Evaluation method for vibration isolation performance of suspension

Abstract

The invention discloses a method for evaluating the vibration isolation performance of a suspension. The method comprises the following steps: building a finite element model of a suspension system; the method comprises the following steps: applying unit force excitation simulation to a wheel to obtain response data at each response point of a suspension, and summing the response of each contact point of the suspension and a vehicle body to obtain the response of a suspension assembly as a simulation result; and exporting a simulation result to obtain a suspension function transfer curve, analyzing the suspension function transfer curve, identifying a main contribution path and a mode, and evaluating the vibration isolation performance of the suspension based on the main contribution path and the mode. According to the method for evaluating the vibration isolation performance of the suspension, comprehensive evaluation is conducted on the basis of the finite element theory in combination with the modal and modal contribution analysis method, the transfer force analysis method and the transfer function analysis method, the vibration isolation performance of the suspension can be comprehensively and accurately evaluated, a main vibration transfer path is recognized, and the vibration isolation performance of the suspension is evaluated. And guidance is provided for the optimization direction of the vibration isolation performance of the suspension.

Description

Technical Field

[0001] The invention relates to the field of vehicle body noise control, and in particular to a method for evaluating suspension vibration isolation performance. Background Art

[0002] Road noise is an important performance indicator of vehicle NVH performance. The road noise performance of a vehicle is mainly affected by the suspension and body. About two-thirds of the road noise transmitted through the structure comes from the suspension system. Therefore, in the early stage of vehicle model project development, the evaluation of suspension vibration isolation performance independent of the body system is of great significance.

[0003] Traditional evaluation methods are mainly based on tests, which have disadvantages such as high cost, long cycle and low efficiency. The finite element method can effectively overcome these disadvantages and provide a new means for evaluating the vibration isolation performance of suspension. Summary of the invention

[0004] The object of the present invention is to provide a method for evaluating the vibration isolation performance of a suspension to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for evaluating the vibration isolation performance of a suspension, and building a finite element model of a suspension system;

[0006] By applying unit force excitation simulation to the wheel, the response data at each response point of the suspension is obtained, and by summing the responses of each contact point between the suspension and the vehicle body, the response of the suspension assembly is obtained as the simulation result;

[0007] The simulation results are exported to obtain the suspension transfer function curve, which is analyzed to identify the main contribution paths and modes, and based on this, the suspension vibration isolation performance is evaluated.

[0008] Preferably, the components of the suspension finite element model include: a subframe, a control arm, a rim, a shock absorber, a coil spring, a powertrain suspension bracket, a stabilizer bar, and a drive shaft component. The connection between the components is simulated using elastic units or rigid units, and dynamic stiffness parameters and damping parameters are assigned according to actual conditions.

[0009] Preferably, when analyzing the suspension transfer function curve, the suspension transfer function curve is compared with the performance target curve to determine whether the suspension vibration isolation performance meets the target requirement.

[0010] Preferably, the response force of each path from the suspension wheel center to the vehicle body is compared with the response force of the suspension assembly to obtain the contribution of each transmission path, contribution = (root mean square value of transmission path GPFORCE / root mean square value of suspension system GPFORCE) * 100%, and the contribution of each transmission path is sorted from large to small to determine the main contribution path, which refers to the transmission path that contributes the most to the peak value of the suspension transfer function.

[0011] Preferably, when analyzing the vibration isolation amount of the suspension bushing in the main contribution path, the vibration isolation amount of the suspension bushing is calculated to determine whether the vibration isolation amount of the suspension bushing meets the performance target requirements. If the vibration isolation amount of the suspension bushing does not meet the performance requirements, the dynamic stiffness of the bushing is optimized first. If the vibration isolation amount of the suspension bushing meets the performance requirements, the suspension component mode is adjusted or the suspension hard point position is optimized.

[0012] Preferably, the vibration isolation amount = [1-(acceleration of the passive side of the bushing / acceleration of the active side of the bushing)]*100%.

[0013] Preferably, the processing of simulation results is:

[0014] Export the GPFORCE result curve at the body side suspension installation point of each transfer path;

[0015] Calculate the RSS value of GPFORCE at the body side suspension installation point of each transfer path to obtain the suspension transfer function;

[0016] Calculate the RMS value of GPFORCE at the body side suspension installation point of each transfer path to obtain the root mean square value.

[0017] Preferably, the lower the value of the suspension transfer function curve within the target frequency range, the smaller the vibration transmission of the suspension within the frequency range, the better the vibration isolation performance, and the smaller the root mean square value, the smaller the overall transmission of road noise by the suspension.

[0018] Preferably, by applying unit force excitation simulation to the wheel, the specific working conditions are: SPC constrains the vehicle body side suspension mounting point and the tire grounding point;

[0019] The left and right wheels are stimulated by the same and opposite XYZ unit forces respectively, where the X and Z unit forces stimulate the suspension wheel center, and the Y unit force stimulates the suspension wheel rim near the ground, for a total of 6 working conditions;

[0020] GPFORCE is output at each transfer path body side suspension mounting point.

[0021] Preferably, the suspension system modes are calculated, and a PFMODE or MODESELECT modal contribution analysis is performed to identify the suspension modal vibration type with prominent modal contribution at the peak frequency of the suspension transfer function, so as to optimize the suspension modes.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a method for evaluating the vibration isolation performance of a suspension. The method is based on finite element theory and combines three methods, namely, modal and modal contribution analysis, transmission force analysis, and transfer function analysis, for comprehensive evaluation. The method can comprehensively and accurately evaluate the vibration isolation performance of the suspension, identify the main vibration transmission path, and provide guidance for optimizing the vibration isolation performance of the suspension. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] This embodiment provides a method for evaluating the vibration isolation performance of a suspension. 1. Construction of a finite element model of the suspension system

[0026] The suspension finite element model includes: subframe, control arm, rim, shock absorber, coil spring, powertrain suspension bracket, stabilizer bar, drive shaft and other components.

[0027] To improve simulation efficiency, the powertrain is represented by the CONM2 unit which contains mass inertia information.

[0028] The connection between the components is simulated using elastic units or rigid units, and dynamic stiffness parameters, damping parameters, etc. are assigned according to actual conditions.

[0029] Suspension transmission analysis unit force loading condition:

[0030] SPC constrains the body side suspension mounting point and the tire grounding point.

[0031] The left and right wheels are excited by the same and opposite XYZ unit forces respectively. The X and Z unit forces excite the suspension wheel center, and the Y unit force excites the ground side of the suspension rim (simulating the tire boundary). There are 6 working conditions in total.

[0032] GPFORCE is output at the body side suspension mounting point of each transfer path, that is, the response force of the point in the three directions of XYZ.

[0033] Simulation result processing

[0034] Export the GPFORCE result curve at the body side suspension installation point of each transfer path.

[0035] Calculate the RSS value of GPFORCE at the body side suspension installation point of each transfer path to obtain the suspension transfer function.

[0036] Calculate the RMS value of GPFORCE at the body side suspension installation point of each transfer path to obtain the root mean square value.

[0037] Simulation Results Analysis

[0038] The suspension transfer function curve and RMS value results are used to determine whether the suspension vibration isolation performance meets the requirements.

[0039] The lower the value of the suspension transfer function curve in the target frequency range, the smaller the vibration transmission of the suspension in the frequency range and the better the vibration isolation performance. The smaller the RMS value, the smaller the overall transmission of road noise by the suspension.

[0040] If the vibration isolation performance of the suspension does not meet the requirements, the ratio of each transmission path to the root mean square value of the GPFORCE of the suspension system is calculated to obtain the contribution of each transmission path.

[0041] Calculation formula: Contribution (%) = (transmission path GPFORCE root mean square value / suspension system GPFORCE root mean square value) * 100%

[0042] Sort the contribution of each transfer path from large to small and determine the main contribution path. The main contribution path refers to the transfer path that contributes the most to the peak value of the suspension transfer function.

[0043] Analyze the vibration isolation of the bushing in the main contribution path. If the vibration isolation of the suspension bushing is low, optimize the dynamic stiffness of the bushing until the vibration isolation of the bushing meets the requirements.

[0044] Calculation formula: Isolation Rate IR = [1-(bushing passive side acceleration / bushing active side acceleration)] * 100%

[0045] If the vibration isolation level of the suspension bushing is acceptable, calculate the suspension system mode, combine PFMODE and MODESELECT to perform modal contribution analysis, identify the modal vibration shape with prominent modal contribution at the peak frequency of the suspension transfer function, and optimize the suspension mode. The optimization direction can be considered: optimizing the structure of suspension components, adjusting its modal frequency, adjusting the bushing stiffness, adjusting the suspension hard point layout position, etc.

[0046] The evaluation method proposed in this embodiment objectively evaluates the vibration isolation performance of the suspension, which is convenient for horizontal comparison. This method can comprehensively and accurately evaluate the vibration isolation performance of the suspension, and provide quantitative evaluation indicators to facilitate horizontal comparison of different suspension schemes; clarify the optimization direction of the suspension vibration isolation performance. This method can identify the main contribution paths and modes at the peak frequency of the suspension transfer function, and provide a clear direction for the optimization of the suspension vibration isolation performance; shorten the vehicle development cycle and improve development efficiency. This method can simulate and analyze the suspension system independently from the body system, reduce the number of tests, shorten the vehicle development cycle, and improve development efficiency.

[0047] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for evaluating suspension vibration isolation performance, characterized in that: The steps include: Build a finite element model of the suspension system; By applying unit force excitation simulation to the wheel, the response data at each response point of the suspension is obtained, and by summing the responses of each contact point between the suspension and the vehicle body, the response of the suspension assembly is obtained as the simulation result; The simulation results are exported to obtain the suspension transfer function curve, which is analyzed to identify the main contribution paths and modes, and based on this, the suspension vibration isolation performance is evaluated.

2. The method for evaluating suspension vibration isolation performance according to claim 1, characterized in that: The components of the suspension finite element model include: subframe, control arm, rim, shock absorber, coil spring, powertrain suspension bracket, stabilizer bar, and drive shaft components. The connections between the components are simulated using elastic units or rigid units, and dynamic stiffness parameters and damping parameters are assigned according to actual conditions.

3. The method for evaluating suspension vibration isolation performance according to claim 1, characterized in that: When analyzing the suspension transfer function curve, compare the suspension transfer function curve with the performance target curve to determine whether the suspension vibration isolation performance meets the target requirements.

4. The method for evaluating suspension vibration isolation performance according to claim 1, characterized in that: Compare the response force of each path from the suspension wheel center to the vehicle body with the response force of the suspension assembly to obtain the contribution of each transfer path, contribution = (root mean square value of transfer path GPFORCE / root mean square value of suspension system GPFORCE) * 100%, sort the contribution of each transfer path from large to small, and determine the main contribution path. The main contribution path refers to the transfer path that contributes the most to the peak value of the suspension transfer function.

5. The method for evaluating suspension vibration isolation performance according to claim 4, characterized in that: When analyzing the vibration isolation of the suspension bushing in the main contribution path, calculate the vibration isolation of the suspension bushing to determine whether it meets the performance target requirements. If the vibration isolation of the suspension bushing does not meet the performance requirements, prioritize bushing dynamic stiffness optimization. If the vibration isolation of the suspension bushing meets the performance requirements, adjust the suspension component mode or optimize the suspension hard point position.

6. The method for evaluating suspension vibration isolation performance according to claim 1, characterized in that: Vibration isolation amount = [1-(acceleration on the passive side of the bushing / acceleration on the active side of the bushing)]*100%.

7. The method for evaluating suspension vibration isolation performance according to claim 1, characterized in that: Processing of simulation results: Export the GPFORCE result curve at the body side suspension installation point of each transfer path; Calculate the RSS value of GPFORCE at the body side suspension installation point of each transfer path to obtain the suspension transfer function; Calculate the RMS value of GPFORCE at the body side suspension installation point of each transfer path to obtain the root mean square value.

8. The method for evaluating suspension vibration isolation performance according to claim 1, characterized in that: The lower the value of the suspension transfer function curve within the target frequency range, the smaller the vibration transmission of the suspension within the frequency range, the better the vibration isolation performance, and the smaller the root mean square value, which indicates that the suspension transmits less overall road noise.

9. The method for evaluating suspension vibration isolation performance according to claim 8, characterized in that: By applying unit force excitation simulation to the wheel, the specific working conditions are: SPC constrains the body side suspension mounting point and the tire grounding point; The left and right wheels are stimulated by the same and opposite XYZ unit forces respectively, where the X and Z unit forces stimulate the suspension wheel center, and the Y unit force stimulates the suspension wheel rim near the ground, for a total of 6 working conditions; GPFORCE is output at each transfer path body side suspension mounting point.

10. The method for evaluating suspension vibration isolation performance according to claim 9, characterized in that: Calculate the suspension system mode, perform PFMODE or MODESELECT modal contribution analysis, identify the suspension modal vibration shape with prominent modal contribution at the peak frequency of the suspension transfer function, and use it to optimize the suspension mode.