Pre-offset cementing method for stiffened wallboard stringer

Abstract

The invention discloses a pre-offset cementing method for a stiffened wallboard stringer. A composite material stiffened wallboard theoretical model is divided into a plurality of characteristic sections in the normal direction of a stringer axis plane; measuring the number of stringers, the horizontal distance between each stringer at a specified position and the geometric central axis of the wallboard, the maximum distance between the outermost stringer at a specified position and the geometric central axis of the wallboard, the actual length of each stringer, the section shape identifier of each stringer and the theoretical thickness of each stringer web at a specified position in the theoretical model of the composite stiffened wallboard; the theoretical thickness of the skin glued with each stringer at the specified position is measured; calculating the pre-offset amount of each stringer at each specified position according to the measurement result; according to the calculated pre-offset amount, the corresponding offset amount is preset for each stringer in the direction away from the geometric center axis of the wall plate through laser projection, and then glue joint positioning is conducted; and after the pre-offset glue joint positioning is completed, packaging and curing are conducted on the stiffened wall plate.

Description

Technical Field

[0001] This invention belongs to the field of aircraft composite material manufacturing technology, and in particular, a pre-offset adhesive bonding method for stiffened panel stringers. Background Technology

[0002] Composite integral stiffened wall panels typically use adhesive bonding processes to combine multiple T-shaped, I-shaped, or J-shaped stringers with the skin into an integral structure. Among them, the manufacturing of large composite stiffened wall panels generally uses molding technology that co-bonds cured stringers with uncured skin.

[0003] In traditional autoclave molding, the stringer undergoes slight displacement as the skin thickness decreases, leading to stringer misalignment. Additionally, during bag making with reinforced panels, multiple pleats are required, resulting in bag pressure imbalance on both sides of the stringer's uprights. Under curing pressure, this also causes stringer displacement, resulting in a "converging offset" (i.e., offset towards the center of the skin's curvature). This offset causes the stringer's final axis position to deviate from the theoretical design axis, severely impacting the panel's load-bearing efficiency and assembly quality. Summary of the Invention

[0004] The purpose of this invention is to provide a pre-offset adhesive bonding method for stiffened wall panel stringers, in order to solve the problem that during the curing and molding process of stiffened wall panels, the stringer is offset, resulting in the final axis position of the stringer deviating from the theoretical design axis, which seriously affects the load-bearing efficiency and assembly quality of the wall panel.

[0005] The technical solution of this invention is as follows: This invention provides a pre-offset adhesive bonding method for stiffened wall panel stringers. By pre-offsetting the theoretical bonding position of the stringers to be bonded on the wall panel, the offset of the stringers during the curing process is compensated. The method includes: Step 1: Divide the theoretical model of the composite stiffened panel into multiple characteristic sections along the normal direction of the stringer axis plane. The axial coordinates of each characteristic section are denoted as follows: Location; Step 2: The following parameters were measured in the theoretical model of the composite stiffened panel: number of stringers. Each truss is in the designated Horizontal distance from the geometric center axis of the wall panel The outermost stringer is in the designated Maximum distance from the position to the geometric center axis of the wall panel Actual length of each truss Markings of the cross-sectional shape of each girder Each long girder web is in the designated... Theoretical thickness of the location and with each truss in the designated Theoretical thickness of the skin bonded at the location ; Step 3: Based on the parameters measured in Step 2, calculate the parameters for each truss at each specified location. Pre-offset of position ; Step 4, based on the calculations in Step 3, each stringer is placed in its designated position. Pre-offset of position After using laser projection to pre-set the corresponding offset of each stringer in the direction away from the geometric center axis of the wall panel, the gluing is then performed for positioning. Step 5: After completing the pre-biased adhesive bonding positioning, the stiffened wall panel is encapsulated and cured.

[0006] Optionally, in the pre-offset bonding method for stiffened panel girder as described above, step 3 calculates the girder at each specified... Pre-offset of position The method is as follows: Substitute the parameters measured in step 2 into the following pre-bias calculation formula: ; Calculate the values ​​of each long girder at each specified location. Pre-offset required for position ,in, These are the process experience coefficients calibrated through experiments. These are the weighting coefficients. For shape correction factor, thickness correction factor Used to quantify in a specified The effect of thickness differences between the various struts and the bonded skin on curing deformation.

[0007] Optionally, in the pre-offset adhesive bonding method for a stiffened wall panel truss as described above, The shape correction coefficient The value is determined based on the cross-sectional shape of the girder; for T-type girder, the value is 1.2, for I-type girder, the value is 1.0, and for J-type girder, the value is 0.9.

[0008] Optionally, in the pre-offset adhesive bonding method for a stiffened wall panel truss as described above, The weighting coefficient The value ranges from 1.5 to 2.0, and it is used to characterize the nonlinear edge effect caused by pressure transmission attenuation during the bonding process of multiple stringers. It is calibrated by preparing stiffened wall panel test specimens and measuring the offset of the stringers during the curing process; the weighting coefficient... The larger the value of , the stronger the edge effect of the wall panel, and the more obvious the pressure decays from the center to the outside. Therefore, the outermost stringer needs the most compensation. The smaller the value, the more uniform the pressure distribution, and the smaller the difference in compensation required between the inner and outer stringers.

[0009] Optionally, in the pre-offset adhesive bonding method for a stiffened wall panel truss as described above, The process experience coefficient The value ranges from 0.08 to 0.12, and it is calibrated by preparing stiffened wall panel test specimens and measuring the offset of the stringer during the curing process; the process empirical coefficient The larger the value, the higher the risk of systematic deviation caused by the current process, such as bag compression, materials, and adhesives; the smaller the value, the lower the risk of systematic deviation of the current process.

[0010] Optionally, in the pre-offset adhesive bonding method for a stiffened wall panel truss as described above, When the stiffened wall panel is a variable cross-section wall panel, or when the lengths of the various stringers are inconsistent, the pre-offset calculation formula is as follows: and The value is obtained by selecting at least three different Location (including but not limited to the starting end of each stringer) Middle position and The measured value was obtained from the measurement, and The selection of locations must cover areas where the geometric center of the wall panel changes significantly, and areas where the number of stringers changes, and multiple locations must be considered. The arithmetic mean of the positions is used as the representative value for each girder. .

[0011] Optionally, in the pre-offset adhesive bonding method for stiffened panel trusses as described above, the thickness correction coefficient... The expression is: 1+0.5 .

[0012] Optionally, in the pre-offset adhesive bonding method for a stiffened panel truss as described above, the weighting coefficient and process experience coefficient The value is determined by the following steps: S1, Prepare composite reinforced wall panel test specimens without applying a pre-biasing amount, and then cure them; S2, Measure the actual axial offset of each stringer after the stiffened wall panel test specimen has been cured and molded. ; S3, the actual offset The formula for calculating the pre-bias amount By fitting the data and using least squares or nonlinear regression analysis, the predicted offset values ​​of each stringer are back-calculated to obtain the actual measured axial offset values. The weighting coefficient with the smallest overall error and process experience coefficient .

[0013] The beneficial effects of this invention are as follows: This invention provides a pre-offset adhesive bonding method for stiffened wall panel stringers. By establishing a mathematical model that considers the influence of multiple factors such as the number, position, length, shape, and thickness of the stringers, the pre-offset amount of each stringer is calculated, thereby compensating for stringer offset caused by uneven bag pressure during the curing process. Compared with the prior art, this invention reduces the reliance on complex physical tooling, improves the stringer axis control accuracy and process consistency, and is applicable to various stringer configurations and complex-shaped wall panels. Using the pre-offset adhesive bonding method provided by this invention for encapsulating and curing stiffened wall panels has the following advantages: First, the pre-biased bonding method provided by this invention is simple to implement. It uses the core mechanism of "the stringer returning to its theoretical position through reverse pre-biasing and curing slip" to simplify the complex problem and obtain the calculation formula. The calculation of stringer pre-biasing is simple. Secondly, the pre-biased bonding method provided by the present invention has high bonding quality and reliability, abandons the traditional bag outer card plate positioning method, and has more uniform pressure transmission, reducing the risk of bonding interface defects. Third, the pre-biased bonding method provided by this invention has low cost, reduces reliance on complex high-precision molds and physical tooling, and reduces manufacturing costs and manufacturing cycle. Fourth, the pre-biased bonding method provided by this invention has strong adaptability and is applicable to various wall panel shapes such as rectangles and trapezoids, as well as various stringer structures such as T-shaped, I-shaped, and J-shaped. Fifth, the pre-biased bonding method provided by this invention can be continuously optimized. The formula can be iteratively optimized based on historical process data to continuously improve prediction accuracy. Attached Figure Description

[0014] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0015] Figure 1 This is a schematic diagram of the T-shaped stiffened wall panel used in an embodiment of the present invention; Figure 2 This is a cross-sectional view of the first section of the T-shaped stiffened wall panel used in the embodiment of the present invention; Figure 3 This is a cross-sectional view of the second section of the T-shaped stiffened wall panel used in the embodiment of the present invention; Figure 4 This is a cross-sectional view of the third section of the T-shaped stiffened wall panel used in the embodiment of the present invention; Explanation of reference numerals in the attached figures: 1-Geometric center axis, 2-First girder, 3-Second girder, 4-Third girder, 5-Fourth girder, 6-Fifth girder, 7-Skin, 8-First section, 9-Second section, 10-Third section. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0017] As explained in the background section, during the curing process of the stiffened wall panel, the stringer shifts, causing the final axis position of the stringer to deviate from the theoretical design axis, which seriously affects the load-bearing efficiency and assembly quality of the wall panel.

[0018] Currently, most mainstream methods in engineering rely on high-precision physical positioning clamps for limiting the position of the stringer, as seen in patents CN108943776A (A detachable adjustable stringer clamping and positioning device and method) and CN115302819A (A sliding stiffened wall panel stringer axis degree control device and method of use). These methods constrain the spatial position of the stringer during the curing process through physical slots, edges, etc. However, this method has several inherent drawbacks: 1) High cost: Positioning plates usually need to be precision machined from Invar steel or composite materials, which results in long design and manufacturing cycles and high costs; 2) Poor adaptability: A single pallet is typically designed only for a specific product, lacking flexibility. When design parameters change, the original pallet may become unusable, making it difficult to quickly respond to changes in design iterations and manufacturing requirements; 3) Limited accuracy: Machining errors of the card itself, assembly gaps, and wear during repeated use will directly affect the final positioning accuracy; 4) Weak compensation capability: The traditional clamping method is a passive constraint method that cannot intelligently compensate for nonlinear deformation caused by complex factors such as uneven bag pressure and resin chemical shrinkage. The tooling only attempts to "block" the offset, rather than "eliminate" the root cause of the offset, resulting in large residual stress inside the stringer after curing, which may still cause the axis to exceed the tolerance.

[0019] Therefore, for the problem of stringer axis misalignment in composite reinforced panel, there is an urgent need for a stringer axis alignment control method that can get rid of the dependence on high-cost positioning plates and can actively and accurately compensate for curing deformation, so as to meet the urgent needs of modern aerospace manufacturing industry for cost reduction, efficiency improvement and high-quality control.

[0020] Based on the above requirements, the present invention provides a pre-offset adhesive bonding method for stiffened wall panel stringers. The composite material stiffened wall panel manufactured using this method has accurate stringer axis positioning, high adhesive bonding quality, significantly reduced overall manufacturing cost, and high adaptability to design changes.

[0021] The present invention provides the following specific embodiments, which can be combined with each other. For the same or similar concepts or processes, they may not be described again in some embodiments.

[0022] The pre-offset bonding method for stiffened wall panel stringers provided by this invention compensates for the stringer's offset during the curing process by pre-offsetting the theoretical bonding position of the stringer to be bonded on the wall panel. The method provided by this invention includes the following steps: Step 1: Divide the theoretical model of the composite stiffened panel into multiple characteristic sections along the normal direction of the stringer axis plane. The axial coordinates of each characteristic section are denoted as follows: Location; Step 2: The following parameters were measured in the theoretical model of the composite stiffened panel: number of stringers. Each truss is in the designated Horizontal distance from the geometric center axis of the wall panel The outermost stringer is in the designated Maximum distance from the position to the geometric center axis of the wall panel Actual length of each truss Markings of the cross-sectional shape of each girder Each long girder web is in the designated... Theoretical thickness of the location and with each truss in the designated Theoretical thickness of the skin bonded at the location ; Step 3: Based on the parameters measured in Step 2, calculate the parameters for each truss at each specified location. Pre-offset of position ; Step 4, based on the calculations in Step 3, each stringer is placed in its designated position. Pre-offset of position After using laser projection to pre-set the corresponding offset of each stringer in the direction away from the geometric center axis of the wall panel, the gluing is then performed for positioning. Step 5: After completing the pre-biased adhesive bonding positioning, the stiffened wall panel is encapsulated and cured.

[0023] In one implementation of this invention, step 3 above calculates the stringer at each specified location. Pre-offset of position The method is as follows: Substitute the parameters measured in step 2 into the following pre-bias calculation formula: ; Calculate the values ​​of each long girder at each specified location. Pre-offset required for position ,in, These are the process experience coefficients calibrated through experiments. These are the weighting coefficients. For shape correction factor, thickness correction factor Used to quantify in a specified The effect of thickness differences between the various struts and the bonded skin on curing deformation.

[0024] In one implementation of this invention, the shape correction coefficient The value is determined based on the cross-sectional shape of the girder; for T-type girder, the value is 1.2, for I-type girder, the value is 1.0, and for J-type girder, the value is 0.9.

[0025] In one implementation of this invention, the aforementioned weighting coefficients The value ranges from 1.5 to 2.0, and is used to characterize the nonlinear edge effect caused by pressure transmission attenuation during the bonding process of multiple stringers. It is calibrated by preparing stiffened wall panel test specimens and measuring the offset of the stringers during the curing process.

[0026] It should be noted that the weighting coefficients The larger the value, the stronger the edge effect of the wall panel, and the more obvious the pressure decays from the center to the outside. Therefore, the outermost stringer needs the most compensation. The smaller the value, the more uniform the pressure distribution, and the smaller the difference in compensation required between the inner and outer stringers.

[0027] In one implementation of this invention, the process experience coefficient The value ranges from 0.08 to 0.12, and it is calibrated by preparing reinforced wall panel test specimens and measuring the offset of the stringer during the curing process.

[0028] It should be noted that the process experience coefficient The larger the value, the higher the risk of systematic deviation caused by the current process, such as bag compression, materials, and adhesives; the smaller the value, the lower the risk of systematic deviation of the current process.

[0029] In one implementation of this invention, when the stiffened wall panel is a variable cross-section wall panel, or when the lengths of the various stringers are inconsistent, the pre-offset calculation formula is as follows: and The value is obtained by selecting at least three different Location (including but not limited to the starting end of each stringer) Middle position and The measured value was obtained from the measurement, and The selection of locations must cover areas where the geometric center of the wall panel changes significantly, and areas where the number of stringers changes, and multiple locations must be considered. The arithmetic mean of the positions is used as the representative value for each girder. .

[0030] In one implementation of this invention, the thickness correction coefficient The expression is: 1+0.5 .

[0031] In one implementation of this invention, the weighting coefficient and process experience coefficient The value is determined by the following steps: S1, Prepare composite reinforced wall panel test specimens without applying a pre-biasing amount, and then cure them; S2, Measure the actual axial offset of each stringer after the stiffened wall panel test specimen has been cured and molded. ; S3, the actual offset The formula for calculating the pre-bias amount By fitting the data and using least squares or nonlinear regression analysis, the predicted offset values ​​of each stringer are back-calculated to obtain the actual measured axial offset values. The weighting coefficient with the smallest overall error and process experience coefficient .

[0032] This invention provides a pre-offset adhesive bonding method for stiffened wall panel stringers. By establishing a mathematical model considering the influence of multiple factors such as the number, position, length, shape, and thickness of the stringers, the pre-offset amount of each stringer is calculated, thereby compensating for stringer offset caused by uneven bag pressure during the curing process. Compared with existing technologies, this invention reduces reliance on complex physical tooling, improves the control accuracy of the stringer axis and process consistency, and is applicable to various stringer configurations and complex-shaped wall panels. Using the pre-offset adhesive bonding method provided by this invention for encapsulating and curing stiffened wall panels has the following advantages: First, the pre-biased bonding method provided by this invention is simple to implement. It uses the core mechanism of "the stringer returning to its theoretical position through reverse pre-biasing and curing slip" to simplify the complex problem and obtain the calculation formula. The calculation of stringer pre-biasing is simple. Secondly, the pre-biased bonding method provided by the present invention has high bonding quality and reliability, abandons the traditional bag outer card plate positioning method, and has more uniform pressure transmission, reducing the risk of bonding interface defects. Third, the pre-biased bonding method provided by this invention has low cost, reduces reliance on complex high-precision molds and physical tooling, and reduces manufacturing costs and manufacturing cycle. Fourth, the pre-biased bonding method provided by this invention has strong adaptability and is applicable to various wall panel shapes such as rectangles and trapezoids, as well as various stringer structures such as T-shaped, I-shaped, and J-shaped. Fifth, the pre-biased bonding method provided by this invention can be continuously optimized. The formula can be iteratively optimized based on historical process data to continuously improve prediction accuracy.

[0033] The following is an illustrative example illustrating the implementation of the pre-offset adhesive bonding method for stiffened wall panel trusses provided by the present invention.

[0034] Implementation Example like Figures 1 to 4 As shown in the example, this embodiment uses a co-bonding process to manufacture composite material T-shaped stiffened panels. The composite material T-shaped panel in this embodiment includes: 5 cured T-shaped stringers: first stringer 2, second stringer 3, third stringer 4, fourth stringer 5, and fifth stringer 6. Each T-shaped stringer is bonded to the uncured skin 7 using an adhesive film.

[0035] The pre-offset adhesive bonding method for stiffened wall panel trusses provided in this embodiment includes the following steps: Step 1: On the theoretical model of the composite stiffened panel, divide the space along the normal direction of the girder axis into three typical characteristic sections: the two starting ends, the ending ends, and the middle position. These are: Section 1 (8), Section 2 (9), and Section 3 (10). The axial coordinates of the three typical characteristic sections are denoted as follows: , , Location.

[0036] Step 2: In the theoretical model of the composite stiffened panel, the following parameters were obtained by measuring the first section 8: number of stringers. The first girder 2 is in the designated The horizontal distance from the position to the geometric center axis 1 of the wall panel is The second long truss 3 is in the designated The horizontal distance from the position to the geometric center axis 1 of the wall panel is The long girder is 3 meters from the wall panel at the specified distance. The horizontal distance from the position to the geometric center axis 1 of the wall panel is The long girder is 4 meters from the wall panel in the specified location. The horizontal distance from the position to the geometric center axis 1 of the wall panel is The long girder 5 is at the specified distance from the wall panel. The horizontal distance from the position to the geometric center axis 1 of the wall panel is The outermost stringer is in the designated The location is at its maximum distance from the geometric center axis 1 of the wall panel. The actual lengths of the five long beams are as follows: , , , , Cross-sectional shape markings of the five long trusses Five long truss webs are in the designated The theoretical thicknesses at the locations are respectively , , , , and with each truss at the designated The theoretical thicknesses of the bonded skin 7 at the location are respectively , , , , .

[0037] Referring to the parameters measured at section 8 in the theoretical model of the stiffened wall panel, the parameters of section 9 and section 10 are measured as follows: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , .

[0038] The process experience coefficient of this wall panel was determined through experiments. Weighting coefficients Known The thickness correction factors for each of the eight girder sections in the first section are as follows: , , , , .

[0039] Referring to the calculation method for the thickness correction factor of the first section 8 mentioned above, the thickness correction factors for each girder of the second section 9 and the third section 10 are calculated as follows: , , , , , , , , , .

[0040] Based on the following formula The pre-offset of the first section 8 and the first stringer 2 was calculated to be... The pre-offset of the first girder 2 of the second section 9 is The pre-offset of the first stringer 2 of the third section 10 is The pre-offset of the first girder 2 is the arithmetic mean of the pre-offsets of three typical sections, specifically: .

[0041] Referring to the calculation method for the pre-offset of the first stringer 2 described above, the pre-offsets of the remaining four stringers are calculated as follows: 0.34 , 0 , 0.33 , 1.2 .

[0042] According to the laser projection, the first stringer 2 to the fifth stringer 6 are pre-biased in a direction away from the geometric center axis 1. 0.34 0 0.33 1.2 Adhesive bonding and positioning are performed with skin 7. After pre-biased adhesive bonding and positioning are completed, the stiffened wall panel is encapsulated and cured.

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method of pre-biased bonding of stringer longerons of a stiffened panel, characterized in that, The method comprises the following steps: Step 1, the theoretical model of composite stiffened panel is divided into a plurality of characteristic sections along the normal of the long string axial plane, the axial coordinate of each characteristic section is marked as Position; Step 2, measure the following parameters in the theoretical model of the composite stiffened panel: number of stringers , horizontal distance of each stringer from the geometric center axis of the panel at a specified location , maximum horizontal distance of the outermost stringer from the geometric center axis of the panel at a specified location , actual length of each stringer , stringer cross-sectional shape identifier , theoretical thickness of each stringer web at a specified location , and theoretical thickness of the skin bonded to each stringer at a specified location ; Step 3, based on the parameters measured in Step 2, calculate the pre- bias amount for each string at each designated position ;​ Step 4, based on the calculations in Step 3, each stringer is placed in its designated position. Pre-offset of position After using laser projection to pre-set the corresponding offset of each stringer in the direction away from the geometric center axis of the wall panel, the gluing is then performed for positioning. Step 5, after the pre-offset adhesive positioning is completed, the stiffened wallboard is packaged and cured.

2. The method of claim 1, wherein the method further comprises: The pre-bias amount of the long strut at each specified position in Step 3 is calculated in the following manner: ​​ The parameters measured in step 2 are substituted into the following pre-offset calculation formula: ； The pre-bias amount required for each long string at each designated position is calculated respectively wherein, is the process experience coefficient calibrated by experiment, is the weight coefficient, is the shape correction coefficient, thickness correction coefficient used to quantify the influence of the thickness difference between each long string and the glued skin at the designated position on the curing deformation.

3. The pre-offset adhesive method for the stiffened wallboard stringer according to claim 2, characterized in that, The shape correction coefficient According to the type of the cross-sectional shape of the longeron; the value of the T-shaped longeron is 1.2, the value of the I-shaped longeron is 1.0, and the value of the J-shaped longeron is 0.

9.

4. The pre-offset adhesive method for the stiffened wallboard stringer according to claim 2, characterized in that, The weight coefficient The value range of the weight coefficient is 1.5-2.0, which is used to represent the nonlinear edge effect caused by pressure transmission attenuation in the process of stringer bonding. The calibration is carried out by preparing a stiffened wall test piece and measuring the displacement of the stringer during the curing process.

5. The pre-offset adhesive method for the stiffened wallboard stringer according to claim 2, characterized in that, The process experience coefficient The value range of the process experience coefficient is 0.08-0.12, which is calibrated by preparing a stiffened panel test piece and measuring the displacement of the longeron during the curing process.

6. The pre-offset adhesive method for the stiffened wallboard stringer according to claim 2, characterized in that, When the stiffened wallboard is a variable cross-section wallboard, or when the lengths of the stringers are inconsistent, the pre-bias amount calculation formula has and values obtained by selecting measurement values of at least three different positions, and the selection of the at least three different positions requires covering positions where the geometric center of the wallboard changes greatly, positions where the number of stringers changes, and taking the arithmetic mean of multiple positions as the representative value of each stringer ; wherein the at least three different positions include the starting end , the middle position of each stringer.

7. The method of claim 2, wherein the method further comprises: The thickness correction coefficient The expression is: 1+0.5 。 8. A method of pre-biased bonding of stringer longerons of a stringer- walled panel according to claim 4 or 5, wherein, the weight coefficient and the process experience coefficient are calibrated by the following steps: S1, prepare a composite material stiffened wallboard test piece without applying a pre-offset amount and cure and form; S2, measured axis offset of each stringer after curing and molding of the stiffened wall panel test piece ; S3, the actual offset with the pre-offset calculation formula fitting, by least squares method or nonlinear regression analysis, to get the offset prediction value of each long bar and its measured axis offset the weight coefficient of the minimum overall error and the process experience coefficient .

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