Method for evaluating suspension vibration isolation performance

Abstract

The application discloses an evaluation method for suspension vibration isolation performance, and builds a finite element model of a suspension system; response data of each response point of the suspension is obtained by simulating unit force excitation applied to wheels; the response of the suspension assembly is obtained by summing the responses of each point of the suspension in contact with the vehicle body, and is taken as a simulation result; a suspension transfer function curve is derived from the simulation result, the suspension transfer function curve is analyzed, main contribution paths and modes are identified, and the suspension vibration isolation performance is evaluated based on the same. The application provides an evaluation method for suspension vibration isolation performance, which is based on finite element theory, combines modal and modal contribution analysis, transfer force analysis and transfer function analysis, and comprehensively evaluates the suspension vibration isolation performance, identifies main vibration transmission paths, and provides guidance for the optimization direction of the suspension vibration isolation performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicle body noise control, in particular to a suspension vibration isolation performance evaluation method. BACKGROUND

[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 the vehicle body, and about two-thirds of the road noise transmitted by the structure comes from the suspension system. Therefore, in the early stage of vehicle project development, the evaluation of the suspension vibration isolation performance independent of the vehicle body system is of great significance.

[0003] The traditional evaluation method is mainly based on tests, which has the disadvantages of high cost, long cycle and low efficiency. The finite element method can effectively overcome these disadvantages and provide a new means for the evaluation of the suspension vibration isolation performance. SUMMARY

[0004] The purpose of the present application is to provide a suspension vibration isolation performance evaluation method to solve the problems raised in the background.

[0005] To solve the above technical problems, the present application provides the following technical scheme: a suspension vibration isolation performance evaluation method, a suspension system finite element model is built;

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

[0007] The suspension transfer function curve is derived from the simulation result, the suspension transfer function curve is analyzed, the main contribution path and mode are identified, and the suspension vibration isolation performance is evaluated based on this.

[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 connections between the components are simulated using elastic elements or rigid elements, and dynamic stiffness parameters and damping parameters are assigned according to the actual situation.

[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 requirements.

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

[0011] Preferably, the vibration isolation amount of the suspension bushing in the main contribution path is analyzed, the vibration isolation amount of the suspension bushing is calculated, whether the vibration isolation amount of the suspension bushing meets the performance target requirement is judged, if the vibration isolation amount of the suspension bushing does not meet the performance requirement, the bushing dynamic stiffness optimization is preferentially carried out, and if the vibration isolation amount of the suspension bushing meets the performance requirement, the suspension component modal or the suspension hard point position is adjusted.

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

[0013] Preferably, the simulation result is processed:

[0014] The GPFORCE result curve of each transfer path at the suspension mounting point of the vehicle body is derived.

[0015] The RSS value of GPFORCE at the suspension mounting point of the vehicle body of each transfer path is calculated to obtain the suspension transfer function.

[0016] The RMS value of GPFORCE at the suspension mounting point of the vehicle body of each transfer path is calculated to obtain the root mean square value.

[0017] Preferably, 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, and the smaller the root mean square value, the smaller the overall transmission amount of the suspension to road noise.

[0018] Preferably, the simulation is carried out by applying a unit force excitation to the wheel, and the specific working condition is that the SPC constrains the suspension mounting point of the vehicle body and the tire contact point.

[0019] The left and right wheels are respectively excited by unit forces in the same direction and in the opposite direction in the XYZ direction, wherein the X and Z direction unit forces excite the suspension wheel center, and the Y direction unit force excites the suspension rim near the ground side, and there are 6 working conditions.

[0020] GPFORCE is output at the suspension mounting point of the vehicle body of each transfer path.

[0021] Preferably, the suspension system modal is calculated, the PFMODE or MODESELECT modal contribution amount analysis is carried out, the modal vibration mode with prominent modal contribution amount at the peak frequency of the suspension transfer function is identified, and the suspension modal is optimized.

[0022] Compared with the prior art, the method has the beneficial effects that:

[0023] The application provides an evaluation method for the vibration isolation performance of a suspension. The method is based on the finite element theory, and combines modal and modal contribution amount analysis, transfer force analysis, and transfer function analysis to comprehensively evaluate the vibration isolation performance of the suspension, identify the main vibration transmission path, and provide guidance for the optimization direction of the vibration isolation performance of the suspension. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort 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 system. 1. Construction of a finite element model of the suspension system.

[0026] The suspension finite element model includes components such as: subframe, control arms, wheel rims, shock absorbers, coil springs, powertrain suspension brackets, stabilizer bars, and drive shafts.

[0027] To improve simulation efficiency, the powertrain is represented using CONM2 elements that contain mass inertia information.

[0028] The connections between components are simulated using elastic or rigid elements, and dynamic stiffness parameters, damping parameters, etc. are assigned according to the actual situation.

[0029] Suspension transfer function analysis under unit force loading conditions:

[0030] SPC constrains the vehicle body side suspension mounting points and tire contact points.

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

[0032] GPFORCE is output at each suspension mounting point on the vehicle side along the transmission path, which is the response force at that point in the XYZ directions.

[0033] Simulation result processing

[0034] Export the GPFORCE result curves at the vehicle side suspension mounting points for each transmission path.

[0035] Calculate the RSS value of GPFORCE at the suspension mounting point on the vehicle side of each transmission path to obtain the suspension transmission function.

[0036] Calculate the RMS value of GPFORCE at the suspension mounting point on the vehicle side of each transmission path to obtain the root mean square value.

[0037] Simulation Result Analysis

[0038] The suspension vibration isolation performance is determined by analyzing the suspension transfer function curve and root mean square value.

[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 root mean square value, the smaller the overall transmission of the suspension to road noise.

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

[0041] The calculation formula is: contribution (%) = (transfer path GPFORCE root mean square value / suspension system GPFORCE root mean square value)*100%

[0042] The contribution of each transfer path is sorted from large to small to determine the main contribution path. The main contribution path refers to the transfer path that contributes 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 suspension bushing vibration isolation is low, optimize the dynamic stiffness of the bushing until the bushing vibration isolation meets the requirements.

[0044] The calculation formula is: isolation rate IR (Isolation Rate) = [1-(bushing passive side acceleration / bushing active side acceleration)]*100%

[0045] If the suspension bushing isolation level is acceptable, calculate the suspension system modal, combine PFMODE and MODESELECT for modal contribution analysis, and identify the modal shape with prominent modal contribution at the peak frequency of the suspension transfer function. Optimize the suspension modal. The optimization direction can be considered: optimize the structure of the suspension parts, adjust the modal frequency, adjust the bushing stiffness, adjust the suspension hard point arrangement position, etc.

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

[0047] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method of evaluating suspension vibration isolation performance, characterized by: The method comprises the following steps: Building a finite element model of the suspension system; By applying a unit force excitation to the wheels, the response data of each response point of the suspension is obtained, and the response of the suspension assembly is obtained by summing the responses of each point of contact between the suspension and the vehicle body, serving as the simulation result; Exporting the simulation result to obtain the suspension transfer function curve, analyzing the suspension transfer function curve, identifying the main contribution path and mode, and evaluating the suspension vibration isolation performance based on the same; Subframe, control arm, rim, shock absorber, helical spring, powertrain suspension support, stabilizer bar, drive shaft components, the connection between each component is simulated using elastic or rigid elements, and dynamic stiffness parameters and damping parameters are assigned according to the actual situation; 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; 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 transmission path, the contribution=(transmission path GPFORCE root mean square value / suspension system GPFORCE root mean square value) * 100%, sort the contribution of each transmission path from large to small to determine the main contribution path, which is the transmission path with the largest contribution to the suspension transfer function peak value; When analyzing the suspension bushing vibration isolation of the main contribution path, calculate the suspension bushing vibration isolation, determine whether the suspension bushing vibration isolation meets the performance target requirements, if the suspension bushing vibration isolation does not meet the performance requirements, prioritize the optimization of the bushing dynamic stiffness, if the suspension bushing vibration isolation meets the performance requirements, adjust the suspension component mode or optimize the suspension hard point position; By applying a unit force excitation to the wheels, the response data of each response point of the suspension is obtained, and the response of the suspension assembly is obtained by summing the responses of each point of contact between the suspension and the vehicle body, serving as the simulation result; Excite the left and right wheels with the same and opposite XYZ direction unit force respectively, among which the X and Z direction unit force excites the suspension wheel center and the Y direction unit force excites the suspension rim near the ground, a total of 6 working conditions; Output GPFORCE at the suspension mounting point of each transmission path on the vehicle body side.

2. The method of claim 1, wherein: Vibration isolation=[1-(bushing passive side acceleration / bushing active side acceleration)]*100%.

3. The method of claim 1, wherein: Simulation result processing: Export the GPFORCE result curve at the suspension mounting point of each transmission path on the vehicle body side; Calculate the RSS value of GPFORCE at the suspension mounting point of each transmission path on the vehicle body side to obtain the suspension transfer function; Calculate the RMS value of GPFORCE at the suspension mounting point of each transmission path on the vehicle body side to obtain the root mean square value.

4. The method of claim 1, wherein: The lower the value of the suspension transfer function curve in the target frequency range, the smaller the vibration transmission of the suspension in this frequency range, and the better the vibration isolation performance, and the smaller the root mean square value, the smaller the overall transmission of the suspension to road noise.

5. The method of claim 1, wherein: Calculate the suspension system mode, perform PFMODE or MODESELECT modal contribution analysis, identify the suspension modal shape with prominent modal contribution at the suspension transfer function peak frequency, and optimize the suspension mode.