Dynamic Stiffness Testing Method and Device

Abstract

The present application discloses a dynamic stiffness test method and device, wherein the dynamic stiffness test method includes: measuring the amplitude data of the suspension system under actual working conditions; calculating the deformation of the suspension rubber under actual working conditions according to the measured amplitude data; exciting the vibration of the suspension system, and measuring the force of exciting the suspension system, and obtaining the transfer function of the suspension system under the action of external force; calculating the force and deformation of the suspension rubber under the unit excitation force of the external force; and calculating the dynamic stiffness of the suspension rubber according to the force and deformation of the suspension rubber under the unit excitation force of the external force. The present application can quickly obtain the dynamic stiffness of the suspension rubber, shorten the test adjustment cycle, and reduce the vehicle R&D cost.

Description

Technical Field

[0001] The present application relates to the technical field of vehicles, and particularly to a dynamic stiffness testing method and device. Background Art

[0002] In the NVH development of vehicles under conditions such as idling and acceleration, it is necessary to test the mid-high frequency dynamic stiffness of the mounting rubber to judge the influence of the mounting transmission on the in-vehicle noise and vibration. At present, most of the dynamic stiffness of rubber is tested by using a test bench. However, the test bench equipment of most vehicle manufacturers can only test frequencies below 500 Hz. If a vehicle manufacturer needs to obtain the mid-high frequency dynamic stiffness of the mounting rubber, it is necessary to entrust specialized domestic and foreign institutions for testing.

[0003] The existing dynamic stiffness testing method for mounting rubber has the following problems: First, the existing method requires the work of disassembling and assembling the mounts both on the whole vehicle and on the test bench, and special tooling parts need to be designed for the mount installation on the test bench, so that there are more preparatory works before the test and the required working hours are longer. In addition, since the existing method needs to use an exciter for excitation, the installation and debugging of the exciter require a lot of working hours and the test process is complex. In addition, the existing method usually uses the direct method to obtain the dynamic stiffness of the mounting rubber. Due to the existence of resonance of the tooling parts, the test data of the mid-high frequency dynamic stiffness is distorted and the test accuracy is low. Moreover, when the existing method uses the direct method to obtain the dynamic stiffness of the mounting rubber, due to the existence of resonance of the tooling parts, the effective range of its test frequency is low, and the frequency that can be tested is often less than 500 Hz.

[0004] The foregoing description is provided to give a general background information and does not necessarily constitute prior art. Summary of the Invention

[0005] The purpose of the present application is to provide a dynamic stiffness testing method and device, which can quickly obtain the dynamic stiffness of the mounting rubber, shorten the test calibration cycle, and reduce the vehicle R & D cost.

[0006] To achieve the above object, the technical solution of the present application is realized as follows:

[0007] In a first aspect, an embodiment of the present application provides a dynamic stiffness testing method, including: measuring the amplitude data of the mounting system under actual working conditions; calculating the deformation amount of the mounting rubber under actual working conditions according to the measured amplitude data; exciting the vibration of the mounting system and measuring the acting force that excites the mounting system to obtain the transfer function of the mounting system under the action of an external force; calculating the force and deformation amount of the mounting rubber under a unit excitation force of the external force; and calculating the dynamic stiffness of the mounting rubber according to the force and deformation amount of the mounting rubber under the unit excitation force of the external force.

[0008] As one of the implementation manners, measuring the amplitude data of the mounting system under actual working conditions further includes:

[0009] A vibration sensor is arranged at the connection between the bracket and the suspension rubber, and the vibration sensor is connected to a signal acquisition instrument. The signal acquisition instrument acquires the amplitude data collected by the vibration sensor and sends the acquired amplitude data to a test computer.

[0010] As one of the implementation manners, obtaining the transfer function of the suspension system under the action of an external force includes:

[0011] Obtaining the acceleration / force transfer function of the suspension system under the action of an external force;

[0012] According to the acceleration / force transfer function, obtaining the displacement / force transfer function of the suspension system.

[0013] As one of the implementation manners, obtaining the acceleration / force transfer function of the suspension system under the action of an external force includes:

[0014] Receiving the suspension system with the pipeline and grounding wire removed in the actual vehicle state to obtain a simplified suspension system;

[0015] Selecting test conditions and excitation amplitudes. Among them, the test conditions include: the preload and temperature are consistent with the actual vehicle idle condition. The selection of the amplitude includes: obtaining the amplitude of the suspension system in real time during the external force test and adjusting the external force until the amplitude corresponding to the idle condition, or selecting the external force hammering excitation amplitude data corresponding to the actual vehicle idle suspension system amplitude after multiple external force tests;

[0016] Measuring the acceleration amplitude of the active side bracket, the acceleration amplitude of the passive side bracket and the acting force of the external force. According to the measured acceleration amplitude and the acting force of the external force, obtaining the origin frequency response acceleration / force transfer function of the active side bracket of the suspension system and coherence, the origin frequency response acceleration / force transfer function of the passive side bracket and coherence, the acceleration / force transfer function from the active side bracket to the passive side bracket and coherence, and judging whether the coherence of the acceleration / force transfer function is higher than a preset value;

[0017] If the coherence is higher than the preset value, taking the obtained various transfer functions as the final transfer functions;

[0018] If the coherence is not higher than the preset value, continue to perform the steps of selecting test conditions and excitation amplitudes.

[0019] As one of the implementation manners, according to the acceleration / force transfer function, obtaining the displacement / force transfer function of the suspension system specifically includes:

[0020] The acceleration / force transfer function is integrated twice to obtain the displacement / force transfer function, where the origin frequency response displacement / force transfer function of the active side bracket , the origin frequency response displacement / force transfer function of the passive side bracket , and the displacement / force transfer function from the active side bracket to the passive side bracket .

[0021] As one of the implementation manners, calculate the force and deformation of the mounting rubber under the external force of unit excitation force, including:

[0022] According to the formula , calculate the force of the mounting rubber under the external force of unit excitation force , and according to the formula , calculate the deformation of the mounting rubber under the external force of unit excitation force , where is the origin frequency response displacement / force transfer function of the active side bracket, is the origin frequency response displacement / force transfer function of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, is the origin frequency response displacement / force transfer function of the active side bracket phase, is the displacement / force transfer function from the active side bracket to the passive side bracket phase, is the force on the active side bracket, is the angular velocity.

[0023] As one of the implementation manners, calculate the dynamic stiffness of the mounting rubber according to the force and deformation of the mounting rubber under the external force of unit excitation force, including: According to the formula , calculate the dynamic stiffness of the mounting rubber , where is the origin frequency response displacement / force transfer function of the active side bracket, is the origin frequency response displacement / force transfer function of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, is the origin frequency response displacement / force transfer function of the active side bracket phase, is the displacement / force transfer function from the active side bracket to the passive side bracket phase, is the angular velocity.

[0024] In a second aspect, an embodiment of the present application provides a dynamic stiffness testing device, including: a vibration sensor, a signal acquisition instrument, a test computer, an external force application device, and a force sensor. The test computer includes a deformation amount calculation module, a transfer function acquisition module, a force and deformation amount calculation module, and a dynamic stiffness calculation module, where;

[0025] The vibration sensor is used to measure the amplitude data of the suspension system under actual working conditions;

[0026] The deformation amount calculation module is used to calculate the deformation amount of the suspension rubber under actual working conditions according to the measured amplitude data;

[0027] The external force application device is used to excite the vibration of the suspension system;

[0028] The force sensor is used to measure the acting force that excites the suspension system;

[0029] The transfer function acquisition module is used to acquire the transfer function of the suspension system under the action of an external force;

[0030] The force and deformation amount calculation module is used to calculate the force and deformation amount of the suspension rubber under a unit excitation force of the external force;

[0031] The dynamic stiffness calculation module is used to calculate the dynamic stiffness of the suspension rubber according to the force and deformation amount of the suspension rubber under a unit excitation force of the external force.

[0032] The beneficial effects brought by the technical solution provided by the embodiment of the present application are:

[0033] The dynamic stiffness testing method and device provided by the embodiments of the present application measure the amplitude data of the mounting system under actual working conditions; calculate the deformation of the mounting rubber under actual working conditions according to the measured amplitude data; excite the vibration of the mounting system and measure the acting force that excites the mounting system to obtain the transfer function of the mounting system under external force; calculate the force and deformation of the mounting rubber under a unit exciting force of the external force; and calculate the dynamic stiffness of the mounting rubber according to the force and deformation of the mounting rubber under a unit exciting force of the external force. The present application conducts transfer function testing on the mounting system based on actual vehicle conditions, and then calculates the force and deformation of the mounting rubber under a unit force of the force hammer, thereby indirectly calculating the medium and high-frequency dynamic stiffness of the mounting rubber under actual vehicle conditions. Compared with the previous method of using bench testing, the process of disassembling and assembling the mounts on the vehicle and on the bench is eliminated, the preparatory work before testing is simplified, the working efficiency of the testing can be improved, and the R & D cycle can be shortened. In addition, the present application can eliminate the influence of the resonance of the tooling parts in the previous direct measurement method, extend the testing frequency to medium and high frequencies, and since the testing is carried out on the actual vehicle, it can be directly associated with the NVH problems of the actual vehicle, which helps to decompose the problems and lock in the causes, shorten the R & D cycle, and has actual application results in the NVH development of a certain vehicle model, which can improve the efficiency and reduce the cost. In addition, the present application uses the external force hammering method to test the medium and high-frequency dynamic stiffness of the mounting rubber, which simplifies the testing process compared with the previous method of using an exciter for excitation. In addition, in the previous direct method testing, due to the existence of the resonance of the tooling parts, the effective range of the testing frequency is relatively low, often less than 500 Hz. The method of the present application eliminates the influence of the resonance of the bracket and can extend the testing frequency to the effective range of the force hammer (the plastic hammer head can reach 1000 Hz, and the steel hammer head can reach 2000 Hz), expanding the range of the dynamic stiffness testing frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic flowchart of the dynamic stiffness testing method provided by the embodiments of the present application;

[0035] Figure 2a is a schematic diagram of the amplitude test of the mounting system under the idle condition of the present application;

[0036] Figure 2b is a schematic diagram of the deformation of the mounting rubber under the idle condition of the present application;

[0037] Figure 3a is a schematic flowchart of the acceleration / force transfer function test of the mounting system of the present application;

[0038] Figure 3b is a schematic diagram of the acceleration / force transfer function test of the mounting system of the present application;

[0039] Figure 4 is a schematic diagram of the comparison of the mounting amplitude tested under the idle condition and the hammering method of the present application;

[0040] Figure 5 Schematic diagram of the coherence of the acceleration / force transfer function of the suspension system of the present application;

[0041] Figure 6 Schematic diagram of the acceleration / force transfer function of the suspension system of the present application;

[0042] Figure 7 Schematic diagram of the displacement / force transfer function of the suspension system of the present application;

[0043] Figure 8 Schematic diagram of the force on the suspension rubber of the present application;

[0044] Figure 9 Schematic diagram of the deformation of the suspension rubber of the present application;

[0045] Figure 10 Schematic diagram of the dynamic stiffness of the suspension rubber of the present application;

[0046] Figure 11 Schematic diagram of the dynamic stiffness of the rubber before and after the countermeasures of the suspension system of the present application;

[0047] Figure 12 Schematic diagram of the in-vehicle front-row noise spectrum analysis before and after the countermeasures of the suspension system of the present application;

[0048] Figure 13 Block diagram of the dynamic stiffness test device provided by the embodiment of the present application. Detailed implementation manners

[0049] The technical solution of the present application will be further described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0050] Figure 1 It is a flow schematic diagram of the dynamic stiffness test method provided by the embodiment of the present application. The method can quickly obtain the dynamic stiffness of the suspension rubber, shorten the test tuning cycle, and reduce the vehicle R & D cost. Please refer to Figure 1 , the dynamic stiffness test method of this embodiment includes the following steps:

[0051] Step S101, measure the amplitude data of the suspension system under the actual working condition.

[0052] Among them, the actual working condition can be the idle speed condition. Idle speed is a working condition of the vehicle, which refers to the operating condition of the engine in the neutral gear. As Figure 2aAs shown, the suspension system may include a suspension rubber 20, an engine-side bracket 21, a body-side bracket 22, a pipeline 24, a grounding wire 25, etc. disposed between the body-side bracket 22 and the engine 23. The suspension rubber 20 is disposed between the engine-side bracket 21 and the body-side bracket 22, and plays a role in buffering and vibration damping for the vehicle.

[0053] In step S101, it may specifically include: disposing a vibration sensor 26 at the connection between the bracket and the suspension rubber 20, connecting the vibration sensor to a signal acquisition instrument 27. The vibration sensor 26 is used to collect the amplitude data of the suspension system. The signal acquisition instrument 27 obtains the amplitude data collected by the vibration sensor 26, and sends the obtained amplitude data to a test device, such as a test computer 28.

[0054] Furthermore, there are at least two vibration sensors 26, at least one is disposed on the engine-side bracket 21, and at least one is disposed on the body-side bracket 22. The vibration sensor 26 can be a three-axis accelerometer, and is used to test the amplitude data of the suspension system, such as the amplitude data of vibration acceleration.

[0055] In actual testing, a Siemens SCADAS signal acquisition instrument, a B&K4524B type three-axis accelerometer, and a test device, such as a test computer, etc. can be used. The test computer is connected to the signal acquisition instrument. The signal acquisition instrument sends the obtained amplitude data to the test computer. The two vibration sensors are respectively disposed on the engine-side bracket of the suspension and the body-side bracket, as Figure 2a shown.

[0056] Step S102, calculate the deformation amount of the suspension rubber under the actual working condition according to the measured amplitude data.

[0057] Among them, the actual working condition can be an idle condition. In step S102, it may specifically include: the vibration sensor can test and obtain the amplitude of the vibration acceleration of the engine-side (also known as the active side) bracket and the amplitude of the vibration acceleration of the body-side (also known as the passive side) bracket . The test device, such as a test computer, can obtain the deformation amount of the suspension rubber under the idle condition after spectrum analysis of the two amplitudes , as Figure 2b shown. Various existing spectrum analysis methods can be used for spectrum analysis.

[0058] Step S103, excite the vibration of the suspension system, measure the acting force that excites the suspension system, and obtain the transfer function of the suspension system under the action of an external force (for example, the external force can be applied by a force hammer 30).

[0059] Preferably, step S103 may specifically include step S1031 and step S1032.

[0060] Step S1031: Excite the vibration of the suspension system, measure the force exciting the suspension system, and obtain the acceleration / force transfer function of the suspension system under the action of an external force (for example, the external force can be applied by a force hammer).

[0061] Among them, an external force application device such as a force hammer 30 can excite the vibration of the suspension system. A force sensor connected to the external force application device can measure the force exciting the suspension system. The signal acquisition instrument is also used to obtain the force measured by the force sensor and send the obtained force data to the test computer. The test device obtains the acceleration / force transfer function. Among them, the force sensor can be arranged in the external force application device. The acceleration / force transfer function is the transfer function of the ratio of acceleration to force.

[0062] Preferably, in step S1031, it may specifically include, for example Figure 3a the following steps:

[0063] Step S301: Simplify the suspension system; Step S302: Select the test conditions and excitation amplitude; Step S303: Determine whether the coherence is higher than a preset value. If it is higher than the preset value, proceed to step S304. If it is not higher than the preset value, proceed to step S302; Step S304: Determine the final acceleration / force transfer function.

[0064] In step S301, it may specifically include: receiving the suspension system with the pipelines and grounding wires near the suspension rubber removed in the real vehicle state to obtain a simplified suspension system. The acceleration / force transfer function can be tested by the external force hammering method, using a Siemens SCADAS signal acquisition instrument, a PCB086C01 type force hammer, a B&K4524B type three-axis accelerometer, and a test computer, etc. Among them, as Figure 3b shown, the vibration sensor layout points are the same as those of the vibration isolation test layout of the suspension system in Figure 2a . During the test, in order to make the displacement of the passive side be the force on the rubber a single excitation, it is necessary to remove the pipelines and grounding wires near the suspension rubber to simplify the suspension system. Among them, is the angular velocity.

[0065] The test results of the suspension dynamic stiffness are usually affected by preload, temperature, and amplitude. To ensure that the preload and temperature are consistent with the actual vehicle idle condition, the test of the transfer function should be carried out on the actual vehicle after the actual idle test is completed. Therefore, when selecting the test conditions and excitation amplitude in step S302, it can be selected by the test equipment, such as the test computer. The test conditions can specifically include: the preload and temperature are consistent with the actual vehicle idle condition, and it is an actual vehicle. The selection of the amplitude includes: it is necessary to obtain the amplitude of the suspension system in real time during the external force test and adjust the external force to adjust to the amplitude corresponding to the idle condition, or select the external force hammer excitation amplitude data corresponding to the amplitude of the suspension system at the actual vehicle idle after the end of multiple external force tests to ensure that the transfer function test is consistent with the deformation of the suspension rubber under the actual idle condition Basically consistent. The amplitude data selected this time is as Figure 4 shown, and the amplitudes of the two are basically equivalent.

[0066] In steps S303 and S304, it can specifically include: measuring the acceleration amplitude of the active side bracket, the acceleration amplitude of the passive side bracket (which can be measured by a vibration sensor), and the acting force of the external force (for example, the external force is applied by a force hammer) (which can be measured by a force sensor). The test equipment, such as the test computer, can obtain the origin frequency response acceleration / force transfer function of the active side bracket of the suspension system according to the measured acceleration amplitude and the acting force of the external force and coherence, the origin frequency response acceleration / force transfer function of the passive side bracket and coherence, the acceleration / force transfer function from the active side bracket to the passive side bracket and coherence, and judge whether the coherence of the acceleration / force transfer function is higher than the preset value. The acceleration / force transfer function and phase are as Figure 6 shown. If the coherence is higher than the preset value, the obtained transfer functions are used as the final transfer functions; if the coherence is not higher than the preset value, the steps of selecting the test conditions and excitation amplitude are continued. The transfer function is usually expressed by the ratio of acceleration to force. According to the formula for obtaining the transfer function from acceleration and the acting force of the force hammer, it can be calculated by existing formulas, which will not be elaborated here. Here, when the strike of the force hammer and the acceleration response are at the same point, this point is called the origin. The acting force of the force hammer can be measured by the set force sensor, and the acceleration amplitudes of the active side bracket and the passive side bracket can be measured by vibration sensors.

[0067] In this way, it is ensured that the transfer functions obtained by the test have a coherence higher than the preset value in the frequency range of 200 - 1000 Hz, for example, higher than 0.9. The coherence can reflect whether the selected acceleration / force transfer function is reliable. When the coherence reaches 0.9, it indicates that the selected acceleration / force transfer function has high reliability.

[0068] In this embodiment, in order to obtain a high coherence within the frequency range of 200 Hz - 1000 Hz, a plastic hammer head or various other types of impact hammers can be used, and their coherence is as shown in Figure 5 . It is slightly lower at 200 Hz - 300 Hz, and a coherence above 0.9 is achieved within the range of 300 Hz - 1000 Hz, indicating that the test results have high reliability.

[0069] Step S1032: Obtain the displacement / force transfer function of the suspension system according to the acceleration / force transfer function.

[0070] The test equipment can obtain the displacement / force transfer function by performing double integration on the acceleration / force transfer function. The conversion result (i.e., the displacement / force transfer function) is as shown in Figure 7 . Among them, is the origin frequency response displacement / force transfer function of the active side bracket, , is the origin frequency response displacement / force transfer function of the passive side bracket, , is the origin frequency response acceleration / force transfer function of the active side bracket, is the origin frequency response acceleration / force transfer function of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, , is the acceleration / force transfer function from the active side bracket to the passive side bracket.

[0071] Step S105: Calculate the force and deformation of the suspension rubber under a unit excitation force of an external force.

[0072] The test equipment can calculate the force on the suspension rubber under a unit excitation force of an external force according to the formula, and the force on the suspension rubber is as shown in . The deformation Figure 8 of the suspension rubber under a unit excitation force of an external force can be calculated according to the formula , and the deformation of the suspension rubber is as shown in . Among them, Figure 9 : is the origin frequency response displacement / force transfer function of the active side bracket, is the origin frequency response displacement / force transfer function of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, is the origin frequency response displacement / force transfer function of the active side bracket is the phase of the displacement / force transfer function from the active side bracket to the passive side bracket, is the force on the active side bracket, is the angular velocity.

[0073] In step S106, the dynamic stiffness of the mounting rubber is calculated according to the force and deformation of the mounting rubber under the external unit excitation force.

[0074] The dynamic stiffness can be the mid-high frequency dynamic stiffness, for example, between the frequencies of 200 Hz and 1000 Hz. The test equipment can calculate the dynamic stiffness of the mounting rubber according to the formula The calculation result is as Figure 10 shown. Among them, is the origin frequency response displacement / force transfer function of the active side bracket, is the origin frequency response displacement / force transfer function of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, is the origin frequency response displacement / force transfer function of the active side bracket phase, is the displacement / force transfer function from the active side bracket to the passive side bracket phase, is the angular velocity.

[0075] This application extracts the mid-high frequency dynamic stiffness of the mounting rubber by using the test results of the real vehicle idle mounting system and the test results of the transfer function of the mounting system under the vehicle state. In order to verify the engineering practicability of this method, an experiment was carried out with the extraction of the mid-high frequency dynamic stiffness of 200 Hz - 1000 Hz under the idle condition of a certain vehicle model as an example, and further verified the change of the mid-high frequency dynamic stiffness of the rubber extracted by using this method after the change of the mounting rubber hardness and its influence on the in-vehicle idle noise.

[0076] The hardness of the original mounting rubber is 52, and the hardness of the rubber of the countermeasure part is reduced to 48. Using the above-mentioned hammering method test and extraction method, the dynamic stiffness of the right mounting rubber of rubbers with different hardnesses was extracted as shown in Figure 11 . The results show that after reducing the rubber hardness, the dynamic stiffness of the mounting rubber decreases by about near the frequency of 400 Hz, and decreases by about at the peak in the frequency range of 800 - 900 Hz.

[0077] At the same time, the improvement effect of the in-vehicle noise is as shown in Figure 12 . Since there are other path contributions besides the right mounting, the effect of the change in the dynamic stiffness of the rubber is not fully reflected in the sound pressure level. The sound pressure level of the in-vehicle front row noise decreases by about 2 - 3 dB(A) near the frequency of 400 Hz, and decreases by about 4 - 5 dB(A) in the frequency range of 800 - 900 Hz, and the total sound pressure level decreases by about 1.2 dB(A).

[0078] As can be seen from the above results, the method for testing and extracting the medium and high frequency dynamic stiffness of rubber based on the hammering method under the vehicle state can effectively extract the medium and high frequency dynamic stiffness of the mounting rubber and can be quickly applied to the NVH development of vehicle models. Taking the idle speed as an example, the extraction and application of the medium and high frequency dynamic stiffness of the right mounting rubber from 200 to 1000 Hz were studied and demonstrated. In the actual application process, this method can be extended to working conditions such as small throttle acceleration where the rubber limit is not touched according to the working load of the rubber, and the test range can also be extended to around 2000 Hz by using different hammer heads.

[0079] The following is the device embodiment of the present application. For details not described in detail in the device embodiment, reference can be made to the corresponding method embodiment above.

[0080] Figure 13 It is a block diagram of the dynamic stiffness test device provided by the embodiment of the present application. Please refer to Figure 13 The dynamic stiffness test device includes: a vibration sensor, a signal acquisition instrument, a test device (such as a test computer), an external force application device (such as a force hammer or other devices that can apply force), and a force sensor. The test computer includes a deformation amount calculation module 111, a transfer function acquisition module 112, a force and deformation amount calculation module 113, and a dynamic stiffness calculation module 114, where;

[0081] The vibration sensor is used to measure the amplitude data of the mounting system under actual working conditions;

[0082] The deformation amount calculation module is used to calculate the deformation amount of the mounting rubber under actual working conditions according to the measured amplitude data;

[0083] The external force application device is used to excite the vibration of the mounting system;

[0084] The force sensor is used to measure the acting force that excites the mounting system;

[0085] The transfer function acquisition module is used to acquire the transfer function of the mounting system under the action of an external force;

[0086] The force and deformation amount calculation module is used to calculate the force and deformation amount of the mounting rubber under the unit excitation force of the external force;

[0087] The dynamic stiffness calculation module is used to calculate the dynamic stiffness of the mounting rubber according to the force and deformation amount of the mounting rubber under the unit excitation force of the external force. Among them, the force sensor can be arranged in the external force application device.

[0088] Preferably, the vibration sensor is arranged at the connection between the bracket and the rubber. The vibration sensor is connected to the signal acquisition instrument. The vibration sensor is used to collect the amplitude data of the mounting system. The signal acquisition instrument obtains the amplitude data collected by the vibration sensor and sends the obtained amplitude data to the test computer.

[0089] Preferably, the signal collector is further configured to obtain the acting force measured by the force sensor and send the obtained acting force data to the test computer.

[0090] Preferably, the transfer function acquisition module is further configured to obtain the acceleration / force transfer function of the suspension system under the action of an external force; and obtain the displacement / force transfer function of the suspension system according to the acceleration / force transfer function.

[0091] Preferably, the transfer function acquisition module is further configured to receive the suspension system with the pipelines and grounding wires removed in the actual vehicle state to obtain a simplified suspension system; select the test conditions and excitation amplitude, where the test conditions include: the preload and temperature are consistent with the actual vehicle idle condition, and the selection of the amplitude includes: obtaining the amplitude of the suspension system in real time during the external force test and adjusting the external force to adjust to the amplitude corresponding to the idle condition, or selecting the external force hammering excitation amplitude data corresponding to the actual vehicle idle suspension system amplitude after multiple external force tests; measuring the acceleration amplitude of the active side bracket, the acceleration amplitude of the passive side bracket and the acting force of the external force, and obtaining the acceleration / force transfer function of the origin frequency response of the active side bracket of the suspension system and coherence, the acceleration / force transfer function of the origin frequency response of the passive side bracket and coherence, the acceleration / force transfer function from the active side bracket to the passive side bracket and coherence, and determine whether the coherence of the acceleration / force transfer function is higher than a preset value; if the coherence is higher than the preset value, use the obtained transfer functions as the final transfer functions; if the coherence is not higher than the preset value, continue with the steps of selecting the test conditions and excitation amplitude.

[0092] Preferably, the transfer function acquisition module is further configured to obtain the displacement / force transfer function by performing double integration on the acceleration / force transfer function, where is the displacement / force transfer function of the origin frequency response of the active side bracket, , is the displacement / force transfer function of the origin frequency response of the passive side bracket, , is the acceleration / force transfer function of the origin frequency response of the active side bracket, is the acceleration / force transfer function of the origin frequency response of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, , is the acceleration / force transfer function from the active side bracket to the passive side bracket, is the angular velocity.

[0093] Preferably, the force and deformation calculation module is further configured to calculate according to the formula , the force on the mounting rubber under the external unit excitation force is calculated , according to the formula , the deformation of the mounting rubber under the external unit excitation force is calculated , where is the origin frequency response displacement / force transfer function of the active side bracket, is the origin frequency response displacement / force transfer function of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, is the origin frequency response displacement / force transfer function of the active side bracket of the phase, is the displacement / force transfer function from the active side bracket to the passive side bracket of the phase, is the force on the active side bracket, is the angular velocity.

[0094] Preferably, the dynamic stiffness calculation module is further configured to calculate the dynamic stiffness of the mounting rubber according to the formula , , where is the origin frequency response displacement / force transfer function of the active side bracket, is the origin frequency response displacement / force transfer function of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, is the origin frequency response displacement / force transfer function of the active side bracket of the phase, is the displacement / force transfer function from the active side bracket to the passive side bracket of the phase, is the angular velocity.

[0095] In summary, the dynamic stiffness testing method and testing device provided by the embodiments of the present application measure the amplitude data of the mounting system under actual working conditions; calculate the deformation of the mounting rubber under actual working conditions according to the measured amplitude data; excite the vibration of the mounting system and measure the acting force that excites the mounting system to obtain the transfer function of the mounting system under external force; calculate the force and deformation of the mounting rubber under a unit exciting force of the external force; and calculate the dynamic stiffness of the mounting rubber according to the force and deformation of the mounting rubber under a unit exciting force of the external force. The present application conducts transfer function testing on the mounting system based on actual vehicle conditions, and then calculates the force and deformation of the mounting rubber under a unit force of the impact hammer, thereby indirectly calculating the medium and high frequency dynamic stiffness of the mounting rubber under actual vehicle conditions. Compared with the previous method of using bench testing, the process of disassembling and assembling the mounts on the vehicle and on the bench is eliminated, the preparation work before testing is simplified, the testing efficiency can be improved, and the R & D cycle can be shortened. In addition, the present application can eliminate the influence of the resonance of the tooling parts in the previous direct measurement method, expand the testing frequency to medium and high frequencies, and because the testing is carried out on the actual vehicle, it can be directly related to the NVH problems of the actual vehicle, which helps to decompose the problems and lock the causes, shorten the R & D cycle, and has actual application results in the NVH development of a certain vehicle model, which can improve efficiency and reduce costs. In addition, the present application uses the external force hammering method to test the medium and high frequency dynamic stiffness of the mounting rubber, which simplifies the testing process compared with the previous method of using an exciter for excitation. In addition, in the previous direct method testing, due to the existence of the resonance of the tooling parts, the effective range of the testing frequency is relatively low, often less than 500 Hz. The method of the present application eliminates the influence of the resonance of the bracket and can expand the testing frequency to the effective range of the impact hammer (the plastic hammer head can reach 1000 Hz, and the steel hammer head can reach 2000 Hz), expanding the range of the dynamic stiffness testing frequency.

[0096] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered that the scope described in this specification.

[0097] It should be noted that in this document, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus that includes a series of elements includes not only those elements but also other elements not expressly listed, or elements that are inherent to such process, method, article or apparatus. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or apparatus that includes the element. In addition, components, features, and elements with the same name in different embodiments of this application may have the same meaning or different meanings, and their specific meanings need to be determined based on their interpretations in the specific embodiments or further in combination with the context in the specific embodiments.

[0098] It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this document, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein can be interpreted as "when" or "upon" or "in response to determining". Furthermore, as used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context indicates otherwise. It should be further understood that the terms "comprise", "include" indicate the presence of the stated features, steps, operations, elements, components, items, kinds, and / or groups, but do not exclude the presence, occurrence or addition of one or more other features, steps, operations, elements, components, items, kinds, and / or groups. The term "or" and "and / or" as used herein are interpreted as inclusive, or meaning any one or any combination. Thus, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". An exception to this definition only occurs when the combination of elements, functions, steps or operations are mutually exclusive in some way.

[0099] It should be understood that although the steps in the flowchart in the embodiments of the present application are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, there is no strict order restriction for the execution of these steps, and they can be executed in other orders. Moreover, at least a part of the steps in the figure may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or sub-steps or stages of other steps.

[0100] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A dynamic stiffness testing method, characterized in that, it includes: measuring the amplitude data of the mounting system under actual working conditions; calculating the deformation of the mounting rubber under actual working conditions according to the measured amplitude data; exciting the vibration of the mounting system and measuring the acting force that excites the mounting system to obtain the transfer function of the mounting system under external force, including: obtaining the acceleration / force transfer function of the mounting system under external force, specifically including: receiving the mounting system with the pipelines and grounding wires removed in the actual vehicle state to obtain a simplified mounting system; selecting the test conditions and excitation amplitude; Measure the acceleration amplitude of the active-side bracket, the acceleration amplitude of the passive-side bracket, and the acting force of the external force. Based on the measured acceleration amplitude and the acting force of the external force, obtain the acceleration / force transfer function of the origin frequency response of the active-side bracket of the suspension system and coherence, and the acceleration / force transfer function of the origin frequency response of the passive-side bracket and coherence, and the acceleration / force transfer function from the active-side bracket to the passive-side bracket and coherence, and determine whether the coherence of the acceleration / force transfer function is higher than a preset value; if the coherence is higher than the preset value, taking the obtained transfer functions as the final transfer functions; if the coherence is not higher than the preset value, continue with the steps of selecting the test conditions and excitation amplitude; obtaining the displacement / force transfer function of the mounting system according to the acceleration / force transfer function; calculating the force and deformation of the mounting rubber under the unit excitation force of the external force, including: According to the formula , the force on the mounting rubber under the unit excitation force of the external force is calculated , according to the formula , the deformation of the mounting rubber under the unit excitation force of the external force is calculated , Among them, is the origin frequency response displacement / force transfer function of the active side bracket, is the origin frequency response displacement / force transfer function of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, is the origin frequency response displacement / force transfer function of the active side bracket phase, is the displacement / force transfer function from the active side bracket to the passive side bracket phase, is the force on the active side bracket, is the angular velocity; calculating the dynamic stiffness of the mounting rubber according to the force and deformation of the mounting rubber under the unit excitation force of the external force.

2. The method according to claim 1, characterized in that, measuring the amplitude data of the mounting system under actual working conditions further includes: setting a vibration sensor at the connection between the bracket and the mounting rubber, connecting the vibration sensor to a signal acquisition instrument, the signal acquisition instrument obtaining the amplitude data collected by the vibration sensor, and sending the obtained amplitude data to the test computer.

3. The method according to claim 1, characterized in that, selecting the test conditions and excitation amplitude, the test conditions include: the test conditions include: the preload and temperature are the same as those in the actual vehicle idle condition, and the selection of the amplitude includes: obtaining the amplitude of the mounting system in real time during the external force test and adjusting the external force until the amplitude corresponding to the idle condition, or selecting the external force hammer excitation amplitude data corresponding to the actual vehicle idle mounting system amplitude after multiple external force tests.

4. The method according to claim 1, characterized in that, obtaining the displacement / force transfer function of the mounting system according to the acceleration / force transfer function, specifically including: The acceleration / force transfer function is integrated twice to obtain the displacement / force transfer function, where the origin frequency response displacement / force transfer function of the active side bracket , the origin frequency response displacement / force transfer function of the passive side bracket , and the displacement / force transfer function from the active side bracket to the passive side bracket .

5. The method according to claim 1, characterized in that, Calculate the dynamic stiffness of the mounting rubber based on the force and deformation of the mounting rubber under the excitation force of the external force unit, including: according to the formula , calculate the dynamic stiffness of the mounting rubber , Among them, is the origin frequency response displacement / force transfer function of the active side bracket, is the origin frequency response displacement / force transfer function of the passive side bracket, is the displacement / force transfer function from the active side bracket to the passive side bracket, is the origin frequency response displacement / force transfer function of the active side bracket phase, is the displacement / force transfer function from the active side bracket to the passive side bracket phase, is the angular velocity.

6. A dynamic stiffness testing device, characterized in that, used to implement the dynamic stiffness testing method according to any one of claims 1 to 5, the device includes: a vibration sensor, a signal acquisition instrument, a test computer, an external force application device, a force sensor, and the test computer includes a deformation calculation module, a transfer function acquisition module, a force and deformation calculation module, and a dynamic stiffness calculation module, wherein; the vibration sensor is used to measure the amplitude data of the mounting system under actual working conditions; the deformation calculation module is used to calculate the deformation of the mounting rubber under actual working conditions according to the measured amplitude data; the external force application device is used to excite the vibration of the mounting system; the force sensor is used to measure the acting force that excites the mounting system; the transfer function acquisition module is used to obtain the transfer function of the mounting system under external force; the force and deformation calculation module is used to calculate the force and deformation of the mounting rubber under the unit excitation force of the external force; A dynamic stiffness calculation module, which is used to calculate the dynamic stiffness of the mounting rubber according to the force and deformation of the mounting rubber under the external force of a unit excitation force.

7. The device according to claim 6, wherein, the vibration sensor is arranged at the connection between the bracket and the rubber, the vibration sensor is connected to the signal acquisition instrument, the signal acquisition instrument acquires the amplitude data collected by the vibration sensor, and sends the acquired amplitude data to the test computer.

8. The device according to claim 6, wherein, the transfer function acquisition module is further configured to acquire the acceleration / force transfer function of the mounting system under the action of an external force; and acquire the displacement / force transfer function of the mounting system according to the acceleration / force transfer function.

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