of the shorter girder should be less than the measured actual maximum deformation capacity H of the girder. Specifically, the girder was placed on the original station surface, with its large and small ends constrained to the new inner skin surface. The maximum distance from the bottom surface of the girder (generally near the middle) to the new inner skin surface was measured. This distance should be less than the actual maximum deformation capacity H of the girder.

[0079] The measured maximum distance between the No. 1 stringer and the new surface is 0.176 mm, which is less than its maximum deformation capacity of 0.31 mm.

[0080] The maximum distance between the actual side No. 2 stringer and the new surface is 0.351mm, which is less than its maximum deformation capacity of 1.04mm.

[0081] After the above verification steps, a qualified repair model surface was obtained. It was determined that the re-verified surface meeting the requirements could be used for the repair model of the wall panel tooling. The wall panel tooling was then repaired or newly manufactured according to this standard, i.e., iterative verification of the parts. During actual manufacturing, no scrapping issues occurred due to mismatch between the deformation capacity of the stringer and the product after the repair.

[0082] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any modifications or substitutions made by those skilled in the art within the scope of the technology disclosed in this application should be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for determining the surface of a composite reinforced wall panel forming process based on the deformation capacity of a stringer, characterized in that, The composite reinforced wall panel is composed of a skin and stringers, and is manufactured using a co-bonding process. The stringers are arranged along the length of the skin, and multiple stringers are parallel in the width of the skin. The stringers are first formed and cured, and then co-bonded with the uncured skin to form a whole. The ribs are then assembled onto the designated positions. Includes the following steps: Determining the deformation capacity of the S1 girder: Place the girder on the inspection fixture and raise both ends of the girder at the same height to determine the actual maximum deformation capacity of the girder; S2 Composite Reinforced Panel Shape Inspection and "Zero" Position Determination: Measure the shape of the composite reinforced panel, analyze the measurement data, determine the inflection point area of ​​the composite reinforced panel shape deformation, and determine the position of the "zero" position. Determining the upper limit of S3 modification amount: Place the stringer on the inspection fixture, raise the large end of the stringer near the root of the skin until the "zero" position is just off the inspection fixture, record the height of the large end of each stringer raised, and take the smallest value among the recorded values ​​as the upper limit of modification amount. S4 initially determines the surface of the composite reinforced wall panel forming fixture; in CATIA, based on the theoretical surface of the composite reinforced wall panel forming fixture, a composite reinforced wall panel forming fixture is generated with the selected deviation. Verification of the deformation capacity of the S5 stringer; Based on S4, verify the deformation capacity of the stringer. S6 physical verification.

2. The method for determining the surface of the composite reinforced wall panel forming process based on the deformation capacity of a stringer, as described in claim 1, is characterized in that... Determination of the deformation capacity of the S1 stringer; Place the stringer on the inspection fixture, raise both ends of the stringer to the same height, and continuously increase the height until the stringer just detaches from the inspection fixture. The criterion is that a 0.2mm thick feeler gauge can just pass through it. The height at both ends raised at this point is H, which is the actual maximum deformation capacity of the stringer.

3. The method for determining the surface of the composite reinforced wall panel forming process based on the deformation capacity of a stringer, as described in claim 2, is characterized in that... S2 composite reinforced wall panel shape inspection and "zero" position determination; The composite reinforced wall panel is placed in the assembly position, the shape of the composite reinforced wall panel is measured, the measurement data is analyzed, the inflection point area of ​​the deformation of the composite reinforced wall panel is determined, and the "zero" position is set on the position of the rib near the inflection point area.

4. The method for determining the surface of the composite reinforced wall panel forming process based on the deformation capacity of a stringer, as described in claim 3, is characterized in that... Determination of the upper limit of S3 modification amount; Select the stringer that passes through the "zero" position, place the stringer on the inspection fixture, and shim the large end of the stringer near the root of the skin until the "zero" position just detaches from the inspection fixture. Use the 0.2mm thick feeler gauge that just passes through as the judgment criterion, and record the height of the shim at the large end of each stringer. The smallest value among the recorded values ​​is taken as the upper limit of the modification amount.

5. The method for determining the surface of the composite reinforced wall panel forming process based on the deformation capacity of a stringer, as described in claim 4, is characterized in that... S4 initially determined the surface of the composite reinforced wall panel molding and decoration model; Based on the actual manufacturing process of composite reinforced wall panels, a modification amount is selected below the upper limit of the modification amount as the maximum modification amount at the root of the skin. The modification amount at the position of each rib from the root of the skin to the "zero" position is set in the form of an arithmetic sequence. In CATIA, this is used as the deviation amount. Based on the theoretical composite reinforced wall panel forming tooling surface, a composite reinforced wall panel forming tooling model surface is generated. In CATIA, the deviation between the bottom surface of the selected stringer at the large end near the root of the skin and at the position of the upper rib of the stringer and the surface of the theoretical composite reinforced wall panel forming tooling and the composite reinforced wall panel forming tooling model is measured and recorded as the basis for verifying the deformation capacity of the stringer. In CATIA, the maximum distance from the measuring station to the surface of the composite reinforced wall panel molding model, excluding the stringer at the "zero" position, must be below H. If it exceeds H, the shaping amount at the large end near the root of the skin and at the station of the upper rib of the stringer needs to be reduced, and adjusted sequentially until this height is below H.

6. The method for determining the surface of the composite reinforced wall panel forming process based on the deformation capacity of a stringer, as described in claim 5, is characterized in that... Verification of the deformation capability of the S5 stringer; Place the stringer, positioned at the "zero" position, on the inspection fixture. Raise the large end of the stringer near the skin root by the amount recorded in S4 as the deviation at the large end near the skin root. Then measure the distance between the inspection fixture and the position pointing towards the first rib in the "zero" direction. If this distance is below the deviation recorded in S4 for the position of the first rib in the "zero" direction, the deformation capacity at this point is considered to meet the requirements. Continue raising the position of the first rib in the "zero" direction by the amount recorded in S4. Record the deviation at the position of the first rib pointing towards the "zero" position. Then measure the distance between the position of the second rib pointing towards the "zero" position and the inspection fixture. If this distance is below the deviation at the position of the second rib pointing towards the "zero" position recorded in S4, the deformation capacity at this point is considered to meet the requirements. This process continues until the deformation capacity at the position of each rib before the "zero" position meets the requirements, and the "zero" position is in close contact with the inspection fixture, and a 0.2mm thick feeler gauge cannot pass through. Then the deformation capacity of the stringer is considered to meet the requirements. During the process, if the distance between any rib's position and the inspection fixture is greater than the deviation of the corresponding position recorded in S4, or if the gap between the "zero" position and the inspection fixture allows a 0.2mm thick feeler gauge to pass through, it is necessary to return to S4 and readjust the maximum trimming amount at the skin root and the trimming amount at each rib's position from the skin root to the "zero" position until the requirements are met. At this time, the trimming amount at each rib's position from the skin root to the "zero" position does not need to be set in the form of an arithmetic sequence.

7. The method for determining the surface of the composite reinforced wall panel forming process based on the deformation capacity of a stringer, as described in claim 6, is characterized in that... S6 physical verification; After determining the deviation amount that ensures each station passes through the "zero" position and meets the requirements, the surface of the composite reinforced wall panel forming tooling is considered to be the actual surface of the composite reinforced wall panel forming tooling. The composite reinforced wall panel forming tooling is repaired or newly manufactured according to this repaired surface. The repaired or newly manufactured composite reinforced wall panel forming tooling is used for actual production. The S2~S6 process is repeated on the newly produced composite reinforced wall panels until the newly produced composite reinforced wall panels meet the theoretical requirements.

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