A performance co-simulation method of a helicopter multi-landing gear

Abstract

The application discloses a helicopter multi-landing gear performance joint simulation method, comprising the following steps: step 1, taking the body coordinate system as a reference, the dynamics balance equation of the body is established by calculating the coordinates of each force point on the body; step 2, the numerical value of each force in the dynamics balance equation obtained in step 1 is calculated; step 3, the input quantity is given to the constructed dynamics balance equation, and iterative calculation is carried out, the whole machine landing performance calculation is completed, or the motion data results of the body in each direction are obtained. The technical scheme provided by the application takes the body as a rigid body, solves the landing load and work under the conditions of different weight gravity centers, different attitudes and different landing speeds of the body through the dynamics balance equation, so as to obtain the landing gear landing performance data, and obtains the taxiing response of the corresponding road after inputting the road spectrum.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aviation structure design, and particularly relates to a performance joint simulation method of a helicopter multi-landing gear. BACKGROUND

[0002] Landing gear performance calculation is the core technology of landing gear design, and the landing gear load and gravity overload in the performance calculation result directly affect the structural design parameters of the helicopter, and the energy absorption amount in the result directly determines whether the landing gear meets the design requirements and whether the personnel in the machine can land safely. In the landing gear performance calculation, establishing a correct calculation model is the key and basis for the accuracy of the calculation result.

[0003] The existing helicopter landing gear cushion performance calculation method is to load a reduction mass at each landing gear installation position, and the reduction mass is required to make the vertical acceleration of the installation point equal to the vertical acceleration of the current stress state of the whole machine. The subsequent drop test is performed by matching the drop energy under each working condition with the energy obtained in the performance calculation. This simplified algorithm is fast in calculation, and the test verification is relatively simple, and is the standard method for landing gear drop performance calculation and test checking. However, when the calculation wheel touch point height is different or for working conditions such as two-point landing and maximum head-up landing, since each landing gear is calculated independently, the energy transfer caused by the attitude change of the fuselage cannot be considered, and there is a risk that the calculation result is greatly different from the actual situation. SUMMARY

[0004] The purpose of the present application is to solve the above problems, and the embodiment of the present application provides a performance joint simulation method of a helicopter multi-landing gear to solve the problem that the existing helicopter landing gear cushion performance calculation method has a great difference between the calculation result and the actual situation when the calculation wheel touch point height is different or for working conditions such as two-point landing and maximum head-up landing, since the energy transfer caused by the attitude change of the fuselage cannot be considered.

[0005] The technical scheme of the present application is that the embodiment of the present application provides a performance joint simulation method of a helicopter multi-landing gear, comprising:

[0006] Step 1, taking the machine body coordinate system as the reference, the dynamic balance equation of the machine body is established by calculating the coordinates of each force point on the machine body;

[0007] Step 2, calculating the numerical value of each force in the dynamic balance equation obtained in step 1;

[0008] Step 3, inputting the given input to the established dynamic balance equation and performing iterative calculation to complete the whole machine drop performance calculation and obtain the machine body motion data result;

[0009] In the performance joint simulation method, the fuselage is regarded as a rigid body, and the landing load and work of the fuselage under different weight gravity center conditions, different attitudes and different landing speeds are solved through a dynamic balance equation to obtain the landing gear shock absorption performance data, and the corresponding runway response is obtained after inputting a road spectrum.

[0010] Optionally, in the performance joint simulation method of the helicopter multi-landing gear as described above, the force points in step 1 include: each landing gear mounting point, the main rotor center point, the tail rotor center point, and the body gravity center point.

[0011] The dynamic balance equation of the fuselage in step 1 includes:

[0012] The external forces on each force point are projected on the body coordinate system, and the body structure is regarded as a rigid body to establish the dynamic balance equation of the body, including: the dynamic balance equation of the three-axis force of the body, and the dynamic balance equation of the three-axis moment of the body.

[0013] The dynamic balance equation of the spring mass of each landing gear is established by analyzing the spring mass of each landing gear.

[0014] Optionally, in the performance joint simulation method of the helicopter multi-landing gear as described above, the dynamic balance equation established in step 1 includes:

[0015] The dynamic balance equation of the three-axis force of the body is:

[0016]

[0017] The dynamic balance equation of the three-axis moment of the body is:

[0018]

[0019] In step 1, by analyzing the spring mass of each landing gear, the shock absorber is equivalent to a parallel spring and damper, and the wheel is equivalent to a spring, and the dynamic balance equation of the spring mass of each landing gear is established as:

[0020]

[0021] Wherein, m is the whole machine mass of the body, [F xi ,F yi ,F zi ] T is the force of the landing gear in each direction, [0, 0, mg] T is the gravity of the body structure, [F zjx , F zjy , F zjz ] T is the three-component force of the main rotor applied to the body, [Fwjx , F wjy , F wjz ] T is the three-component force applied by the tail rotor to the fuselage;

[0022] I is the moment of inertia matrix of the fuselage, R is the distance matrix from each landing gear mounting point to the center of gravity of the fuselage, R zj is the coordinates of the main rotor hub in the body coordinate system, R wj is the coordinates of the tail rotor in the body coordinate system, [M zjx , M zjy , M zjz ] T is the torque of the main rotor in each direction, [M wjx , M wjy , M wjz ] T is the torque of the tail rotor in each direction;

[0023] P jli is the vertical force of the wheel, m ki g is the weight of the unsprung mass of the landing gear, F zi is the buffer load, F xi is the heading load transmitted through the buffer, F yi is the lateral load transmitted through the buffer; for symmetric landing conditions, F yi = 0; σ i is the height of the center point of each wheel from the ground, i represents the landing gear number.

[0024] Optionally, in the helicopter multi-landing gear performance joint simulation method described above, the step 2 comprises:

[0025] Step 21, calculating the vertical force P jli of the wheel, the vertical force P jli of the wheel is determined by σ i -R0+ σ di :

[0026] Taking R0 as the unloaded radius of the tire, the vertical force P jli of the wheel is calculated as follows:

[0027] If σ i -R0 is greater than 0, the tire is not in contact with the ground, and P jli = 0;

[0028] If σ i -R0 is less than 0, the corresponding relationship between P jli and σ i -R0 is established by establishing a static pressure curve, and then P jli is obtained by interpolation;

[0029] For the process of sliding on uneven ground, the ground height σdi As a correction amount, the ability to calculate the response of the helicopter on the uneven runway is realized.

[0030] Optionally, in the helicopter multi-landing gear performance joint simulation method as described above, the step 2 further includes:

[0031] Step 22, calculate the buffer load F zi ; The buffer load F zi is composed of three parts, and the step 22 includes:

[0032] Step 22a, calculate the buffer air chamber force as:

[0033]

[0034] Wherein, p0 is the initial inflation pressure of the air chamber, F k is the exhaust area, V0 is the air chamber volume, SH is the buffer compression amount, and n is the gas polytropic index;

[0035] Step 22b, calculate the buffer oil damping force as:

[0036]

[0037] Wherein, ρ is the hydraulic oil density, F y is the oil pressing area, C d is the oil damping coefficient, f is the oil hole area, and dSH is the buffer compression speed;

[0038] Step 22c, calculate the buffer friction force:

[0039] P m =k m P kq ;

[0040] Wherein, k m is the friction coefficient, and P kq is the air chamber force.

[0041] Optionally, in the helicopter multi-landing gear performance joint simulation method as described above, the way to calculate the buffer friction force in the step 22c is:

[0042] The Dahl friction force model is used for calculation, and the Dahl friction force model is:

[0043]

[0044] Wherein, v is the relative speed, σ is the stiffness coefficient, and α parameter determines the shape of the curve. The greater the α, the greater the curvature of the Dahl friction force model curve;

[0045] The calculated buffer friction force is:

[0046]

[0047] The buffer load F is obtained zi

[0048] F zi = P kq + sign(dSH)(P y + P m ).

[0049] Optionally, in the helicopter multi-landing gear performance joint simulation method described above, the iterative calculation in step 3 comprises:

[0050] Step 31, after determining the basic parameters of each dynamic equilibrium equation, input the time history of the main rotor force and the tail rotor force, and determine the initial state of the fuselage, and then solve the force applied to the machine body by each landing gear in step 2;

[0051] Step 32, substitute the calculation results of the previous step into the dynamic equilibrium equation in step 1 to obtain the 6-DOF acceleration, velocity, and displacement of the machine body;

[0052] Step 33, through the calculation results of the previous step, the compression amount, load, and work amount of each landing gear at the next time can be obtained, and then the force applied to the machine body by each landing gear is solved again in step 2;

[0053] Steps 32 and 33 are repeatedly executed for iterative calculation.

[0054] Optionally, in the helicopter multi-landing gear performance joint simulation method described above, the termination mode of the iterative calculation in step 3 comprises:

[0055] When the landing energy is dissipated by the oil damping force and the friction force, the buffer compression amount no longer changes, and the full machine landing performance calculation of this weight state is completed; or

[0056] Within a specified time, the helicopter ground taxi simulation is completed by using the dynamic equilibrium equation to obtain the machine body motion data results.

[0057] ​The beneficial effects of the present application are: the helicopter multi-landing gear performance joint simulation method provided by the embodiments of the present application, through force analysis of the machine body, taking the machine body coordinate system as the reference, through calculating the coordinates of each force point on the machine body, the dynamic balance equation of the machine body is established; the numerical value of each force in the established dynamic balance equation is calculated; for the constructed dynamic balance equation, the input quantity is given, and the iterative calculation is carried out, and the machine body motion data result is obtained. The performance joint simulation method provided by the embodiments of the present application, on the one hand, the rigid body dynamics is used for machine dynamics analysis, and the load calculation of multiple landing gears can be carried out at the same time, and such calculation method can better simulate the shock work curve of the landing gear under the conditions of asymmetric landing, different landing gear stiffness, etc. On the other hand, the dynamic balance equation constructed by the present application can be used to calculate the response of the whole machine to the road spectrum by applying different road spectra to each wheel. The technical scheme provided by the embodiments of the present application has the following beneficial effects:

[0058] First, each landing gear has two independent degrees of freedom of buffer compression and wheel compression, and only when the force transmitted to the buffer by the lower mass exceeds the starting force of the buffer can the buffer be started, and the effect of static friction is successfully simulated;

[0059] Second, the dynamic balance equation constructed by the present application regards the machine body as a rigid body, and simplifies each landing gear force to a three-dimensional force acting on the landing gear mounting point, which not only omits the process of equivalent calculation of the reduced mass of the whole machine, but also theoretically can better simulate the response of the whole machine under various working conditions;

[0060] Third, after limiting the rotation freedom of the machine body, the weight state of each type under the landing condition of three points is consistent with the result of the traditional algorithm, and it can be considered that the calculation result of the dynamic balance equation is reliable;

[0061] Fourth, the calculation is fast: since the friction force is smoothly transitioned, the problem of difficult nonlinear mechanics calculation is alleviated;

[0062] Fifth, widely used: can be used for whole machine shock performance calculation, helicopter ground sliding response calculation. BRIEF DESCRIPTION OF DRAWINGS

[0063] The accompanying drawings are used to provide a further understanding of the technical scheme of the present application, and constitute a part of the specification, and together with the embodiments of the present application, are used to explain the technical scheme of the present application, and do not constitute a limitation on the technical scheme of the present application.

[0064] Figure 1 The schematic diagram of the force of the machine body in the helicopter multi-landing gear performance joint simulation method provided by the embodiments of the present application;

[0065] Figure 2 Coulomb friction model;

[0066] Figure 3 a schematic diagram of a curve of the Dahl friction model when alpha = 1;

[0067] Figure 4 a calculation result of a simulation example of the performance joint simulation method of the multi-landing gear of the helicopter provided by the embodiment of the application; Figure 4 a graph a in the figure is a local graph of the vertical load of the front landing gear tire, and a graph b is a local graph of the vertical load of the main landing gear tire. DETAILED DESCRIPTION

[0068] The accompanying drawings are used to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification, and are used to explain the technical solutions of the present application together with the embodiments of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0069] As described in the above background, the importance of the landing gear performance calculation in the design of the landing gear is explained, however, the existing calculation method of the cushion performance of the landing gear of the helicopter has the following problems:

[0070] Firstly, for the touchdown height of the computer wheel, there is a difference or for the working conditions such as two-point landing and maximum nose-up landing, since the energy transmission caused by the attitude change such as the pitch of the fuselage cannot be considered, there is a risk that the calculation result is greatly different from the actual situation;

[0071] Secondly, in the traditional calculation of the performance of the landing gear, the existence of the friction makes the mechanical model discontinuous, which leads to the existence of singular points in the dynamic calculation;

[0072] Thirdly, the existing calculation model cannot be used for the calculation of the uneven road surface, and the universality of the model is small.

[0073] In order to solve the above three problems, the present application provides a performance joint simulation method of the multi-landing gear of the helicopter, a continuous landing gear dynamic model is constructed, the fuselage is regarded as a rigid body, the landing load and the work under the conditions of different weight and gravity centers, different attitudes and landing speeds are solved through dynamic balance, so that more accurate landing gear shock absorption performance data can be obtained, and the sliding response of the road surface can be obtained after the input of the road spectrum.

[0074] The following several specific embodiments provided by the present application can be combined with each other, and the same or similar concepts or processes can not be described in some embodiments.

[0075] The embodiment of the present application provides a performance joint simulation method of the multi-landing gear of the helicopter, which comprises the following steps:

[0076] Step 1, taking the body coordinate system as a reference, a dynamics balance equation of the body is established by calculating coordinates of each force point on the body;

[0077] Step 2, numerical values of each force in the dynamics balance equation obtained in step 1 are calculated;

[0078] Step 3, input is given to the established dynamics balance equation, and iterative calculation is performed to complete full-machine drop performance calculation, and each direction motion data result of the body is obtained;

[0079] In the performance joint simulation method, the body is taken as a rigid body, landing loads and work amounts of the body under different weight center of gravity states, different attitudes and different landing speed conditions are solved through the dynamics balance equation, so that landing gear drop performance data are obtained, and corresponding runway response is obtained after input of a road spectrum.

[0080] In an implementation manner of the embodiment of the application, as shown in Figure 1 Fig. 1 is a schematic diagram of body force in a performance joint simulation method of a multi-landing gear helicopter provided by the embodiment of the application. Each force point in step 1 includes: each landing gear mounting point, a main rotor center point, a tail rotor center point and a body center of gravity point.

[0081] In the implementation manner, the dynamics balance equation of the body in step 1 includes:

[0082] The external force on each force point is projected on the body coordinate system, the body structure is regarded as a rigid body, and the dynamics balance equation of the body is established, including: a dynamics balance equation of body three-axis force and a dynamics balance equation of body three-axis moment.

[0083] The dynamics balance equation of body three-axis force is:

[0084]

[0085] The dynamics balance equation of body three-axis moment is:

[0086]

[0087] Wherein, m is the whole-machine quality of the body, [F xi ,F yi ,F zi ] T is force of the landing gear in each direction, [0, 0, mg] T is gravity of the body structure, [F zjx , F zjy , F zjz ] T is three-component force of the main rotor applied to the body, [F wjx , F wjy , Fwjz ] T It is the three-part force exerted by the tail rotor on the fuselage;

[0088] I is the body moment of inertia matrix, R is the distance matrix from each landing gear installation point to the center of gravity of the body, R zj The coordinates of the main propeller point in the body coordinate system, R wj is the coordinate of the tail rotor in the body coordinate system, [M zjx , M zjy , M zjz ] T The axial torque of the main propeller, [M wjx , M wjy , M wjz ] T is the axial torque of the tail rotor.

[0089] By analyzing the unsprung mass of each landing gear, the buffer is equivalent to a parallel spring and damper, and the wheel is equivalent to a spring. The dynamic equilibrium equation of the unsprung mass of each landing gear is established as follows:

[0090]

[0091] Among them, P jli is the wheel vertical force, m ki g is the weight of the unsprung mass of the landing gear, F zi is the buffer load, F xi F is the heading load transmitted through the buffer, which reacts as a rebound load during the rolling landing. yi is the lateral load transmitted through the buffer; for the symmetrical landing condition F yi =0;σ i is the height of each wheel center point above the ground, and i represents the landing gear number.

[0092] For each dynamic equilibrium equation obtained in the above implementation, the calculation of the values ​​of each force in the dynamic equilibrium equation obtained in step 1 in step 2 includes the following calculations:

[0093] Step 21, calculate the wheel vertical force P jli , the wheel vertical force P jli By σ i -R0+σ di Sure:

[0094] Taking R0 as the tire unloaded radius, the vertical force P of the wheel is jli The calculation method is:

[0095] If σ i -R0 is greater than 0, the tire is not touching the ground, P jli =0;

[0096] If σ i -R0 is less than 0, P jli is obtained by establishing the P i -R0 corresponding relationship, and then interpolating P jli ;

[0097] For the uneven road surface sliding process, by adding the ground height σ di as a correction, the ability to calculate the response of the helicopter on the uneven road surface sliding is realized.

[0098] Step 22, calculate the buffer load F zi ; the buffer load F zi is composed of three parts, and the calculation methods of the three parts are as follows:

[0099] (a) buffer air chamber force:

[0100]

[0101] Wherein, p0 is the initial inflation pressure of the air chamber, F k is the exhaust area, V0 is the air chamber volume, SH is the buffer compression amount, and n is the gas polytropic index;

[0102] (b) buffer oil damping force:

[0103]

[0104] Wherein, ρ is the hydraulic oil density, F y is the oil pressure area, C d is the oil damping coefficient, f is the oil hole area, and dSH is the buffer compression speed.

[0105] (c) buffer friction force:

[0106] P m =k m P kq ;

[0107] Wherein, k m is the friction coefficient, and P kq is the air chamber force.

[0108] It should be noted that in the traditional calculation, it is judged when the buffer compression speed is 0, and it is difficult to find the speed 0 point in numerical calculation, so a speed threshold is added, and it is considered that the buffer completes the energy absorption of the positive stroke and starts the reverse motion at this moment, that is, the buffer is in static friction state at this moment. But this algorithm brings the following problems:

[0109] Problem 1, as Figure 2In the shown Coulomb friction model, the static friction is distributed on the axis of v=0 and changes with the external force input; in the calculation process, the calculation of the static friction is difficult;

[0110] Problem 2, the jump of friction at the speed threshold boundary will cause the problem of the buffer restarting at the boundary and the like and unable to converge.

[0111] To solve the above problems, the Dahl friction model is used in the embodiment of the application, namely:

[0112]

[0113] Wherein, v is the relative speed, sigma is the stiffness coefficient, and alpha parameter determines the shape of the curve, the greater the alpha, the greater the curvature of the curve, and when alpha=1, it is as shown in the Dahl friction model. Figure 3 The buffer friction force can be obtained as follows:

[0114]

[0115] The Dahl friction model is used in the embodiment of the application, which can avoid the problem that the static friction calculated by using the Coulomb friction model makes the mechanical model incoherent, thereby causing singular points in the dynamics calculation and further causing the termination of the model calculation.

[0116] The buffer load F is obtained by comprehensively: zi

[0117] F zi =P kq +sign(dSH)(P y +P m ).

[0118] In one implementation manner of the embodiment of the application, the implementation manner of the step 3 can include:

[0119] After the basic parameters of each dynamics balance equation are determined, the time history of the main propeller force and the tail propeller force is input, and after the initial state of the fuselage is determined, the forces applied to the machine body by each landing gear can be solved through the step 2.

[0120] The calculation results of the above step are substituted into the dynamics balance equation of the step 1 to obtain the 6-DOF acceleration, speed and displacement of the machine body;

[0121] The landing gear compression amount, load and work amount at the next time can be obtained through the calculation results of the above step, and then the forces applied to the machine body by each landing gear are solved through the step 2 again;

[0122] ​The result calculated in the last step is substituted into the dynamic equilibrium equation in step 1, and the Runge-Kutta method is used to obtain the acceleration, velocity and displacement of the body 6 in the next moment; and iteration is performed.

[0123] Finally, after the energy of the shock absorption is dissipated by the oil damping force and the friction force at a certain position, the compression amount of each shock absorber no longer changes, and the full machine shock absorption performance calculation in this weight state is completed; or the dynamic equilibrium equation is used to complete the helicopter ground taxi simulation within a specified time, and the motion data of the body in each direction is obtained.

[0124] The embodiment of the present application provides a performance joint simulation method of a helicopter multi-landing gear, through force analysis of the body, taking the body coordinate system as the reference, the dynamic equilibrium equation of the body is established by calculating the coordinates of each force point on the body; the values of each force in the established dynamic equilibrium equation are calculated; for the constructed dynamic equilibrium equation, the input quantity is given, and iterative calculation is performed to obtain the motion data of the body in each direction. The performance joint simulation method provided by the embodiment of the present application has the following beneficial effects:

[0125] Firstly, the shock absorber compression amount and the wheel compression amount of each landing gear exist two independent degrees of freedom, and only when the force transmitted to the shock absorber by the lower mass exceeds the starting force of the shock absorber, the shock absorber can be started, and the effect of static friction can be successfully simulated;

[0126] Secondly, the dynamic equilibrium equation constructed by the present application regards the body as a rigid body, and simplifies each landing gear force to three-direction force acting on the landing gear mounting point, which not only omits the process of equivalent calculation of the reduced mass of the whole machine, but also theoretically can better simulate the response of the whole machine under various working conditions;

[0127] Thirdly, after limiting the rotational degrees of freedom of the body, the results of each weight state of the type under the three-point horizontal landing condition are consistent with the results of the traditional algorithm, and it can be considered that the calculation results of the dynamic equilibrium equation are reliable;

[0128] Fourthly, the calculation is fast: since the friction force is smoothly transitioned, the problem of difficult nonlinear mechanics calculation is alleviated;

[0129] Fifthly, the application is wide: the full working condition and full machine shock absorption performance calculation, and the helicopter ground taxi response calculation can be performed.

[0130] The following provides a simulation example of the performance joint simulation method for multiple landing gear of a helicopter provided by an embodiment of the present invention.

[0131]

[0132]

[0133] like Figure 4 , which are calculation results of a simulation example using the performance joint simulation method for helicopter multiple landing gears provided by an embodiment of the present invention; Figure 4 Figure a is a local diagram of the vertical load on the front tire, and Figure b is a local diagram of the vertical load on the main tire.

[0134] Although the embodiments disclosed herein are as described above, the contents are merely provided to facilitate understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art may make any modifications and variations in the form and details of the embodiments without departing from the spirit and scope of the present invention. However, the scope of patent protection of the present invention shall remain subject to the scope defined by the appended claims.

Claims

1. A method for performance co-simulation of a helicopter multi-landing gear, characterized in that, The method comprises the following steps: Step 1, taking the body coordinate system as a reference, a dynamics balance equation of the body is established by calculating the coordinates of each force point on the body; Step 2, the values of each force in the dynamics balance equation obtained in step 1 are calculated; Step 3, the input quantity is given to the established dynamics balance equation, and iterative calculation is performed to complete the full-aircraft landing shock performance calculation and obtain the motion data of the body in each direction; In the performance joint simulation method, the body is taken as a rigid body, and the landing load and work of the body under different weight and gravity center conditions, different attitudes and different landing speeds are solved by the dynamics balance equation, so that the landing gear landing shock performance data are obtained, and the corresponding runway response is obtained after the input road spectrum is obtained; In step 1, each force point includes: each landing gear mounting point, the center point of the main rotor, the center point of the tail rotor, and the body gravity center point; The iterative calculation in step 3 includes: Step 31, after the determination of each basic parameter of the established dynamics balance equation, the time history of the main rotor force and the tail rotor force is input, and the force applied to the body by each landing gear is solved through step 2 after the initial state of the body is determined; Step 32, the calculation results of the previous step are substituted into the dynamics balance equation of step 1 to obtain the 6-DOF acceleration, velocity and displacement of the body; Step 33, the compression amount, load and work of each landing gear at the next moment can be obtained through the calculation results of the previous step, and then the force applied to the body by each landing gear is solved through step 2 again; Steps 32 and 33 are repeatedly executed for iterative calculation; The termination mode of the iterative calculation in step 3 includes: When the landing shock energy is dissipated by the oil damping force and the friction force, the compression amount of each shock absorber no longer changes, and the full-aircraft landing shock performance calculation of this weight state is completed; or The ground sliding simulation of the helicopter is completed within a specified time by using the dynamics balance equation to obtain the motion data of the body in each direction.

2. The method for performance co-simulation of a multi-landing-gear of a helicopter according to claim 1, characterized in that, The dynamics balance equation of the body established in step 1 includes: The external forces on each force point are projected on the body coordinate system, the body structure is regarded as a rigid body, and the dynamics balance equation of the body is established, including the dynamics balance equation of the three-axis force of the body and the dynamics balance equation of the three-axis moment of the body; Through the analysis of the unsprung mass of each landing gear, the dynamics balance equation of the unsprung mass of each landing gear is established.

3. The method for performance co-simulation of a multi-landing-gear of a helicopter according to claim 2, characterized in that, The established dynamics balance equation in step 1 includes: The dynamics balance equation of the three-axis force of the body is: ； The dynamics balance equation of the three-axis moment of the body is: ； In step 1, through the analysis of the unsprung mass of each landing gear, the shock absorber is equivalent to a parallel spring and damper, and the wheel is equivalent to a spring, and the dynamics balance equation of the unsprung mass of each landing gear is established as: ； Among them, m is the overall mass of the machine body, is the force of the landing gear in each direction, The gravity acting on the body structure, The three-point force applied to the aircraft by the main propeller is It is the three-part force exerted by the tail rotor on the fuselage; I is the moment of inertia matrix of the body, R is the distance matrix from each landing gear mounting point to the center of gravity of the body, R zj is the coordinates of the main rotor in the body coordinate system, wj is the coordinates of the tail rotor in the body coordinate system, is the torque of the main rotor in each direction, is the torque of the tail rotor in each direction; is the vertical force on the wheel, is the weight of the unsprung mass of the landing gear, is the suspension load, is the lateral load transferred by the suspension, is the lateral load transferred by the suspension; for symmetric landing conditions ; σ i is the height of the wheel center point above the ground, i denotes the landing gear number.

4. The method for performance co-simulation of a multi-landing-gear of a helicopter according to claim 3, characterized in that, Step 2 includes: Step 21, computer wheel vertical force , the wheel vertical force by σ i -R0+σ di determined: With R0 as the unloaded radius of the tire, the vertical force of the wheel The calculation is as follows: if σ i - R0 is greater than 0, the tire is not grounded, P jli = 0; If σ i -R0 is less than 0, then the corresponding relationship between σ P jli and σ i -R0 is established by fitting a curve to the static pressure data, and σ P jli is then interpolated from this curve. For the roughness surface takeoff process, the ground height σ di is added as a correction to achieve the ability to calculate the response of a helicopter taking off from a roughness surface.

5. The method for performance co-simulation of a helicopter multi-landing-gear according to claim 4, characterized in that, Step 2 further includes: Step 22, calculating buffer load ; the buffer load The step 22 consists of three parts, which are: Step 22a, calculating the force of the shock absorber air chamber is: ； Wherein, p0 is the initial inflation pressure of the air chamber, F k is the exhaust area, V0 is the volume of the air chamber, SH is the compression amount of the bumper, and n is the polytropic index of the gas. Step 22b, calculating the oil damping force of the shock absorber is: ； wherein, F is the hydraulic oil density, F y C is the oil pressure area, C d f is the oil damping coefficient, f is the oil hole area, and dSH is the buffer compression speed; Step 22c, calculating the friction force of the shock absorber is: ； where k m is the friction coefficient, P kq is the air cavity force.

6. The method for performance co-simulation of a helicopter multi-landing-gear according to claim 5, characterized in that, The calculation method of the friction force of the shock absorber in step 22c is: A Dahl friction force model is used for calculation, and the Dahl friction force model is: ； Where v is the relative velocity, σ is the stiffness coefficient, and α is a parameter that determines the shape of the curve. The greater the value of α, the greater the curvature of the Dahl friction model curve. The calculated buffer friction force is: ； Obtaining buffer load is: 。

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