A method of designing a load adjustable beam
By setting the relationship between the end loads and geometric constraints of the beam and optimizing the beam design using Euler's formula, the problem of low efficiency in traditional aircraft structural design is solved, achieving lightweight and efficient beam design.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAN AIRCRAFT DESIGN INST OF AVIATION IND OF CHINA
- Filing Date
- 2022-10-12
- Publication Date
- 2026-05-15
AI Technical Summary
In traditional aircraft structural design, beams are inefficient to design, have heavy structural weight and low stiffness, long design cycles, and layout design relies on experience, leading to uncertainty.
By setting the four standard end loads of the beam, the constraint relationship between the end loads and the geometric dimensions of the beam is determined. Using Euler's formula, the axial compression load, moment of inertia and number of segments of the beam flange are calculated. The number of segments of the beam web and flange is optimized, and the specific structural design of the beam is determined.
It reduced structural weight, improved structural performance, shortened the design cycle, and reduced the uncertainty of design reliance on experience.
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Figure CN115544660B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of aircraft structural design technology, and specifically relates to a design method for an adjustable load beam. Background Technology
[0002] In aircraft structural design, the fuselage often incorporates numerous beams due to assembly, docking, or functional requirements (such as cargo loading and unloading). Traditionally, beam design involves designers relying on their experience to create an initial layout, establish a finite element model, calculate the stress distribution under severe loads, adjust structural dimensions based on this stress distribution, and iterate until the final structural form is obtained. This traditional approach, because the initial layout design is dependent on the designer's experience, limits the effectiveness of subsequent dimensional design. The final result often exhibits a heavy structure with low stiffness and high stress. Furthermore, the uncertainty of the layout design leads to inefficiency and significantly impacts the design cycle.
[0003] Therefore, it is of great significance to study a new design method to reduce structural weight, improve structural performance, and shorten the design cycle, in order to address the shortcomings of traditional design methods and existing technologies. Summary of the Invention
[0004] The purpose of this application is to provide a design method for beams with adjustable loads, in order to solve the problem that the design of beams in the prior art deviates greatly from the actual requirements, resulting in low design efficiency.
[0005] The technical solution of this application is: a design method for an adjustable load beam, comprising: setting four standard end-point loads of the beam; determining the constraint relationship between the end-point loads and the beam geometry based on the end-point loads; determining the constraint relationship between the axial compression load of the beam flange and the cross-sectional length of the beam flange based on the beam geometry and the end-point loads; determining the elastic modulus of the beam flange and the material; obtaining the constraint relationship between the moment of inertia, axial compression load, and number of segments of the beam flange based on Euler's formula and the axial compression load of the beam flange; and obtaining the relationship between the cross-sectional length of the beam flange and the axial compression load of the beam flange. The constraint relationships between the moments of inertia of the beam flanges are determined; the critical stress coefficients for axial compression and shear stress under typical conditions are determined; based on the geometric dimensions and material properties of the beam web, the constraint relationships between the allowable axial compression stress and the number of beam web segments, and the allowable combined shear stress and the number of beam web segments are obtained; based on the working stress of the beam web and the allowable combined axial compression and shear stress, the number of beam web segments and the number of beam flange segments are obtained; based on the axial compression load, moment of inertia of the beam flange, and the allowable combined axial compression and shear stress of the beam web, the cross-sectional length of the beam flange is determined.
[0006] Preferably, the relationship between the end load of the beam and the geometric constraints of the beam is as follows:
[0007]
[0008] Among them, Q A Q B Q C Q D Let F be the load perpendicular to the endpoints A, B, C, and D of the beam. A F B F C F D Let L be the horizontal load at the endpoints A, B, C, and D of the beam, a be the distance between the endpoints A and B, and b be the distance between the endpoints C and D.
[0009] Preferably, the axial compression load includes the beam flange axial compression load under vertical load and the beam flange axial compression load under horizontal load, wherein the beam flange axial compression load N1 under vertical load is:
[0010]
[0011] The axial compressive load N2 on the beam edge strip under the horizontal load is:
[0012]
[0013] The axial compressive load N3 is:
[0014] N3 = N1 + N2
[0015] Where t is the thickness of the beam web and c is the length of the flange section.
[0016] Preferably, the constraint relationship between the moment of inertia of the beam flange, the axial compressive load N3, and the number of beam flange segments is as follows:
[0017] Where n1 is the number of beam edge segments, and E is the elastic modulus of the material.
[0018] Preferably, the constraint relationship between the beam flange section length and the beam flange moment of inertia is as follows:
[0019]
[0020] Preferably, the constraint relationship between the allowable axial compressive stress of the beam web and the number of beam web segments is as follows:
[0021]
[0022] The constraint relationship between the allowable shear stress of the beam web and the number of beam web segments is as follows:
[0023]
[0024] Where μ is the material's elastic Poisson's ratio, n2 is the number of segments in the beam web, and K C K is the critical stress coefficient for axial compression. Cr This is the critical shear stress coefficient.
[0025] Preferably, the formula for calculating the number of segments in the beam web is:
[0026]
[0027] The formula for calculating the number of segments in the beam edge strip is:
[0028]
[0029] Preferably, the formula for calculating the length of the beam flange section is:
[0030]
[0031] This application discloses a design method for an adjustable-load beam. First, the length of the beam web is determined by the constraint relationship between the beam's end loads and its geometric dimensions. Then, the constraint relationship between the beam's axial compression load and the length of the beam's flange section is determined based on the beam's geometric dimensions and end loads. The constraint relationships between the beam flange moment of inertia, axial compression load, and the number of beam flange segments are obtained using Euler's formula and the beam flange axial compression load. Finally, the number of beam flange segments and the number of beam web segments are obtained by substituting standard parameters under typical conditions, thus finally determining the beam flange section length.
[0032] The structural layout design does not need to be based on experience. The specific structural design of the beam can be determined only based on the actual size and load requirements, which can reduce the structural weight, improve the structural performance, and shorten the design cycle. Attached Figure Description
[0033] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.
[0034] Figure 1 This is a schematic diagram of the overall process of this application;
[0035] Figure 2 This is a schematic diagram of the overall beam structure of this application;
[0036] Figure 3 This is a schematic diagram of the beam flange section of this application;
[0037] Figure 4 This is a schematic diagram of the beam web layout structure in this application. Detailed Implementation
[0038] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.
[0039] A method for designing beams with adjustable loads requires obtaining parameters such as the number of segments in the beam flange, the number of segments in the beam web, and the cross-sectional length of the beam flange. The beam design is carried out by using multiple intermediate parameters.
[0040] like Figure 1-2 As shown, given: material elastic modulus E = 70000 MPa, material elastic Poisson's ratio μ = 0.33, and beam horizontal load F... A =30000N, F B =10000N, F C =0N,F D = -40000N, vertical load Q of beam A =6000N, Q B =2000N, Q C =-1000N, Q D = -5000N.
[0041] include:
[0042] Step S100: Set the four standard end loads of the beam, and determine the constraint relationship between the end loads and the beam's geometry based on the end loads.
[0043]
[0044] By substituting the known quantities above, we can obtain:
[0045] 2L + 5a - 10b = 0
[0046] Assuming the beam web thickness t = 2 mm, the beam width on one side a = 400 mm, and the beam width on the other side b = 300 mm, we can obtain the beam web length l = 500 mm.
[0047] like Figure 3 As shown, in step S200, the constraint relationship between the axial compression load of the beam flange and the cross-sectional length of the beam flange is determined based on the beam's geometric dimensions and the load at the beam's endpoints. Substituting the above parameters, we obtain:
[0048]
[0049] Step S300: Determine the elastic modulus of the beam flange and the material. Based on Euler's formula and the axial compression load of the beam flange, obtain the constraint relationship between the moment of inertia of the beam flange, the axial compression load, and the number of segments of the beam flange. Combined with formula (2), we obtain:
[0050]
[0051] Step S400: Based on the moment of inertia of the beam flange, obtain the constraint relationship between the cross-sectional length of the beam flange and the moment of inertia of the beam flange, that is:
[0052]
[0053] Step S500: Determine the critical stress coefficient of axial compression and the critical stress coefficient of shear under typical conditions. Based on the geometric dimensions and material properties of the beam web, obtain the constraint relationship between the allowable axial compression stress of the beam web and the number of beam web segments, and the allowable combined shear stress and the number of beam web segments.
[0054] This typical state is: when L / n1 = a / n2, K C =4,K Cr =24. Substituting this into formula (1)-(4), we get:
[0055] The constraint relationship between the allowable axial compressive stress of the beam web and the number of segments in the beam web is as follows:
[0056]
[0057] The constraint relationship between the allowable shear stress of the beam web and the number of beam web segments is as follows:
[0058]
[0059] Where μ is the material’s elastic Poisson’s ratio, and n2 is the number of segments in the beam web.
[0060] By substituting typical state points to eliminate intermediate quantities, the relationship between known parameters and unknown quantities is established, so that the unknown quantities can be effectively obtained.
[0061] Step S600: Based on the working stress of the beam web and the allowable combined axial compression and shear stress, determine the number of segments in the beam web and the number of segments in the beam edge strip, according to existing formulas:
[0062]
[0063]
[0064]
[0065] Combining formulas (5) and (6), we get:
[0066]
[0067] We get: n2 = 3.59, and the number of segments is rounded down to n2 = 4.
[0068] Based on l / n1 = a / n2 in step 4, we can obtain n1 = 5, such as Figure 4 As shown.
[0069] By substituting the existing formulas into the calculation of typical state points, the number of beam web segments and beam edge strip segments can be accurately determined.
[0070] Step S700: Determine the cross-sectional length of the beam flange based on the axial compression load, moment of inertia, and the allowable combined axial compression and shear stress of the beam web.
[0071] Combining formulas (1)-(6), we get:
[0072]
[0073] Therefore, c = 8.84 mm.
[0074] This application designs beams by introducing intermediate parameters such as the axial compression load of the beam flange, the moment of inertia of the beam flange, the working stress of the beam web, and the allowable combined axial compression and shear stress. First, the length of the beam web is determined by the constraint relationship between the beam's end loads and its geometric dimensions. Then, based on the beam's geometric dimensions and end loads, the constraint relationship between the axial compression load and the length of the beam flange section is determined. Using Euler's formula and the axial compression load of the beam flange, the constraint relationships between the moment of inertia, axial compression load, and the number of segments of the beam flange are obtained. By substituting standard parameters under typical conditions, the number of segments of the beam flange and the number of segments of the beam web are obtained, thus finally determining the length of the beam flange section. This eliminates the need for empirical structural layout design; the specific structural design of the beam can be determined solely based on actual dimensions and load requirements, reducing structural weight, improving structural performance, and shortening the design cycle.
[0075] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method for designing a beam with adjustable load, characterized in that, include: Set the four standard end loads of the beam, and determine the constraint relationship between the end loads of the beam and the beam geometry based on the end loads of the beam. The constraint relationship between the axial compression load of the beam flange and the cross-sectional length of the beam flange is determined based on the beam's geometric dimensions and the loads at the beam's endpoints. Determine the beam flange and the elastic modulus of the material. Based on Euler's formula and the axial compression load on the beam flange, obtain the constraint relationship between the moment of inertia of the beam flange, the axial compression load, and the number of segments of the beam flange. The constraint relationship between the cross-sectional length of the beam flange and the moment of inertia of the beam flange is obtained based on the moment of inertia of the beam flange. Determine the critical stress coefficient of axial compression and critical stress coefficient of shear under typical conditions, and obtain the constraint relationship between the allowable axial compression stress of the beam web and the number of beam web segments, and the allowable combined shear stress and the number of beam web segments based on the geometric dimensions and material properties of the beam web. The number of segments in the beam web and the number of segments in the beam edge strip are obtained based on the working stress of the beam web and the allowable combined stress of axial compression and shear. The length of the beam flange section is determined based on the axial compression load, moment of inertia, and the allowable combined axial compression and shear stress of the beam web. The constraint relationship between the allowable axial compressive stress of the beam web and the number of segments in the beam web is as follows: ； The constraint relationship between the allowable shear stress of the beam web and the number of beam web segments is as follows: ； in, The elastic Poisson's ratio of the material, The number of segments in the beam web. This is the critical stress coefficient for axial compression. It is the critical shear stress coefficient; The formula for calculating the number of segments in the beam web is: ； The formula for calculating the number of segments in the beam edge strip is: 。 2. The design method for an adjustable load beam as described in claim 1, characterized in that, The relationship between the end load of the beam and the geometric constraints of the beam is as follows: ； in, , , , Let A be the load perpendicular to the endpoints A, B, C, and D of the beam. , , , Let A be the horizontal load at the endpoints A, B, C, and D of the beam. Let be the length of the beam. The distance between the A and B endpoints of the beam. The distance between the endpoints C and D of the beam is given.
3. The design method for an adjustable load beam as described in claim 2, characterized in that: The axial compression load includes the beam flange axial compression load under vertical load and the beam flange axial compression load under horizontal load. The beam flange axial compression load under vertical load... for: ； The axial compression load on the beam flange under the horizontal load for: ； Then axial compression load for: ； in, For the thickness of the beam web, is the length of the flange cross section.
4. The design method for an adjustable load beam as described in claim 2, characterized in that, The moment of inertia and axial compression load of the beam flange The constraint relationship between the number of segments and the beam edge strip is as follows: ; in, The number of segments for the beam edge strip. This is the elastic modulus of the material.
5. The design method for an adjustable load beam as described in claim 1, characterized in that: The constraint relationship between the cross-sectional length of the beam flange and the moment of inertia of the beam flange is as follows: 。 6. The method for designing an adjustable load beam as described in claim 1, characterized in that: The formula for calculating the length of the beam flange section is: 。