A vibration response calculation method based on a whole vehicle simulation model

Abstract

The application discloses a kind of vibration response calculation methods based on whole vehicle simulation model, it is characterized in that, including the following steps: using equal-section beam element to simulate frame, body and chassis suspension structure;Passenger, goods, power assembly structure are simulated using mass element;Using bushing unit simulates the structure between body and frame, frame and suspension, and suspension and suspension;Material attribute is endowed;In static equilibrium state, calculate the front and rear wheel hub load of whole vehicle model;Directly apply measured acceleration load spectrum at front and rear wheel hub;Submit ABAQUS to solve calculation;According to the calculation result, scheme adjustment is carried out.The application does not depend on tire and road surface, and the simulation scale of whole vehicle model is also greatly reduced, the whole vehicle vibration response is calculated quickly, and the simulation efficiency is improved by more than 80%.

Description

Technical Field

[0001] This invention belongs to the field of whole vehicle test vibration response calculation technology, specifically involving a vibration response calculation method based on a whole vehicle simulation model. Background Technology

[0002] During vehicle performance testing, prototype vehicles may encounter various performance issues, such as durability and ride comfort, affecting the body, chassis, and powertrain. Current methods for addressing these issues typically involve: first, reproducing the test problems through simulation; second, optimizing the design by making structural or system improvements and using simulation to further refine durability and ride comfort; and finally, conducting tests for verification. However, current methods suffer from the following problems: the vehicle simulation model is often too large, resulting in slow calculation speeds and ultimately no results; even when results are obtained, the file size is too large to process; vehicle simulation methods rely on tire models, and inaccurate tire models lead to unreliable simulation results; and vehicle simulation methods also depend on road surfaces, which sometimes require scanning, resulting in high costs.

[0003] Taking a certain model as an example, during the product development process, when the prototype vehicle underwent reinforced road testing, the vibration acceleration amplitude of the vehicle body floor was larger than that of other similar vehicles, and the rate of vibration acceleration decay was slower than that of other similar vehicles. The large acceleration response amplitude and slow decay rate directly affected the ride comfort.

[0004] To quickly identify the root cause of the problem, it is necessary to establish a multi-body dynamics simulation model of the whole vehicle. The traditional method is to combine the multi-body dynamics simulation model of the whole vehicle with a tire model and a scanned road surface to conduct a test track bad road simulation, calculate the vibration acceleration time history response at the actual measurement points in the whole vehicle test, and compare it with the test. Adjust the simulation model to make the simulated acceleration response consistent with the test acceleration response to ensure the correctness of the simulation model. On this basis, adjust the stiffness and damping characteristics of the shock absorber, the stiffness and damping characteristics of the rubber bushing, the position and number of the rubber bushing, and other variables, and recalculate the vibration acceleration response at the test position to see if the response amplitude will decrease or the acceleration decay rate will increase. Select the best improvement scheme for test verification.

[0005] However, current simulation methods have some problems: 1. To ensure simulation accuracy, the vehicle body and frame need to be made into flexible bodies in the multibody dynamics model, resulting in a large simulation model size and affecting computational efficiency; 2. The whole vehicle simulation model depends on the tire model, and if the tire model is inaccurate, it will also affect the simulation results; 3. The whole vehicle simulation model depends on scanning the road surface, which is relatively expensive; 4. During the improvement and optimization process, it is necessary to adjust the stiffness and damping of the shock absorber, the stiffness and damping of the rubber bushing, and the number and position of the rubber bushing. There are many optimization variables, and each time the optimization variables are changed, a simulation is required. Large-scale simulation models cannot meet the needs of rapid solution. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, this invention provides a vibration response calculation method based on a whole vehicle simulation model. This method is independent of tires and road surfaces, and the simulation scale of the whole vehicle model is greatly reduced. It enables rapid calculation of the whole vehicle vibration response and improves simulation efficiency by more than 80%.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for calculating vibration response based on a whole vehicle simulation model includes the following steps:

[0009] S1. Uniform cross-section beam elements are used to simulate the vehicle frame, body, and chassis suspension structure; mass elements are used to simulate the passenger, cargo, and powertrain structures.

[0010] S2. The structure between the vehicle body and frame, the frame and suspension, and the suspensions is simulated using a busing unit.

[0011] S3. Assign material properties;

[0012] S4. Under static equilibrium conditions, calculate the wheel center loads of the front and rear wheels of the vehicle model;

[0013] S5. Apply the measured acceleration load spectrum directly at the front and rear wheel centers;

[0014] S6. Submit the ABAQUS solution;

[0015] S7. Adjust the plan based on the calculation results.

[0016] Further, step S1 includes:

[0017] S11. Use beam elements with equal cross-sections to simulate the vehicle frame, and use mass elements to simulate the passenger, cargo, and vehicle skin structure.

[0018] S12. The crossbeams and longitudinal beams of the frame are simulated using beam elements with equal cross sections, and the powertrain is simulated using mass elements;

[0019] S13. The third step is to use equal-section beam units to simulate the suspension structure, including the steering knuckle, control arm, stabilizer bar, connecting rod, torsion bar spring, and axle housing structure.

[0020] Furthermore, step S11 also includes: comparing the modal and bending stiffness of the equivalent front and rear vehicle body structures of the model, with the deviation not exceeding 3%.

[0021] Furthermore, step S12 also includes: comparing the modalities and stiffness of the equivalent front and rear frame structures of the model, with the deviation not exceeding 3%.

[0022] Further, step S2 includes: using a bushing unit to simulate the rubber connecting bushing between the vehicle body and the frame, using a bushing unit to simulate the rubber connecting bushing between the frame and the suspension, using a bushing unit to simulate the rubber connecting bushing between suspension structural components, using a bushing unit to simulate a limit block, using a Cylinder unit to simulate a shock absorber, and using a Spring unit to simulate a spring.

[0023] Further, step S3 includes: establishing and assigning material and section properties to the equivalent beam units of the frame, body, and suspension; establishing and assigning stiffness and damping properties to the bushing unit, spring unit, and shock absorber unit.

[0024] Further, step S4 includes: under static balance conditions, calculating the wheel center loads of the front and rear wheels of the vehicle model, and the wheel center loads should deviate from the measured wheel center loads by less than 3%.

[0025] Further, step S5 includes: wheel center loading, applying the measured wheel center acceleration load spectrum to the wheel center positions of the four wheels respectively using ABAQUS.

[0026] Further, step S6 includes: submitting the simulation model to ABAQUS for calculation to obtain the displacement, acceleration, and force response of the floor, vehicle body, and rubber suspension positions.

[0027] Furthermore, step S7 includes: adjusting the bushing stiffness and damping, adjusting the damper stiffness and damping, adjusting the number and position of bushings; repeating steps S1 to S6 to verify the improved solution.

[0028] The present invention has the following advantages:

[0029] 1. This invention uses beam elements to simulate the frame, body, and chassis suspension structure, which greatly reduces the number of elements and nodes and shrinks the simulation scale;

[0030] 2. This invention applies the actual measured wheel center acceleration load spectrum directly to the wheel center of the whole vehicle simulation model, avoiding tire and road surface modeling, thereby improving simulation efficiency and accuracy;

[0031] 3. This invention rapidly verifies whether the time history response amplitude and decay rate of physical quantities such as displacement, acceleration, and force at the locations of interest in the improved scheme have been improved by adjusting the stiffness and damping of the bushings, the stiffness and damping of the dampers, and the number and position of the bushings, thereby guiding structural optimization and improvement. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0033] Figure 1 This is a flowchart of a vibration response calculation method based on a whole vehicle simulation model, as described in an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of a finite element model of a car body using traditional calculation methods.

[0035] Figure 3 This is a simplified vehicle body model of the uniform cross-section beam element described in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of a finite element model of a vehicle frame using traditional calculation methods.

[0037] Figure 5 This is a simplified chassis model of the uniform cross-section beam element described in an embodiment of the present invention.

[0038] Figure 6 This is a schematic diagram of a finite element model of a chassis suspension using traditional calculation methods.

[0039] Figure 7 This is a schematic diagram of a simplified chassis suspension model using a uniform cross-section beam element, as described in an embodiment of the present invention.

[0040] Figure 8 This is a schematic diagram of a simplified vehicle model equivalent to a beam element of a certain vehicle type according to an embodiment of the present invention. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0042] Explanation of the vehicle coordinate system: The positive X-axis (direction 1) is from the front to the rear of the vehicle, and the positive Z-axis (direction 3) is vertically upward. The positive Y-axis of the vehicle coordinate system is governed by the right-hand screw rule, and the rotation directions around the X, Y, and Z axes represent directions 4, 5, and 6, respectively.

[0043] Example

[0044] Taking a complete vehicle simulation model as an example, this paper details the implementation steps of a vibration response calculation method based on a complete vehicle simulation model, as described in the present invention. Figure 1 As shown:

[0045] S1. Uniform cross-section beam elements are used to simulate the vehicle frame, body, and chassis suspension structure; mass elements are used to simulate passenger, cargo, and powertrain structures.

[0046] The first step is to simulate the vehicle body frame using beam elements with uniform cross-sections, and to simulate the passenger, cargo, and body skin structures using mass elements, such as... Figure 2 , Figure 3 As shown, the number of body units has been reduced from 3.53 million to 1014. The modal and bending stiffness of the equivalent front and rear body structures in the model should not deviate by more than 3%. If the deviation exceeds the specified range, the beam cross-section size, mass unit mass and other properties need to be adjusted.

[0047] The second step involves using constant cross-section beam elements to simulate the crossbeams and longitudinal beams of the vehicle frame, and using mass elements to simulate the powertrain, such as... Figure 4 , 5 As shown, the number of frame units has been reduced from 520,000 to 836. The modal and stiffness of the equivalent front and rear frame structures in the comparison model must not deviate by more than 3%. If the deviation exceeds the specified range, the beam section size properties need to be adjusted.

[0048] The third step involves using constant cross-section beam elements to simulate the suspension structure, including the steering knuckle, control arm, stabilizer bar and connecting rod, torsion bar spring, and axle housing. Figure 6 , 7 As shown, the number of chassis suspension units has been reduced from 1.62 million to 526.

[0049] S2. The structure between the vehicle body and frame, the frame and suspension, and the suspension units is simulated using a bushing unit:

[0050] The fourth step involves using a bushing unit to simulate the rubber connecting bushing between the vehicle body and the frame, the rubber connecting bushing between the frame and the suspension, the rubber connecting bushing between suspension structural components, the limit block, the shock absorber, and the spring unit.

[0051] S3. Assign material properties:

[0052] The fifth step is to establish and assign material and section properties to the equivalent beam elements of the frame, body, and suspension; and to establish and assign stiffness and damping properties to the bushing elements, spring elements, and damper elements.

[0053] S4. Under static equilibrium conditions, calculate the wheel center loads of the front and rear wheels of the vehicle model:

[0054] Step 6: Under static equilibrium, calculate the wheel center loads of the front and rear wheels of the vehicle model. The wheel center loads should deviate from the actual wheel center loads by less than 3%. If they exceed the range, the mass units of passengers, cargo, and powertrain need to be adjusted until the simulation structure is consistent with the actual results.

[0055] S5. Apply the measured acceleration load spectrum directly at the front and rear wheel centers:

[0056] Step 7: Wheel center loading. Using ABAQUS basic motion simulation technology, apply the measured wheel center acceleration load spectrum to the wheel center positions of each of the four wheels, as shown below. Figure 8 As shown;

[0057] S6. Submit the ABAQUS solution for calculation:

[0058] The eighth step is to submit the simulation model to ABAQUS for calculation, which quickly obtains the response of physical quantities such as displacement, acceleration, and force at the locations of interest, such as the floor, vehicle body, and rubber suspension.

[0059] S7. Adjust the plan based on the calculation results:

[0060] Step 9: Adjust the bushing stiffness and damping, adjust the damper stiffness and damping, adjust the number and position of bushings, and repeat steps S1 to S6 to quickly verify whether the time history response amplitude and decay rate of physical quantities such as displacement, acceleration, force and other physical quantities at the focus of the improvement scheme have improved, thereby guiding structural optimization and improvement.

[0061] The advantages of this embodiment are:

[0062] The vehicle body assembly, frame assembly, and chassis suspension assembly structures are all modeled using beam elements with uniform cross-sections. The modal and torsional stiffness of the original body assembly model and the equivalent beam element model are compared, with the deviation not exceeding 3%. Similarly, the modal and torsional stiffness of the original frame assembly model and the equivalent beam element model are compared, with the deviation not exceeding 3%. Bushing elements are used to simulate rubber bushings and limit blocks, spring elements to simulate springs, and cylinder elements to simulate shock absorbers. Mass elements are used to simulate passengers, cargo, and the powertrain. After assigning material and cross-sectional properties to the beam elements, and stiffness and damping properties to the bushing, spring, and shock absorber elements, the overall structure is calculated. The front and rear wheel center loads are compared with the measured wheel center load values, and the deviation should not exceed 3% to ensure the correctness of the simulation model. The measured acceleration load spectrum is applied to the wheel center positions of the entire vehicle, and the time history of physical quantities such as displacement, acceleration, and force at the locations of interest, such as the vehicle floor, seats, and rubber suspensions, is calculated. At the same time, the response amplitude and decay rate of the relevant physical quantities are obtained. By adjusting variables such as the stiffness and damping of the shock absorber unit, the stiffness and damping of the bushing unit and spring unit, and the position of the rubber bushing unit, the time history of physical quantities such as displacement, acceleration, and force at the locations of interest is quickly simulated, thereby judging whether the response amplitude or decay rate of the relevant physical quantities has been improved, and further guiding the design.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for calculating vibration response based on a whole vehicle simulation model, characterized in that, Includes the following steps: S1. Uniform cross-section beam elements are used to simulate the vehicle frame, body, and chassis suspension structure; mass elements are used to simulate the passenger, cargo, and powertrain structures. S2. The structure between the vehicle body and frame, the frame and suspension, and the suspensions is simulated using a bushing unit; S3. Assign material properties, including: creating and assigning material and section properties to the equivalent beam elements of the frame, body, and suspension; creating and assigning stiffness and damping properties to the bushing elements, spring elements, and damper elements; S4. Under static equilibrium conditions, calculate the wheel center loads of the front and rear wheels of the vehicle model; S5. Apply the measured acceleration load spectrum directly at the front and rear wheel centers; S6. Submit the ABAQUS solution for calculation; S7. Adjust the scheme according to the calculation results, including: adjusting the bushing stiffness and damping, adjusting the damper stiffness and damping, and adjusting the number and position of bushings; repeat steps S1 to S6 to verify the improved scheme.

2. The vibration response calculation method based on a whole vehicle simulation model as described in claim 1, characterized in that, Step S1 includes: S11. The vehicle body frame is simulated using beam elements with equal cross sections, and the passenger, cargo and body skin structures are simulated using mass elements. S12. The crossbeams and longitudinal beams of the frame are simulated using beam elements with equal cross sections, and the powertrain is simulated using mass elements; S13. The third step is to use equal-section beam units to simulate the suspension structure, including the steering knuckle, control arm, stabilizer bar, connecting rod, torsion bar spring, and axle housing structure.

3. The vibration response calculation method based on a whole vehicle simulation model as described in claim 2, characterized in that, Step S11 further includes: comparing the modal and bending stiffness of the equivalent front and rear vehicle body structures of the model, with the deviation not exceeding 3%.

4. The vibration response calculation method based on a whole vehicle simulation model as described in claim 2, characterized in that, Step S12 further includes: comparing the modalities and stiffness of the equivalent front and rear frame structures of the model, with the deviation not exceeding 3%.

5. The vibration response calculation method based on a whole vehicle simulation model as described in claim 1, characterized in that, Step S2 includes: using a bushing unit to simulate the rubber connecting bushing between the vehicle body and the frame, using a bushing unit to simulate the rubber connecting bushing between the frame and the suspension, using a bushing unit to simulate the rubber connecting bushing between suspension structural components, using a bushing unit to simulate a limit block, using a Cylinder unit to simulate a shock absorber, and using a Spring unit to simulate a spring.

6. The vibration response calculation method based on a whole vehicle simulation model as described in claim 1, characterized in that, Step S4 includes: under static balance, calculating the wheel center loads of the front and rear wheels of the vehicle model, and the wheel center loads should deviate from the measured wheel center loads by less than 3%.

7. The vibration response calculation method based on a whole vehicle simulation model as described in claim 1, characterized in that, Step S5 includes: wheel center loading, applying the measured wheel center acceleration load spectrum to the wheel center positions of the four wheels respectively using ABAQUS.

8. The vibration response calculation method based on a whole vehicle simulation model as described in claim 1, characterized in that, Step S6 includes: submitting the simulation model to ABAQUS for calculation to obtain the displacement, acceleration, and force response of the floor, vehicle body, and rubber suspension positions.

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