A finite element analysis method and system for automobile pedal vibration

Abstract

The application relates to a finite element analysis method and system for automobile pedal vibration, S1: an initial whole vehicle finite element model is established; S2: modal analysis is carried out on the initial whole vehicle finite element model, system modal of a pedal model and a front wall plate model and pedal modal are calculated; S3: if the system modal and the pedal modal can both meet the frequency avoidance requirement, WOT working condition excitation is applied to the initial whole vehicle finite element model and modal analysis is carried out, the initial whole vehicle finite element model is optimized according to the vibration response of the pedal, and an intermediate whole vehicle finite element model is formed; S4: actual working condition excitation is applied to the intermediate whole vehicle finite element model and modal analysis is carried out, the intermediate whole vehicle finite element model is further optimized according to the vibration response of the pedal, and a final whole vehicle finite element model is formed. The application reduces the possibility of modal coupling and reduces the later rectification cost.

Description

Technical Field

[0001] This invention relates to the field of finite element simulation technology, specifically to the resonance vibration analysis technology of clutch pedal, accelerator pedal and brake pedal. Background Technology

[0002] The three pedals in a car refer to the clutch pedal, accelerator pedal, and brake pedal; they include foot-operated, movable pedal elements fixed to a base element and equipped with foot pads. In today's fast-paced world, the high demands for time and efficiency have made cars a necessity, and automotive NVH performance has received increasing attention. Major automakers have invested significant human, material, and financial resources in analyzing and optimizing the overall NVH performance of their vehicles. Among these, the vibration of the three pedals, due to their close contact with the driver throughout the driving process, is a crucial issue for manufacturers. With the increase in hybrid models, the changes in the mass and center of gravity of the new brake pump compared to traditional gasoline vehicles have resulted in a more densely packed modal structure in the front panel and brake pedal, increasing the possibility of modal coupling.

[0003] Among the currently disclosed patents related to pedals, there are few patents related to or similar to this invention. Only one patent for finite element analysis of a pedal was found: CN107239605A discloses a method for calculating the force-displacement of an automotive clutch pedal, including the following steps: obtaining the force-displacement characteristic curve data of the small end of the designed clutch diaphragm spring using finite element software simulation; extracting the design parameters of each component in the clutch operating system; calculating and plotting the force-displacement and other related characteristic curves of the clutch pedal; solving and plotting the key curves affecting the comfort performance of the clutch pedal using a certain instantaneous coordinate transformation and force relationship; and optimizing the parameters of the clutch itself and the various parameters of the operating mechanism according to the principle of clutch pedal operation comfort to obtain the ideal clutch pedal force-displacement curve. This invention can be used to guide the setting and optimization of clutch and its operating system parameters during the product development stage, so that the clutch and its operating system can better meet the comfort and stability performance of automobile driving and solve problems such as heavy clutch pedal and clutch slippage. The patent analyzes and optimizes the clutch pedal from the perspective of the stiffness of driving performance. Its main focus and optimization point are the clutch pedal system itself, and the force-displacement is met by adjusting some geometric dimensional parameters. Summary of the Invention

[0004] One of the objectives of this invention is to provide a finite element analysis method for automotive pedal vibration, in order to address the problem that with the increase in hybrid vehicle models, the changes in the mass and center of gravity of the new brake pump compared to traditional fuel vehicles make the front panel modes and brake pedal modes more dense, increasing the possibility of modal coupling.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A finite element analysis method for automobile pedal vibration.

[0007] S1: Establish the initial finite element model of the whole vehicle, including the pedal model and the front wall panel model;

[0008] S2: Perform modal analysis on the initial finite element model of the whole vehicle, and calculate the system modes and pedal modes composed of the pedal model and the front wall panel model;

[0009] S3: If both the system mode and the pedal mode can meet the frequency avoidance requirements, then apply WOT condition excitation to the initial vehicle finite element model and perform response analysis. Based on the vibration response of the pedal, optimize the initial vehicle finite element model to form an intermediate vehicle finite element model.

[0010] S4: Apply actual working condition excitation to the intermediate vehicle finite element model and perform response analysis. Based on the vibration response of the pedal, further optimize the intermediate vehicle finite element model to form the final vehicle finite element model.

[0011] Furthermore, before step S3, if the pedal mode or front panel mode does not meet the frequency avoidance requirement, the vibration transfer function curve from each suspension attachment point to the pedal response point is calculated, and all structures on the force transmission path corresponding to the vibration transfer function curve with an amplitude greater than the set amplitude are optimized until the amplitude of all the vibration transfer function curves is less than or equal to the set amplitude, and then step S3 is performed.

[0012] Furthermore, in S4, the actual operating condition excitation includes suspension passive side vibration data under POT condition, suspension passive side vibration data under WOT condition, or suspension passive side vibration data under braking condition.

[0013] Furthermore, in S4, after calculating the vibration response of the pedal, the indicators that do not meet the design objectives are screened, and the intermediate vehicle finite element model is analyzed and optimized based on the indicators, which are vibration velocity, vibration acceleration, or displacement.

[0014] Furthermore, in S3 or S4, before applying WOT condition excitation to the initial vehicle finite element model or before applying WOT condition suspension passive side vibration data to the intermediate vehicle finite element model, it is necessary to add an additional force to the accelerator pedal of the initial vehicle finite element model or the intermediate vehicle finite element model, with the direction perpendicular to the accelerator pedal surface.

[0015] A finite element analysis system for automobile pedal vibration based on the above-mentioned finite element analysis method includes:

[0016] The model building unit is configured to build an initial finite element model of the whole vehicle, including the pedal model and the front wall panel model;

[0017] The modal analysis unit is configured to perform modal analysis on the initial whole vehicle finite element model, and calculate the system modes and pedal modes composed of the pedal model and the front wall panel model.

[0018] The judgment unit is configured to determine whether the system mode and the pedal mode can meet the frequency avoidance requirements;

[0019] The first optimization unit is configured to apply WOT condition excitation to the initial vehicle finite element model and perform response analysis if both the system mode and the pedal mode can meet the frequency avoidance requirements. Based on the vibration response of the pedal, the initial vehicle finite element model is optimized to form an intermediate vehicle finite element model.

[0020] The second optimization unit is configured to apply actual working condition excitation to the intermediate vehicle finite element model and perform response analysis, and further optimize the intermediate vehicle finite element model based on the vibration response of the pedal to form the final vehicle finite element model.

[0021] Furthermore, if the judgment unit determines that the pedal mode or the front panel mode does not meet the frequency avoidance requirement, the first optimization unit calculates the vibration transfer function curve from each suspension attachment point to the pedal response point, optimizes all structures on the force transmission path corresponding to the vibration transfer function curve with an amplitude greater than the set amplitude, until the amplitude of all the vibration transfer function curves is less than or equal to the set amplitude.

[0022] Furthermore, the actual operating condition excitation includes suspension passive side vibration data under POT condition, suspension passive side vibration data under WOT condition, or suspension passive side vibration data under braking condition.

[0023] Furthermore, after the second optimization unit calculates the vibration response of the pedal, it filters out the indicators that do not meet the design objectives, and analyzes and optimizes the intermediate vehicle finite element model based on the indicators, which are vibration velocity, vibration acceleration, or displacement.

[0024] Furthermore, before applying WOT condition excitation to the initial vehicle finite element model or before applying WOT condition suspension passive side vibration data to the intermediate vehicle finite element model, it is necessary to add an additional force to the accelerator pedal of the initial vehicle finite element model or the intermediate vehicle finite element model, with the direction perpendicular to the accelerator pedal surface.

[0025] The beneficial effects of this invention are:

[0026] This invention first sets up an initial whole vehicle finite element model and performs modal analysis. Under the premise of achieving reasonable frequency avoidance between the three-pedal mode and the front wall panel mode to avoid resonance, WOT condition excitation is applied to the initial whole vehicle finite element model, and the initial whole vehicle finite element model is optimized according to the vibration response of the pedal. Then, in the later stage, by applying the actual vehicle condition excitation, the whole vehicle finite element model is further optimized according to the vibration response of the pedal. This allows the three-pedal vibration problem to be exposed as much as possible in the early stage and optimized through structural optimization, reducing the possibility of modal coupling and reducing the cost of later rectification.

[0027] When the system mode or pedal mode composed of the pedal model and the front panel model cannot meet the frequency avoidance requirements, this invention clarifies the required structure by calculating the vibration transfer function curves from each suspension attachment point to the pedal response point, thereby further reducing the vibration impact of the whole vehicle finite element model. Attached Figure Description

[0028] Figure 1 A flowchart of the finite element analysis method for automobile pedal vibration;

[0029] Figure 2 This is a schematic diagram of the three pedals and the front wall panel.

[0030] Figure 3 The VTF function graph for a three-pedal system;

[0031] Figure 4 The vibration response diagram of the three pedals under WOT conditions for the whole vehicle;

[0032] Figure 5 Schematic diagram illustrating the addition of extra load to the accelerator pedal during acceleration;

[0033] Figure 6 This is a structural diagram of a finite element analysis system for automobile pedal vibration.

[0034] Among them, 1-model building unit; 2-modal analysis unit; 3-judgment unit; 4-first optimization unit; 5-second optimization unit. Detailed Implementation

[0035] The following description, with reference to the accompanying drawings and preferred embodiments, illustrates the implementation of the technical solution of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0036] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0037] This embodiment proposes a finite element analysis method for automobile pedal vibration, such as... Figure 1 As shown, the specific method is as follows:

[0038] Step 1: Establish an initial finite element model of the whole vehicle, including the three-pedal model and the front wall panel model, and then perform mesh generation and relative motion relationship modeling.

[0039] Step 1 involves creating a complete vehicle model based on data provided by the product design department, including finite element models of the three-pedal system and the front panel. The degrees of freedom of some components are adjusted using 1D elements to ensure correct and reasonable motion relationships. For structures such as the brake booster pump, which generally lack detailed internal structures, their external contours are simulated using Shell elements, with the interior filled with a solid mesh. Material density and other parameters are adjusted according to the mass and center of gravity provided by the design department to ensure consistency with the design. The overlap of internal components in the brake pump system is simulated based on actual overlap conditions.

[0040] In this embodiment, the entire vehicle model is built in HyperWorks or other modeling software. The three pedal models are all modeled according to their initial CAD data, and their rotational degrees of freedom are released through 1D element stiffness. The initial finite element model of the entire vehicle is checked according to the modeling guidelines.

[0041] The three-pedal model in this embodiment includes a brake pedal model, an accelerator pedal model, and a clutch pedal model.

[0042] Step 2: Perform modal analysis on the initial vehicle finite element model, and calculate the system modes and pedal modes composed of the pedal model and the front wall panel model.

[0043] Step 2 specifically involves calculating the whole vehicle modes. Since the modal calculation result file of the whole vehicle model is too large and the front panel mode is not easy to identify, it is recommended to calculate the modes by truncating a part of the model. The requirement for truncating the model is that the distance from the pedal and the front panel is more than 800mm, and the nodes of the truncated model section are constrained. Calculate the modes in the range of 0-100Hz, identify the pedal mode and the front panel in the result file. Since the front panel mode is more complex, frequency response curves are used to assist in the identification of the modes, and a modal distribution table is completed.

[0044] In this step, modal calculation boundaries are set according to modal analysis specifications, and modal calculations are performed using solvers such as NASTRAN or OPTISTRUCT. Since the modal results file of the whole vehicle model occupies too much storage space, and the front panel modes are not easily identified, modal calculations are performed by truncating a portion of the model. The truncated model must be at least 800mm away from the pedals and front panel, and the nodes of the truncated model section are constrained. Modal values ​​in the 0-100Hz range are calculated. The calculated results file is then post-processed and modally identified in HyperView software, focusing on the system modes composed of the three pedals and the front panel, as well as the elastic modes of the three pedals.

[0045] And complete the modal distribution table, the modal analysis results are as follows: Figure 2 As shown in Table 1, the modal distribution is presented in the table.

[0046] Table 1 Modal Distribution Table

[0047]

[0048] Step 3: Determine whether the system mode composed of the three pedals and the front wall panel and the elastic mode of the three pedals meet the frequency avoidance requirement. In this embodiment, the frequency avoidance requirement needs to meet 3 Hz. For example, if a certain pedal mode is 80 Hz, then the system mode must be lower than 77 or higher than 83. If the frequency avoidance requirement is met, proceed to step 5; otherwise, proceed to step 4.

[0049] Step 4: Calculate and optimize the VTF from the suspension attachment point to the pedal response point.

[0050] In this step, such as Figure 3 As shown, the vibration transfer function (VTF) curves from each suspension attachment point to the three pedal response points are calculated, i.e., the vibration transfer function curves from each suspension attachment point to the accelerator pedal, brake pedal, and clutch pedal in the X, Y, and Z directions. Then, it is determined whether the peak value of each VTF curve is greater than the peak value threshold. If it is greater, the amplitude is too large. Subsequently, all structures of the transmission path corresponding to the VTF curve are optimized until the amplitude of all VTF curves is less than or equal to the amplitude threshold.

[0051] VTF calculation preprocessing is completed in HyperWorks software, the calculation is performed using NASTRAN or OPTISTRUCT solvers, and post-processing is completed in HyperView.

[0052] Step 5: Apply WOT (Work Over Time) excitation to the initial vehicle finite element model, calculate the vibration response of the three pedals under WOT conditions, and optimize the initial vehicle finite element model based on the vibration response results. Generally, the optimization targets are the front panel reinforcement and the path reinforcement from the suspension to the pedal mounting point, forming an intermediate finite element model. The vibration response results of the accelerator pedal in this implementation are as follows: Figure 4 As shown.

[0053] In step 5, based on the modal distribution table obtained in step 2, if the key modes in the distribution table can be reasonably avoided, or if the VTF optimization in step 3 is successful, the pedal vibration response under the WOT condition is calculated, and the vibration risk of the three pedals is assessed in conjunction with the target. When calculating the accelerator pedal vibration under the WOT condition, an additional force needs to be added to the accelerator pedal. The magnitude of the force is determined by model calibration, and the direction is perpendicular to the accelerator pedal surface. Specifically, a spring is added perpendicularly to the accelerator pedal surface, and its stiffness and damping are confirmed based on the model accuracy calibration. Preprocessing is completed in HyperWorks software, calculations are performed using NASTRAN or OPTISTRACT solvers, and post-processing is completed in HyperView.

[0054] Adding a WOT (Whiplash Overload) excitation to the full vehicle model is important because three-pedal vibration typically occurs under POT (Power On Threat) or braking conditions. The initial calculation of pedal vibration under the WOT condition is necessary because POT or braking excitation data is unavailable at the outset. However, since WOT excitation data is generally larger than POT or braking excitation data, adding WOT excitation data can be used to assess pedal vibration characteristics initially and combine this with a risk assessment based on the target. Figure 5 As shown, when calculating the accelerator pedal vibration under acceleration conditions such as WOT and POT, an additional force needs to be added to the accelerator pedal. The magnitude of the force is determined by model calibration, and the direction is perpendicular to the accelerator pedal surface.

[0055] Step 6: Apply actual working condition excitation to the intermediate vehicle finite element model and perform response analysis. Based on the vibration response of the pedal, further optimize the intermediate vehicle finite element model to form the final vehicle finite element model.

[0056] The actual operating condition excitation in this embodiment includes the suspension passive side vibration data under POT condition, the suspension passive side vibration data under WOT condition, or the suspension passive side vibration data under braking condition.

[0057] After calculating the vibration response of the pedal, the indicators that do not meet the design objectives are screened out, and the intermediate vehicle finite element model is optimized based on the indicator analysis. The indicators are vibration velocity, vibration acceleration, or displacement.

[0058] The vibration data of the passive side of the suspension under the corresponding working conditions where the three pedals vibrate were extracted, verified, and the analysis and optimization were completed.

[0059] For example, if the vibration acceleration of the accelerator pedal during acceleration does not meet the target, how can we analyze and optimize it? First, we need to decompose the cause of this result. The first thing to look at is the excitation end, that is, the excitation provided by the engine. If the engine excitation is too large, we can reduce the engine excitation by adjusting the electronic fuel injection data. If it is a problem with the transmission path, the optimization method is the same as in step 4 above.

[0060] Step 6 specifically involves the hybrid vehicle stage. The testing department extracts the passive side vibration data of the suspension under problematic operating conditions and loads it into the vehicle model. The vibration response of the three pedals is calculated, and indicators exceeding the acceptable response are analyzed and optimized. Similarly, calculating the accelerator pedal vibration under WOT conditions requires adding an additional load, in the same way as in step 5. In this embodiment, the indicators represent vibration velocity, vibration acceleration, and displacement.

[0061] Step 6, the hybrid vehicle stage: The testing department assesses the risks of the tooling vehicle based on the performance of the hybrid vehicle in the actual test. This performance allows for the prediction of the three-pedal vibration of the product. For problematic operating conditions, the testing department extracts the vibration data from the passive side of the suspension, simulates the vibration response of the pedals under these conditions, compares it with the design targets, and analyzes and optimizes any indicators that do not meet the targets. Preprocessing is performed in HyperWorks software, calculations are performed using NASTRAN or OPTISTRACT solvers, and post-processing is performed in HyperView.

[0062] This embodiment also proposes a finite element analysis system for automobile pedal vibration, based on the above analysis method, such as... Figure 6 As shown. Includes:

[0063] Model building unit 1 is configured to build an initial finite element model of the whole vehicle, including the pedal model and the front wall panel model;

[0064] Modal analysis unit 2 is configured to perform modal analysis on the initial whole vehicle finite element model, and calculate the system modes and pedal modes composed of the pedal model and the front wall panel model.

[0065] Judgment unit 3 is configured to determine whether the system mode and pedal mode can meet the frequency avoidance requirements;

[0066] The first optimization unit 4 is configured to apply WOT condition excitation to the initial vehicle finite element model and perform response analysis if both the system mode and the pedal mode can meet the frequency avoidance requirements. Based on the vibration response of the pedal, the initial vehicle finite element model is optimized to form an intermediate vehicle finite element model.

[0067] The second optimization unit 5 is configured to apply actual working condition excitation to the intermediate vehicle finite element model and perform response analysis, and further optimize the intermediate vehicle finite element model based on the vibration response of the pedal to form the final vehicle finite element model.

[0068] If the judgment unit 3 determines that the pedal mode or the front wall panel mode does not meet the frequency avoidance requirement, then the first optimization unit 4 calculates the vibration transfer function curve from each suspension attachment point to the pedal response point, optimizes all structures on the force transmission path corresponding to the vibration transfer function curve with an amplitude greater than the set amplitude, until the amplitude of all vibration transfer function curves is less than or equal to the set amplitude.

[0069] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A finite element analysis method for automobile pedal vibration, characterized in that: S1: Establish the initial finite element model of the whole vehicle, including the pedal model and the front wall panel model; S2: Perform modal analysis on the initial finite element model of the whole vehicle, calculate the system modes and pedal modes composed of the pedal model and the front wall panel model; determine whether the system modes and pedal modes can meet the frequency avoidance requirements. If the frequency avoidance requirements are not met, calculate the vibration transfer function curves from each suspension attachment point to the pedal response point, optimize all structures on the force transmission path corresponding to the vibration transfer function curves with amplitudes greater than the set amplitude, until the amplitudes of all the vibration transfer function curves are less than or equal to the set amplitude, and proceed to S3; where the frequency avoidance requirement means a frequency difference ≥ 3Hz; S3: If both the system mode and the pedal mode can meet the frequency avoidance requirements, then apply WOT condition excitation to the initial vehicle finite element model and perform response analysis. Based on the vibration response of the pedal, optimize the initial vehicle finite element model to form an intermediate vehicle finite element model. S4: Apply actual working condition excitation to the intermediate vehicle finite element model and perform response analysis. Based on the vibration response of the pedal, further optimize the intermediate vehicle finite element model to form the final vehicle finite element model.

2. The finite element analysis method for automobile pedal vibration according to claim 1, characterized in that: In S4, the actual operating condition excitation includes suspension passive side vibration data under POT condition, suspension passive side vibration data under WOT condition, or suspension passive side vibration data under braking condition.

3. The finite element analysis method for automobile pedal vibration according to claim 2, characterized in that: In step S4, after calculating the vibration response of the pedal, the indicators that do not meet the design objectives are screened, and the intermediate vehicle finite element model is analyzed and optimized based on the indicators, which are vibration velocity, vibration acceleration, or displacement.

4. The finite element analysis method for automobile pedal vibration according to claim 2, characterized in that: In S3 or S4, before applying WOT condition excitation to the initial vehicle finite element model or before applying WOT condition suspension passive side vibration data to the intermediate vehicle finite element model, it is necessary to add an additional force to the accelerator pedal of the initial vehicle finite element model or the intermediate vehicle finite element model, with the direction perpendicular to the accelerator pedal surface.

5. A finite element analysis system for automobile pedal vibration based on the finite element analysis method according to any one of claims 1-4, characterized in that: include: The model building unit is configured to build an initial finite element model of the whole vehicle, including the pedal model and the front wall panel model; The modal analysis unit is configured to perform modal analysis on the initial whole vehicle finite element model, and calculate the system modes and pedal modes composed of the pedal model and the front wall panel model. The judgment unit is configured to determine whether the system mode and the pedal mode can meet the frequency avoidance requirement; where the frequency avoidance requirement means that the frequency difference is ≥3Hz. The first optimization unit is configured as follows: if the judgment unit determines that the pedal mode or the front panel mode does not meet the frequency avoidance requirement, the first optimization unit calculates the vibration transfer function curves from each suspension attachment point to the pedal response point, optimizes all structures on the force transmission path corresponding to the vibration transfer function curves with amplitudes greater than the set amplitude, until the amplitudes of all the vibration transfer function curves are less than or equal to the set amplitude; if both the system mode and the pedal mode meet the frequency avoidance requirement, then WOT condition excitation is applied to the initial whole vehicle finite element model and response analysis is performed, and the initial whole vehicle finite element model is optimized based on the pedal vibration response to form an intermediate whole vehicle finite element model; The second optimization unit is configured to apply actual working condition excitation to the intermediate vehicle finite element model and perform response analysis, and further optimize the intermediate vehicle finite element model based on the vibration response of the pedal to form the final vehicle finite element model.

6. The finite element analysis system for automobile pedal vibration according to claim 5, characterized in that: The actual operating condition excitation includes suspension passive side vibration data under POT condition, suspension passive side vibration data under WOT condition, or suspension passive side vibration data under braking condition.

7. The finite element analysis system for automobile pedal vibration according to claim 6, characterized in that: After the second optimization unit calculates the vibration response of the pedal, it filters out the indicators that do not meet the design objectives, and analyzes and optimizes the intermediate vehicle finite element model based on the indicators, which are vibration velocity, vibration acceleration or displacement.

8. The finite element analysis system for automobile pedal vibration according to claim 7, characterized in that: Before applying WOT condition excitation to the initial vehicle finite element model or before applying WOT condition suspension passive side vibration data to the intermediate vehicle finite element model, an additional force needs to be added to the accelerator pedal of the initial vehicle finite element model or the intermediate vehicle finite element model, with the direction perpendicular to the accelerator pedal surface.

Images