Aircraft wing rib section mass discretization method

Abstract

The invention belongs to the technical field of aircraft design, and relates to an aircraft wing rib section mass discretization method, which comprises the following steps of: (1) setting a virtual trapezoidal shape covering a wing, and equidistantly setting a plurality of chordwise grid points on each spanwise tangent plane on the virtual trapezoidal shape along the spanwise direction of the wing; (2) determining the position of the mass gravity center of the rib section on the spanwise tangent plane; (3) dispersing the mass of the rib sections to adjacent spanwise tangent planes along the spanwise direction according to a lever ratio; (4) dispersing the mass of the section to chordwise grid points along the chordwise direction according to trapezoidal distribution; (5) segmental integration is carried out to calculate the quality of chordwise grid points; according to the method, a trapezoidal shape is arranged along the shape of a wing, the mass of a wing rib section is dispersed to adjacent spanwise sections along the spanwise direction of the wing according to a lever ratio, and the mass of the sections is dispersed to chordwise grid points along the chordwise direction of the wing according to trapezoidal distribution. The mass is reasonably dispersed under the condition that the mass gravity center of the rib section is not changed, so that the wing mass distribution is closer to the real condition, the wing load calculation precision is improved, and the structural design is safer and more reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft design, relates to aircraft load calculation technology, and specifically relates to a mass discretization method for aircraft wing rib sections. Background Art

[0002] The mass data of an aircraft is very important for the calculation of aircraft loads, and the accuracy of the mass data directly determines the calculation accuracy of the aircraft loads. In the wing mass data, the mass greater than 0.5kg is often given in the form of concentrated mass; while the mass less than 0.5kg and the structural mass that cannot be divided (such as wall panels, beams, ribs, etc.) are often given in the form of rib segment mass, that is, all small masses and indivisible structural masses in a rib segment (between adjacent ribs) are given in the form of a total mass. In the process of wing load calculation, if the rib segment mass is calculated as a total mass, the calculation result will be seriously distorted, resulting in excessive load at the center of gravity and too small load far away from the center of gravity. The calculated wing load is very different from the actual situation, which will cause serious errors. Summary of the invention

[0003] Purpose of the present invention:

[0004] In order to solve the problem of large error in load calculation when directly using the mass of wing rib segments, the present invention provides a method for discretizing the mass of aircraft wing rib segments. The method sets a trapezoidal shape along the wing shape, discretizes the mass of the wing rib segments along the wing span direction according to the lever ratio to the adjacent span direction sections, and discretizes the section mass along the wing chord direction according to the trapezoidal distribution to the chord direction grid points. The mass is discretized reasonably while ensuring that the center of gravity of the rib segment mass remains unchanged, so that the wing mass distribution is closer to the actual situation, the calculation accuracy of the wing load is improved, and the structural design is safer and more reliable.

[0005] The technical solution of the present invention:

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

[0007] (1) a virtual trapezoidal shape covering the wing is set, and along the span direction of the wing, equally spaced spanwise sections are set on the virtual trapezoidal shape, and a number of chord-wise grid points are set on each spanwise section at equal intervals;

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

[0009] (3) Discretize the mass of the rib segment along the span direction according to the leverage ratio to adjacent span-wise sections;

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

[0011] (5) Calculate the quality of the chord-wise grid points by piecewise integration.

[0012] Furthermore, the span direction is from the wing root to the wing tip, and the coordinate is defined as the Z direction; the chord direction is from the wing trailing edge to the wing leading edge, and the coordinate is defined as the X direction.

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

[0014] Further, step (1) specifically comprises:

[0015] The coordinates of the four vertices of the virtual trapezoidal shape are obtained by measurement, among which the coordinates of the two end points of the wing root section are (X 11 , Z 11 )、(X 12 , Z 12 ), the coordinates of the two endpoints of the wing tip 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 set along the wing span according to the number of actual ribs, and the spanwise coordinate of the i-th spanwise section is The chord coordinates of the two endpoints of the i-th section are The chord length L of the i-th section i =X i1 -X i2 ; On the spanwise section, N2 equally spaced chordwise grid points are evenly set along the chordwise direction of the wing according to the length of the rib. The chordwise coordinate of the jth grid point on the i-th section is

[0016]

[0017] Further, step (2) is specifically as follows: usually the ribs are distributed parallel to the span direction of the wing. If the coordinates of the mass center of gravity of the rib segment in the span direction are known, the position of the mass center of gravity of the rib segment in the span direction section can be obtained. The specific process is as follows:

[0018] The spanwise coordinate of the mass center of the rib segment is Z0, and the spanwise coordinate of the section is Z i , when Z i ≤Z0≤Z i+1 When the mass center of gravity of the rib segment is located between the i-th spanwise section and the i+1-th spanwise section, the distance between the mass center of gravity of the rib segment and the i-th spanwise section is H1=Z0-Z i , the distance from the i+1th spanwise section is H2=Z i+1 -Z0.

[0019] Further, step (3) is 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 section iand the mass M of the i+1th spanwise section i+1 ;

[0020]

[0021] Furthermore, in step (4), the shape of the wing section is approximately a trapezoid, so discretizing the wing section mass along the chord direction to the chord-wise grid points according to a trapezoidal distribution conforms to the actual situation; wherein the area of ​​the trapezoidal distribution is the span-wise section mass, the height of the trapezoidal distribution is the span-wise section length, the two bases of the trapezoidal distribution are the distributed masses at both ends of the span-wise section, and the centroid position of the trapezoidal distribution is the distance from the center of mass of the span-wise section to one end of the span-wise 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 M i , the length of the section is L i , the distributed mass at both ends of the spanwise section is m i1 、m i2 , the chord-wise coordinate of the mass center of gravity 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 trapezoid area calculation formula: And the centroid calculation formula: The distributed mass at both ends of the spanwise section is derived:

[0024] Furthermore, step (5) is to discretize the spanwise section mass to the chordwise grid points according to a trapezoidal distribution along the chordwise direction to obtain a trapezoidal distribution mass, and a piecewise integral calculation is required to obtain the chordwise grid point mass;

[0025] The specific process is: the trapezoidal distribution mass is expressed by the function: The chord-wise grid points divide the section into N segments, where x is the variable along the chord-wise coordinate and the mass M of the jth segment is ij for:

[0026]

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

[0028] Beneficial effects of the present invention:

[0029] The present invention proposes a method for discretizing the mass of an aircraft wing rib segment, wherein a trapezoidal shape is set along the wing shape, the mass of the wing rib segment is discretized to adjacent spanwise sections according to the lever ratio along the wing span direction, and the section mass is discretized to chordwise grid points according to a trapezoidal distribution along the wing chord direction. The mass is discretized reasonably while ensuring that the center of gravity of the rib segment mass remains unchanged, so that the wing mass distribution is closer to the actual situation. The problem of directly using the mass of the wing rib segment to calculate the load, resulting in excessive load near the center of gravity and excessive load far from the center of gravity, which is significantly different from the actual situation and has serious errors, is solved. The calculation accuracy of the wing load is improved, making the structural design safer and more reliable. Moreover, this method for discretizing the mass of an aircraft wing rib segment can be extended to the discrete calculation of other loads, and has great value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram for setting the trapezoidal shape, span-wise section, and chord-wise grid points;

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

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

[0033] Among them, 8-rib segment mass M, 9-adjacent section mass M i , 10- adjacent section quality M i+1 , 11- distance from the adjacent section H1, 12- distance from the adjacent section H2.

[0034] Figure 3 Schematic diagram of trapezoidal distribution of chord direction

[0035] Among them, 9-cut surface quality M i , 13-distributed mass m at one end of the section i1 、14-Distributed mass at the other end of the section m i2 , 15- section length L i , 16-chordal virtual grid points.

[0036] Figure 4 Schematic diagram of virtual grid point quality calculation by piecewise integration

[0037] Among them, the mass m distributed at one end of the 13-section i1 、14-Distributed mass at the other end of the section m i2 , 15- section length L i , 17-Mass of the mesh point M in the jth segment of the chord ij .

[0038] Figure 5This is a schematic diagram of the second embodiment for setting a trapezoidal shape, a spanwise section, and chordwise grid points;

[0039] Figure 6 Schematic diagram of the second embodiment of the rib segment mass being discretized into adjacent sections along the span direction according to the lever ratio;

[0040] Figure 7 It is a schematic diagram of the second embodiment in which the section mass is discretized to the chord-wise grid points in a trapezoidal distribution along the chord-wise direction. DETAILED DESCRIPTION

[0041] An embodiment of the present invention is:

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

[0043] (1) Set a virtual trapezoidal shape covering the wing, set equally spaced spanwise sections on the virtual trapezoidal shape along the span direction of the wing, and set a number of chord-wise grid points equally spaced on each spanwise section; from the wing root to the wing tip is the spanwise direction, and the coordinate is defined as the Z direction; from the wing trailing edge to the wing leading edge is the chordwise direction, and the coordinate is defined as the X direction. In step (1), the wing shape is approximately a trapezoid, and a virtual trapezoidal shape is set along the wing shape as the range of mass discreteness. 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 are obtained by measurement, among which the coordinates of the two end points of the wing root section are (X 11 , Z 11 )、(X 12 , Z 12 ), the coordinates of the two endpoints of the wing tip 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 set along the wing span according to the number of actual ribs, and the spanwise coordinate of the i-th spanwise section is The chord coordinates of the two endpoints of the i-th section are The chord length L of the i-th section i =X i1 -X i2 ; On the spanwise section, N2 equally spaced chordwise grid points are evenly set along the chordwise direction of the wing according to the length of the rib. The chordwise coordinate of the jth grid point on the i-th section is

[0046]

[0047] (2) Determine the position of the mass center of gravity of the rib segment on the spanwise section. Specifically, the ribs are usually distributed parallel to the wing span. If the coordinates of the mass center of gravity of the rib segment in the spanwise direction are known, the position of the mass center of gravity of the rib segment in the spanwise section can be obtained. The specific process is as follows:

[0048] The spanwise coordinate of the mass center of the rib segment is Z0, and the spanwise coordinate of the section is Z i , when Z i ≤Z0≤Z i+1 When the mass center of gravity of the rib segment is located between the i-th spanwise section and the i+1-th spanwise section, the distance between the mass center of gravity of the rib segment and the i-th spanwise section is H1=Z0-Z i , the distance from the i+1th spanwise section is H2=Z i+1 -Z0.

[0049] (3) The mass of the rib segment is discretized into adjacent spanwise sections according to the leverage ratio along the span direction; specifically, the mass of the wing rib segment M is calculated according to the leverage ratio formula to discretize the mass of the wing rib segment M into the mass M of the i-th spanwise section. i and the mass M of the i+1th spanwise section i+1 ;

[0050]

[0051] (4) discretizing the section mass along the chord direction to the chord-wise grid points according to a trapezoidal distribution; in step (4), the shape of the wing section is approximately a trapezoid, so discretizing the wing section mass along the chord direction to the chord-wise grid points according to a trapezoidal distribution is in line with the actual situation; wherein the area of ​​the trapezoidal distribution is the span-wise section mass, the height of the trapezoidal distribution is the span-wise section length, the two bases of the trapezoidal distribution are the distributed masses at both ends of the span-wise section, and the centroid position of the trapezoidal distribution is the distance from the center of gravity of the span-wise section mass to one end of the span-wise 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 M i , the length of the section is L i , the distributed mass at both ends of the spanwise section is m i1 、m i2 , the chord-wise coordinate of the mass center of gravity 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 trapezoid area calculation formula: And the centroid calculation formula: The distributed mass at both ends of the spanwise section is derived:

[0054] (5) Calculate the quality of the chord-wise grid points by piecewise integration.

[0055] This step is to discretize the spanwise section mass to the chordwise grid points in a trapezoidal distribution along the chordwise direction to obtain the trapezoidal distribution mass, which needs to be calculated by piecewise integration to obtain the chordwise grid point mass;

[0056]

[0057] The grid divides the section into N segments, x is the variable along the chord coordinate, and the mass M of the jth segment is ij for:

[0058]

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

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

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

[0062] The specific process is:

[0063] (1) Set the trapezoidal shape, span-wise section, and chord-wise grid points, such as Figure 5 As shown, the span length of a certain wing is 1900mm, the chord length of the wing root is 900mm, the chord length of the wing tip is 500mm, and there are 5 ribs arranged from the wing root to the wing tip. A trapezoidal shape is set along the wing shape to control the discrete range of mass. The trapezoidal shape is slightly larger than the wing shape. The coordinates of the four vertices of the trapezoid can be obtained, among which the coordinates of the two endpoints of the section at the middle wing root are (0,0) and (1000,0), and the coordinates of the two endpoints of the section at the wing tip are (0,2000) and (600,2000). Five sections are evenly set along the span direction, among which the span coordinates of the second section are The spanwise coordinates of the third section are The coordinates of the two endpoints of the second section are The coordinates of the two endpoints of the third 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-wise grid points are evenly set along the chordwise direction of the wing according to the length of the rib. The coordinates of the first grid point of the second section are Similarly, the coordinates of the 2nd, 3rd, and 4th grid points can be calculated: 22 =337.5mm, X23 =562.5mm, X 24 =787.5mm, the coordinates of the 1st, 2nd, 3rd, and 4th grid points of the 3rd section are: X 31 =100mm, X 32 =300mm, X 33 =500mm, X 34 =700mm.

[0064] (2) Determine the position of the mass center of gravity of the rib segment on the spanwise section, such as Figure 6 The mass of the rib segment shown is M = 20Kg, and the coordinates of the center of gravity are X = 300mm, Z = 450mm. It is known that the coordinates of the second section are Z2 = 250mm, the coordinates of the third section are Z3 = 500mm, the coordinates of the center of gravity are Z = 450mm, 250mm≤450mm≤500m, and the mass M of the rib segment is located between the second section and the third section. The distance from the second section is H1 = 450-250 = 200mm, and the distance from the third section is H2 = 500-450 = 50mm.

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

[0066] Second section quality

[0067] The quality of the third section

[0068] (4) Discretize the section mass along the chord direction into grid points in a trapezoidal distribution, such as Figure 7 As shown, the mass of the second section M1 = 4kg, the length of the second section L2 = 900mm, the mass center of the second section X2 = 300-0 = 300mm, and the distributed mass at both ends of the section can be calculated:

[0069]

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

[0071]

[0072] (5) Calculate the mass of the grid points in the chord direction by piecewise integration. There are 4 grid points evenly distributed along the chord direction on the second section. The mass of grid points 1, 2, 3, and 4 is calculated in sequence as follows:

[0073]

[0074] The third section has 4 grid points evenly distributed along the chord direction, such as Figure 7As shown, the quality of grid points 1, 2, 3, and 4 is calculated in sequence as follows:

[0075]

[0076] Through the above calculations, the rib segment mass M = 20kg is discretized to adjacent spanwise sections according to the lever ratio along the wing span, and the section mass is discretized to the chordwise grid points according to the trapezoidal distribution along the wing chord. The mass is discretized reasonably while ensuring that the center of gravity of the rib segment mass remains unchanged, so that the wing mass distribution is closer to the actual situation. The problem of directly using the wing rib segment mass to calculate the load, resulting in excessive load near the center of gravity and excessive load far from the center of gravity, which is quite different from the actual situation and has serious errors, is solved. The calculation accuracy of the wing load is improved, making the structural design safer and more reliable. Moreover, this aircraft wing rib segment mass discretization method can be extended to the discrete calculation of other loads, which is of great value.

Claims

1. A method for discretizing the mass of an aircraft wing rib segment, characterized in that: The following steps are involved: (1) a virtual trapezoidal shape covering the wing is set, and along the span direction of the wing, equally spaced spanwise sections are set on the virtual trapezoidal shape, and a number of chord-wise grid points are set on each spanwise section at equal intervals; (2) Determine the position of the mass center of gravity of the rib segment on the spanwise section; (3) Discretize the mass of the rib segment along the span direction according to the leverage ratio to adjacent span-wise sections; (4) Discretize the section mass along the chord direction into grid points in a trapezoidal distribution; (5) Calculate the quality of the chord-wise grid points by piecewise integration.

2. The aircraft wing rib segment mass discretization method according to claim 1, characterized in that: The span direction is from the wing root to the wing tip, and the coordinate is defined as the Z direction; the chord direction is from the wing trailing edge to the wing leading edge, and the coordinate is defined as the X direction.

3. The aircraft wing rib segment mass discretization method according to claim 1, characterized in that: In step (1), the wing shape is approximately a trapezoid, and a virtual trapezoidal shape is set along the wing shape as a mass discrete range. In order to include the entire wing, the trapezoid is slightly larger than the wing shape.

4. The aircraft wing rib segment mass discretization method according to claim 3, characterized in that: Step (1) specifically includes: The coordinates of the four vertices of the virtual trapezoidal shape are obtained by measurement, among which the coordinates of the two end points of the wing root section are (X 11 , Z 11 )、(X 12 , Z 12 ), the coordinates of the two endpoints of the wing tip 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 set along the wing span according to the number of actual ribs, and the spanwise coordinate of the i-th spanwise section is The chord coordinates of the two endpoints of the i-th section are The chord length L of the i-th section i =X i1 -X i2 ; On the spanwise section, N2 equally spaced chordwise grid points are evenly set along the chordwise direction of the wing according to the length of the rib. The chordwise coordinate of the jth grid point on the i-th section is 5. The aircraft wing rib segment mass discretization method according to claim 4, characterized in that: Step (2) is specifically as follows: Usually, the ribs are distributed parallel to the span direction of the wing. If the coordinates of the mass center of gravity of the rib segment in the span direction are known, the position of the mass center of gravity of the rib segment in the span direction section can be obtained. The specific process is as follows: The spanwise coordinate of the mass center of the rib segment is Z0, and the spanwise coordinate of the section is Z i , when Z i ≤Z0≤Z i+1 When the mass center of gravity of the rib segment is located between the i-th spanwise section and the i+1-th spanwise section, the distance between the mass center of gravity of the rib segment and the i-th spanwise section is H1=Z0-Z i , the distance from the i+1th spanwise section is H2=Z i+1 -Z0.

6. The aircraft wing rib segment mass discretization method according to claim 5, characterized in that: Step (3) is as follows: 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 section: i and the mass M of the i+1th spanwise section i+1 ; 7. The aircraft wing rib segment mass discretization method according to claim 6, characterized in that: In step (4), the shape of the wing section is approximately a trapezoid, so discretizing the wing section mass along the chord direction to the chord-wise grid points according to a trapezoidal distribution conforms to the actual situation; wherein the area of ​​the trapezoidal distribution is the span-wise section mass, the height of the trapezoidal distribution is the span-wise section length, the two bases of the trapezoidal distribution are the distributed masses at both ends of the span-wise section, and the centroid position of the trapezoidal distribution is the distance from the center of mass of the span-wise section to one end of the span-wise 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 M i , the length of the section is L i , the distributed mass at both ends of the spanwise section is m i1 、m i2 , the chord-wise coordinate of the mass center of gravity of the rib segment is X0; 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 trapezoid area calculation formula: And the centroid calculation formula: The distributed mass at both ends of the spanwise section is derived:

8. The aircraft wing rib segment mass discretization method according to claim 7, characterized in that: Step (5) is to discretize the spanwise section mass to the chordwise grid points in a trapezoidal distribution along the chordwise direction to obtain a trapezoidal distribution mass, which requires piecewise integral calculation to obtain the chordwise grid point mass; The specific process is: the trapezoidal distribution mass is expressed by the function: The chord-wise grid points divide the section into N segments, where x is the variable along the chord-wise coordinate and the mass M of the jth segment is ij for: After the above steps, the mass of the wing rib section is reasonably discretized while ensuring that the mass center of gravity of the rib section remains unchanged, making the wing mass distribution closer to the actual situation.

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