A method for discretizing the mass of an aircraft wing rib segment

Abstract

This invention belongs to the field of aircraft design technology and relates to a method for discretizing the mass of an aircraft wing rib segment. The method includes the following steps: (1) setting a virtual trapezoidal shape covering the wing, and along the wing spanwise direction, setting equally spaced spanwise sectional surfaces on the virtual trapezoidal shape, with several chordal grid points equally spaced on each spanwise sectional surface; (2) determining the position of the rib segment mass center of gravity on the spanwise sectional surface; (3) discretizing the rib segment mass along the spanwise direction to adjacent spanwise sectional surfaces according to the lever ratio; (4) discretizing the sectional surface mass along the chordwise direction to chordal grid points according to a trapezoidal distribution; (5) calculating the chordal grid point mass by piecewise integration. This invention sets a trapezoidal shape along the wing profile, discretizes the wing rib segment mass along the wing spanwise direction to adjacent spanwise sectional surfaces according to the lever ratio, and discretizes the sectional surface mass along the wing chordwise direction to chordal grid points according to a trapezoidal distribution. While ensuring the rib segment mass center of gravity remains unchanged, the method reasonably discretizes the mass, making the wing mass distribution closer to reality, improving the accuracy of wing load calculation, and making the structural design safer and more reliable.

Description

Technical Field

[0001] This invention belongs to the field of aircraft design technology, and relates to aircraft load calculation technology, specifically to a method for discretizing the mass of an aircraft wing rib segment. Background Technology

[0002] Aircraft mass data is crucial for aircraft load calculations, and the accuracy of the mass data directly determines the accuracy of the calculated loads. In wing mass data, masses greater than 0.5 kg are often given as lumped masses; while masses less than 0.5 kg and structural masses that cannot be divided (such as panels, beams, and ribs) are often given as rib segment masses. This means that all small masses within a rib segment (between adjacent ribs) and the indivisible structural masses are given as a total mass. In wing load calculations, if the rib segment mass is calculated as a total mass, the results will be severely distorted, leading to excessively high loads at the center of gravity and insufficient loads further away from the center of gravity. This results in calculated wing loads that deviate significantly from the actual loads, causing serious errors. Summary of the Invention

[0003] The purpose of this invention:

[0004] To address the issue of significant errors in load calculations using the mass of wing rib segments directly, this invention provides a method for discretizing the mass of aircraft wing rib segments. This method establishes a trapezoidal shape along the wing profile, discretizing the mass of the wing rib segments along the spanwise direction to adjacent spanwise sectional planes according to leverage ratios. The mass of these sectional planes is then discretized along the chordwise direction to chordwise grid points using a trapezoidal distribution. By reasonably discretizing the mass while maintaining a constant center of gravity for the rib segments, the mass distribution of the wing more closely approximates reality, improving the accuracy of wing load calculations and making structural design safer and more reliable.

[0005] The technical solution of this invention:

[0006] A method for discretizing the mass of an aircraft wing rib segment includes the following steps:

[0007] (1) Set a virtual trapezoidal shape covering the wing. Along the span of the wing, set equally spaced spanwise cross-sections on the virtual trapezoidal shape. On each spanwise cross-section, set several chordal grid points at equal intervals.

[0008] (2) Determine the position of the center of gravity of the rib segment on the spanwise tangential plane;

[0009] (3) Discretize the mass of the rib segment along the span direction to adjacent span tangent planes according to the lever ratio;

[0010] (4) Discretize the cross-sectional mass along the chord direction into chord grid points in a trapezoidal distribution;

[0011] (5) Calculate the mass of the chordal grid points by piecewise integration.

[0012] Furthermore, the spanwise direction is defined as from the wing root to the wingtip, and the coordinate system is defined as the Z-axis; the chordwise direction is defined as from the trailing edge to the leading edge of the wing, and the coordinate system is defined as the X-axis.

[0013] Furthermore, in step (1), the wing shape is approximately trapezoidal, and a virtual trapezoidal shape is set along the wing shape as the range of mass dispersion. In order to include the entire wing, the trapezoid is slightly larger than the wing shape.

[0014] Furthermore, step (1) specifically involves:

[0015] The coordinates of the four vertices of the virtual trapezoidal shape were obtained by measurement, among which the coordinates of the two endpoints of the wing root section were (X... 11 Z 11 ), (X 12 Z 12 The coordinates of the two endpoints of the wingtip section are (X... 21 Z 21 ), (X 22 Z 22 Parallel to the root section of the virtual trapezoidal shape, N1 equally spaced spanwise sections are evenly arranged along the wing span according to the actual number of ribs. The spanwise coordinate of the i-th spanwise section is... The chordal coordinates of the two endpoints of the i-th tangential plane are: The chord length L of the i-th tangential surface i =X i1 -X i2 On the spanwise section, N2 equally spaced chordwise grid points are uniformly arranged along the chord direction of the wing according to the length of the rib. The chordwise coordinate of the j-th grid point on the i-th section is...

[0016]

[0017] Furthermore, step (2) specifically involves: The ribs are typically distributed parallel to the spanwise direction of the wing. Knowing the coordinates of the center of mass of the rib segment in the spanwise direction, the position of the center of mass of the rib segment in the spanwise tangent plane can be obtained. The specific process is as follows:

[0018] The mass center of gravity of the rib segment is Z0 in the spanwise direction and Z0 in the spanwise tangential direction. i When Z i ≤Z0≤Z i+1 At this point, the center of mass of the rib segment is located between the i-th spanwise section and the (i+1)-th spanwise section, and the distance from the center of mass of the rib segment to the i-th spanwise section is H1 = Z0 - Z. i The distance from the (i+1)th spanwise tangent is H2 = Z. i+1 -Z0.

[0019] Furthermore, step (3) specifically involves: the mass M of the wing rib segment, which is discretized into the mass M of the i-th spanwise section using the lever ratio formula. iThe mass M of the (i+1)th spanwise section i+1 ;

[0020]

[0021] Furthermore, in step (4), the shape of the wing section is approximately trapezoidal. Therefore, distributing the wing section mass along the chord direction into trapezoidal grid points is consistent with the actual situation. The area of ​​the trapezoidal distribution is the spanwise section mass, the height of the trapezoidal distribution is the length of the spanwise section, the two bases of the trapezoidal distribution are the distributed masses at both ends of the spanwise section, and the centroid of the trapezoidal distribution is the distance from the centroid of the spanwise section mass to one end of the spanwise section.

[0022] The specific process is as follows: the mass M of the wing rib segment is discretized to the mass of the i-th spanwise section, which is Mi. i The length of the cross section is L i The mass distribution at both ends of the span is m i1 m i2 The chordal coordinate of the center of mass of the rib segment is X0;

[0023] The distance from the center of mass of the spanwise section to one end of the spanwise section is X. i =X0-X i1 According to the formula for calculating the area of ​​a trapezoid: Centroid calculation formula: Derive the mass distribution at both ends of the span:

[0024] Furthermore, step (5) is to discretize the spanwise tangential mass along the chord direction into trapezoidal distribution to the chordal grid points. The resulting mass is a trapezoidal distribution, which needs to be calculated by piecewise integration to obtain the mass of the chordal grid points.

[0025] The specific process is as follows: The mass of the trapezoidal distribution can be represented by the following function: The chord-oriented grid points divide the tangent into N segments, where x is the variable along the chord direction coordinate, and the mass M of the j-th segment is... ij for:

[0026]

[0027] After the above steps, the mass of the wing ribs is reasonably distributed while ensuring that the center of gravity of the rib mass remains unchanged, so that the mass distribution of the wing is closer to the actual situation.

[0028] The beneficial effects of this invention are:

[0029] This invention proposes a method for discretizing the mass of aircraft wing rib segments. A trapezoidal shape is established along the wing's outline, and the mass of the wing rib segments is discretized along the wing spanwise to adjacent spanwise sectional planes according to the lever ratio. The mass of these sectional planes is then discretized along the wing chordwise direction to chordwise grid points according to a trapezoidal distribution. This method achieves reasonable mass discretization while maintaining a constant center of gravity for the rib segment mass, making the wing mass distribution closer to reality. It solves the problem of directly calculating loads using the wing rib segment mass, which leads to excessively large loads near the center of gravity and excessively small loads far from the center of gravity, resulting in significant discrepancies and serious errors. This improves the accuracy of wing load calculations, making structural design safer and more reliable. Furthermore, this method for discretizing the mass of aircraft wing rib segments can be extended to the discretization calculation of other loads, demonstrating significant value. Attached Figure Description

[0030] Figure 1 This is a schematic diagram showing the trapezoidal shape, spanwise tangent, and chordwise grid points.

[0031] Among them, 1-wing shape, 2-wing rib, 3-trapezoidal shape, 4-spanwise section, 5-chordwise grid point, 6-wing spanwise coordinate Z-direction, 7-wing chordwise coordinate X-direction.

[0032] Figure 2 This is a schematic diagram of the spanwise discreteness according to the leverage ratio;

[0033] Wherein, 8 represents the mass of the rib segment M, and 9 represents the mass of the adjacent cross-section M. i 10 - Adjacent section mass M i+1 11 - Distance H1 from adjacent cut surfaces, 12 - Distance H2 from adjacent cut surfaces.

[0034] Figure 3 This is a schematic diagram of the chordal distribution in a trapezoidal pattern.

[0035] Among them, the 9-section mass M i , 13-mass distribution at one end of the cross section m i1 14-The mass m distributed at the other end of the cross section i2 15 - Section length L i 16-chord virtual grid points.

[0036] Figure 4 This is a schematic diagram of piecewise integration calculation of virtual grid point quality.

[0037] Among them, the mass m distributed at one end of the 13-section is i1 14-The mass m distributed at the other end of the cross section i2 15 - Section length L i 17-Chord-direction j-th segment mesh point mass M ij .

[0038] Figure 5This is a schematic diagram of the trapezoidal shape, spanwise sectional plane, and chordwise grid points in Embodiment 2;

[0039] Figure 6 This is a schematic diagram of the mass of the rib segment along the span direction and discretely distributed to adjacent cross-sections according to the lever ratio in Example 2;

[0040] Figure 7 This is a schematic diagram of the cross-sectional mass of Example 2, which is discretely distributed along the chord direction in a trapezoidal pattern to the chord-direction grid points. Detailed Implementation

[0041] One embodiment of the present invention is:

[0042] A method for discretizing the mass of an aircraft wing rib segment includes the following steps:

[0043] (1) Set a virtual trapezoidal shape to cover the wing. Along the span of the wing, set equally spaced spanwise cross-sections on the virtual trapezoidal shape. On each spanwise cross-section, set several chordal grid points at equal intervals. The spanwise direction is defined as the direction from the wing root to the wingtip, and the coordinate is defined as the Z direction. The chordal direction is defined as the direction from the trailing edge to the leading edge of the wing, and the coordinate is defined as the X direction. In step (1), the wing shape is approximately trapezoidal. A virtual trapezoidal shape is set along the wing shape to represent the range of mass dispersion. In order to include the entire wing, the trapezoid is slightly larger than the wing shape.

[0044] Specifically:

[0045] The coordinates of the four vertices of the virtual trapezoidal shape were obtained by measurement, among which the coordinates of the two endpoints of the wing root section were (X... 11 Z 11 ), (X 12 Z 12 The coordinates of the two endpoints of the wingtip section are (X... 21 Z 21 ), (X 22 Z 22 Parallel to the root section of the virtual trapezoidal shape, N1 equally spaced spanwise sections are evenly arranged along the wing span according to the actual number of ribs. The spanwise coordinate of the i-th spanwise section is... The chordal coordinates of the two endpoints of the i-th tangential plane are: The chord length L of the i-th tangential surface i =X i1 -X i2 On the spanwise section, N2 equally spaced chordwise grid points are uniformly arranged along the chord direction of the wing according to the length of the rib. The chordwise coordinate of the j-th grid point on the i-th section is...

[0046]

[0047] (2) Determine the position of the center of mass of the rib segment on the spanwise plane; specifically: ribs are usually distributed parallel to the spanwise direction of the wing. Knowing the coordinates of the center of mass of the rib segment on the spanwise direction, the position of the center of mass of the rib segment on the spanwise plane can be obtained. The specific process is as follows:

[0048] The mass center of gravity of the rib segment is Z0 in the spanwise direction and Z0 in the spanwise tangential direction. i When Z i ≤Z0≤Z i+1 At this point, the center of mass of the rib segment is located between the i-th spanwise section and the (i+1)-th spanwise section, and the distance from the center of mass of the rib segment to the i-th spanwise section is H1 = Z0 - Z. i The distance from the (i+1)th spanwise tangent is H2 = Z. i+1 -Z0.

[0049] (3) Discretize the rib mass along the spanwise direction to adjacent spanwise tangents according to the lever ratio; specifically: calculate the mass M of the wing rib segment along the spanwise direction to the mass M of the i-th spanwise tangent according to the lever ratio formula. i The mass M of the (i+1)th spanwise section i+1 ;

[0050]

[0051] (4) Discretize the cross-sectional mass along the chord direction into trapezoidal grid points; In step (4), the shape of the wing cross-section is approximately trapezoidal, so dispersing the wing cross-sectional mass along the chord direction into trapezoidal grid points is consistent with the actual situation; where the area of ​​the trapezoidal distribution is the spanwise cross-sectional mass, the height of the trapezoidal distribution is the length of the spanwise cross-section, the two bases of the trapezoidal distribution are the distributed masses at both ends of the spanwise cross-section, and the centroid of the trapezoidal distribution is the distance from the centroid of the spanwise cross-sectional mass to one end of the spanwise cross-section;

[0052] The specific process is as follows: the mass M of the wing rib segment is discretized to the mass of the i-th spanwise section, which is Mi. i The length of the cross section is L i The mass distribution at both ends of the span is m i1 m i2 The chordal coordinate of the center of mass of the rib segment is X0;

[0053] The distance from the center of mass of the spanwise section to one end of the spanwise section is X. i =X0-X i1 According to the formula for calculating the area of ​​a trapezoid: Centroid calculation formula: Derive the mass distribution at both ends of the span:

[0054] (5) Calculate the mass of the chordal grid points by piecewise integration.

[0055] This step involves discretizing the spanwise tangential mass into trapezoidal distribution along the chord to chordally grid points. The resulting mass is a trapezoidal distribution, which requires piecewise integration to calculate the chordally grid point mass.

[0056] The specific process is as follows: The mass of the trapezoidal distribution can be represented by the following function:

[0057] The chord-oriented grid points divide the tangent into N segments, where x is the variable along the chord direction coordinate, and the mass M of the j-th segment is... ij for:

[0058]

[0059] After the above steps, the mass of the wing ribs is reasonably distributed while ensuring that the center of gravity of the rib mass remains unchanged, so that the mass distribution of the wing is closer to the actual situation.

[0060] The second embodiment of the present invention is:

[0061] This invention is a method for discretizing the mass of an aircraft wing rib segment. The invention consists of five steps: (1) setting a trapezoidal shape, spanwise tangent, and chordal grid points; (2) determining the position of the center of gravity of the rib segment mass on the spanwise tangent; (3) discretizing the rib segment mass along the spanwise direction to adjacent spanwise tangents according to the lever ratio; (4) discretizing the tangent mass along the chordwise direction according to the trapezoidal distribution to chordal grid points; and (5) calculating the mass of the chordal grid points by piecewise integration.

[0062] The specific process is as follows:

[0063] (1) Set the trapezoidal shape, spanning section, and chordal grid points, such as Figure 5 As shown, a certain wing has a spanwise length of 1900mm, a root chord length of 900mm, and a wingtip chord length of 500mm. Five ribs are arranged from the wing root to the wingtip. A trapezoidal shape is set along the wing profile to control the mass dispersion range. The trapezoidal shape is slightly larger than the wing profile, and the coordinates of the four vertices of the trapezoid can be obtained. The coordinates of the two endpoints of the wing root section are (0,0) and (1000,0), and the coordinates of the two endpoints of the wingtip section are (0,2000) and (600,2000). Five sections are evenly arranged along the spanwise direction, with the spanwise coordinates of the second section being... The spanwise coordinates of the third section are: The coordinates of the two endpoints of the second cross-section are The coordinates of the two endpoints of the third cross-section are The length of the second section is L2 = 900 - 0 = 900 mm, and the length of the third section is L3 = 800 - 0 = 800 mm. On the spanwise section, four chord-direction grid points are evenly distributed along the wing chord direction according to the length of the ribs. The coordinates of the first grid point on the second section are... Similarly, the coordinates of grid points 2, 3, and 4 can be calculated: X22 =337.5mm, X 23 =562.5mm, X 24 = 787.5mm, the coordinates of the 1st, 2nd, 3rd, and 4th grid points on the 3rd cross-section are: X 31 =100mm, X 32 =300mm, X 33 =500mm, X 34 =700mm.

[0064] (2) Determine the position of the center of gravity of the rib segment in the spanwise tangential plane, such as Figure 6 The rib segment shown has a mass M = 20 kg, and its center of gravity coordinates are X = 300 mm and Z = 450 mm. Given that the coordinates of the second sectional plane are Z2 = 250 mm, the coordinates of the third sectional plane are Z3 = 500 mm, and the center of gravity coordinate is Z = 450 mm, where 250 mm ≤ 450 mm ≤ 500 mm, the mass M of the rib segment lies between the second and third sectional planes. The distance from the second sectional plane is H1 = 450 - 250 = 200 mm, and the distance from the third sectional plane is H2 = 500 - 450 = 50 mm.

[0065] (3) Discretize the mass of the rib segment along the span direction to adjacent tangents according to the lever ratio.

[0066] Second section quality

[0067] Quality of the third section

[0068] (4) Discretize the cross-sectional mass along the chord direction into trapezoidal grid points, such as... Figure 7 As shown, the mass of the second cut surface is M1 = 4 kg, the length of the second cut surface is L2 = 900 mm, and the center of gravity of the second cut surface is X2 = 300 - 0 = 300 mm. The mass distribution at both ends of the cut surface can be calculated as follows:

[0069]

[0070] The mass of the third cut surface is M2 = 16 kg, the length of the third cut surface is L3 = 800 mm, and the center of gravity of the third cut surface is X3 = 300 - 0 = 300 mm. The mass distribution at both ends of the cut surface can be calculated as follows:

[0071]

[0072] (5) Calculate the mass of the chord-direction grid points by piecewise integration. The second tangent has 4 grid points evenly distributed along the chord direction. Calculate the mass of grid points 1, 2, 3, and 4 in sequence as follows:

[0073]

[0074] The third cross-section has four grid points evenly distributed along the chord direction, such as... Figure 7 As shown, the masses of grid points 1, 2, 3, and 4 are calculated sequentially as follows:

[0075]

[0076] The above calculations discretize the rib mass M = 20 kg along the wing spanwise to adjacent spanwise cross-sections according to the lever ratio. The cross-sectional mass is then discretized along the wing chordwise to chordwise grid points according to a trapezoidal distribution. This reasonable mass discretization, while ensuring the center of gravity of the rib mass remains constant, makes the wing mass distribution closer to reality. This solves the problem of directly using the wing rib mass to calculate loads, which leads to excessively large loads near the center of gravity and excessively small loads far from the center of gravity, resulting in significant discrepancies and serious errors. It improves the accuracy of wing load calculations, making structural design safer and more reliable. Furthermore, this method of discretizing aircraft wing rib mass can be extended to the discretization calculation of other loads, demonstrating significant value.

Claims

1. A method for discretizing the mass of an aircraft wing rib segment, characterized in that, Includes the following steps: (1) Set a virtual trapezoidal shape covering the wing. Along the span of the wing, set equally spaced spanwise cross-sections on the virtual trapezoidal shape. On each spanwise cross-section, set several chordal grid points at equal intervals. (2) Determine the position of the center of gravity of the rib segment on the spanwise tangential plane; (3) Discretize the mass of the rib segment along the spanwise direction to adjacent spanwise tangents according to the lever ratio. Specifically, the mass M of the wing rib segment is calculated according to the lever ratio formula to discretize the mass M of the wing rib segment to the mass M of the i-th spanwise tangent. i The mass M of the (i+1)th spanwise section i+1 ; ； ； H1 is the distance from the centroid of the rib mass to the i-th spanwise section, and H2 is the distance from the centroid of the rib mass to the (i+1)-th spanwise section. (4) Discretize the cross-sectional mass along the chord direction into trapezoidal grid points; In this step, the shape of the wing cross-section is approximately trapezoidal, so dispersing the wing cross-sectional mass along the chord direction into trapezoidal grid points is consistent with the actual situation; where the area of ​​the trapezoidal distribution is the spanwise cross-sectional mass, the height of the trapezoidal distribution is the length of the spanwise cross-section, the two bases of the trapezoidal distribution are the distributed masses at both ends of the spanwise cross-section, and the centroid of the trapezoidal distribution is the distance from the centroid of the spanwise cross-sectional mass to one end of the spanwise cross-section; The specific process is as follows: the mass M of the wing rib segment is discretized to the mass of the i-th spanwise section. The length of the cross section is The mass distribution at both ends of the span is , The chordal coordinate of the center of mass of the rib segment is ; The distance from the center of mass of the spanwise section to one end of the spanwise section is According to the formula for calculating the area of ​​a trapezoid: Centroid calculation formula: ; Derive the mass distribution at both ends of the span: , ; (5) Calculate the mass of the chordal grid points by piecewise integration.

2. The method for mass discretization of aircraft wing rib segments according to claim 1, characterized in that, The spanwise direction, from the wing root to the wingtip, is defined as the Z-axis; the chordwise direction, from the trailing edge to the leading edge, is defined as the X-axis.

3. The method for mass discretization of aircraft wing rib segments according to claim 1, characterized in that, In step (1), the wing shape is approximately trapezoidal. A virtual trapezoidal shape is set along the wing shape as the range of mass dispersion. In order to include the entire wing, the trapezoid is slightly larger than the wing shape.

4. The method for mass discretization of aircraft wing rib segments according to claim 3, characterized in that, Step (1) specifically involves: The coordinates of the four vertices of the virtual trapezoidal shape were obtained by measurement, among which the coordinates of the two endpoints of the wing root section are ( , )、( , The coordinates of the two endpoints of the wingtip section are ( , )、( , Parallel to the root section of the virtual trapezoidal shape, N1 equally spaced spanwise sections are evenly arranged along the wing span according to the actual number of ribs. The spanwise coordinate of the i-th spanwise section is... The chord coordinates of the two endpoints of the i-th tangent are: , chord length of the i-th tangential surface ; On the spanwise section, N2 equally spaced chordwise grid points are uniformly arranged along the chord direction of the wing according to the length of the rib. The chordwise coordinate of the j-th grid point on the i-th section is... .

5. The method for mass discretization of aircraft wing rib segments according to claim 4, characterized in that, Step (2) specifically involves: The ribs are typically distributed parallel to the spanwise direction of the wing. Knowing the coordinates of the center of mass of the rib segment along the spanwise direction, the position of the center of mass of the rib segment on the spanwise tangent plane can be obtained. The specific process is as follows: The spanwise coordinate of the center of mass of the rib segment is The coordinates along the span direction tangent are ,when At that time, the center of mass of the rib segment is located between the i-th spanwise section and the (i+1)-th spanwise section, and the distance from the center of mass of the rib segment to the i-th spanwise section is... The distance from the (i+1)th spanwise tangent is .

6. The method for mass discretization of aircraft wing rib segments according to claim 5, characterized in that, Step (5) is to discretize the spanwise tangential mass along the chord direction into trapezoidal distribution to the chord grid points. The resulting mass is a trapezoidal distribution, which needs to be calculated by piecewise integration to obtain the mass of the chord grid points. The specific process is as follows: The mass of the trapezoidal distribution can be represented by the following function: The chord-oriented grid points divide the tangent into N segments, where x is the variable along the chord direction coordinate, and the mass of the j-th segment is... for: ； After the above steps, the mass of the wing ribs is reasonably distributed while ensuring that the center of gravity of the rib mass remains unchanged, so that the mass distribution of the wing is closer to the actual situation.

Images