Helicopter landing gear dynamics modeling method based on adams

Abstract

The application provides a kind of helicopter landing gear dynamics modeling method based on Adams, three-dimensional model of helicopter body and landing gear is respectively established, and the three-dimensional model is imported into Adams;Hydro-pneumatic buffer is equivalent to a gas spring, an oil damper and a friction damper parallel mechanism, the mathematical model of hydro-pneumatic buffer is established;Combined with Adams in Faila tire mechanics model and tire model interface, the modeling of tire vertical force, longitudinal force, lateral force and turning moment is carried out;The current time tire motion state information is obtained from the tire model interface of Adams, the tire force and torque are calculated and output, and the tire model interface is returned to Adams, the motion state of the next simulation time is calculated, and iterative analysis is carried out.The technical scheme of the application can solve the problem of long solving time and low efficiency of traditional dynamics modeling method of helicopter landing gear, realize the rapid solution of helicopter dynamics characteristics and adjustable dynamics model parameters.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aviation technology, and particularly relates to a helicopter landing gear dynamics modeling method based on Adams. BACKGROUND

[0002] The helicopter landing gear is an important supporting structure of the helicopter, and is used for bearing the static and dynamic load generated when the helicopter contacts with the landing surface, absorbing and consuming the impact energy when the helicopter lands, and protecting the safety of the machine body and the airborne personnel. The helicopter landing gear is a dynamic interface between the helicopter and the landing surface, and the accuracy of the dynamic modeling of the helicopter landing gear directly affects the simulation accuracy of the dynamic response of the helicopter landing process.

[0003] The commonly used helicopter landing gear dynamics modeling methods include a theoretical modeling method and a finite element method. The theoretical modeling method needs to be simplified to different degrees, and the precision is greatly reduced and the solving result is not intuitive. Although the finite element method can ensure high precision, the solving time is long and the parameterization degree is low, and the replacement of the wheel characteristics often needs to re-model. The dynamic link library based on the mathematical model and the Faila tire mechanics model are called by using Adams, and the dynamics modeling of the buffer and the wheel of the helicopter landing gear is performed, so that the above problems can be effectively solved. SUMMARY

[0004] The helicopter landing gear dynamics modeling method based on Adams provided in the embodiments of the application can solve the problems of long solving time and low efficiency of the traditional helicopter landing gear dynamics modeling method, and realize the rapid solving of the helicopter dynamics characteristics and the adjustable dynamics model parameters.

[0005] In the embodiments of the application, a helicopter landing gear dynamics modeling method based on Adams is provided, which comprises the following steps:

[0006] S101, three-dimensional models of the helicopter body and the landing gear are respectively established, and the three-dimensional models are imported into Adams;

[0007] S102, the oil-gas buffer is equivalent to a parallel mechanism of a gas spring, an oil damping device and a friction damper, a mathematical model of the oil-gas buffer is established, that is, mathematical models of the gas spring force F a , the oil damping force F h and the friction force F f are respectively established;

[0008] S103, a tire attribute file and a road surface attribute file are written, and the characteristics of the tire and the road surface are defined; the Faila tire mechanics model and the tire model interface in Adams are combined, and the modeling of the vertical force, the longitudinal force, the lateral force and the turning moment of the tire is performed;

[0009] S104, obtaining the tire motion state information at the current time from the Adams tire model interface, calculating and outputting the tire force and torque, transmitting back to Adams through the tire model interface, calculating the motion state at the next simulation time, and iteratively analyzing.

[0010] Further, the mathematical models of the gas spring force F a , the oil damping force F h and the friction force F f are established respectively, including:

[0011] For the single-cavity oil-gas damper, the gas spring force F a is a function of the damper stroke S, and the gas spring force F a is represented by a gas compression polytropic equation,

[0012]

[0013] where P Air0 is the initial pressure of the gas cavity, V Air0 is the initial volume of the gas cavity, A Air is the gas cavity area, S is the damper stroke, γ is the polytropic index, and P AMB is the standard atmospheric pressure.

[0014] The oil damping force F h is a function of the damper compression velocity . Assuming that the oil is incompressible fluid, the oil damping force F h can be obtained by Bernoulli equation and continuity equation, and is represented as

[0015]

[0016] where ρ is the oil density, A FL is the effective oil compression area of the oil cavity, C d0 and C d1 are the positive and negative stroke main oil hole contraction coefficients respectively, A oil0 and A oil1 are the positive and negative stroke oil hole areas respectively, and is the damper compression velocity, i.e. the relative velocity of the piston and the sleeve.

[0017] The damper friction force is assumed to be the resultant force of the internal friction force caused by the internal pressure of the damper and the internal friction force caused by the bending displacement of the damper, and is represented as

[0018] where k m is the friction coefficient, and the damper resultant force F is F = F a + F h + F f .

[0019] Further, the method comprises:

[0020] Define the components of the buffer stroke on the X, Y, Z coordinate axes as disx, disy, disz respectively; define the components of the buffer compression velocity on the X, Y, Z coordinate axes as velx, vely, velz respectively; define the integer array IPAR1(3) for storing the bodyid of the piston and sleeve; define the buffer resultant force, gas spring force, oil damping force, friction force as F, Fa, Fh, Ff respectively; define the initial gas cavity volume, gas cavity pressure area, initial gas cavity pressure, standard atmospheric pressure, polytropic index as VAir, AAir, PAir, PAMB, ra respectively; define the oil density, effective oil cavity pressure oil area, positive stroke oil hole area, positive stroke main oil hole contraction coefficient, negative stroke oil hole area, negative stroke main oil hole contraction coefficient as Den, AFL, AOIL0, Cd0, AOIL1, Cd1 respectively; define the friction coefficient as Km;

[0021] Call the SYSFNC function to collect the components of the relative displacement and relative velocity of the piston and sleeve on the three coordinate axes, obtain the buffer stroke and compression velocity, and calculate the buffer resultant force, gas spring force, oil damping force, and friction force; call at least the OPEN and WRITE commands to output the parameters of time, stroke, and buffer force, which are used for drawing the dynamic response time history curve.

[0022] Further, in combination with the Faila tire mechanics model in Adams and the tire model interface, the modeling of the vertical force, longitudinal force, lateral force, and turning moment of the tire is carried out, including:

[0023] The vertical force F of the ground on the tire z is composed of the spring force F zk and the damping force F zc , which depends on the load, tire stiffness, and damping, and the vertical force F z is calculated by the following formula

[0024] F z = min(0.0, {F zk +F zc})

[0025] F zk = -vertical_stiffness × pen

[0026] F zc = -vertical_damping × Vpen

[0027] where vertical_stiffness is the tire vertical stiffness, pen is the tire penetration into the road surface, vertical_damping is the tire vertical damping, Vpen is the rate of change of the tire penetration into the road surface;

[0028] The longitudinal force depends on the vertical force F z , the longitudinal slip ratio S s , the side slip angle a and the current friction coefficient U, defining a critical longitudinal slip ratio S_critical,

[0029]

[0030] U = U max - (U max - U min ) x S s a

[0031]

[0032] where S s a is the overall slip ratio, S s is the longitudinal slip ratio, a is the side slip angle, U is the current friction coefficient, U max is the static friction coefficient, U min is the sliding friction coefficient, S_critical is the critical longitudinal slip ratio, CSLIP is the longitudinal force coefficient at small slip ratio;

[0033] When |S s | < S_critical, i.e. the tire is in elastic deformation, the longitudinal force is

[0034] F x = -CSLIP x S s

[0035] When |S s | > S_critical, i.e. the tire is in sliding, the longitudinal force is

[0036]

[0037] Further, the method comprises:

[0038] The lateral force depends on the vertical force F z and the current friction coefficient U, similarly to the longitudinal force calculation, defining a critical side slip angle a_critical,

[0039]

[0040] where CALPHA is the lateral force coefficient at small side slip angle;

[0041] If alpha < alpha_critical, i.e. the tire is in elastic deformation state, the lateral force is

[0042] F y = -U x |F z | x (1-H 3 ) x sign(alpha)

[0043]

[0044] If alpha = alpha_critical, i.e. the tire is in sliding state, the lateral force is

[0045] F y = -U x |F z | x sign(alpha)

[0046] The aligning moment is only calculated when there is a non-slippage area between the tire and the ground, and when the tire is in a completely sliding state, the aligning moment is 0.

[0047] When alpha < alpha_critical, i.e. the tire is in elastic deformation state, the aligning moment is

[0048] M z = U x |F z | x WIDTH x (1-H) x H 3 x sign(alpha)

[0049] When alpha > alpha_critical, i.e. the tire is in completely sliding state, the aligning moment is M z = 0.

[0050] Further, the method comprises:

[0051] After the buffer and the wheel dynamics modeling are completed, the model weight is set, and a moving pair is added; a concentrated load is established at the center of gravity of the body, and the load size is equal to the weight of the body; a fixed pair is created between the concentrated load and the body model; a fixed pair is created between the buffer sleeve and the body model; and a moving pair is created between the buffer piston and the buffer sleeve.

[0052] The beneficial effects brought by the application are as follows:

[0053] As can be seen from the above scheme, the embodiment of the application provides a helicopter landing gear dynamics modeling method based on Adams, three-dimensional models of a helicopter body and a landing gear are respectively established, and the three-dimensional models are imported into Adams; an oil-gas buffer is equivalent to a parallel mechanism of a gas spring, an oil liquid damper and a friction damper, a mathematical model of the oil-gas buffer is established, a tire attribute file and a road surface attribute file are written, and characteristics of the tire and the road surface are defined; modeling of vertical force, longitudinal force, lateral force and rotation torque of the tire is performed in combination with a Faila tire mechanics model in Adams and a tire model interface; tire motion state information at a current time is obtained from the tire model interface in Adams, force and torque of the tire are calculated and output, and the force and torque are returned to Adams through the tire model interface, motion states at a next simulation time are calculated, and iterative analysis is performed. The technical scheme of the application can solve the problem of long solving time and low efficiency of a traditional dynamics modeling method of a helicopter landing gear, and realize fast solving of dynamics characteristics of a helicopter and adjustment of parameters of a dynamics model. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 A helicopter landing gear dynamics modeling flowchart of a helicopter landing gear dynamics modeling method based on Adams according to the embodiment of the application;

[0055] Figure 2 A helicopter landing gear buffer dynamics modeling flowchart of a helicopter landing gear dynamics modeling method based on Adams according to the embodiment of the application;

[0056] Figure 3 A helicopter landing gear dynamics modeling flowchart of a helicopter landing gear dynamics modeling method based on Adams according to the embodiment of the application;

[0057] Figure 4 A landing gear buffer force real-time display schematic diagram of a helicopter landing gear dynamics modeling method based on Adams according to the embodiment of the application;

[0058] Figure 5 A right front wheel buffer force time history curve diagram of a helicopter landing gear dynamics modeling method based on Adams according to the embodiment of the application;

[0059] Figure 6 A right tail wheel vertical force and lateral force time history curve diagram of a helicopter landing gear dynamics modeling method based on Adams according to the embodiment of the application. DETAILED DESCRIPTION

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0061] This invention provides a method for modeling the dynamics of helicopter landing gear based on Adams, including a buffer dynamics modeling method and a wheel dynamics modeling method. Buffer dynamics modeling is used to simulate the dynamic characteristics of the buffers in the helicopter landing gear. The buffer is equivalent to a parallel mechanism of a gas spring, a hydraulic damper, and a friction damper. A mathematical model of the buffer is established, and a subroutine file (.f) is written in Fortran to solve for the buffer forces based on the mathematical model. This is compiled into a dynamic link library (.dll) using IVF (Intel Visual Fortran), serving as an external solver that Adams can call. The subroutine obtains relevant motion parameters from the current motion state of the Adams model and passes them to the dynamic link library based on the mathematical model. The dynamic link library calculates and returns the buffer forces under the current motion state for state calculation at the next simulation moment, thus performing iterative analysis. Wheel dynamics modeling is used to simulate the dynamic characteristics of the wheels in the helicopter landing gear. By creating tire property files (.tir) and road surface property files (.rdf), the characteristics of the tire and road surface are defined. Combining the Faila tire mechanics model and tire model interface in Adams, the vertical force, longitudinal force, lateral force, and rotational torque of the tire are modeled. The tire model obtains the current tire motion state information from the Adams tire model interface, calculates and outputs the tire's forces and torques, and then transmits them back to Adams through the tire model interface to calculate the motion state at the next simulation moment, thus performing iterative analysis.

[0062] like Figures 1 to 6 As shown, Figure 1 A flowchart illustrating a helicopter landing gear dynamics modeling method based on Adams according to an embodiment of the present invention; Figure 2 A flowchart illustrating the dynamic modeling process of a helicopter landing gear buffer, representing an embodiment of the present invention, using an Adams-based method for modeling helicopter landing gear dynamics. Figure 3 A flowchart illustrating the helicopter landing gear wheel dynamics modeling method based on Adams, according to an embodiment of the present invention; Figure 4 A schematic diagram illustrating the real-time display of landing gear damper force, representing an embodiment of the Adams-based helicopter landing gear dynamics modeling method of the present invention.Figure 5 A right front wheel buffer force time history curve diagram of a helicopter landing gear dynamics modeling method based on Adams of an embodiment of the application is shown in the figure; Figure 6 A right tail wheel vertical force and lateral force time history curve diagram of a helicopter landing gear dynamics modeling method based on Adams of an embodiment of the application is shown in the figure.

[0063] In the figure, a helicopter landing gear dynamics modeling method based on Adams comprises:

[0064] S101, three-dimensional models of a helicopter body and a landing gear are respectively established, and the three-dimensional models are imported into Adams;

[0065] S102, an oil-gas buffer is equivalent to a parallel mechanism of a gas spring, an oil damping device and a friction damping device, a mathematical model of the oil-gas buffer is established, that is, mathematical models of gas spring force F a , oil damping force F h and friction force F f are respectively established;

[0066] S103, a tire attribute file and a road surface attribute file are written, characteristics of the tire and the road surface are defined, a Faila tire mechanics model in Adams is combined with a tire model interface, modeling of tire vertical force, longitudinal force, lateral force and rotation torque is performed;

[0067] S104, tire motion state information at a current time is obtained from the tire model interface of Adams, tire force and torque are calculated and output, the tire model interface is returned to Adams, motion states at a next simulation time are calculated, and iterative analysis is performed.

[0068] In the embodiment of the application, the helicopter landing gear dynamics modeling method based on Adams can improve the calculation efficiency of helicopter dynamics characteristic solving and shorten the solving time; through editing the tire attribute file, modification of dynamics parameters such as wheel size, appearance and stiffness, damping and friction can be realized, and re-establishment of the wheel model is avoided; animation display of the helicopter landing process can be realized, and motion and mechanical parameters are output in real time.

[0069] In an embodiment of the application, the mathematical models of the gas spring force F a , the oil damping force F h and the friction force F f comprise:

[0070] For a single-cavity oil-gas buffer, the gas spring force F a is a function of the buffer stroke S, and the gas spring force F a is represented by a gas compression polytropic equation,

[0071]

[0072] In the formula, P Air0 V is the initial pressure of the air chamber. Air0 Let A be the initial volume of the air chamber. Air Where S is the air chamber pressure area, S is the buffer slippage, γ is the polytropic index, and P is the pressure area of ​​the air chamber. AMB Standard atmospheric pressure;

[0073] Oil damping force F h It's about the buffer compression speed. The function of the oil, assuming the oil is an incompressible fluid, and the oil damping force F h It can be obtained from the Bernoulli equation and the continuity equation, expressed as:

[0074]

[0075] In the formula, ρ is the oil density, and A FL C is the effective oil pressure area of ​​the oil cavity. d0 C d1 These are the flow reduction coefficients of the main oil orifice in both forward and reverse strokes, A oil0 A oil1 These represent the areas of the oil holes for forward and reverse strokes, respectively. The compression speed of the buffer is the relative speed between the piston and the sleeve.

[0076] The frictional force of the buffer is assumed to be the resultant force of the internal frictional force caused by the internal pressure of the buffer and the internal frictional force caused by the bending displacement of the buffer, and is expressed as follows:

[0077]

[0078] In the formula, k m Given the coefficient of friction, the net force F of the buffer is F = F a +F h +F f .

[0079] In one embodiment of the present invention, the method includes:

[0080] Define the components of the buffer stroke in the X, Y, Z coordinate axes as disx, disy, disz respectively; define the components of the buffer compression velocity in the X, Y, Z coordinate axes as velx, vely, velz respectively; define the integer array IPAR1(3) for storing the bodyid of the piston and sleeve; define the buffer resultant force, gas spring force, oil damping force, friction force as F, Fa, Fh, Ff respectively; define the initial gas cavity volume, gas cavity pressure area, initial gas cavity pressure, standard atmospheric pressure, polytropic index as VAir, AAir, PAir, PAMB, ra respectively; define the oil density, effective oil cavity pressure oil area, positive stroke oil hole area, positive stroke main oil hole contraction coefficient, negative stroke oil hole area, negative stroke main oil hole contraction coefficient as Den, AFL, AOil0, Cd0, AOil1, Cd1 respectively; define the friction coefficient as Km;

[0081] The SYSFNC function is called to collect the components of the relative displacement and relative velocity of the piston and sleeve in three coordinate axes, to obtain the buffer misalignment stroke and compression velocity, to calculate the buffer resultant force, gas spring force, oil damping force and friction force; at least the OPEN and WRITE commands are called to output the parameters of time, misalignment stroke, buffer force, which are used for drawing the dynamic response time history curve.

[0082] In an embodiment of the present application, the modeling of the vertical force, longitudinal force, lateral force and rotation torque of the tire is combined with the Faila tire mechanics model in Adams and the tire model interface, including:

[0083] The vertical force F of the ground on the tire z The spring force F zk and the damping force F zc are composed, and are determined by the load, tire stiffness and damping, the vertical force F z is calculated by the following formula

[0084] F z = min(0.0, {F zk +F zc})

[0085] F zk =-vertical_stiffness×pen

[0086] F zc =-vertical_damping×Vpen

[0087] In the formula, vertical_stiffness is the vertical stiffness of the tire, pen is the tire penetration depth, vertical_damping is the vertical damping of the tire, and Vpen is the change rate of the tire penetration depth;

[0088] Longitudinal force depends on vertical force F z , longitudinal slip rate S s , side slip angle a and current friction coefficient U, defines critical longitudinal slip rate S_critical,

[0089]

[0090] U = U max - (U max - U min ) x S s a

[0091]

[0092] In the formula, S s a is the comprehensive slip rate, S s is the longitudinal slip rate, a is the side slip angle, U is the current friction coefficient, U max is the static friction coefficient, U min is the sliding friction coefficient, S_critical is the critical longitudinal slip rate, CSLIP is the longitudinal force coefficient when the slip rate is small;

[0093] When |S s | < S_critical, that is, the tire is in the elastic deformation state, the longitudinal force is

[0094] F x = -CSLIP x S s

[0095] When |S s | > S_critical, that is, the tire is in the sliding state, the longitudinal force is

[0096]

[0097] In an embodiment of the present application, the method comprises:

[0098] Lateral force depends on vertical force F z and current friction coefficient U, similar to the calculation of longitudinal force, defines critical side slip angle a_critical,

[0099]

[0100] In the formula, CALPHA is the lateral force coefficient when the side slip angle is small;

[0101] If a < a_critical, that is, the tire is in the elastic deformation state, the lateral force is

[0102] F y = -U x |F z| x (1-H 3 ) x sign (a)

[0103]

[0104] If a = a_critical, the lateral force is

[0105] F y = -U|F z | x sign (a)

[0106] The aligning moment is only calculated when there is a non-slip area between the tire and the ground, and when the tire is in a completely sliding state, the aligning moment is 0.

[0107] When a < a_critical, the aligning moment is

[0108] M z = U x |F z | x WIDTH x (1-H) x H 3 x sign (a)

[0109] When a > a_critical, the aligning moment is M z = 0.

[0110] In an embodiment of the application, the method comprises:

[0111] After the buffer and the wheel dynamics modeling is completed, the model weight is set, and a motion pair is added; a concentrated load is established at the center of gravity of the body, and the load size is equal to the weight of the body; a fixed pair is created between the concentrated load and the body model; a fixed pair is created between the buffer sleeve and the body model; and a moving pair is created between the buffer piston and the buffer sleeve.

[0112] Figure 1 In the three-dimensional modeling software, a three-dimensional model of the helicopter body and the landing gear is established, and is imported into Adams. Buffer dynamics modeling and wheel dynamics modeling are performed respectively. Finally, the model quality is set, and a motion pair is added, to complete the helicopter landing gear modeling process. The buffer dynamics modeling is used to simulate the dynamic characteristics of the buffer in the helicopter landing gear.

[0113] The buffer dynamics modeling process is as follows: Figure 2The buffer subroutine files GFOSUB1.f, GFOSUB2.f and GFOSUB3.f of the left front wheel buffer, the right front wheel buffer and the tail wheel buffer are respectively established; and the buffer subroutine files GFOSUB1.f, GFOSUB2.f and GFOSUB3.f are compiled into the dynamic link library mysub.dll file by using the Fortran compiling environment IVF (Intel Visual Fortran).

[0114] The buffer force between the piston and the sleeve is established in Adams. Specifically, a General Force is created in the Forces module of Adams, the sleeve is selected as the action part, the piston is selected as the reaction part, the definition mode is selected through a subroutine, and the corresponding buffer subroutine files (GFOSUB1.f, GFOSUB2.f and GFOSUB3.f) are selected; in the Simulation module, the compiled dynamic link library mysub.dll file is selected as an external solver to complete the association of the buffer force and the dynamic link library.

[0115] The subroutine obtains relevant motion parameters from the current motion state of the Adams model, and transmits the motion parameters to the dynamic link library based on a mathematical model. The dynamic link library calculates and returns the buffer force in the current motion state for the calculation of the motion state in the next simulation time, and the iteration analysis is performed in this way. Thus, the buffer dynamics modeling of the helicopter landing gear is completed.

[0116] The wheel dynamics modeling is used to simulate the dynamic characteristics of the wheels in the helicopter landing gear. The wheel dynamics modeling process is as shown in Figure 3

[0117] The properties of the tire and the road surface are defined by writing the tire property file.tir and the road surface property file.rdf. The basic parameters of the tire, such as the tire type, the tire shape and size, the stiffness, the damping and the friction coefficient, are set in the self-compiled tire property file.tir. The tire type is set as Fiala tire. The basic parameters of the road surface, such as the road surface type, the size and the position, are set in the self-compiled road surface property file.rdf.

[0118] The tire (including the left front wheel, the right front wheel and the left tail wheel and the right tail wheel) and the road surface model are created in Adams, and the mass (inertia) and the position information are set. Then the corresponding tire property file and the road surface property file are loaded. Then the rotational pair between the hub and the axle is created.

[0119] The vertical force, the longitudinal force, the lateral force and the turning moment of the tire are modeled by combining the Fiala tire mechanical model in Adams and the tire model interface. ​

[0120] The helicopter landing gear dynamics modeling is completed, and a schematic diagram of real-time display of the landing gear buffer force during the helicopter landing process is shown in Figure 4 , a time history curve of the right front wheel buffer force is shown in Figure 5 , and a time history curve of the right tail wheel vertical force and lateral force is shown in Figure 6 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 .

[0121] The helicopter landing gear dynamics modeling method can improve the calculation efficiency of the helicopter dynamics characteristics solution, ensure the simulation accuracy, realize the animation display of the helicopter landing process, real-time output the motion and mechanical parameters, and realize the rapid modification of the buffer and wheel parameters.

[0122] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A helicopter landing gear dynamics modeling method based on Adams, characterized in that, The method includes: S101. Create 3D models of the helicopter fuselage and landing gear respectively, and import the 3D models into Adams; S102. Equivalently model the oil-gas buffer as a parallel mechanism consisting of a gas spring, an oil damper, and a friction damper, and establish a mathematical model of the oil-gas buffer, i.e., establish the gas spring force... F a Oil damping force F h and friction F f Mathematical model; S103. Write tire property files and road surface property files to define the characteristics of the tire and road surface; combining the Faila tire mechanics model and tire model interface in Adams, model the tire's vertical force, longitudinal force, lateral force, and rotational torque, including: Vertical force of the ground on the tire F z Due to spring force F zk With damping force F zc The composition depends on the load, tire stiffness and damping, and vertical force. F z Calculated by the following formula In the formula, vertical_stiffness For the vertical stiffness of the tire, pen The depth of tire penetration into the road surface is represented by , and vertical_damping is the vertical damping of the tire. Vpen The rate of change of tire penetration depth into the road surface; Longitudinal force depends on vertical force F z Longitudinal slip ratio S s Side slip angle α and current coefficient of friction U Define the critical longitudinal slip ratio S_critical, In the formula, S s α For the overall slip ratio, S s Where α is the longitudinal slip ratio and α is the sideslip angle. U Given the current coefficient of friction, U max The static friction coefficient is U min The coefficient of sliding friction is S_critical The critical longitudinal slip ratio, CSLIP This is the longitudinal force coefficient at a small slip ratio; when That is, when the tire is in an elastic deformation state, the longitudinal force is when That is, when the tire is in a slipping state, the longitudinal force is ； S104. Obtain the current tire motion state information from Adams' tire model interface, calculate and output the tire's force and torque, and return them to Adams through the tire model interface to calculate the motion state at the next simulation moment, and perform iterative analysis in this way.

2. The helicopter landing gear dynamics modeling method based on Adams according to claim 1, characterized in that, Establish gas spring force respectively F a Oil damping force F h and friction F f The mathematical models include: For a single-chamber oil-gas buffer, the gas spring force F a It's about the buffer travel. S The function of gas spring force F a Represented by the gas compression polytropic equation, In the formula, P Air0 This represents the initial pressure of the air chamber. V Air0 This is the initial volume of the air chamber. A Air The air chamber pressure area. S For the buffer misalignment stroke, γ It is a variable index. P AMB Standard atmospheric pressure; Oil damping force F h It's about the buffer compression speed. The function, assuming the oil is an incompressible fluid, the oil damping force F h It can be obtained from the Bernoulli equation and the continuity equation, expressed as: In the formula, ρ For the density of the oil, A FL The effective oil pressure area of ​​the oil chamber. C d0 ,C d1 These are the flow reduction coefficients of the main oil orifice during forward and reverse strokes, respectively. A oil0 ,A oil1 These represent the areas of the oil holes for forward and reverse strokes, respectively. The compression speed of the buffer is the relative speed between the piston and the sleeve. The frictional force of the buffer is assumed to be the resultant force of the internal frictional force caused by the internal pressure of the buffer and the internal frictional force caused by the bending displacement of the buffer, and is expressed as follows: In the formula, k m The coefficient of friction is the resultant force of the buffer. F for F = F a + F h + F f .

3. The method for modeling helicopter landing gear dynamics based on Adams according to claim 2, characterized in that, The method includes: Define the components of the buffer travel on the X, Y, and Z coordinate axes as follows: disx , disy , disz Define the components of the buffer compression velocity on the X, Y, and Z coordinate axes as follows: velx,vely , velz Define an integer array IPAR1(3) The bodyid is used to store the piston and sleeve; the resultant force of the buffer, the gas spring force, the oil damping force, and the friction force are defined as follows: F , Fa , Fh , Ff The initial volume of the air chamber, the pressure area of ​​the air chamber, the initial pressure of the air chamber, the standard atmospheric pressure, and the polytropic index are defined as follows: VAir , AAir , PAir , PAMB , ra Define the oil density, effective pressure area of ​​the oil cavity, area of ​​the forward stroke oil orifice, coefficient of constriction of the forward stroke main oil orifice, area of ​​the reverse stroke oil orifice, and coefficient of constriction of the reverse stroke main oil orifice as follows: Den , AFl , AOil0 , Cd0 , AOil1 , Cd1 The coefficient of friction is defined as Km; The SYSFNC function is called to collect the components of the relative displacement and relative velocity of the piston and sleeve on three coordinate axes, obtain the shock absorber slippage and compression speed, and calculate the shock absorber resultant force, gas spring force, oil damping force and friction force; the parameters of time, slippage and shock absorber force are output by calling at least the OPEN and WRITE commands for the dynamic response time-history curve plotting.

4. The method for modeling helicopter landing gear dynamics based on Adams according to claim 2, characterized in that, The method includes: Lateral force depends on vertical force F z and current coefficient of friction U， Similar to longitudinal force calculation, the critical sideslip angle is defined. α_ critical, In the formula, CALPHA This is the lateral force coefficient at small sideslip angles; like That is, when the tire is in an elastic deformation state, the lateral force is like That is, when the tire is in a slipping state, the lateral force is The self-aligning torque is calculated only when there is a non-slip zone between the tire and the ground. When the tire is in a fully slipping state, the self-aligning torque is 0. when That is, when the tire is in an elastic deformation state, the self-aligning torque is when That is, when the tire is in a fully slipping state, the self-centering torque is .

5. The method for modeling helicopter landing gear dynamics based on Adams according to claim 1, characterized in that, The method includes: After the dynamic modeling of the buffer and wheel is completed, set the model weight and add kinematic pairs; establish a concentrated load at the center of gravity of the machine, with the load size equal to the weight of the machine; create a fixed pair between the concentrated load and the machine model; create a fixed pair between the buffer sleeve and the machine model; and create a sliding pair between the buffer piston and the buffer sleeve.

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