Commercial vehicle smoothness performance improving method and system giving consideration to vehicle frame light weight

Abstract

The invention relates to a method and a system for improving the smoothness performance of a commercial vehicle considering the lightweight of a vehicle frame, and the method comprises the following steps: S1, determining three optimization elements: an optimization target, a constraint condition and an optimization variable according to the characteristics of the commercial vehicle; s2, constructing a commercial vehicle rigid body dynamic model, and constructing a cab finite element model and a frame finite element model; based on the three models, constructing a whole vehicle rigid-flexible coupling dynamic model; s3, establishing a vehicle smoothness performance multi-objective optimization process, setting optimization iteration times, and applying a multi-objective optimization algorithm to carry out commercial vehicle multi-disciplinary performance optimization design; s4, judging whether the output result meets the optimization target and the constraint condition at the same time or not, and if yes, outputting an optimization scheme; if not, the optimization variable continues to be calculated until all optimization iterations are completed; while the smoothness performance of the vehicle is improved, the light weight of the vehicle frame is taken into account.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and in particular to a method and system for improving the smoothness of commercial vehicles while taking into account the lightweight chassis. Background Technology

[0002] The ride smoothness of commercial vehicles directly impacts passenger comfort. Excessive vibration and impact during driving can cause discomfort and even harm to the health of passengers, a feeling that is more pronounced during long-distance driving. Therefore, researching overall vehicle ride smoothness is crucial for improving passenger comfort.

[0003] Currently, the smoothness tuning of commercial vehicles requires meticulous adjustments and optimizations to components such as the chassis, suspension system, and tires to achieve better shock absorption and handling stability. It also necessitates testing and evaluation on specialized testing grounds or actual roads to ensure the vehicle's smoothness performance meets requirements. This work relies heavily on the extensive experience of driving test drivers and technicians, and requires the direct translation of subjective impressions into design parameters, often necessitating lengthy testing periods and significant investment of human and material resources. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a method and system for improving the ride comfort of commercial vehicles while simultaneously achieving lightweight chassis. By optimizing the layout of the cab suspension and chassis structure, it is possible to improve vehicle ride comfort while maintaining a lightweight chassis. This method not only saves chassis materials but also effectively reduces problems such as long work cycles, high debugging costs, and unpredictable results in subsequent ride comfort improvements for commercial vehicles.

[0005] This invention is achieved using the following technical solution:

[0006] A method for improving the ride smoothness of commercial vehicles while also considering lightweight chassis includes the following steps:

[0007] S1, based on the characteristics of commercial vehicles, establishes three key elements for optimization: optimization objectives, constraints, and optimization variables;

[0008] S2, construct a rigid body dynamics model of the commercial vehicle, and construct a finite element model of the cab and a finite element model of the frame; based on the three models, construct a rigid-flexible coupled dynamics model of the whole vehicle;

[0009] S3: Establish a multi-objective optimization process for the smoothness performance of the whole vehicle, set the number of optimization iterations, and apply multi-objective optimization algorithms to carry out multi-disciplinary performance optimization design for commercial vehicles;

[0010] S4. Determine whether the output result satisfies both the optimization objective and the constraints. If both are satisfied, output the optimization solution. If not, continue to calculate the optimization variables until all optimization iterations are completed.

[0011] As a further explanation of the invention, step S1 includes:

[0012] The optimization targets are the overall vehicle smoothness performance and the overall frame quality.

[0013] The constraints are frame torsional stiffness, frame bending stiffness, frame free mode, and vehicle handling stability performance indicators.

[0014] The vehicle frame shape and dimensions, the thickness and material of the transverse and longitudinal beams, the suspension stiffness and damping, and the cab suspension stiffness were used as optimization variables.

[0015] As a further explanation of the invention, step S2 is as follows:

[0016] Within the ADAMS software, construct a rigid body dynamics model for a commercial vehicle;

[0017] Within the HyperMesh software, construct the finite element model of the cab and the finite element model of the chassis;

[0018] In ADAMS software, the modal neutral files of the cab finite element model and the frame finite element model are imported and replaced with the corresponding rigid body components in the rigid body dynamics model of the commercial vehicle. The damping ratio of each mode shape and the modal cutoff order of the flexible body are set to complete the establishment of the rigid-flexible coupling dynamics model of the whole vehicle.

[0019] As a further explanation of the invention, step S3 includes:

[0020] Set the optimization range of variables according to the optimization objective and constraints; the number of optimization iterations should be no less than 1 / 3 of the total sum of all factors of the design variables, and at the same time, it should be ensured that the feasible result is no less than 1 / 4 of the total number of iterations;

[0021] The multi-objective optimization algorithm employs optimization algorithms including, but not limited to, NSGA-II.

[0022] As a further explanation of the invention, step S3 also includes:

[0023] Within the ADAMS software, the vehicle dynamics parameters of the rigid-flexible coupling dynamics model are automatically modified;

[0024] Within the HyperMesh software, the structural parameters of the chassis in the finite element model are automatically modified.

[0025] As a further explanation of the invention, obtaining the vehicle smoothness performance index by performing step S3 includes the following steps:

[0026] Based on the rigid-flexible coupling dynamic model of the whole vehicle, different road surface levels and different speed conditions were set, and dynamic simulation was carried out in ADAMS software to obtain the weighted acceleration of vibration at the foot plate, seat cushion and backrest of the cab.

[0027] As a further explanation of the invention, obtaining the vehicle handling stability performance index by performing step S3 includes the following steps:

[0028] Based on the rigid-flexible coupling dynamic model of the whole vehicle, steady-state turning, steering return and serpentine tests were carried out in ADAMS software to obtain understeer, car body tilt, residual yaw rate, total variance of yaw rate, peak average yaw rate, peak average steering wheel angle, peak average lateral acceleration and peak average roll angle.

[0029] As a further explanation of the invention, obtaining the frame torsional stiffness, frame bending stiffness, and frame free modes during step S3 includes the following steps:

[0030] Based on the finite element model of the chassis, the torsional stiffness, bending stiffness, and free modes of the chassis were obtained in HyperMesh software.

[0031] As a further explanation of the invention, step S4 includes:

[0032] If the output result satisfies both the optimization objective and the constraint requirements, it is output as a feasible solution to the optimization solution library; if one or more indicators of the output result exceed the corresponding constraint conditions, it is considered an infeasible solution and discarded, and the operation is repeated to optimize the calculation parameters until all optimization iterations are completed.

[0033] A system for improving the ride comfort of a commercial vehicle, comprising any one of the methods for improving the ride comfort of a commercial vehicle described above; the system includes:

[0034] The module for establishing rigid body dynamics models of commercial vehicles is used to establish rigid body dynamics models of commercial vehicles.

[0035] Driver's cab finite element model creation module; used to create a driver's cab finite element model.

[0036] The chassis finite element model creation module is used to create a chassis finite element model;

[0037] The whole vehicle rigid-flexible coupling dynamics model establishment module is used to establish the whole vehicle rigid-flexible coupling dynamics model;

[0038] The cab and frame modal solution module is used to solve the modal neutral file of the cab and frame.

[0039] The vehicle ride comfort performance analysis module is used to obtain vehicle ride comfort performance indicators;

[0040] The vehicle handling stability performance analysis module is used to obtain vehicle handling stability performance indicators.

[0041] The frame structure analysis module is used to obtain the frame torsional stiffness, frame bending stiffness, and frame free modes.

[0042] Compared with the prior art, the present invention has the following beneficial technical effects:

[0043] (1) The vibration coupling effect of the cab flexibility and frame flexibility of commercial vehicles on the other systems is comprehensively considered, which greatly improves the calculation accuracy of the overall vehicle smoothness and handling stability performance, and is closer to the motion state of the real vehicle, while taking into account both simulation accuracy and calculation efficiency.

[0044] (2) The established multidisciplinary optimization system for commercial vehicles takes into account the coupled influence of frame structure performance and overall vehicle ride comfort performance. The optimization results can simultaneously meet the requirements of both performance indicators, thus improving the reliability of the optimization scheme.

[0045] (3) By writing command scripts for HyperMesh and other related software, the software code is solved in the background using the bat command. The optimization process built on this basis can realize the automated operation from parameter modification to result output, realize rapid optimization iteration, and improve computational efficiency.

[0046] (4) This invention is applicable to the design of smoothness performance improvement for commercial vehicles with various layout configurations. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the method for improving the smoothness performance of commercial vehicles while taking into account the lightweight chassis provided by the present invention.

[0048] Figure 2 This is a schematic diagram of the principle of the commercial vehicle smoothness performance improvement system that takes into account the lightweight chassis provided by the present invention;

[0049] Figure 3 This is a comparison of the optimization objectives of the original and optimized solutions provided by this invention. Figure 1 ;

[0050] Figure 4 This is a comparison of the optimization objectives of the original and optimized solutions provided by this invention. Figure 2 . Detailed Implementation

[0051] Prerequisites:

[0052] ADAMS software refers to automatic analysis software for mechanical system dynamics. The ADAMS / Car module is a functional module of ADAMS software, used for modeling, simulation, and optimization analysis of the whole vehicle.

[0053] HyperWorks software is a finite element simulation software, consisting of the pre-processing module HyperMesh and the post-processing module HyperView. Morphing is the rapid deformation module in HyperMesh software, which contains MorphingVolumes blocks and Handles point sets, and can quickly deform the mesh to adjust the size parameters of the model.

[0054] The optimization algorithm of NSGA-II refers to a dominance-based multi-objective optimization algorithm.

[0055] like Figure 1-4 As shown, the present invention provides a method for improving the smoothness performance of commercial vehicles while taking into account the lightweight chassis, comprising the following steps:

[0056] S1, based on the characteristics of commercial vehicles, establishes three key elements for optimization: optimization objectives, constraints, and optimization variables;

[0057] S2, construct a rigid body dynamics model of the commercial vehicle, and construct a finite element model of the cab and a finite element model of the frame; based on the three models, construct a rigid-flexible coupled dynamics model of the whole vehicle;

[0058] S3: Establish a multi-objective optimization process for the smoothness performance of the whole vehicle, set the number of optimization iterations, and apply multi-objective optimization algorithms to carry out multi-disciplinary performance optimization design for commercial vehicles;

[0059] S4. Determine whether the output result satisfies both the optimization objective and the constraints. If both are satisfied, output the optimization solution. If not, continue to calculate the optimization variables until all optimization iterations are completed.

[0060] Furthermore, step S1 includes:

[0061] Based on the characteristics of existing commercial vehicles and comprehensively considering various influencing indicators of overall vehicle performance optimization, three key elements for optimization design are established:

[0062] The optimization targets are the overall vehicle smoothness performance and the overall frame quality.

[0063] The constraints are frame torsional stiffness, frame bending stiffness, frame free mode, and vehicle handling stability performance indicators; the range should meet or exceed the standard values ​​of relevant performance for commercial vehicles.

[0064] The vehicle frame shape and dimensions, the thickness and material of the transverse and longitudinal beams, the suspension stiffness and damping, and the cab suspension stiffness are used as optimization variables; one or more of these variables can be selected for optimization design.

[0065] Furthermore, step S2 is as follows:

[0066] Within the ADAMS / Car module of the ADAMS software, a rigid body dynamics model of a commercial vehicle is constructed; the model may include the cab, front and rear suspensions, steering system, frame, tires, and cargo box.

[0067] Within the HyperMesh software, construct the finite element model of the cab and the finite element model of the chassis; obtain the modal neutral files (*.mnf) of the cab and the chassis;

[0068] In ADAMS software, import the modal neutral files (*.mnf) of the cab finite element model and the frame finite element model and replace the corresponding rigid body components in the rigid body dynamics model of the commercial vehicle. Connect the corresponding boundary points, set the damping ratio of each mode of the flexible body and the modal cutoff order, and complete the establishment of the rigid-flexible coupling dynamics model of the whole vehicle.

[0069] Furthermore, step S3 includes:

[0070] The optimization range of variables is set according to the optimization objectives and constraints; the process may include establishing an optimization model and solving for vehicle dynamics and chassis structure indices.

[0071] The number of optimization iterations should be no less than 1 / 3 of the total sum of all factors of the design variables, and at the same time, the number of feasible results should be no less than 1 / 4 of the total number of iterations. If a large number of infeasible solutions appear, the constraints should be reset.

[0072] The multi-objective optimization algorithm employs optimization algorithms including, but not limited to, NSGA-II.

[0073] Furthermore, step S3 also includes:

[0074] Within the ADAMS software, the vehicle dynamics parameters of the rigid-flexible coupled dynamics model can be automatically modified. Specifically, a batch file is written to call the ADAMS / cmd command script, which automatically imports the modal neutral file and replaces the original rigid body model, creates dynamic conditions, and realizes the modification of the vehicle dynamics parameters.

[0075] Within HyperMesh software, the structural parameters of the chassis finite element model can be automatically modified. Specifically, a batch file is written to call the TCL command code included in HyperMesh software to automatically model the chassis and set and modify parameters such as thickness and material. Correspondingly, the Morphing automatic parametric technology in HyperMesh software is applied to create appropriate Morphing Volumes blocks and Handles point sets on the longitudinal beams, some crossbeams, and stiffening plates of the chassis. By moving some Handles points, the chassis model is locally deformed according to the set rules, thereby adjusting the chassis shape, cross-sectional dimensions, and related crossbeam position parameters.

[0076] Furthermore, the vehicle smoothness performance index is obtained by performing step S3, including the following steps:

[0077] Based on the rigid-flexible coupling dynamic model of the whole vehicle, different road surface grades (such as B grade, C grade, D grade, E grade, corrugated road, etc.) and different speed conditions (such as vehicle speed 30km / h, 60km / h, 90km / h, etc.) are set, and dynamic simulation is carried out in the ADAMS / Car module of the ADAMS software to obtain the weighted acceleration of vibration at the footwell, seat cushion and backrest of the cab, thereby obtaining the smoothness performance index of the whole vehicle.

[0078] Furthermore, the vehicle handling stability performance indicators are obtained by performing step S3, including the following steps:

[0079] Based on the rigid-flexible coupling dynamic model of the whole vehicle, steady-state turning, steering return and serpentine tests are carried out in ADAMS software to obtain understeer, car body tilt, residual yaw rate, total variance of yaw rate, peak average yaw rate, peak average steering wheel angle, peak average lateral acceleration and peak average roll angle, thereby obtaining the vehicle handling stability performance index.

[0080] Furthermore, by executing step S3, the frame torsional stiffness, frame bending stiffness, and frame free modes are obtained respectively, including the following steps:

[0081] Based on the finite element model of the chassis, the torsional stiffness, bending stiffness, and free modes of the chassis were obtained in HyperMesh software.

[0082] Specifically, the calculation conditions for the frame torsional stiffness are as follows: constrain the X, Y, and Z degrees of freedom of the center positions of the left and right front supports of the rear leaf spring, and apply opposite Z-direction loads of F = 10000N to the center positions of the left and right front supports of the front leaf spring. The calculation formula is:

[0083]

[0084] In the formula, It is the torsional modulus, G is the shear modulus, L is the force application distance, Phi is the torsional angle, and Mt is the torque load;

[0085] The calculation of the frame bending stiffness simplifies the frame as a simply supported beam, constraining the Z-direction freedom at the center position of the left support of the front leaf spring and the Y and Z-direction freedom at the center position of the right support, and constraining the X and Z-direction freedom at the center position of the left support of the rear leaf spring and the X, Y, and Z-direction freedom at the center position of the right support. A downward Z-direction load of F = 10000 N is applied to the upper flange surface of the frame at the center positions of the front and rear constraints. The calculation formula is as follows:

[0086]

[0087] In the formula, EI is the bending stiffness, L is the center distance between the front and rear leaf springs, F is the applied force, and d zmax The deformation in the Z direction at the loading point;

[0088] Free modal analysis was performed on the finite element model of the chassis, with modal constraints set in the range of 0–100 Hz, and the modal frequencies and mode shapes of the chassis were calculated.

[0089] Furthermore, step S4 includes:

[0090] By adding judgment conditions in step S3, it is determined whether the output results meet the optimization objectives and constraints. If all output results meet the requirements, they are output as feasible solutions to the optimization solution library. If one or more indicators of the output results exceed the corresponding constraints, they are treated as infeasible solutions and discarded. At the same time, the optimization calculation parameters are optimized and the operation is repeated until all optimization iterations are completed.

[0091] This invention also provides a commercial vehicle smoothness performance improvement system, including any of the above-mentioned commercial vehicle smoothness performance improvement methods; the system includes:

[0092] The module for establishing rigid body dynamics models of commercial vehicles is used to establish rigid body dynamics models of commercial vehicles.

[0093] Driver's cab finite element model creation module; used to create a driver's cab finite element model.

[0094] The chassis finite element model creation module is used to create a chassis finite element model;

[0095] The whole vehicle rigid-flexible coupling dynamics model establishment module is used to establish the whole vehicle rigid-flexible coupling dynamics model;

[0096] The cab and frame modal solution module is used to solve the modal neutral file of the cab and frame.

[0097] The vehicle ride comfort performance analysis module is used to obtain vehicle ride comfort performance indicators;

[0098] The vehicle handling stability performance analysis module is used to obtain vehicle handling stability performance indicators.

[0099] The frame structure analysis module is used to obtain the frame torsional stiffness, frame bending stiffness, and frame free modes.

[0100] The following specific example illustrates the application of the method and system for improving the smoothness of commercial vehicles while taking into account the lightweight chassis involved in the above embodiments.

[0101] Taking a certain light truck model as an example, the three key elements for optimization are established:

[0102] The optimization objectives are to minimize the total weighted acceleration at the foot of the cab and the frame mass at a speed of 60 km / h on a Class B road surface.

[0103] The optimization variables are the position of the third crossbeam of the frame (frame shape and dimensions), the thickness of the frame beam, the stiffness of the front and rear axle leaf springs, the damping of the front and rear suspension shock absorbers, and the X, Y, and Z three-dimensional stiffness of the front and rear suspensions of the cab; the parameters are continuously adjusted to seek optimization.

[0104] The constraints are: understeer, car body roll, residual yaw rate, total variance of yaw rate, peak mean yaw rate (vehicle handling stability performance index), frame torsional modulus, frame bending stiffness, and frame free modes (first 3 free modes).

[0105] Based on the above parameters, establish the corresponding commercial vehicle dynamics model, cab finite element model and frame finite element model; thereby constructing the rigid-flexible coupling dynamics model of the whole vehicle.

[0106] The comparison of the total weighted acceleration at the foot of the driver's cab at a speed of 60km / h on Class B road surface before and after optimization is as follows: Figure 3 As shown, the total weighted acceleration at the footwell of the optimized cab is significantly lower, resulting in a marked improvement in ride comfort. Based on this, the comparison of the frame mass before and after optimization is as follows: Figure 4 As shown, the frame mass has also been reduced. It is evident that the optimization scheme improves the vibration isolation rate of the suspension system while taking into account the frame mass. At the same time, all other constraints are met, thus enhancing the reliability of the optimization scheme.

Claims

1. A method for improving the smoothness performance of commercial vehicles while also considering lightweight chassis, characterized in that, Includes the following steps: S1, based on the characteristics of commercial vehicles, establishes three key elements for optimization: optimization objectives, constraints, and optimization variables; S2, construct a rigid body dynamics model of the commercial vehicle, and construct a finite element model of the cab and a finite element model of the frame; based on the three models, construct a rigid-flexible coupled dynamics model of the whole vehicle; S3: Establish a multi-objective optimization process for the smoothness performance of the whole vehicle, set the number of optimization iterations, and apply multi-objective optimization algorithms to carry out multi-disciplinary performance optimization design for commercial vehicles; S4, determine whether the output result satisfies both the optimization objective and the constraints. If both are satisfied, output the optimization solution. If the conditions are not met, the optimization variables continue to be calculated until all optimization iterations are completed.

2. The method for improving the smoothness of commercial vehicles while taking into account the lightweight chassis, as described in claim 1, is characterized in that... Step S1 includes: The optimization targets are the overall vehicle smoothness performance and the overall frame quality. The constraints are frame torsional stiffness, frame bending stiffness, frame free mode, and vehicle handling stability performance indicators. The vehicle frame shape and dimensions, the thickness and material of the transverse and longitudinal beams, the suspension stiffness and damping, and the cab suspension stiffness were used as optimization variables.

3. The method for improving the smoothness of commercial vehicles while taking into account the lightweight chassis, as described in claim 2, is characterized in that... Step S2 is as follows: Within the ADAMS software, construct a rigid body dynamics model for a commercial vehicle; Within the HyperMesh software, construct the finite element model of the cab and the finite element model of the chassis; In ADAMS software, the modal neutral files of the cab finite element model and the frame finite element model are imported and replaced with the corresponding rigid body components in the rigid body dynamics model of the commercial vehicle. The damping ratio of each mode shape and the modal cutoff order of the flexible body are set to complete the establishment of the rigid-flexible coupling dynamics model of the whole vehicle.

4. The method for improving the smoothness of commercial vehicles while taking into account the lightweight chassis, as described in claim 3, is characterized in that... Step S3 includes: Set the optimization range of variables according to the optimization objective and constraints; the number of optimization iterations should be no less than 1 / 3 of the total sum of all factors of the design variables, and at the same time, it should be ensured that the feasible result is no less than 1 / 4 of the total number of iterations; The multi-objective optimization algorithm employs optimization algorithms including, but not limited to, NSGA-II.

5. The method for improving the smoothness of commercial vehicles while taking into account the lightweight chassis, as described in claim 4, is characterized in that... Step S3 also includes: Within the ADAMS software, the vehicle dynamics parameters of the rigid-flexible coupling dynamics model are automatically modified; Within the HyperMesh software, the structural parameters of the chassis in the finite element model are automatically modified.

6. The method for improving the smoothness of commercial vehicles while taking into account the lightweight chassis, as described in claim 5, is characterized in that... Obtaining the overall vehicle smoothness performance index by executing step S3 includes the following steps: Based on the rigid-flexible coupling dynamic model of the whole vehicle, different road surface levels and different speed conditions were set, and dynamic simulation was carried out in ADAMS software to obtain the weighted acceleration of vibration at the foot plate, seat cushion and backrest of the cab.

7. The method for improving the smoothness of commercial vehicles while taking into account the lightweight chassis, as described in claim 6, is characterized in that... Obtaining vehicle handling stability performance indicators by performing step S3 includes the following steps: Based on the rigid-flexible coupling dynamic model of the whole vehicle, steady-state turning, steering return and serpentine tests were carried out in ADAMS software to obtain understeer, car body tilt, residual yaw rate, total variance of yaw rate, peak average yaw rate, peak average steering wheel angle, peak average lateral acceleration and peak average roll angle.

8. The method for improving the smoothness of commercial vehicles while taking into account the lightweight chassis, as described in claim 7, is characterized in that... By executing step S3, the frame torsional stiffness, frame bending stiffness, and frame free modes are obtained respectively, including the following steps: Based on the finite element model of the chassis, the torsional stiffness, bending stiffness, and free modes of the chassis were obtained in HyperMesh software.

9. The method for improving the smoothness of commercial vehicles while taking into account the lightweight chassis, as described in claim 8, is characterized in that... Step S4 includes: If the output result satisfies both the optimization objective and the constraint requirements, it is output as a feasible solution to the optimization solution library; if one or more indicators of the output result exceed the corresponding constraint conditions, it is considered an infeasible solution and discarded, and the operation is repeated to optimize the calculation parameters until all optimization iterations are completed.

10. A smoothness performance enhancement system for commercial vehicles, characterized in that, The system includes the method for improving the smoothness of commercial vehicles as described in any one of claims 1-9; the system includes: The module for establishing rigid body dynamics models of commercial vehicles is used to establish rigid body dynamics models of commercial vehicles. Driver's cab finite element model creation module; used to create a driver's cab finite element model. The chassis finite element model creation module is used to create a chassis finite element model; The whole vehicle rigid-flexible coupling dynamics model establishment module is used to establish the whole vehicle rigid-flexible coupling dynamics model; The cab and frame modal solution module is used to solve the modal neutral file of the cab and frame. The vehicle ride comfort performance analysis module is used to obtain vehicle ride comfort performance indicators; The vehicle handling stability performance analysis module is used to obtain vehicle handling stability performance indicators. The frame structure analysis module is used to obtain the frame torsional stiffness, frame bending stiffness, and frame free modes.

Images