A method for determining pre-tension of a high-speed tracked vehicle

Abstract

The present application belongs to the technical field of tracked vehicles, and particularly relates to a method for determining the pre-tensioning force of a high-speed tracked vehicle, comprising the following steps: establishing a topological graph of a high-speed tracked vehicle system; establishing a discretized mass model of a lower track section; establishing a continuum verification model of the lower track section; checking the discretized mass model; establishing a dynamic model of the road wheels and the vehicle body; establishing a multi-level coupled vibration model of the vehicle; establishing an excitation model of road unevenness and different vehicle speeds; constructing an objective function of simultaneous passability and task load stability; setting the pre-tensioning force as a design variable and defining its variation range; using an optimization algorithm to optimize the pre-tensioning force under different structural masses and excitation conditions; and substituting the optimal solution of the pre-tensioning force into the multi-level coupled vibration model for solving and verification. The present application can provide theoretical support for setting the pre-tensioning force of a high-speed tracked vehicle.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tracked vehicles, and particularly relates to a method for determining the pre-tension of a high-speed tracked vehicle. BACKGROUND

[0002] The pre-tension of a track is the tension applied to the track by a track tensioning device. When the vehicle is running at high speed, if the value is set too small, the ground pressure under each track roller will increase, and the track may even fall off, reducing the passability of the vehicle. If the value is set too large, the passability of the vehicle will be improved, but the track may be broken, reducing the service life of the track system and directly affecting the dynamic characteristics of the vehicle. The traditional setting of the pre-tension of a high-speed tracked vehicle mainly focuses on the passability of the vehicle, ignoring the stability of the task load. In addition, in actual engineering applications, the setting of the pre-tension often depends on the experience and subjective judgment of engineers, and lacks theoretical basis. Therefore, it is necessary to provide a method for determining the pre-tension of a tracked vehicle that takes into account the passability and stability of the task load, in order to improve the dynamic performance of the vehicle. SUMMARY

[0003] (I) Technical problem to be solved

[0004] The technical problem to be solved by the application is how to provide a method for determining the pre-tension of a tracked vehicle that takes into account the passability and stability of the task load.

[0005] (II) Technical solution

[0006] To solve the above technical problem, the application provides a method for determining the pre-tension of a high-speed tracked vehicle, which comprises the following steps:

[0007] Step 1: establishing a topological graph of the vehicle system of a high-speed tracked vehicle according to the actual structure;

[0008] Step 2: establishing a discrete mass model of the lower track section considering the tension;

[0009] Step 3: establishing a continuous body verification model of the lower track section considering the tension;

[0010] Step 4: correcting the discrete mass model using the continuous body model of the lower track section;

[0011] Step 5: establishing a dynamic model of the track roller and the vehicle body;

[0012] Step 6: establishing a multi-level coupled vibration model of the vehicle based on the subsystem dynamic model;

[0013] Step 7: establishing an excitation model of the road roughness and different vehicle speeds;

[0014] Step 8: constructing an objective function for passability and task load stability.

[0015] Step 9: set the pre-tensioning force as a design variable and define its range of variation;

[0016] Step 10: use optimization algorithm to optimize the pre-tensioning force under different structural mass and excitation conditions;

[0017] Step 11: substitute the optimal solution of pre-tensioning force into the multi-level coupled vibration model for solution verification.

[0018] In step 1, the vehicle is divided into different systems according to functions, including track system, road wheel, power subsystem, vehicle body system and task system; the topological graph of the whole vehicle system is drawn according to the connection and contact relationship of each part.

[0019] In step 2, the track is discretized into a 6-degree-of-freedom lumped mass model according to the distribution of road wheels on the track, and the vibration differential equations of each mass point are integrated to obtain the matrix form of the lumped mass model:

[0020]

[0021] where represents a column vector composed of the transverse vibration displacement of each mass point;

[0022] The mass matrix M r and the stiffness matrix K r are respectively:

[0023] The mass matrix M r :

[0024]

[0025] where m r is the equivalent mass of the track;

[0026] The stiffness matrix K r :

[0027]

[0028] where L is the length of the lower track segment, and T is the tension during vibration.

[0029] In step 3, it is assumed that the track makes a small transverse vibration, and the tension T only changes direction during vibration, and the size remains unchanged, then the relationship between the force acting on the micro segment in z direction and its transverse vibration acceleration at any instant is represented as:

[0030]

[0031] where is the intercepted chord micro segment;

[0032]

[0033] p represents the linear density of the track;

[0034] In step 4, the continuum model is used to check and correct the discrete mass model to test the model accuracy for further establishing the vertical vibration coupling model of the track and the track roller.

[0035] In step 5, the vertical vibration differential equation of each track roller on both sides of the vehicle body is obtained according to Newton's second law of motion without considering the damping effect:

[0036]

[0037] Wherein, m is the mass of the track roller, F t,Li ,F t,Ri is the constraint force acting on the left and right track rollers; Z Li ,Z Ri is the vertical displacement of the left and right track rollers;

[0038] The vehicle body vibrates under the action of power excitation and road excitation, ignoring the damping effect, considering the three degrees of freedom of the vehicle body in the vertical, pitch and roll directions, the vibration differential equation is:

[0039]

[0040] Wherein, M is the mass of the vehicle body;

[0041] Z is the vertical displacement of the vehicle body;

[0042] I x ,I y is the moment of inertia of the vehicle body around the X and Y axes;

[0043] is the rotation angle of the vehicle body around the X and Y axes;

[0044] F t,Li ,F t,Ri is the constraint force acting on the track roller;

[0045] F b,zj ,F b,yk is the constraint force acting on the vehicle body by the power suspension;

[0046] d L ,d R is the geometric parameter of the vehicle body in the left and right width directions;

[0047] d yL ,d yRGeometric dimensions of the front and rear suspensions of the power plant subsystem;

[0048] d fx ,d bx Geometric dimensions of the left and right suspensions of the power plant subsystem;

[0049] d z Height of the suspension of the power plant subsystem.

[0050] In step 6, based on the established whole vehicle system topology graph, the coupling of the vehicle body subsystem and the power suspension, the track and the load wheel is comprehensively considered, and a whole vehicle dynamics model of the high-speed tracked vehicle is established.

[0051] In step 7, the road roughness excitation model is used to simulate the excitation of the vehicle in the driving process by the road impact load; different vehicle speed excitations are used to simulate that the load action time lag period is different, causing different vibration responses of the whole vehicle with the change of the driving speed.

[0052] In step 8, the passability of the high-speed tracked vehicle is specifically the ability of the vehicle to pass through a ditch, a vertical strong and a side slope; the task load stability is to ensure the realization of the specified task action, and is specifically the vibration characteristics of the task load system.

[0053] In step 9, by adjusting the pretightening force, the adjustment of the inherent frequency of the track, the load wheel and the vehicle body of different materials is realized, and the resonance phenomenon with the task load system is avoided.

[0054] In step 10, for the optimization problem considering the passability and the task load stability at the same time, NSGA-II is used to optimize the track pretightening force;

[0055] The different materials are specifically steel vehicle body and track system, and titanium alloy vehicle body and track system;

[0056] In step 11, the optimal solution of the pretightening force obtained in step 10 is substituted into the multi-level coupled vibration model for solving, and the correctness of the proposed pretightening force optimization design method is proved.

[0057] (Three) beneficial effects

[0058] Compared with the prior art, the present application has the following beneficial effects:

[0059] (1) The pretightening force determination method proposed in the present application simultaneously considers the whole vehicle passability and the task load stability;

[0060] (2) The multi-objective optimization adopts the NSGA-II algorithm, which increases the search ability of the optimization algorithm and can effectively eliminate the influence of local convergence;

[0061] (3) can effectively improve the phenomenon of coupling vibration inherent mode frequency coincidence caused by structural material replacement and incentive load change. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 The total flowchart of the method for determining the pre-tensioning force of the high-speed tracked vehicle.

[0063] Figure 2 The topological graph of the high-speed tracked vehicle system is established according to the actual structure.

[0064] Figure 3 The influence of the speed and pre-tensioning force of the steel vehicle body on the sensitive frequency.

[0065] Figure 4 The influence of the speed and pre-tensioning force of the titanium alloy vehicle body on the sensitive frequency. DETAILED DESCRIPTION

[0066] In order to make the purpose, content and advantages of the present application clearer, the specific embodiments of the present application will be further described in detail below in combination with the drawings and examples.

[0067] To solve the above technical problems, the present application provides a method for determining the pre-tensioning force of a high-speed tracked vehicle, which comprises:

[0068] Step 1: establishing a topological graph of the high-speed tracked vehicle system according to the actual structure;

[0069] Step 2: establishing a discrete mass model of the lower track section considering the tension;

[0070] Step 3: establishing a continuum verification model of the lower track section considering the tension;

[0071] Step 4: correcting the discrete mass model by using the continuum model of the lower track section;

[0072] Step 5: establishing a dynamic model of the road wheel and the vehicle body;

[0073] Step 6: establishing a multi-level coupled vibration model of the whole vehicle based on the subsystem dynamic model;

[0074] Step 7: establishing an excitation model of the road roughness and different vehicle speeds;

[0075] Step 8: constructing an objective function of the simultaneous passability and task load stability;

[0076] Step 9: setting the pre-tensioning force as a design variable and defining the change range thereof;

[0077] Step 10: optimizing the pre-tensioning force under different structural mass and excitation conditions by using an optimization algorithm;

[0078] Step 11: Substitute the optimal solution of pre-tensioning force into the multi-level coupled vibration model to solve and verify.

[0079] In the step 1, the vehicle is divided into different systems according to functions, including a track system, a road wheel, a power subsystem, a vehicle body system and a task system; and a topological graph of the vehicle system is drawn according to connection and contact relations of the parts.

[0080] In the step 2, the track is discretized into a 6-degree-of-freedom lumped mass model according to distribution of the road wheel on the track, and vibration differential equations of each mass point are integrated to obtain a matrix form of the lumped mass model:

[0081]

[0082] wherein represents a column vector composed of transverse vibration displacements of each mass point;

[0083] a mass matrix M r and a stiffness matrix K r are respectively:

[0084] a mass matrix M r :

[0085]

[0086] wherein m r is an equivalent mass of the track;

[0087] a stiffness matrix K r :

[0088]

[0089] wherein L is a length of a lower track segment, and T is a tension in the vibration process.

[0090] In the step 3, it is assumed that the track makes a slight transverse vibration, the tension T only changes in direction and keeps unchanged in size in the vibration process, and then a relationship between a force in the z direction acting on the micro segment and an acceleration of the transverse vibration of the micro segment at any instant is represented as:

[0091]

[0092] wherein is the intercepted chord micro segment;

[0093]

[0094] ρ represents a linear density of the track;

[0095] In step 4, the continuum model is used to check and correct the discrete mass model for further establishment of the vertical vibration coupling model of the track and the road wheels, and the model accuracy is tested; if the model accuracy does not meet the requirements, steps 2-4 are repeated.

[0096] In step 5, the vibration differential equations of the road wheels on both sides of the vehicle body in the vertical direction are obtained according to Newton's second law of motion without considering the damping effect:

[0097]

[0098] Wherein, m is the mass of the road wheel, F t,Li ,F t,Ri is the constraint force acting on the left and right road wheels; Z Li ,Z Ri is the displacement of the left and right road wheels in the vertical direction;

[0099] The vehicle body vibrates under the action of power excitation and road surface excitation, ignoring the damping effect, considering the degrees of freedom of the vehicle body in the vertical, pitch and roll directions, the vibration differential equation is:

[0100]

[0101] Wherein, M is the mass of the vehicle body;

[0102] Z is the vertical displacement of the vehicle body;

[0103] I x ,I y is the moment of inertia of the vehicle body around the X and Y axes;

[0104] is the rotation angle of the vehicle body around the X and Y axes;

[0105] F t,Li ,F t,Ri is the constraint force acting on the road wheel;

[0106] F b,zj ,F b,yk is the constraint force of the power suspension acting on the vehicle body;

[0107] d L ,d R is the geometric parameter of the vehicle body in the left and right width directions;

[0108] d yL ,d yR is the geometric size of the left and right suspensions of the power device subsystem;

[0109] d fx ,d bx is the geometric size of the front and rear suspensions of the power device subsystem;

[0110] d z Height of the power plant subsystem suspension.

[0111] In step 6, based on the established whole vehicle system topology, the coupling of the vehicle body subsystem and the power suspension, the track and the load wheel is comprehensively considered, and the whole vehicle dynamics model of the high-speed tracked vehicle is established.

[0112] In step 7, the road roughness excitation model is used to simulate the excitation of the vehicle in the driving process by the road impact load; different vehicle speed excitations are used to simulate the different vibration responses of the whole vehicle caused by the different load action time lag periods with the change of the driving speed.

[0113] In step 8, the passability of the high-speed tracked vehicle is specifically the ability of the vehicle to pass through a ditch, a vertical slope and a roll slope; the task load stability is to ensure the realization of the specified task action, and is specifically the vibration characteristics of the task load system.

[0114] In step 9, by adjusting the pre-tensioning force, the inherent frequency adjustment of the track, the load wheel and the vehicle body of different materials is realized, and the resonance phenomenon with the task load system is avoided.

[0115] In step 10, for the optimization problem considering the passability and the task load stability at the same time, the NSGA-II is used to optimize the track pre-tensioning force;

[0116] The different materials are specifically steel vehicle body and track system, titanium alloy vehicle body and track system;

[0117] In step 11, the optimal solution of the pre-tensioning force obtained in step 10 is substituted into the multi-level coupled vibration model for solving, and the correctness of the proposed pre-tensioning force optimization design method is proved.

[0118] Embodiment 1

[0119] In this embodiment, Figure 1 A method for determining the pre-tensioning force of a high-speed tracked vehicle is shown in a total flowchart, and the specific steps are as follows:

[0120] In one specific embodiment, as Figure 2 shown, the whole vehicle system topology of the high-speed tracked vehicle is established according to the actual structure.

[0121] In one specific embodiment, a discrete mass model of the lower track section considering tension is established, which is specifically:

[0122]

[0123] In which, represents a column vector composed of transverse vibration displacement of each mass point;

[0124] mass matrix M r

[0125]

[0126] wherein m r is the equivalent mass of the track;

[0127] stiffness matrix K r

[0128]

[0129] wherein, L is the length of the track under section, and T is the tension in the vibration process;

[0130] In one embodiment, a continuous body verification model of the track under section considering the tension is established, specifically:

[0131]

[0132] wherein, is the intercepted chord micro-section, ρ represents the linear density of the track;

[0133] In one embodiment, the correctness of the discrete mass model established by the continuous body model verification is verified, and if the accuracy requirement is not met, steps 2-4 are repeated until the requirement is met;

[0134] In one embodiment, a track dynamics model is established, specifically:

[0135]

[0136] wherein, m is the mass of the track, F t,Li ,F t,Ri is the constraint force acting on the left and right track wheels; Z Li ,Z Ri is the vertical displacement of the left and right track wheels;

[0137] In one embodiment, a vehicle body dynamics model is established, specifically:

[0138]

[0139] wherein, M is the mass of the vehicle body;

[0140] Z is the vertical displacement of the vehicle body;

[0141] I x ,I y is the moment of inertia of the vehicle body around the X and Y axes;

[0142] rotation angle of the vehicle body around the X axis and the Y axis;

[0143] F t,Li ,F t,Ri constraint force acting on the load wheel;

[0144] F b,zj ,F b,yk constraint force acting on the vehicle body by the power suspension;

[0145] d L ,d R geometric parameter of the vehicle body in the left-right width direction;

[0146] d yL ,d yR geometric size of the left-right suspension of the power device subsystem;

[0147] d fx ,d bx geometric size of the front-rear suspension of the power device subsystem;

[0148] d z height of the suspension of the power device subsystem.

[0149] In one specific embodiment, a multi-level coupled vibration model of the whole vehicle is established, specifically:

[0150]

[0151]

[0152]

[0153] In the formula, X = {X b ; X e ; X w ; X r} represents the overall displacement vector; represents the freedom of the vehicle body in the vertical, roll and pitch directions; X e = [x, y, z, θ x , θ y , θ z ] T represents the freedom of the power suspension; X w = [z L1 ,…, z L6 , z R1 ,…, z R6 ] T represents the freedom of the left and right load wheels of the vehicle body in the vertical direction; F represents the degree of freedom of the discretized double-track lumped mass model. r (t) and F e (t) represent the road excitation and dynamic excitation column vectors during the motion, respectively. Here K b,e K represents the stiffness influence matrix of the power suspension subsystem on the vehicle body; K b,w K represents the stiffness influence matrix of the load wheel on the vehicle body; K w,r K represents the stiffness influence matrix of the track on the load wheel;

[0154] In one specific embodiment, an excitation model of the road unevenness and different vehicle speeds is established, where the road surface mainly concerns the impact load, and the vehicle speed is set in the range of 0-50 km / h;

[0155] In one specific embodiment, a target function considering both the passability and the task load stability is constructed;

[0156] In one specific embodiment, the pretensioning force is set as a design variable and its variation range is defined, where the pretensioning force range is 15-25 kN;

[0157] In one specific embodiment, the intelligent optimization algorithm is used to determine the pretensioning force under different structural masses and vehicle speeds, where the intelligent optimization algorithm is the non-dominated sorting genetic algorithm (NSGA-II), and the different structural masses are specifically steel vehicle body and titanium alloy vehicle body;

[0158] In one specific embodiment, Figure 3 The influence of the steel vehicle body speed and the pretensioning force on the sensitive frequency is shown;

[0159] In one specific embodiment, Figure 4 The influence of the titanium alloy vehicle body speed and the pretensioning force on the sensitive frequency is shown;

[0160] In one specific embodiment, the optimal solution of the pretensioning force is substituted into the multi-level coupled vibration model for solving and verification.

[0161] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A method for determining the pretension force of a high-speed tracked vehicle, characterized in that, The method includes: Step 1: Establish the topology diagram of the high-speed tracked vehicle system based on the actual structure; Step 2: Establish a discretized mass model of the track lower support section considering tension; Step 3: Establish a verification model of the track lower support segment considering tension; Step 4: Use the track lower support segment continuum model to verify and correct the discretized quality model; Step 5: Establish the dynamic model of the road wheels and vehicle body; Step 6: Establish a multi-level coupled vibration model of the whole vehicle based on the subsystem dynamics model; Step 7: Establish excitation models for road surface unevenness and different vehicle speeds; Step 8: Construct objective functions for simultaneous passability and task load stability; Step 9: Set the pretension force as a design variable and define its range of variation; Step 10: Optimize the pretension force under different structural masses and excitation conditions using an optimization algorithm; Step 11: Substitute the optimal solution of the pretension force into the multi-level coupled vibration model for solution verification; In step 2, based on the distribution of the road wheels on the track, the track is discretized in space into a lumped mass model with 6 degrees of freedom. By combining the vibration differential equations of each mass point, a matrix-form lumped mass model is obtained. in This represents a column vector composed of the lateral vibration displacements of each particle. mass matrix and stiffness matrix These are: mass matrix : in The equivalent mass of the track; Stiffness matrix : ； Where L is the length of the lower track support section, and T is the tension during vibration; In step 6, based on the established vehicle system topology diagram, and taking into account the coupling between the vehicle body subsystem and the power suspension, tracks and road wheels, a dynamic model of the high-speed tracked vehicle is established. Specifically, a multi-level coupled vibration model of the entire vehicle is established as follows: In the formula, Represents the global displacement vector; This indicates the vehicle's degrees of freedom in the vertical, lateral, and pitch directions; Indicates the degrees of freedom of the power suspension; This indicates the degree of freedom of the road wheels on the left and right sides of the vehicle body in the vertical direction; The degrees of freedom represent the discretized lumped mass model of the two-sided track; and These represent the column vectors of road surface excitation and dynamic excitation during the motion process, respectively; here This represents the matrix showing the influence of the power suspension subsystem on the stiffness of the vehicle body. This represents the matrix showing the influence of the road wheels on the stiffness of the vehicle body. This represents the matrix representing the influence of the track on the stiffness of the road wheel.

2. The method for determining the pretension force of a high-speed tracked vehicle as described in claim 1, characterized in that, In step 1, the vehicle is divided into different systems according to its functions, including: track system, road wheels, power subsystem, body system, and mission system; and a topology diagram of the vehicle system is drawn according to the connection and contact relationship of each part.

3. The method for determining the pretension force of a high-speed tracked vehicle as described in claim 1, characterized in that, In step 3, assuming the track undergoes slight lateral vibration, and the tension T changes only in direction while remaining constant in magnitude, then the continuum model of the track's lateral vibration is as follows: in For the extracted string segments; ； Indicates the linear density of the track; In step 4, to further establish the vertical vibration coupling model of the track and the road wheel, the discretized mass model is checked and corrected using the continuum model to verify the model accuracy; if the model accuracy does not meet the requirements, steps 2 to 4 are repeated.

4. The method for determining the pretension force of a high-speed tracked vehicle as described in claim 3, characterized in that, In step 5, without considering the effect of damping, according to Newton's second law of motion, the vibration differential equations in the vertical direction of each load-bearing wheel on both sides of the vehicle body are obtained as follows: Where m is the mass of the load-bearing wheel, and i = 1~6. The constraint force acting on the left and right road wheels; This represents the vertical displacement of the left and right road wheels; The vehicle body vibrates under the action of dynamic excitation and road surface excitation. Neglecting the effect of damping, and considering the degrees of freedom of the vehicle body in the vertical, pitch, and roll directions, the vibration differential equation is: Where M is the vehicle mass; Z represents the vertical displacement of the vehicle body; Let X be the moment of inertia of the vehicle body about the X and Y axes. The rotation angles of the vehicle body around the X and Y axes; The constraint force acting on the road wheel; The constraint force exerted by the power suspension on the vehicle body; These are the geometric parameters in the left and right width directions of the vehicle body; The geometric dimensions of the left and right suspensions of the power unit subsystem; These are the geometric dimensions of the front and rear suspensions of the power unit subsystem; The height at which the power unit subsystem is suspended.

5. The method for determining the pretension force of a high-speed tracked vehicle as described in claim 4, characterized in that, In step 7, the road surface roughness excitation model is used to simulate the excitation of road impact loads on the vehicle during driving; different vehicle speed excitations are used to simulate the different time delay periods of load application caused by changes in driving speed, resulting in different vibration responses of the whole vehicle.

6. The method for determining the pretension force of a high-speed tracked vehicle as described in claim 5, characterized in that, In step 8, the passability of the high-speed tracked vehicle specifically refers to the vehicle's ability to cross trenches, vertical slopes, and side slopes; the stability of the task load is to ensure the realization of the specified task actions, specifically the vibration characteristics of the task load system.

7. The method for determining the pretension force of a high-speed tracked vehicle as described in claim 6, characterized in that, In step 9, the natural frequencies of tracks, road wheels and vehicle bodies made of different materials are adjusted by adjusting the pretension force to avoid resonance with the task load system.

8. The method for determining the pretension force of a high-speed tracked vehicle as described in claim 7, characterized in that, In step 10, for the optimization problem that simultaneously considers passability and task load stability, the NSGA-II is used to optimize the track pretension. The different materials specifically refer to steel vehicle bodies and track systems, and titanium alloy vehicle bodies and track systems; In step 11, the optimal solution of pretension force obtained in step 10 is substituted into the multi-level coupled vibration model for solution, thereby proving the correctness of the proposed pretension force optimization design method.

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