Optimization design method of curved surface type grouser structure

Abstract

An optimal design method of a curved surface type grouser structure belongs to the field of optimal design methods of grouser structures, and comprises the following steps: firstly, establishing a single crawler model with curved surface type grouser, then obtaining a crawler model through a single array, creating a driving wheel, thrust wheel and guide wheel model, and assembling a vehicle body model to obtain a whole vehicle model; and then, establishing a crawler-soil coupling simulation model in simulation software, and carrying out coupling simulation through a step-by-step iteration method. The radius of the bulldozing arc surface of the curved surface type grouser is changed, multiple times of simulation are carried out through the whole vehicle model with different radiuses, simulation results of multiple grouser structures with different curved surface radiuses are obtained, and then the adhesive force of the crawler belt under different curved surface radiuses is calculated. And finally, the structural parameters of the curved surface type grouser are optimized according to the comparison result of the adhesive force, namely, the curved surface radius enabling the adhesive force of the crawler belt to be the maximum is selected as the optimal structural parameters of the curved surface type grouser, and great convenience and powerful support are provided for optimization design of the curved surface type grouser structure.

Description

Technical Field

[0001] The invention relates to the field of optimization design methods for grouser structures, and in particular to an optimization design method for curved grouser structures. Background Art

[0002] As the carrier of agricultural equipment under complex terrain conditions, all-terrain engineering vehicles are usually divided into: wheeled, foot-type, crawler-type, etc. Compared with the other two types, tracked all-terrain vehicles have the advantages of small ground contact pressure, strong climbing ability, small turning radius, and strong obstacle crossing ability. They have gradually become the preferred carrier of agricultural intelligent equipment in mountainous and hilly areas. Tracked vehicles are widely used in forestry, agriculture, mining and other fields due to their large contact area with the soil, good passability and good soil adhesion. However, tracked vehicles are prone to slipping due to insufficient adhesion when driving on soft hilly soil, resulting in complex changes in driving performance, which seriously affects their passability. As an important component to enhance the adhesion and friction between the track and the ground, the structure of the spur structure has an extremely important influence on the adhesion performance of the tracked vehicle.

[0003] The existing spur structures are all linear spurs, that is, long rectangular spur structures. Although a variety of design methods have been used to improve adhesion, the limitations of the linear spur structure itself still restrict the adhesion of the track. Therefore, the spur structure needs to be improved and optimized. Summary of the invention

[0004] The purpose of the present invention is to provide an optimization design method for a curved grouser structure, which can calculate the track adhesion according to simulation results and optimize the structural parameters of the curved grouser according to the comparison results of the adhesion.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: an optimization design method for a curved grouser structure, comprising the following steps: Step 1, using 3D software to establish a crawler monomer model with curved spurs, including a crawler section and a spur of a long strip structure, the length direction of the spur is parallel to the width direction of the crawler, the two sides of the spur along the thickness direction are a base surface and a bottom surface parallel to each other, the base surface is connected to the surface of the crawler, one side of the spur along the width direction is a back-soil plane away from the movement direction of the spur, the other side of the spur along the width direction is a bulldozer arc surface facing the movement direction of the spur, the back-soil plane and the bottom surface are perpendicular to each other, the axis of the bulldozer arc surface and the bottom surface are located in the same reference plane, and the axis of the bulldozer arc surface is located on the side of the bottom surface away from the back-soil plane along the movement direction of the spur, the axis of the bulldozer arc surface is parallel to the length direction of the spur, and the radius of the bulldozer arc surface is not less than the thickness of the spur; Then, the crawler model is arrayed to obtain a crawler model, and the crawler model is assembled with a driving wheel model, a supporting wheel model and a guide wheel model to obtain a complete vehicle model; Step 2: Establish a ground system in the simulation software, load the whole vehicle model on the ground system, and establish a soil bed model on the ground system, so that the soil bed model is located in front of the whole vehicle model along the X-axis direction, thereby establishing a track-soil coupling simulation model in the simulation software; Step 3: Set the simulation time and time step in the simulation software, then make the vehicle model move along the X-axis direction, perform coupled simulation of the interaction between the track and the soil through a step-by-step iterative method, and output the simulation results after the simulation time is reached; Step 4: Change the radius of the bulldozer arc surface of the curved spur, perform multiple simulations on vehicle models with different radii, calculate the track adhesion according to the multiple simulation results, compare the track adhesion under different radii, and select the radius with the largest adhesion as the radius of the bulldozer arc surface, thus completing the structural optimization of the curved spur; The calculation formula for track adhesion is: ; In the above formula, b is the length of the spurs, l is the length of the track shoe in the single-body track model, d is the width of the bottom surface of the spur, R is the radius of the bulldozer arc surface, h is the thickness of the shoe spur, M i is the number of all spurs in the vehicle model; z is the soil subsidence, n is the soil deformation index, c is the soil specific gravity, c is the soil cohesive strength, k c is the soil cohesive deformation modulus, k φ is the soil friction deformation modulus, W Additional load in vertical direction; d is the friction angle between soil and spurs, f is the internal friction angle; When calculating adhesion, z The value is z = h , d The value is d =arcsin( z / R ); fThe method for obtaining the value of is to first replace the curved spurs in the track monomer model with the straight spurs of the rectangular structure, the length of the straight spurs is equal to the length of the curved spurs, the thickness of the straight spurs is equal to the thickness of the curved spurs, and the width of the straight spurs is equal to the bottom width of the curved spurs; then, according to the sliding soil body formed by the straight spurs when pushing the soil, the angle between the soil sliding surface and the horizontal plane is obtained. i , and then according to Get the internal friction angle f The value of .

[0006] Preferably, in step 4, when the radius of the bulldozer arc surface is changed and multiple simulations are performed, the radius value of one of the simulations is set as the thickness of the spur.

[0007] According to the above technical solution, the beneficial effects of the present invention are: The present invention improves the structure of the spur. Compared with the existing straight spur, the designed curved spur changes the surface of the side where the spur pushes the soil into an arc surface, which significantly improves the track adhesion, making the track suitable for different road conditions. When facing complex and harsh road conditions, it can reduce the energy consumption of the spur entering and exiting the soil, improve the adhesion of the soil to the track, and help the track vehicle escape from danger when sinking or slipping, ensuring the normal driving of the vehicle. In order to confirm the structural parameters of the newly designed curved spur, the simulation results of the spur structures with multiple different curved surface radii are obtained by modeling and simulation, and then the adhesion of the track under different curved surface radii is calculated respectively. Finally, the structural parameters of the curved spur are optimized according to the comparison results of the adhesion, and the curved surface radius that maximizes the track adhesion is selected as the optimal structural parameter of the curved spur, which provides great convenience and strong support for the optimization design of the curved spur structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of a curved spur; Figure 2 It is a partial schematic diagram of a crawler with curved grouser installed; Figure 3 It is a side view of the curved spur; Figure 4 This is the side view of the spur when the minimum radius is used; Figure 5 This is the force analysis diagram of the sliding soil when the spur pushes the soil; Figure 6 Schematic diagram of differentiating sliding soil.

[0009] Markings in the figure: 1. Spurs, 2. Tracks, 3. Base surface, 4. Bottom surface, 5. Soil-carrying plane, 6. Bulldozer arc surface, 7. Soil, 8. Sliding soil. DETAILED DESCRIPTION

[0010] With reference to the accompanying drawings, the specific implementation is as follows: An optimization design method for a curved grouser structure comprises the following steps: Step 1: Use 3D software to build a single-body model of a crawler with curved spurs, including a crawler section 2 and a spur 1 with a long strip structure.

[0011] The structure of the curved spur is as follows: Figure 1-3 As shown, the length direction of the spur 1 is parallel to the width direction of the track 2, the two sides of the spur 1 along the thickness direction are a base surface 3 and a bottom surface 4 which are parallel to each other, the base surface 3 is connected to the surface of the track 2, one side of the spur 1 along the width direction is a soil-carrying plane 5 which is away from the movement direction of the spur 1, and the other side of the spur 1 along the width direction is a bulldozer arc surface 6 which is toward the movement direction of the spur 1, the soil-carrying plane 5 and the bottom surface 4 are perpendicular to each other, and the soil-carrying plane 5 extends along the length direction of the spur.

[0012] like Figure 1 , 3 As shown, the axis of the bulldozer arc surface 6 and the bottom surface 4 are located in the same reference plane, and the axis of the bulldozer arc surface 6 is located on the side of the bottom surface 4 away from the back-soil plane 5 along the movement direction of the grouser 1, the axis of the bulldozer arc surface 6 is parallel to the length direction of the grouser 1, and the radius of the bulldozer arc surface 6 is not less than the thickness of the grouser 1. Figure 3 From the side view, the tangent of the bulldozer arc surface 6 at the connection position with the bottom surface 4 is perpendicular to the bottom surface 4 and parallel to the back-soil plane 5, and the position where the other side of the bulldozer arc surface 6 extends to the crawler 2 will change according to the radius of the bulldozer arc surface 6. When the radius of the bulldozer arc surface 6 is the smallest, it is Figure 4 The radius of the bulldozer arc surface 6 shown is equal to the thickness of the spur 1. At this time, the tangent of the bulldozer arc surface 6 at the connection position with the base surface 3 is located on the base surface 3, and the arc angle of the bulldozer arc surface 6 is 90°.

[0013] Then the track monomer model is arrayed to obtain the track model. Figure 2 That is, it is a partial section of the track model that contains two curved spurs. The track model is assembled with the driving wheel model, the supporting wheel model and the guide wheel model to obtain the whole vehicle model.

[0014] Step 2: Establish a ground system in the simulation software, load the whole vehicle model on the ground system, and establish a soil bed model on the ground system so that the soil bed model is located in front of the whole vehicle model along the X-axis direction, thereby establishing a track-soil coupling simulation model in the simulation software.

[0015] Specifically, the simulation environment is constructed by using Recurdyn software and EDEM software together, a ground system is established in Recurdyn software, and the vehicle model is loaded on the ground system and the structural parameters are set. Soil particle models of different geometric shapes and sizes are randomly generated in EDEM software, and then the soil particle models are stacked and bonded using the gravity deposition method according to the Hertz-Mindlin with Bonding contact model, forming bonding bonds between the soil particle models that bear normal and tangential forces within a predetermined range, and finally a soil bed model is established on the ground system, and the soil bed model is located in front of the vehicle model along the X-axis direction, so that the same track-soil coupling simulation model is established in Recurdyn software and EDEM software.

[0016] Step 3: Set the simulation time and time step in the simulation software, then make the whole vehicle model move along the X-axis direction, perform the coupling simulation of the interaction between the track 2 and the soil 7 through a step-by-step iteration method, and output the simulation results after the simulation time is reached.

[0017] Specifically, the track-soil coupling simulation model is simulated and coupled simultaneously in the Recurdyn software and the EDEM software by a step-by-step iteration method. First, the simulation duration is set in the Recurdyn software and the EDEM software, and the time step in the RecurDyn software is set to an integer multiple of the time step in the EDEM software. Then, the whole vehicle model is driven along the X-axis direction, and the coupling simulation of the interaction between the track 2 and the soil 7 is performed through the movement of the whole vehicle model on the soil bed model.

[0018] The Recurdyn software is used to calculate the motion force characteristics of track 2, and the EDEM software is used to calculate the mechanical and motion characteristics of soil bed particles. Recurdyn software and EDEM software exchange data with each other for two-way coupling calculation. After the simulation time is reached, the simulation results are output, and the coupling simulation of the curved spur structure is completed.

[0019] Step 4: Change the radius of the bulldozer arc surface 6 of the curved spur, perform multiple simulations on vehicle models with different radii, calculate the track adhesion based on the simulation results, compare the track adhesion at different radii, and select the radius with the largest adhesion as the radius of the bulldozer arc surface 6, thus completing the structural optimization of the curved spur.

[0020] The force analysis of the curved spur when pushing the soil is as follows: Figure 5As shown, the ABC area is the sliding soil body 8 where the soil 7 is pushed and slides, AB represents the bulldozer arc surface 6, AC represents the base surface 3 of the spur 1 and the surface of the soil 7, and BC is the soil sliding surface of the sliding soil body 8. The dFp arrow represents the force of the bulldozer arc surface 6 acting on the sliding soil body 8, and the f arrow represents the friction between the remaining sliding soil body 8 and the remaining soil 7 when sliding occurs.

[0021] The calculation formula for track adhesion is: ; In the above formula, b is the length of the spurs, l is the length of the track shoe in the single-body track model, d is the width of the bottom surface of the spur, R is the radius of the bulldozer arc surface, h is the thickness of the shoe spur, M i is the number of all spurs in the vehicle model.

[0022] z is the soil subsidence, n is the soil deformation index, c is the soil specific gravity, c is the soil cohesive strength, k c is the soil cohesive deformation modulus, k φ is the soil friction deformation modulus, W Add load in vertical direction.

[0023] d is the friction angle between soil and spurs, f is the internal friction angle.

[0024] Among the above parameters, soil cohesion strength c and soil deformation index n Need to be determined based on simulation results, except d , f , c and n All other parameters can be set directly or selected by referring to the simulation results. d and f The angle will change with the settings of other parameters. d The essence of the angle is equivalent to differentiating the sliding soil, such as Figure 6 As shown in the figure, a differential trapezoid is generated in the sliding soil. The two bases of the differential trapezoid are parallel to the soil sliding surface BC. One oblique side of the differential trapezoid is located on the AC surface of the sliding soil, and the other oblique side is located on the AB surface where the sliding soil contacts the bulldozer arc surface 6, and is parallel to the AB arc in the soil settlement amount.z The angle between the tangent line and the vertical direction is the friction angle between the soil and the spur. d .

[0025] It can be seen that as the soil subsidence z The changes of different depth positions d The angle will also change. To simplify the calculation process and ensure the validity of the calculation results, z The value is z = h , d The value is d =arcsin( z / R ).

[0026] f The value of is determined by first replacing the curved spurs in the track monomer model with the straight spurs of the rectangular structure, the length of the straight spurs is equal to the length of the curved spurs, the thickness of the straight spurs is equal to the thickness of the curved spurs, and the width of the straight spurs is equal to the bottom width of the curved spurs.

[0027] The various parameters of the linear grouser when pushing the soil can be obtained through existing design experience and design methods. Therefore, according to the sliding soil body 8 formed when the linear grouser pushes the soil 7, the angle between the soil sliding surface and the horizontal plane is obtained. i , and then according to Get the internal friction angle f The value of .

[0028] This embodiment uses five different spur structures for comparative simulation experiments, among which the four spur structures are curved spurs with a bottom width of 12 mm and a thickness of 12 mm, and the radii are respectively R Ⅰ =12mm, R Ⅱ =15mm, R Ⅲ =18mm and R Ⅳ =24mm, and the other spur structure is a straight spur as a comparative example, the width of the straight spur is 12mm, the thickness is 12mm, and the length is equal to the four curved spurs. After simulation and calculation of adhesion, the results are shown in the following table.

[0029] Table 1 Comparison of average adhesion of tracks with different spur types The actual test results show that under the same working conditions, the adhesion of the curved track is better than that of the straight track, and the improvement ratio of the curved track on adhesion increases with the decrease of the curvature radius of the track. This is because the soil particles have more interaction with the track surface, which can provide a greater reaction force and is beneficial to enhance the adhesion performance between the track and the soil.

[0030] Therefore, according to the experimental results, we can select R =12mm is taken as the optimal structural parameter of the curved spur, and other parameters can also be optimized through comparative experiments, thus providing great convenience and strong support for the optimal design of the curved spur structure.

Claims

1. An optimization design method for a curved grouser structure, characterized in that: The following steps are involved: Step 1: Use 3D software to establish a single-body model of a track with curved spurs, including a track section (2) and a long strip-shaped spur (1), wherein the length direction of the spur (1) is parallel to the width direction of the track (2), and the two sides of the spur (1) along the thickness direction are a base surface (3) and a bottom surface (4) parallel to each other, and the base surface (3) is connected to the surface of the track (2), and one side of the spur (1) along the width direction is a back-soil plane (5) away from the movement direction of the spur (1), and the spur (1) along the width direction is parallel to the width direction of the track (2). The other side of the direction is a bulldozer arc surface (6) facing the movement direction of the spur (1), the back-soil plane (5) and the bottom surface (4) are perpendicular to each other, the axis of the bulldozer arc surface (6) and the bottom surface (4) are located in the same reference plane, and the axis of the bulldozer arc surface (6) is located on the side of the bottom surface (4) away from the back-soil plane (5) along the movement direction of the spur (1), the axis of the bulldozer arc surface (6) is parallel to the length direction of the spur (1), and the radius of the bulldozer arc surface (6) is not less than the thickness of the spur (1); Then, the crawler model is arrayed to obtain a crawler model, and the crawler model is assembled with a driving wheel model, a supporting wheel model and a guide wheel model to obtain a complete vehicle model; Step 2: Establish a ground system in the simulation software, load the whole vehicle model on the ground system, and establish a soil bed model on the ground system, so that the soil bed model is located in front of the whole vehicle model along the X-axis direction, thereby establishing a track-soil coupling simulation model in the simulation software; Step 3: Set the simulation time and time step in the simulation software, then make the whole vehicle model move along the X-axis direction, perform the coupled simulation of the interaction between the track (2) and the soil (7) by a step-by-step iteration method, and output the simulation result after the simulation time is reached; Step 4: changing the radius of the bulldozer arc surface (6) of the curved spur, performing multiple simulations on vehicle models with different radii, calculating track adhesion according to the multiple simulation results, comparing the track adhesion under different radii, and selecting the radius with the largest adhesion as the radius of the bulldozer arc surface (6), thus completing the structural optimization of the curved spur; The calculation formula for track adhesion is: ； In the above formula, b is the length of the spurs, l is the length of the track shoe in the single-body track model, d is the width of the bottom surface of the spur, R is the radius of the bulldozer arc surface, h is the thickness of the shoe spur, M i is the number of all spurs in the vehicle model; z is the soil subsidence, n is the soil deformation index, γ is the soil specific gravity, c is the soil cohesive strength, k c is the soil cohesive deformation modulus, k φ is the soil friction deformation modulus, W Additional load in vertical direction; δ is the friction angle between soil and spurs, φ is the internal friction angle; When calculating adhesion, z The value is z = h , δ The value is δ =arcsin( z / R ); φ The method for obtaining the value of is to first replace the curved spurs in the track monomer model with the straight spurs of the rectangular structure, the length of the straight spurs is equal to the length of the curved spurs, the thickness of the straight spurs is equal to the thickness of the curved spurs, and the width of the straight spurs is equal to the bottom width of the curved spurs; then, according to the sliding soil body (8) formed when the straight spurs push the soil (7), the angle between the soil sliding surface and the horizontal plane is obtained. θ , and then according to Get the internal friction angle φ The value of .

2. The optimization design method of a curved grouser structure according to claim 1, characterized in that: In step 4, when the radius of the bulldozer arc surface (6) is changed and multiple simulations are performed, the radius value of one of the simulations is set as the thickness of the spur (1).

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