Chassis angle friction squeal suppression method considering damping characteristics

Abstract

The invention relates to a chassis angle friction squeal inhibition method considering damping characteristics. The method comprises the following steps: carrying out a chassis angle friction squeal test; measuring bushing damping and connection damping; establishing an initial finite element model of the chassis angle, performing complex modal analysis in combination with measured bushing damping and connection damping data, and comparing with characteristic frequency acquired in a chassis angle friction squeal test to construct and obtain a chassis angle finite element model conforming to reality; according to the chassis angle finite element model, lining damping and connection damping parameters are changed, vibration responses of a chassis angle system under different damping conditions are simulated, the influence of damping characteristics on the friction squeal is analyzed, and key damping factors influencing the chassis angle friction squeal are determined; and the damping characteristic of the chassis angle system is modified and optimized. Compared with the prior art, the dynamic damping characteristics of the chassis angle are deeply researched, modification and optimization are carried out based on the damping characteristics, and the friction scream between the brake block and the brake disc of the brake can be effectively restrained.

Description

Technical Field

[0001] The present invention relates to the technical field of chassis corner squeal noise suppression, and in particular to a chassis corner friction squeal suppression method taking damping characteristics into consideration. Background Art

[0002] Friction, squeal and noise problems at chassis corners seriously affect vehicle comfort, giving passengers a poor subjective auditory experience, easily causing users to question the quality of the vehicle, and thus affecting the brand image. This is an important issue that needs to be urgently addressed in the automotive industry and has received widespread attention.

[0003] Frictional squeal between the brake pad and disc is a dynamic issue, closely related to the damping properties of the entire chassis corner. Analysis of the damping characteristics' impact on frictional squeal is crucial in studying this issue. However, current standards lack comprehensive requirements for measuring and analyzing chassis corner damping characteristics. Previous research has largely focused on the contact friction of the brake itself, with limited research examining the damping properties of the chassis corner and their impact on frictional squeal during braking.

[0004] In addition, in terms of methods for suppressing friction squeal, traditional methods mostly start from adjusting the material or structure of the brake components, adjusting the modal characteristics of the part structure to suppress the occurrence of brake friction squeal. Few methods start from the perspective of damping characteristics to formulate friction squeal suppression strategies, which limits the effective suppression of friction squeal and the development of related technologies.

[0005] Although some studies have proposed solutions to the noise problem of chassis corners, such as reducing noise by changing the structure or material of brake discs and friction pads, the core of these solutions lies in the adjustment of the components themselves. They have not conducted in-depth research on the impact of damping characteristics on friction squeal, nor have they proposed effective squeal suppression strategies based on damping characteristics. This is not conducive to improving vehicle driving comfort and NVH (Noise, Vibration, Harshness) performance. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a method for suppressing chassis corner friction scream taking into account the damping characteristics. By in-depth study of the chassis corner dynamic damping characteristics and modification and optimization based on the damping characteristics, the friction scream between the brake pad and the brake disc can be effectively suppressed.

[0007] The object of the present invention can be achieved by the following technical solution: A method for suppressing chassis angular friction squeal considering damping characteristics, comprising the following steps:

[0008] S1. Conduct a chassis angular friction squeal test to collect acoustic and vibration characteristic information, operating condition data, and key brake squeal information during braking, including characteristic frequency, amplitude variation trend, and temporal variation of brake squeal.

[0009] S2, measure bushing damping and connection damping;

[0010] S3. Establish an initial finite element model of the chassis angle. Combined with the bushing damping and connection damping data measured in step S2, perform complex modal analysis. Compare the complex modal analysis results with the characteristic frequencies collected in step S1 to construct a finite element model of the chassis angle that is consistent with reality.

[0011] S4. For the chassis corner finite element model, by changing the bushing damping and connection damping parameters, simulate the vibration response of the chassis corner system under different damping conditions, analyze the impact of different damping characteristic parameter changes on friction squeal, and determine the key damping factors affecting chassis corner friction squeal;

[0012] S5. Based on the analysis result of step S4, the damping characteristics of the chassis corner system are modified and optimized to suppress chassis corner friction squeal.

[0013] Furthermore, the specific process of step S1 is as follows: preparing a chassis angle test sample including a suspension, a wheel hub and a complete braking system to simulate the braking condition of the vehicle during actual driving;

[0014] High-precision testing equipment is used to collect acoustic and vibration characteristics during braking, including sound pressure level and vibration acceleration of key chassis corner components. Simultaneously, operating data is recorded, including brake disc speed, brake pressure, and braking torque.

[0015] After data collection is completed, key information about brake squeal is extracted through time domain analysis, frequency domain analysis, and phase diagram analysis, including characteristic frequency, amplitude change trend, and change pattern over time.

[0016] Furthermore, the step S2 specifically measures the bushing damping and the connection damping by using a displacement sensor, a force sensor, and a vibration sensor.

[0017] Furthermore, the process of measuring the bushing damping in step S2 includes: applying dynamic loads to the bushings at the connection points between the suspension and the frame under simulated actual vehicle driving conditions, measuring the force and displacement parameters of the bushings under different frequencies and amplitudes, obtaining the dynamic damping force under different frequencies and other working conditions, and collecting and recording the measurement data, including load size, displacement, and damping coefficient.

[0018] Furthermore, the connection points between the suspension and the frame include the connection between the lower arm and the subframe (front bushing and rear bushing), the connection between the lateral stabilizer bar and the upper support point of the shock absorber.

[0019] Furthermore, the process of measuring the connection damping in step S2 includes: installing the brake caliper and the steering knuckle on a dedicated stiffness test bench to simulate the constraint conditions in an actual vehicle, applying excitations of different frequencies to the brake caliper at the connection between the caliper and the steering knuckle to simulate the force and displacement conditions under complex braking conditions, measuring the dynamic damping characteristics of the connection between the caliper and the steering knuckle under wide-band conditions, including the damping force and displacement response, collecting and recording the measurement data, and obtaining the connection damping value between the brake caliper and the steering knuckle.

[0020] Furthermore, the specific process of step S3 is as follows: using finite element analysis software to establish an initial finite element model of the chassis corner, defining the material properties, contact relationships, constraints and load conditions of each component of the chassis corner;

[0021] In the initial finite element model of the chassis corners, damping parameters were set for the bushings at the connection points between the suspension and the frame, as well as the connection points between the brake caliper and the steering knuckle, based on the measured bushing damping and connection damping data to simulate the actual dynamic damping characteristics.

[0022] Perform complex modal analysis on the initial finite element model of the chassis angle to obtain the complex modal analysis results of the chassis angle system. Compare the complex modal analysis results with the characteristic frequencies collected in step S1. If the deviation between the two exceeds the threshold, correct the connection relationship in the initial finite element model of the chassis angle, and then perform complex modal analysis again until a corrected chassis angle finite element model that is consistent with the actual situation is obtained.

[0023] Furthermore, the complex modal analysis results include the natural frequencies, vibration shapes and unstable modes of the chassis angle system, and the complex eigenvalues ​​of the chassis angle system are obtained during the complex modal analysis process.

[0024] Furthermore, the real part of the complex eigenvalue represents the attenuation characteristics of the chassis angle system, and the imaginary part corresponds to the natural frequency of the chassis angle system. When the real part of the complex eigenvalue is positive, it indicates that there is an unstable mode in the chassis angle system, which will cause brake squeal.

[0025] Furthermore, step S4 specifically adopts a method of combining numerical simulation with experimental data to analyze the influence of damping characteristics on the probability of occurrence of friction squeal, squeal frequency and squeal intensity, and analyzes the mechanism of action of dynamic damping on friction squeal in different frequency ranges and different braking conditions, and determines the key damping factors affecting chassis angular friction squeal.

[0026] Furthermore, step S5 modifies and optimizes the damping characteristics of the chassis angle system, including:

[0027] Adjust the damping characteristics of the bushings at the suspension connection points, the calipers, and the steering knuckle connections;

[0028] Fine-tune the structure of the brake pad and adjust the damping characteristics of the chassis angle system by changing the contact area and contact pressure distribution between the brake pad and the brake disc.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The present invention first conducts a chassis corner friction squeal test; then measures bushing damping and connection damping; then establishes an initial finite element model of the chassis corner. Combined with the measured bushing and connection damping data, complex modal analysis is performed to construct a chassis corner finite element model that is consistent with actual conditions. The vibration response of the chassis corner system under different damping conditions is simulated by varying the bushing and connection damping parameters within the chassis corner finite element model. The impact of varying damping characteristic parameters on friction squeal is analyzed, and the key damping factors influencing chassis corner friction squeal are identified. Finally, based on the analysis results, the damping characteristics of the chassis corner system are modified and optimized to suppress chassis corner friction squeal. By systematically measuring the bushing and connection damping parameters of the chassis corner and applying them to the complex modal analysis of the chassis corner finite element model, the method overcomes the limitations of existing methods that under-consider damping characteristics, enabling accurate analysis of factors influencing friction squeal. Furthermore, based on the damping characteristics, the damping characteristics are modified to suppress friction squeal, effectively suppressing friction squeal between the brake pad and brake disc.

[0031] This invention innovatively applies chassis angle damping characteristics to brake squeal suppression, specifically focusing on dynamic damping characteristics. Unlike traditional approaches that focus on optimizing the contact between the friction pad and the brake disc, this invention addresses the entire chassis angle system. By adjusting the damping of bushings at the suspension-frame connection and the connection damping between the brake caliper and steering knuckle, it alters the vibration transmission path and energy dissipation, effectively suppressing brake squeal. This innovation breaks through the limitations of traditional thinking, providing a new direction and approach for brake squeal suppression, significantly improving the effectiveness of friction squeal suppression.

[0032] The present invention adopts a comprehensive and precise measurement method in the bushing damping and connection damping measurement links. Damping characteristics of the bushings at the connection points between the suspension and the frame, as well as the connection points between the brake caliper and the steering knuckle, are measured under a variety of different working conditions and conditions. By simulating the vehicle under different driving speeds, brake pressures, road conditions, etc., high-precision displacement sensors, force sensors, etc. are used to obtain multi-dimensional parameter data such as the dynamic damping coefficient and dynamic stiffness of each connection point under different frequency conditions. This comprehensive measurement method can more accurately measure the changing patterns of dynamic damping characteristics in actual use, and provide richer and more accurate data support for subsequent analysis and optimization based on damping characteristics. Compared with traditional measurement methods, it greatly improves the fit to actual working conditions and the reference value of data.

[0033] In the process of finite element modeling and complex modal analysis, the present invention fully considers the dynamic damping characteristics to perform high-precision modeling. Professional finite element analysis software is used to accurately simulate the actual structure and connection relationship of each component of the chassis corner, and the damping parameters are accurately set in the model based on the dynamic damping data of the suspension bushing and brake caliper connection parts actually measured. The model is further subjected to complex modal analysis to obtain the complex eigenvalues ​​of the system. The real part represents the attenuation characteristics of the system, and the imaginary part corresponds to the natural frequency of the system. The results of the complex modal analysis are compared with the test results of the chassis corner friction squeal to ensure that the finite element model can accurately reflect the actual characteristics of the chassis corner system, providing a reliable theoretical basis for subsequent analysis and suppression of friction squeal. Compared with traditional modeling methods, the accuracy and effectiveness of the analysis are greatly improved.

[0034] The present invention adopts a combination of experimental data and high-precision finite element models in the analysis of the influencing factors of damping characteristics on friction squeal. Through the chassis angle friction squeal test, comprehensive and accurate acoustic and vibration characteristics of the braking process, working condition information, and damping data of the bushing and connection parts are obtained. Using these experimental data as input, the finite element model is continuously calibrated and optimized so that the model can more accurately reflect the actual situation. Based on this model, it is possible to systematically analyze the impact of changes in different damping characteristic parameters on the probability, frequency and intensity of friction squeal. Compared with relying solely on theoretical analysis or a single experimental study, this combination can reveal the complex relationship between damping characteristics and friction squeal in a more in-depth and accurate manner, providing a basis for the subsequent formulation of targeted suppression strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the method flow of the present invention;

[0036] Figure 2 A chassis corner test specimen required for carrying out a chassis corner friction squeal test in an embodiment;

[0037] Figure 3This is a diagram of the sensor topology used in the chassis angular friction squeal test carried out in the embodiment;

[0038] Figure 4 A diagram showing the sensor layout for conducting a chassis angular friction squeal test in an embodiment;

[0039] Figure 5a and 5b Time domain and frequency domain plots of scream data collected for example experiments;

[0040] Figure 6 A schematic diagram of the connection between the clamp body and the bracket, the arrangement of sensors, and the application of excitation in the embodiment;

[0041] Figure 7 Schematic diagram of the connection between the back plate and the bracket, the arrangement of sensors and the application of excitation in the embodiment;

[0042] Figure 8 Schematic diagram of finite element modeling of chassis angle in the embodiment;

[0043] Figure 9 Schematic diagram of contact, constraint and load conditions in the chassis corner finite element model of the embodiment;

[0044] Figure 10 This is the unstable frequency distribution diagram in the analysis results of the embodiment. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Example

[0047] This proposal focuses on the chassis angular friction squeal suppression considering the damping characteristics, and proposes a chassis angular friction squeal suppression method considering the damping characteristics, such as Figure 1 As shown, the following steps are included:

[0048] S1. Conduct a chassis angular friction squeal test to collect acoustic and vibration characteristic information, operating condition data, and key brake squeal information during braking, including characteristic frequency, amplitude variation trend, and temporal variation of brake squeal.

[0049] Specifically, chassis corner test specimens including suspension, wheels and complete braking systems are prepared to simulate the braking conditions of the vehicle during actual driving, covering different vehicle speeds, braking pressures and other conditions. High-precision testing equipment, such as multi-channel microphones and three-axis accelerometers, are used to collect acoustic and vibration characteristic information such as the sound pressure level during braking and the vibration acceleration of key chassis corner components. At the same time, speed sensors and pressure sensors are used to record operating data such as brake disc speed, brake pressure, and braking torque to provide comprehensive data support for subsequent analysis. After data collection is completed, time domain analysis, frequency domain analysis, and phase diagram analysis are used to extract key information such as the characteristic frequency of brake squeal, amplitude change trend, and time-varying laws for subsequent verification and optimization of the finite element model.

[0050] S2, measure bushing damping and connection damping;

[0051] Specifically, when measuring bushing damping, high-precision measurement devices such as displacement sensors and force sensors are deployed at the connection points between the suspension and the vehicle frame—namely, the connection between the lower arm and the subframe (front and rear bushings), the connection between the anti-roll bar, and the upper support point of the shock absorber. Dynamic loads are applied to the bushings at these connection points under simulated vehicle driving conditions. Bushing parameters such as force and displacement are measured at different frequencies and amplitudes to obtain dynamic damping forces under different operating conditions. The measurement data, including load magnitude, displacement, and damping coefficient, are collected and recorded to provide a data foundation for subsequent analysis of the suspension's impact on chassis angular friction squeal.

[0052] When measuring joint damping, the brake caliper and steering knuckle are mounted on a dedicated stiffness test bench to simulate the constraints they experience in an actual vehicle. Displacement sensors, force sensors, and other measuring devices are installed at the joint between the caliper and steering knuckle, i.e., the caliper bracket. By applying excitations of varying frequencies (such as swept frequency excitation) to the brake caliper, the forces and displacements under complex braking conditions are simulated. The dynamic damping characteristics of the joint, including damping force and displacement response, are determined over a wide frequency range. The measurement data is collected and recorded to determine the joint damping value between the brake caliper and steering knuckle, providing key data for subsequent analysis of vibration transmission within the braking system.

[0053] S3. Establish an initial finite element model of the chassis angle. Combined with the bushing damping and connection damping data measured in step S2, perform complex modal analysis. Compare the complex modal analysis results with the characteristic frequencies collected in step S1 to construct a finite element model of the chassis angle that is consistent with reality.

[0054] Specifically, a finite element model of the chassis angle is established using finite element analysis software (such as ABAQUS), and the material properties, contact relationships, constraints and load conditions of each component of the chassis angle are defined in detail. The influence of dynamic damping is specially considered in the model. For the bushings at the connection points between the suspension and the frame, and the connection points between the brake caliper and the steering knuckle, the corresponding damping parameters are accurately set according to the damping data measured in step S2 to simulate the actual dynamic damping characteristics. A complex modal analysis is also performed on the model to obtain information such as the natural frequency, vibration shape and unstable mode of the chassis angle system. In order to verify the accuracy of the complex modal analysis results, the complex modal analysis results are compared with the test results in step S1 to ensure that the finite element model can accurately reflect the actual characteristics of the chassis angle system, providing a reliable basis for the subsequent analysis of the influence of dynamic damping characteristics on friction squeal.

[0055] S4. For the chassis corner finite element model, by changing the bushing damping and connection damping parameters, simulate the vibration response of the chassis corner system under different damping conditions, analyze the impact of different damping characteristic parameter changes on friction squeal, and determine the key damping factors affecting chassis corner friction squeal;

[0056] S5. Based on the analysis result of step S4, modify and optimize the damping characteristics of the chassis corner system to suppress chassis corner friction squeal;

[0057] Specifically, for the bushings at the suspension-frame connection and the brake caliper-steering knuckle connection, the damping parameters in the finite element simulation were modified based on the dynamic damping characteristics at different frequencies obtained from the experiments, and the simulation analysis was repeated. The modified results, which took into account the dynamic damping characteristics, were compared with the original chassis corner system to verify that the modified measures based on the damping characteristics reduced the occurrence and intensity of chassis corner friction squeal, and improved vehicle ride comfort and NVH performance.

[0058] This embodiment applies the above solution, and its main contents are:

[0059] 1. Chassis corner friction squeal test

[0060] First, this embodiment prepares Figure 2 The chassis corner test specimen shown includes suspension, wheels, and a complete braking system. This specimen is manufactured strictly according to the structure and parameters of the actual vehicle to simulate various braking conditions during actual driving, covering different vehicle speeds, brake pressures, and other conditions.

[0061] Then, high-precision testing equipment such as microphones and three-axis acceleration sensors equipped with a multi-channel data acquisition system are used to collect acoustic and vibration characteristics such as the sound pressure level during braking and the vibration acceleration of key chassis corner components; at the same time, speed sensors and pressure sensors are used to record operating conditions such as brake disc speed, brake pressure, and braking torque. Typical sensor arrangements are as follows: Figure 3 、 Figure 4 After data collection is completed, time domain analysis, frequency domain analysis and phase diagram analysis methods are used to extract Figure 5a and 5b The key information shown, such as the characteristic frequency of brake squeal, amplitude change trend and time-varying law, provides data support for subsequent analysis. Figure 5a is the time domain diagram of vibration acceleration, Figure 5b It is the frequency domain diagram of vibration acceleration.

[0062] It should be noted that in order to ensure that the chassis angle test samples can accurately simulate actual working conditions, in addition to strictly controlling the dimensions and assembly accuracy of the suspension, wheel hub and braking system components, it is also necessary to establish a systematic pre-detection mechanism for the test samples. Before each test, the key performance indicators of the samples are tested to ensure that the samples meet the test standards, reduce test errors caused by sample differences, and ensure the reliability of the collected data.

[0063] 2. Bushing Damping Measurement

[0064] During this process, this embodiment deploys high-precision displacement and force sensors at various connection points between the suspension and the vehicle frame—the lower arm and subframe connections (front and rear bushings), the stabilizer bar connection, and the upper fulcrum of the shock absorber. Dynamic loads are applied to the bushings under simulated vehicle driving conditions, and parameters such as the dynamic damping coefficient are measured at different frequencies and amplitudes. Load magnitude and displacement data are recorded to determine the bushing's damping characteristics.

[0065] 3. Connection Damping Measurement

[0066] In this process, the brake caliper and steering knuckle are mounted on a dedicated stiffness test bench to simulate the constraints of an actual vehicle. Displacement sensors, force sensors and other measuring devices are installed on the caliper bracket to apply excitation to the brake caliper to simulate the force conditions during braking. For details on the specific fixing method, excitation application method and measurement method, please refer to Figure 6 and Figure 7 The damping characteristics of the connection, such as the damping force and displacement response, are measured under different working conditions and the data is recorded to obtain the damping value of the connection between the brake caliper and the steering knuckle.

[0067] It should be noted that when measuring bushing damping and connection damping, in addition to using displacement sensors and force sensors to obtain basic data, vibration sensors can also be added to the suspension connection points and the connection between the brake caliper and the steering knuckle. The vibration sensor can monitor the vibration of the connection in real time, and combine the displacement and force measurement data to more comprehensively analyze the damping characteristics of the connection. At the same time, in the process of simulating braking force, loading is performed according to the different braking pressure and braking torque combinations that may occur during actual braking, and dynamic damping data under various working conditions and different frequency excitations is collected to obtain dynamic damping values ​​that are more in line with actual braking conditions, providing more accurate data support for subsequent analysis of vibration transmission within the braking system.

[0068] 4. Chassis Corner Finite Element Modeling and Complex Modal Analysis

[0069] This embodiment uses finite element analysis software (such as ABAQUS) to establish Figure 8 The chassis corner finite element model is shown in Figure 1. The material properties, contact relationships, constraints, and load conditions of each component of the chassis corner are defined in detail, such as Figure 9 As shown in the figure, based on the measured bushing and connection damping data, the damping parameters of the bushing at the suspension-frame connection and the brake caliper-steering knuckle connection were precisely set to simulate actual dynamic damping characteristics. Complex modal analysis was then performed to obtain information such as the system's natural frequencies, vibration modes, and unstable modes to understand the dynamic characteristics and stability of the chassis corner system. This was further compared with the results of previous chassis corner friction squeal tests (characteristic frequencies of brake squeal) to ensure that the finite element model accurately reflects the actual characteristics of the chassis corner system, providing a reliable foundation for subsequent analysis of the impact of dynamic damping characteristics on friction squeal.

[0070] During complex modal analysis, the complex eigenvalues ​​of the chassis angle system are obtained. The real part represents the system's attenuation characteristics, while the imaginary part corresponds to the system's natural frequency. A positive real part of the complex eigenvalue indicates the presence of an unstable mode, which may cause brake squeal.

[0071] 5. Analysis of factors affecting damping characteristics on friction squeal

[0072] Based on the established chassis corner finite element model, the vibration response of the chassis corner system under different damping conditions was simulated by changing parameters such as bushing damping and connection damping. The influence of damping characteristics on the probability of friction squeal, squeal frequency and squeal intensity was analyzed by combining numerical simulation and experimental verification, and the following results were obtained: Figure 10 The analysis results shown in the figure indicate that when the real part is greater than zero, the system is considered unstable and prone to brake squeal. Furthermore, the dynamic damping mechanism under different frequency ranges and braking conditions is studied to identify the key damping factors influencing chassis angular friction squeal.

[0073] It should be noted that when analyzing the factors affecting friction squeal due to damping characteristics, in addition to performing simulation analysis by varying parameters such as bushing damping and connection damping, the simulation results can also be calibrated in conjunction with actual test data. The acoustic and vibration characteristic information and operating condition data collected during the chassis corner friction squeal test are compared with the simulation results of the finite element model. Based on the comparison results, the model parameters are adjusted to make the model more consistent with the actual situation. In addition, a parameter sweep method is used to systematically study the effects of varying damping parameters within a certain range on the probability, frequency, and intensity of friction squeal. This, in turn, determines the sensitive range of key damping parameters, which can provide more precise direction for the subsequent formulation of suppression strategies.

[0074] 6. Friction squeal suppression based on damping characteristic modification

[0075] This embodiment makes targeted adjustments to the damping characteristics of the chassis angle system based on the analysis results of the factors affecting friction squeal due to the damping characteristics. For the bushings at the connection points between the suspension and the frame, and the connection points between the brake caliper and the steering knuckle, the damping parameters in the finite element simulation are modified according to the dynamic damping characteristics at different frequencies obtained from the test, and the simulation analysis is repeated. The modified results considering the dynamic damping characteristics are compared with the original system to verify the inhibitory effect of the modification of the damping characteristics on friction squeal. This optimization method is easy to implement and can provide strong guiding value for the adjustment of damping characteristics and the suppression of brake friction squeal in actual vehicles. It can effectively reduce the probability and intensity of friction squeal while ensuring vehicle performance, and provides a practical and efficient solution for the optimization of automobile braking systems.

[0076] It should be noted that when suppressing friction squeal by modifying damping characteristics, in addition to adjusting the damping characteristics of the bushings at the suspension connection points and the caliper-steering knuckle connection, the brake pad structure can also be fine-tuned to adjust the system's damping characteristics by changing the contact area and contact pressure distribution between the brake pad and the brake disc, thereby suppressing friction squeal. After implementing these modifications, not only should the effectiveness of suppressing friction squeal be verified through simulation, but the braking stability and comfort indicators of the vehicle during actual driving should also be verified through testing to ensure that while suppressing friction squeal, it does not negatively impact the vehicle's normal braking and driving experience.

[0077] Through the implementation of the above process, this embodiment comprehensively studies the relationship between the damping characteristics of the chassis angle and friction squeal, and establishes a chassis angle friction squeal suppression method based on the damping characteristics, which can provide support for the optimized design of the automobile braking system.

[0078] In summary, this approach significantly improves the accuracy of research on chassis corner friction squeal. Through comprehensive chassis corner friction squeal tests and precise bushing damping and connection damping measurements, a large amount of real and detailed operating condition data has been obtained. These damping data, covering various operating conditions such as different frequencies, vehicle speeds, and brake pressures, as well as key information such as the characteristic frequency and amplitude change trend of brake squeal, are accurately integrated into the chassis corner finite element model that takes dynamic damping into account. This breaks through the limitations of traditional research on the insufficient consideration of chassis corner damping characteristics and the finite element model's failure to fully consider actual dynamic damping changes. It achieves a more realistic simulation and analysis of the chassis corner friction squeal phenomenon and can more accurately predict the occurrence of friction squeal.

[0079] To address the complex impact of damping characteristics on friction squeal in the chassis corner system, this solution innovatively starts from the overall system and changes the vibration transmission path and energy dissipation method by adjusting the bushing damping at the connection point between the suspension and the frame, as well as the connection damping between the brake caliper and the steering knuckle. This method comprehensively considers the mechanism of dynamic damping in different frequency ranges and different braking conditions, and effectively analyzes the impact of damping characteristics on the probability of friction squeal, squeal frequency, and squeal intensity. This strategy enhances the accuracy of nonlinear damping modeling of the complex modal analysis model and the prediction accuracy of brake squeal. Combined with the modification of damping parameters, it can more effectively reduce the probability and intensity of chassis corner friction squeal, greatly improving the comfort and quietness of the vehicle.

Claims

1. A chassis angular friction squeal suppression method considering damping characteristics, characterized in that: The following steps are involved: S1. Conduct a chassis angular friction squeal test to collect acoustic and vibration characteristic information, operating condition data, and key brake squeal information during braking, including characteristic frequency, amplitude variation trend, and temporal variation of brake squeal. S2, measure bushing damping and connection damping; S3. Establish an initial finite element model of the chassis angle. Combined with the bushing damping and connection damping data measured in step S2, perform complex modal analysis. Compare the complex modal analysis results with the characteristic frequencies collected in step S1 to construct a finite element model of the chassis angle that is consistent with reality. S4. For the chassis corner finite element model, by changing the bushing damping and connection damping parameters, simulate the vibration response of the chassis corner system under different damping conditions, analyze the impact of different damping characteristic parameter changes on friction squeal, and determine the key damping factors affecting chassis corner friction squeal; S5. Based on the analysis result of step S4, the damping characteristics of the chassis corner system are modified and optimized to suppress chassis corner friction squeal.

2. The chassis angular friction squeal suppression method considering damping characteristics according to claim 1 is characterized in that: The specific process of step S1 is: preparing a chassis angle test sample including a suspension, a wheel hub and a complete braking system to simulate the braking condition of the vehicle during actual driving; High-precision testing equipment is used to collect acoustic and vibration characteristics during braking, including sound pressure level and vibration acceleration of key chassis corner components. Simultaneously, operating data is recorded, including brake disc speed, brake pressure, and braking torque. After data collection is completed, key information about brake squeal is extracted through time domain analysis, frequency domain analysis, and phase diagram analysis, including characteristic frequency, amplitude change trend, and change pattern over time.

3. The method for suppressing chassis angular friction squeal considering damping characteristics according to claim 1, characterized in that: The process of measuring the bushing damping in step S2 includes: applying dynamic loads to the bushings at the connection points between the suspension and the frame under simulated actual vehicle driving conditions, measuring the force and displacement parameters of the bushings at different frequencies and amplitudes, obtaining the dynamic damping force under different frequencies and other working conditions, and collecting and recording the measurement data, including load size, displacement, and damping coefficient.

4. The method for suppressing chassis angular friction squeal considering damping characteristics according to claim 3, characterized in that: The connection points between the suspension and the frame include the connection between the lower swing arm and the subframe, the connection between the lateral stabilizer bar and the upper support point of the shock absorber.

5. The chassis angular friction squeal suppression method considering damping characteristics according to claim 3 is characterized in that: The process of measuring the connection damping in step S2 includes: installing the brake caliper and the steering knuckle on a dedicated stiffness test bench to simulate the constraint conditions in an actual vehicle, applying excitation of different frequencies to the brake caliper at the connection between the caliper and the steering knuckle to simulate the force and displacement conditions under complex braking conditions, measuring the dynamic damping characteristics of the connection between the caliper and the steering knuckle under wide-band conditions, including the damping force and displacement response, collecting and recording the measurement data, and obtaining the connection damping value between the brake caliper and the steering knuckle.

6. The chassis angular friction squeal suppression method considering damping characteristics according to claim 5, characterized in that: The specific process of step S3 is: using finite element analysis software to establish an initial finite element model of the chassis corner, defining the material properties, contact relationships, constraints and load conditions of each component of the chassis corner; In the initial finite element model of the chassis corners, damping parameters were set for the bushings at the connection points between the suspension and the frame, as well as the connection points between the brake caliper and the steering knuckle, based on the measured bushing damping and connection damping data to simulate the actual dynamic damping characteristics. Perform complex modal analysis on the initial finite element model of the chassis angle to obtain the complex modal analysis results of the chassis angle system. Compare the complex modal analysis results with the characteristic frequencies collected in step S1. If the deviation between the two exceeds the threshold, correct the connection relationship in the initial finite element model of the chassis angle, and then perform complex modal analysis again until a corrected chassis angle finite element model that is consistent with the actual situation is obtained.

7. The chassis angular friction squeal suppression method considering damping characteristics according to claim 6, characterized in that: The complex modal analysis results include the natural frequencies, vibration shapes and unstable modes of the chassis angle system. The complex eigenvalues ​​of the chassis angle system are obtained during the complex modal analysis process.

8. The chassis angular friction squeal suppression method considering damping characteristics according to claim 7, characterized in that: The real part of the complex eigenvalue represents the attenuation characteristics of the chassis angle system, and the imaginary part corresponds to the natural frequency of the chassis angle system. When the real part of the complex eigenvalue is positive, it indicates that there is an unstable mode in the chassis angle system, which will cause brake squeal.

9. The method for suppressing chassis angular friction squeal considering damping characteristics according to claim 1, characterized in that: The step S4 specifically uses a method of combining numerical simulation with experimental data to analyze the influence of damping characteristics on the probability, frequency and intensity of friction squeal, and analyzes the mechanism of action of dynamic damping on friction squeal in different frequency ranges and different braking conditions, and determines the key damping factors affecting chassis corner friction squeal.

10. The chassis angular friction squeal suppression method considering damping characteristics according to claim 5, characterized in that: The step S5 modifies and optimizes the damping characteristics of the chassis angle system, including: Adjust the damping characteristics of the bushings at the suspension connection points, the calipers, and the steering knuckle connections; Fine-tune the structure of the brake pad and adjust the damping characteristics of the chassis angle system by changing the contact area and contact pressure distribution between the brake pad and the brake disc.

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