Energy conversion-based landing load rapid calculation method for a swing arm landing gear

Abstract

The present application belongs to the landing gear strength design technical field, and particularly relates to a landing load fast calculation method of a support arm type landing gear based on energy conversion, comprising the following steps: step one: obtaining the design input parameters of the support arm type landing gear; step two: carrying out energy consumption analysis on the landing energy of the support arm type landing gear; step three: determining the overall layout inclination angle of the support arm type landing gear; step four: calculating the design stiffness of the support arm type landing gear according to the overall layout inclination angle of the support arm type landing gear; step five: determining the maximum vertical load of the support arm type landing gear according to the design stiffness of the support arm type landing gear; and step six: calculating the complete landing load according to the maximum vertical load.

Description

Technical Field

[0001] This invention belongs to the field of landing gear strength design technology, specifically relating to a rapid calculation method for landing load of a boom-type landing gear based on energy conversion. Background Technology

[0002] Dolly landing gear is widely used in general aviation aircraft and large and medium-sized unmanned aerial vehicles (UAVs). Lightweight landing gear design is an important design direction for aircraft, especially large and medium-sized UAVs, in pursuit of performance. The strength design of dolly landing gear is mainly controlled by landing load, which is directly and closely related to the landing gear configuration and stiffness. Traditional analysis methods calculate the vertical overload of the landing gear based solely on the landing gear layout, aircraft weight, and descent speed. This calculation method does not consider the influence of friction during landing gear deformation under load, so the calculated results often differ significantly from experimental results, and it also cannot determine whether the landing gear has rebounded. Traditional methods determine aircraft attitude as a result of landing gear load and stiffness design, requiring iterative iterations to arrive at a solution. Summary of the Invention

[0003] The objective of this invention is to propose a rapid calculation method for landing loads of a boom landing gear based on energy conversion. This method addresses the issue that boom landing gear absorbs landing energy through tire and structural deformation and dissipates this energy through friction, establishing a theoretical relationship for frictional energy dissipation. Furthermore, it establishes a theoretical relationship between the aircraft's stopping weight and stiffness design requirements under maximum compression. By establishing the relationship between landing gear stiffness and maximum vertical landing load, it provides a basis for landing gear load and layout design while meeting aircraft stopping attitude requirements. This provides a theoretical foundation and rapid method for the rapid design of boom landing gear schemes and landing loads.

[0004] The technical solution of the present invention:

[0005] A rapid calculation method for landing load of a boom landing gear based on energy conversion includes the following steps:

[0006] Step 1: Obtain the design input parameters for the outrigger landing gear;

[0007] Step 2: Perform energy consumption analysis on the landing energy of the boom landing gear;

[0008] Step 3: Determine the overall layout tilt angle of the boom landing gear;

[0009] Step 4: Calculate the design stiffness of the boom landing gear based on the overall layout tilt angle.

[0010] Step 5: Determine the maximum vertical load of the control boom landing gear based on its design.

[0011] Step 6: Calculate the full landing load based on the maximum vertical load.

[0012] Furthermore, in step one, the input parameters include: the static compression amount δ1 of the wheel center, and the maximum compression change δ. max , equivalent landing weight m, equivalent shutdown mass B*m, reserve energy landing equivalent mass C*m, maximum sinking velocity v, and ground friction coefficient μ.

[0013] Furthermore, in step two, the energy dissipation analysis involves establishing a formula for calculating the maximum frictional dissipation capacity:

[0014]

[0015] in, This represents the friction force on the ground; positive and negative signs indicate different directions. A This refers to the energy absorption efficiency of the outrigger landing gear structure during deformation. A The value is obtained through experiments or design experience, ranging from 0.0 to 1.0. α is the angle between the overall layout of the boom landing gear and the vertical plane, and the stiffness at the wheel center point is perpendicular to the boom axial direction. K n δ represents the deformation perpendicular to the axial direction of the outrigger.

[0016] Furthermore, in step three, the overall layout tilt angle of the boom landing gear is determined through the following process:

[0017] Calculate the frictional dissipation efficiency or :

[0018]

[0019] The range of values ​​for the tilt angle α of the overall layout of the boom landing gear is related to the friction dissipation efficiency. or The intersection of elements that are greater than or equal to 1 and satisfy the minimum rollover angle.

[0020] Furthermore, in step four, the design stiffness of the boom landing gear... K n The calculation formula is as follows:

[0021]

[0022] in, , .

[0023] Furthermore, in step five, the maximum vertical load of the outrigger landing gear... The calculation formula is as follows:

[0024]

[0025] Furthermore, in step six, after obtaining the maximum vertical load of the boom landing gear, the complete landing load is calculated according to GJB5435.3-2005 or CCAR23R3 standards.

[0026] Furthermore, step six also includes: determining the final structural stiffness based on the complete landing load. K n ’ and landing payload.

[0027] The beneficial effects of this invention are:

[0028] The method in this invention provides a design basis for the rigidity and layout of the landing gear to meet the overall aircraft design requirements, and provides reliable landing loads closely related to the structure. This provides strong support for the rapid design of landing gear solutions.

[0029] Compared to traditional methods, this approach, by considering the impact of ground friction on landing loads, provides more realistic and reliable calculations. Furthermore, the addition of landing bounce assessment provides a theoretical basis for determining whether relevant national military standards tests can be met, and also provides landing gear roll angle constraints for the overall landing gear layout, thus accelerating the design process. Based on this analytical method, two landing buffer structure design schemes—one with high stiffness and the other with low stiffness—can also be proposed for the overall design, offering greater overall design flexibility and enabling the simultaneous fulfillment of overall parking attitude requirements, facilitating rapid design of the aircraft and landing gear layout. Attached Figure Description

[0030] Figure 1 This is a flowchart of a rapid calculation method for landing load of a boom landing gear based on energy conversion. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] The main technology of this patent is to determine the relationship between the landing gear layout and the rebound to determine the landing gear layout, to determine the design stiffness of the boom landing gear based on the overall shutdown index, and finally to determine the landing load of the boom landing gear based on the layout, stiffness and other conditions.

[0033] (1) Obtain the design input parameters for the boom landing gear

[0034] Based on the aircraft parking design requirements, the input parameters are obtained: the static compression (change) of the wheel center is δ1, and the maximum compression (change) is δ. max Equivalent landing weight m, equivalent shutdown mass B*m, reserve energy landing equivalent mass C*m, maximum sinking velocity v, and ground friction coefficient μ.

[0035] B calculates and determines the corresponding equivalent stopping mass based on the aircraft's center of gravity, the position of the front wheel center when statically stopped, and the position of the main wheel center.

[0036] C is defined according to the energy storage requirements of the drop test, and is usually 1.5.

[0037] (2) Energy consumption analysis of landing power of boom landing gear

[0038] Traditional methods do not consider the dissipation of landing energy by friction. Based on the force characteristics of the boom landing gear during the deceleration and recovery processes, the maximum friction dissipation capacity can be calculated using the following formula:

[0039]

[0040] This represents ground friction; the positive and negative signs indicate different directions. A This refers to the energy absorption efficiency of the outrigger landing gear structure during deformation. A Typically obtained through experimentation or design experience (with a value ranging from 0.0 to 1.0), α is the angle between the overall layout of the boom landing gear and the vertical plane, and the stiffness at the wheel center point is K in the direction perpendicular to the boom axial direction. n δ represents the deformation perpendicular to the axial direction of the outrigger.

[0041] (3) Determine the overall layout tilt angle of the boom landing gear

[0042] The frictional dissipation efficiency η is expressed as:

[0043]

[0044] When η<1, it can be determined that during the landing process, the vertical kinetic energy of the landing gear cannot be completely dissipated by friction, which will cause the landing gear to rebound and leave the ground. This is a relatively dangerous phenomenon for aircraft, especially unmanned aerial vehicles. It is usually required that the landing gear will not rebound during landing.

[0045] Based on the pavement friction coefficient μ of the aircraft's operating scenario, adjust the boom angle α to ensure η≥1, thus preventing the landing gear from rebounding during landing. This step determines the minimum angle α between the overall layout of the boom landing gear and the vertical plane, and this angle must also be greater than the minimum roll angle design requirement for the landing gear.

[0046] Traditional design methods only consider whether the landing gear layout meets the minimum roll angle design requirements, without taking into account whether landing will cause a bounce. This method can determine the minimum angle requirement between the boom landing gear and the vertical plane to prevent bounce based on the ground friction coefficient.

[0047] (4) The design stiffness of the boom landing gear was calculated.

[0048] After determining the angle α between the overall layout of the boom landing gear and the vertical plane, the static compression (change) δ1 and the maximum compression (change) δ1 of the wheel center are determined according to the overall layout requirements. max This establishes the relationship between wheel center deformation and aircraft weight, landing parameters, stiffness, and included angle. Typically, δ... max This occurs when an aircraft lands at its maximum descent speed (with stored energy).

[0049]

[0050] Solving the equations yields the structural stiffness K of the outrigger landing gear. n It needs to be designed as follows:

[0051]

[0052] in, , .

[0053] This method can provide two design schemes: high stiffness and low stiffness, both of which will be used as design parameters for the next step.

[0054] Traditional design methods cannot provide stiffness design requirements based on overall design specifications. They can only pre-determine the landing gear stiffness and then calculate the overall ground deformation, adjusting the stiffness and angle iteratively to meet the overall specifications, resulting in low design efficiency. This method, however, can directly determine the landing gear structural stiffness that meets the overall requirements for the landing gear wheel center position.

[0055] (5) Determine the maximum vertical load of the outrigger landing gear based on the energy principle.

[0056] Based on the stiffness K of the outrigger landing gear structure determined in the previous step n Based on the principle that landing energy equals the integral work done by the vertical load and friction in the vertical direction along the boom axis:

[0057]

[0058] The maximum vertical load during landing of the outrigger landing gear can then be obtained:

[0059]

[0060] Maximum vertical load Given two types of cross-sectional stiffness.

[0061] Compared with traditional calculation methods, this method takes into account the influence of the ground friction coefficient in determining the maximum vertical load, making the load calculation more accurate and reliable. The landing gear structure scheme can also meet the overall requirements of no rebound and no change in wheel center position.

[0062] (6) Calculate the landing load according to relevant standards or specifications.

[0063] To obtain the maximum vertical load Then, the complete landing load can be calculated according to relevant standards or specifications, such as GJB5435.3-2005 and CCAR23R3. An example of calculating the landing load of the left main landing gear according to GJB5435.3-2005 is shown below:

[0064]

[0065] Strength analysis was performed based on the complete landing load and cross-sectional shape design to determine the final selected structural stiffness K. n and landing payload.

[0066] The above description is merely a specific embodiment of the present invention, providing a detailed description of the invention. Parts not covered herein are conventional techniques. However, the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rapid calculation method for landing load of a boom landing gear based on energy conversion, characterized in that: The method includes the following steps: Step 1: Obtain the design input parameters for the control boom landing gear, including the static compression at the wheel center δ1 and the maximum compression change δ. max Equivalent landing weight (m), equivalent shutdown mass , reserve energy landing equivalent mass Maximum sinking velocity v, ground friction coefficient μ; Step 2: Perform energy dissipation analysis on the landing energy of the boom landing gear, specifically, establish the formula for calculating the maximum frictional dissipation capacity: in, This represents the friction force on the ground; positive and negative signs indicate different directions. A This refers to the energy absorption efficiency of the outrigger landing gear structure during deformation. A The value is obtained through experiments or design experience, and its range is (0.0, 1.0], where α is the overall tilt angle of the boom landing gear, and the design stiffness of the boom landing gear is... K n δ represents the deformation perpendicular to the axial direction of the outrigger; Step 3: Determine the overall tilt angle of the boom landing gear layout, as follows: Calculate the frictional dissipation efficiency η : The range of values ​​for α is the frictional dissipation efficiency. η The intersection of values ​​greater than or equal to 1 and satisfying the minimum rollover angle; Step 4: Calculate the design stiffness of the control arm landing gear based on the overall layout and tilt angle. K n The calculation formula is as follows: in, , ; Step 5: Determine the maximum vertical load of the control boom landing gear based on its design stiffness. The calculation formula is as follows: ； Step 6: Calculate the full landing load based on the maximum vertical load.

2. The method according to claim 1, characterized in that: In step six, after obtaining the maximum vertical load of the boom landing gear, the complete landing load is calculated according to GJB5435.3-2005 or CCAR23R3 standards.

3. The method according to claim 2, characterized in that: Step six also includes: determining the final structural stiffness based on the complete landing load. K n ’ and landing payload.

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