CN114705449A

CN114705449A - Analysis method for separating vehicle structure vibration based on acceleration transmission path

Info

Publication number: CN114705449A
Application number: CN202210323136.0A
Authority: CN
Inventors: 王永亮; 刘浩; 郑卿卿; 罗挺; 龚贻鹏
Original assignee: Dongfeng Motor Corp
Current assignee: Dongfeng Motor Corp
Priority date: 2022-03-29
Filing date: 2022-03-29
Publication date: 2022-07-05

Abstract

The invention discloses an analysis method for separating vehicle structure vibration based on an acceleration transmission path, which comprises the following steps: establishing a transmission path analysis model of the vehicle; performing a test, and deducing and calculating a transfer function between the acceleration of the vehicle body side of the suspension bushing and the acceleration of a vehicle body response point; under the working condition of the whole vehicle, acquiring an acceleration spectrum of the vehicle body side of each suspension bushing and calculating the acceleration transmitted by each transmission path; and synthesizing the acceleration of the vehicle body response point under the whole vehicle working condition and the contribution of vibration transmission of each path. Acceleration-acceleration transfer functions of the suspension bushing from the automobile body side to each path of the automobile body response point are derived through tests, and then the transfer path analysis can be carried out by combining vibration acceleration data of the suspension bushing from the automobile body side under any working condition of the whole automobile.

Description

Analysis method for separating vehicle structure vibration based on acceleration transmission path

Technical Field

The invention relates to the technical field of vehicle vibration transmission path analysis, in particular to an analysis method for separating vehicle structure vibration based on an acceleration transmission path.

Background

In the running process of the vehicle, vibration is transmitted to a vehicle body structure by engine excitation and road excitation through suspension-suspension and other paths, so that the vehicle body structure (a steering wheel, a seat, a floor and the like) is forced to vibrate, the process is a typical multi-excitation-multi-path vibration coupling transmission process, and if the path transmission vibration design or the matching is not reasonable, the vibration of the whole vehicle is sensed by a driver, and the quality of the vehicle is seriously influenced.

Transfer Path Analysis (TPA), for example: the classical TPA technology can research the magnitude of vibration transmitted by each path and the contribution to the total vibration, has the technical advantages of positioning and identifying a key path from complex vibration coupling transmission, guiding the giving of a targeted improvement direction and the like, and is widely applied to the field of vehicle vibration noise. However, the classic TPA technology is time consuming and resource demanding to use. (1) More vibration sensors need to be arranged, a large number of vibration transfer functions need to be tested, and dynamic stiffness parameters of a bushing at a key position (suspension and suspension) need to be obtained, three weeks or so are needed from planning to finishing of one TPA test, if NVH problem analysis and troubleshooting tests are carried out, the time consumption is longer, and the classical TPA technology is not suitable for the development period of modern vehicles; (2) besides common NVH test equipment, the equivalent force of an excitation source at a suspension position is calculated by the dynamic stiffness parameter of the bushing, the dynamic stiffness parameter of the bushing is related to the excitation frequency, the excitation amplitude and the preload, a corresponding test method needs to be formulated according to the stress characteristics of the bushing under the working condition of the whole vehicle, the work load of acquiring the dynamic stiffness parameter of the bushing is large, inconvenience is caused, the cost is high, the price of a foreign supplier of the dynamic stiffness equipment within 200Hz of the two-way preload test frequency is up to more than 400 ten thousand, and a host factory does not have equipment for testing the dynamic stiffness of the bushing.

Disclosure of Invention

The invention aims to provide an analysis method for separating vehicle structure vibration based on an acceleration transmission path, and the analysis process is rapid, efficient and novel in concept.

In order to solve the above technical problem, the present invention provides an analysis method for separating vehicle structure vibration based on an acceleration transmission path, comprising the steps of:

the method comprises the following steps: establishing a transmission path analysis model of a vehicle by taking an engine of the vehicle as a vibration source, a suspension bushing of the engine as a transmission path and a vehicle body as a receptor;

step two: performing a test, and deducing and calculating the acceleration a of the suspension bush on the vehicle body side_i(ω) acceleration a of the vehicle body response point_{12_i}Acceleration-acceleration transfer function ATF between (ω)_i(ω) wherein i is the path number and w is the angular frequency;

step three: under the working condition of the whole vehicle, acquiring the acceleration a of the vehicle body side of each suspension bushing_{b_i}(ω) and according to said acceleration-acceleration transfer function ATF_i(ω) and acceleration a of the suspension bush on the vehicle body side_{b_i}(ω) calculating the acceleration a transmitted through each of the transmission paths_{p_i}(ω)；

Step four: acceleration a transmitted according to each of the transmission paths_{p_i}(omega) calculating the acceleration a of the vehicle body response point under the whole vehicle working condition_c(ω) and the contribution amount a of each of the transmission paths_{con_i}(ω)。

In the analysis method for separating the vehicle structure vibration based on the acceleration transmission path, the acceleration-acceleration transmission function on each path from the side of the vehicle body (namely a hammering point) of the suspension bushing to the vehicle body response point is derived through tests, and then the transmission path analysis can be carried out by combining the vibration acceleration data on the side of the vehicle body of the suspension bushing under any working condition of the whole vehicle, so that the equivalent effect at the position of the suspension bushing is not required to be obtained by using the dynamic stiffness parameter of the engine suspension bushing, the complex calculation process is omitted, the technical advantages of high efficiency, low cost and the like are achieved, meanwhile, the TPA analysis is carried out by using the acceleration-acceleration transmission function from the excitation point to the response point, the theoretical derivation is given, and the TPA technology is enriched.

The test is carried out by adopting a vibration exciter method or a force hammer method, and is simple and easy to implement.

As an improvement of the method for analyzing the vibration of the vehicle structure based on the separation of the acceleration transmission paths, in the step one, the suspension bushing of the engine comprises a left suspension, a right suspension and a lower pull rod suspension, the vibration of each suspension bushing has components in the directions of x, y and z, and the total number of the transmission paths is nine, wherein the transmission path numbers i in the directions of x, y and z of the left suspension correspond to 1, 2 and 3 respectively; the numbers i of x-direction transmission paths, y-direction transmission paths and z-direction transmission paths of the right suspension correspond to 4, 5 and 6 respectively; the rear suspension bushings x, y, z correspond to transmission path numbers i of 7, 8, 9, respectively.

Preferably, in the second step, when performing the test: and taking the position of the point 12 on the steering wheel as the vehicle body response point, and taking the direction vertical to the plane of the steering wheel as the target vibration direction.

Assuming that an automobile is acted by m exciting forces, each exciting force has three direction components of x, y and z, each exciting force component corresponds to n specific transmission paths, then the exciting force component and a corresponding transmission path generate a system response component, and the x, y and z directions of the automobile respectively refer to the automobile length direction, the automobile width direction and the automobile height direction.

According to the TPA theory, the vibration of three engines of a vehicle suspended in the x, y and z directions is taken as the input end of the corresponding transmission path, the vibration of a steering wheel 12 point in the direction vertical to the plane of the steering wheel is taken as a target point, and the engines have 9 transmission paths from a suspension bush to the target point, so that a 9 multiplied by 1 transmission path analysis model can be suggested.

As another improvement of the analysis method for separating the structural vibration of the vehicle based on the acceleration transmission path of the present invention, the second step includes:

step A1: testing the ith transmission path to obtain the acceleration a of the vehicle body response point_{12_i}(ω) and the suspension bush vehicle-body side input force F of the i-th transmission path_iAcceleration-force transfer function VTF between (omega)_i(ω)，

Where ω is an angular frequency, i is 1, 2, 3 … n, i is a path number, and n is the number of transmission paths.

Further, in the above-mentioned case,

wherein M is_{12_i}、B_{12_i}、K_{12_i}And the mass matrix, the damping matrix and the rigidity matrix are respectively corresponding to the structural system from the vehicle body side of the suspension bushing of the ith transmission path to the steering wheel 12 point.

Step A2: in the test of the ith transmission path, the acceleration a of the suspension bush on the vehicle body side is acquired_i(ω) and the suspension bush vehicle-body side input force F of the i-th transmission path_iAcceleration-force transfer function IPI between (omega)_i(ω)，

Further, in the above-mentioned case,

wherein M is_i、B_i、K_iThe local mass matrix, the local damping matrix and the local rigidity matrix of the ith path hammering point are respectively provided.

Step A3: according to the acceleration-force transfer function VTF_i(ω) and the acceleration-force transfer function IPI_i(ω) deriving and calculating the acceleration a of the i-th transmission path on the vehicle body side of the suspension liner_i(ω) acceleration a of the vehicle body response point_{12_i}(ω) the acceleration-acceleration transfer function ATF_i(ω)，

Preferably, the first and second liquid crystal materials are,

in a further aspect of the present invention,

in the above steps A1-A3, the acceleration-force transfer function VTF is directly obtained through experiments_i(omega) and IPI_i(omega), and skillfully obtaining the acceleration-acceleration transfer function VTF through derivation calculation of transfer function quotient_i(ω)。

As a further improvement of the method for analyzing the vibration of the structure of the decoupled vehicle based on the acceleration transfer path according to the present invention, in the third step, the ATF is determined according to the acceleration-acceleration transfer function_i(ω) and acceleration a of the suspension bush on the vehicle body side_{b_i}(ω) calculating the acceleration a transmitted through each of the transmission paths_{p_i}(ω) includes:

acceleration a of the suspension bush on the vehicle body side_{b_i}(ω) multiplying said acceleration-acceleration transfer function ATF_i(ω) obtaining the acceleration a transmitted through each of said transmission paths_{p_i}(ω)，

Calculating the formula:

a_{p_i}(ω)＝ATF_i(ω)*a_{b_i}(ω)。...(4)

in addition, in step three, the acceleration a of the vehicle body side of each suspension bushing is acquired_{b_i}(ω) using the vibration acceleration signal in the Z direction on the vehicle body side of the right suspension bushing as a reference point of each acceleration signal phase, and simultaneously acquiring the acceleration a of the vehicle body response point₀(ω) for the acceleration a of the vehicle body response point calculated in the fourth step_c(ω) verification was performed.

As another improvement of the analysis method for separating the structural vibration of the vehicle based on the acceleration transmission path, in the fourth step, the acceleration a of the vehicle body response point under the whole vehicle working condition is calculated_c(ω) includes:

each of saidAcceleration a transmitted by transmission path_{p_i}(omega) in the frequency domain, the acceleration a of the vehicle body response point is obtained by superposition synthesis calculation_c(ω)，

Calculating the formula:

further, in the fourth step, the contribution amount a of each transmission path under the whole vehicle working condition is calculated_{con_i}(ω) includes:

step B1: calculating the acceleration a of the vehicle body response point_cAmplitude of (ω) | a_c(ω) | and the phase phi,

is provided with

Then:

the acceleration a is described above_{12_i}(ω)、a_i(ω)、a_{b_i}(omega) and a_{p_i}(ω), and F_iAnd (omega) are complex numbers and comprise amplitude and phase information, and the calculation between the complex numbers is calculated according to a complex number algorithm.

Step B2: acceleration a transmitted according to each of the transmission paths_{p_i}(ω) and the acceleration a of the vehicle body response point_c(ω) calculating the contribution amount a of each of the transmission paths_{con_i}(ω)，

Calculating the formula:

wherein γ is a_{p_i}(ω) and a_c(ω) angle between them.

In conclusion, by adopting the analysis method for separating the vehicle structure vibration based on the acceleration transmission path, the vibration transmission and path identification of each path in the complex vibration system can be conveniently and quantitatively researched, and the TPA theory and the test technology are enriched. The vibration damping device can be applied to the field of vehicle vibration and can also be expanded and applied in other fields. The technical method has the advantages of high efficiency, low cost and strong application and reference values.

In terms of efficiency: by adopting the acceleration TPA method, the distribution of the sensors is relatively less in the experimental process, the dynamic stiffness parameters of the bushing are not needed, and the time from planning to finishing of one test is about three days; the classic TPA test requires about three weeks from planning to completion;

in terms of low cost: by adopting the acceleration TPA method, the common NVH test equipment can complete the work according to the technical steps and the calculation program in the invention without additionally purchasing equipment and testing and analyzing software; the classic TPA approach requires the purchase of expensive dynamic stiffness equipment to obtain the bushing dynamic stiffness parameters, as well as the purchase of commercial TPA software modules.

Drawings

In the drawings:

FIG. 1 is a flow chart of the method of the present invention.

FIG. 2 is a schematic view of the engine mount bushing position of the present invention.

FIG. 3 is a graph showing the acceleration-force transfer function VTF of the right suspension bush from the vehicle body side to the steering wheel 12 point target direction obtained by the experiment of the present invention_i(ω) spectral signal diagram.

FIG. 4 is a graph showing the acceleration-force transfer function IPI of the right suspension bush on the vehicle body side obtained by the experiment of the present invention_i(ω) spectral signal diagram.

FIG. 5 is a schematic view of the calculation of the present invention to obtain the right suspension bushing body side to steering wheelAcceleration-acceleration transfer function ATF of 12-point target direction_i(ω) spectral signal diagram.

FIG. 6 shows the vibration acceleration a of the right suspension bushing on the vehicle body side under the whole vehicle condition_{b_i}(ω) spectral signal diagram.

FIG. 7 shows that the acceleration a of the steering wheel in the target direction of 12 points is calculated under the whole vehicle working condition_c(ω) and the measured acceleration a of the body response point₀(ω) contrast spectrum signal plot.

FIG. 8 shows the vibration acceleration a transmitted to the steering wheel at 12 points on each transmission path under the whole vehicle working condition_{p_i}(ω)。

FIG. 9 shows the vibration pairs a transmitted by each path at a frequency of 32Hz under the working conditions of the whole vehicle_cContribution of (ω) is illustrated schematically.

Detailed Description

The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto.

Example 1

Definition of key terms:

acceleration TPA: the invention mainly relates to a method for analyzing the transmission path of the vehicle structure vibration by taking the acceleration at a key point as an intermediate parameter, deducing the acceleration-acceleration transfer function from a hammering point to a path according to the acceleration-force transfer function of the path and the acceleration-force transfer function of the hammering point and combining the acceleration data at the key point under the working condition of the whole vehicle.

Vehicle structure vibration: during the running process of the vehicle, the dynamic load of the excitation source (a power assembly, a road surface and the like) transmits vibration energy to the vehicle structure through the transmission path, so that the vehicle structure generates forced vibration.

Vibration synthesis and decomposition: by adopting the acceleration TPA method, the vibration of the response point is calculated by using an acceleration-acceleration transfer function and acceleration data at key points under the working condition of the whole vehicle, and the vibration of the response point is decomposed to each transfer path.

Path contribution amount: the vibration at the response point is decomposed into transmission paths, and the contribution relationship of the vibration transmitted through the transmission paths to the vibration at the response point is studied.

Fig. 1 illustrates an analysis method of separating vehicle structure vibration based on an acceleration transfer path according to the present invention. As shown in fig. 1, the analysis method for separating the vibration of the vehicle structure based on the acceleration transmission path includes the steps of:

the method comprises the following steps: an engine of a vehicle is used as a vibration source, a suspension bush of the engine is used as a transmission path, a vehicle body is used as a receiver, and a transmission path analysis model of the vehicle is established.

Step two: the test was conducted, and the acceleration a of the suspended bush on the vehicle body side was obtained_i(ω) acceleration a of the vehicle body response point_{12_i}(ω) transfer function ATF_i(ω), where ω is the angular frequency, i is the path number, i is 1, 2, 3 … n, and n is the number of transmission paths.

During testing, acceleration sensors are arranged on the position of a steering wheel 12 point and on the side of an engine suspension bush body, force sensors are arranged on a force hammer, as shown in fig. 2, the engine is connected with the vehicle body through three suspension bushes including a left suspension bush, a right suspension bush and a rear pull rod suspension bush, each suspension bush has vibration components in the directions of x, y and z and has nine transmission paths, wherein the path serial number i of the left suspension in the directions of x, y and z is 1, 2 and 3; the path numbers i in the x direction, the y direction and the z direction of the right suspension are 4, 5 and 6; the rear suspension bushings x, y, z-direction path numbers i are 7, 8, 9. And taking a steering wheel 12 point of the vehicle body as a response point, taking a direction vertical to the plane of the steering wheel as a target vibration direction, and performing a test by adopting a vibration exciter or a hammering method to directly measure the transfer function of each transfer path.

The description of the test procedure was carried out by the hammering method:

step A1: testing the ith transmission path to obtain the acceleration a of the vehicle body response point_{12_i}(ω) input force F with the vehicle body side of the suspension bushing of the i-th transmission path_iTransfer function VTF between (omega)_i(ω)。

X, y on the vehicle body side of the engine mount bushing,And (3) hammering the steering wheel in three directions by using a hammer in sequence, wherein a hammering point is as close to the elastic center of the suspension bush as possible, and the acceleration a of the 12 point of the steering wheel in the direction vertical to the plane of the steering wheel (the direction is taken as the target direction of the 12 point of the steering wheel) in the corresponding 9 transmission path tests is obtained in sequence_{12_i}(ω) and input force F corresponding to the vehicle body side of the suspension bush on the transmission path_iAcceleration-force transfer function VTF between (omega)_i(ω)：

Where ω is the angular frequency, i is the path number, i is 1, 2, 3 … n, and n is the number of transmission paths.

Further, in the above-mentioned case,

As shown in fig. 3, the acceleration-force transfer function VTF is the vehicle body side of the right suspension bushing to the target direction of steering wheel 12 point_iAnd the spectrum signal of (omega) comprises an amplitude spectrum and a phase spectrum, wherein three lines respectively refer to acceleration-force transfer function curves of corresponding transfer paths when hammering in the x direction, the y direction and the z direction.

Step A2: in the test of the i-th transfer path, the acceleration a of the suspension bushing on the vehicle body side is acquired_i(ω) input force F with the suspension liner body side of the i-th transmission path_iTransfer function IPI between (omega)_i(ω)。

And acquiring acceleration data around the hammer point (the distance between the acceleration sensor and the hammer point is less than 3cm) at the same time of the test, and acquiring an acceleration-force transfer function IPI (inertial force indicator) responding to the same direction as the excitation at the hammer point_i(ω)：

Further, in the above-mentioned case,

As shown in fig. 4, is the acceleration-force transfer function IPI of the right suspension liner on the body side (i.e., at the hammer point)_i(ω) spectrum signal, wherein three lines indicate acceleration-force transfer function curves corresponding to the transfer path when the hammer is hammered in x, y and z directions.

Step A3: according to transfer function VTF_i(omega) and transfer function IPI_i(ω) calculating the acceleration a of the suspension liner on the vehicle body side of the i-th transmission path_i(ω) acceleration a of the vehicle body response point_{12_i}(ω) transfer function ATF_i(ω)：

Further, in the above-mentioned case,

as shown in FIG. 5, the acceleration-acceleration transfer function ATF of the right suspension bushing body side to the target direction of the steering wheel 12 point_iAnd (omega) spectrum signals, wherein three lines indicate acceleration-acceleration transfer function curves of corresponding transfer paths when the hammer blows in the x direction, the y direction and the z direction respectively.

Acceleration dB:

step three: under the working condition of the whole vehicle, acquiring the acceleration a of the vehicle body side of each suspension bushing_{b_i}(ω) and according to a transfer function ATF_i(omega) and acceleration a of the suspension liner on the vehicle body side_{b_i}(ω) calculating the acceleration a transmitted through each transmission path_{p_i}(ω)：

Acceleration a of the suspension lining on the vehicle body side_{b_i}(ω) multiplying by transfer function ATF_i(ω) obtaining the acceleration a transmitted through each transmission path_{p_i}(ω)，

a_{p_i}(ω)＝ATF_i(ω)*a_{b_i}(ω)。...(4)

Data under any working condition can be measured, for example; the speed changer is in 2 gear, the engine speed is stable at about 1000rpm, the vehicle runs at a constant speed on a good asphalt road (the vibration transmission of a suspension path is reduced by reducing the load input of the road surface), the vibration acceleration signal in the Z direction of the vehicle body side of the right suspension bush is used as the reference point of each acceleration signal phase, and the vibration acceleration a of the vehicle body side of each suspension bush is obtained according to the step in the step two_{b_i}And (omega) spectrum signals comprise an amplitude spectrum and a phase spectrum.

Then, the acceleration a transmitted by each transmission path is calculated according to the formula (4)_{p_i}(ω). The vehicle has three suspension bushings, each suspension bushing has three translation directions, 9 vibration transmission paths are counted, the transmission is in 2 gears, and under the working condition that the rotating speed of the engine is stabilized at about 1000rpm, the final calculation result is shown in fig. 8, wherein the paths with obvious vibration transmission at 32Hz are 3, 6 and 7, and the paths are corresponding vibration transmission paths in the left suspension Z direction, the right suspension Z direction and the lower pull rod bushing X direction.

As shown in FIG. 6, the degree of acceleration a of the right suspension liner with respect to the vehicle body side vibration is shown_{b_i}(ω) spectrum, wherein three lines indicate acceleration-acceleration transfer function curves corresponding to the transfer path when the hammer is hammered in x, y, z directions, respectively.

In addition, the acceleration a of the response point of the vehicle body is obtained simultaneously₀(omega) for the acceleration a of the vehicle body response point calculated in the fourth step_c(ω) verification was performed.Namely, the acceleration a of the steering wheel 12 point target direction in the constant speed running of 1000rpm is obtained₀(ω) spectral signal, as shown in FIG. 7.

Step four: acceleration a transmitted according to each transmission path_{p_i}(omega) calculating the acceleration a of the vehicle body response point under the whole vehicle working condition_c(ω) and contribution amount a of each transmission path_{con_i}(ω). Path contribution amount: the vibration at the response point is decomposed into transmission paths, and the contribution relationship of the vibration transmitted through the transmission paths to the vibration at the response point is studied.

Acceleration a transmitted by each transmission path_{p_i}(omega) adding to obtain the acceleration a of the vehicle body response point_c(ω)，

Calculating the formula:

using the acceleration-acceleration transfer function ATF (omega) from the vehicle body side of the suspension lining to the target direction of 12 points of the steering wheel in the step two and the acceleration a of the vehicle body side of the suspension lining during the constant speed running at 1000rpm in the step three_{b_i}(ω) calculating the acceleration a of the steering wheel 12 in the target direction by the above equation (5)_c(ω) spectral signal, as shown in FIG. 7. The second-order excitation of the four-cylinder machine at 1000rpm is about 33Hz, as shown in FIG. 7, the direct test of 12-point vibration of the steering wheel is 4.8dB (33Hz), the calculation result of the acceleration TPA is 0.79dB (32Hz), the frequency of the calculation result of the acceleration TPA is basically consistent with that of the direct measurement result, the amplitude error is small, and the curve whole vehicle trend is relatively close, thereby illustrating the effectiveness of the acceleration TPA method in the invention on complex engineering problems.

Further, in step four, the contribution a of each transmission path under the working condition of the whole vehicle is calculated_{con_i}(ω) includes:

step B1: calculating the acceleration a of the response point of the vehicle body_cAmplitude and phase of (ω)

Then:

note that the acceleration "a" described above_{12_i}(ω)、a_i(ω)、a_{b_i}(omega) and a_{p_i}(ω), and F_iAnd (omega) are complex numbers and comprise amplitude and phase information, and the calculation between the complex numbers is calculated according to a complex number algorithm.

Step B2: acceleration a transmitted according to each transmission path_{p_i}(ω) acceleration a of vehicle body response point_c(ω) and acceleration a of the vehicle body response point_c(ω) amplitude, calculating the contribution a of each transmission path_{con_i}(ω)，

Calculating the formula:

wherein γ is a_{p_i}(omega) and a_c(ω) angle between them.

Calculating the vibration pairs a transmitted by each path according to the acceleration TPA method in the invention_c(ω) results As shown in FIG. 9, the transmission is in 2 nd gear, the engine speed is stable at about 1000rpm, and the acceleration amplitudes of

paths

3, 6, and 7 transmitted at 32Hz are 0.56m/s2, 0.3m/s2, and 1.09m/s2, respectively, for a_c(ω) vibration contribution with respective acceleration amplitude at a_cProjection in the (ω) direction.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the scope of protection thereof, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: after reading this disclosure, those skilled in the art will be able to make various changes, modifications and equivalents to the embodiments of the invention, which fall within the scope of the appended claims.

Claims

1. An analysis method for separating vehicle structure vibration based on an acceleration transmission path, characterized by comprising the steps of:

step two: performing a test, and deducing and calculating the acceleration a of the suspension bush on the vehicle body side_i(ω) acceleration a of the vehicle body response point_{12_i}Acceleration-acceleration transfer function ATF between (ω)_i(ω), where ω is angular frequency, i is path number, i is 1, 2, 3.. n, n is the number of transmission paths;

step three: under the working condition of the whole vehicle, acquiring the acceleration a of the body side of each suspension bushing_{b_i}(ω) and according to said acceleration-acceleration transfer function ATF_i(ω) and acceleration a of the suspension bush on the vehicle body side_{b_i}(ω) calculating the acceleration a transmitted through each of the transmission paths_{p_i}(ω)；

2. The method for analyzing structural vibration of a vehicle based on separation of acceleration transmission paths as claimed in claim 1, wherein in the first step, the suspension bushing of the engine comprises a left suspension, a right suspension and a lower pull rod suspension, and the vibration of each suspension bushing has components in x, y and z directions, which are nine transmission paths, wherein the x, y and z transmission path numbers i of the left suspension correspond to 1, 2 and 3; the numbers i of x-direction transmission paths, y-direction transmission paths and z-direction transmission paths of the right suspension correspond to 4, 5 and 6 respectively; the rear suspension bushings x, V, z correspond to transmission path numbers i of 7, 8, 9, respectively.

3. The method for analyzing structural vibration of a vehicle based on separation of an acceleration transmission path according to claim 1 or 2, wherein in the second step, at the time of the test: and taking the position of the point 12 on the steering wheel as the vehicle body response point, and taking the direction vertical to the plane of the steering wheel as the target vibration direction.

4. The method for analyzing structural vibration of a vehicle based on separation of an acceleration transmission path according to claim 1, wherein the second step comprises:

step A1: testing the ith transmission path to obtain the acceleration a of the vehicle body response point_{12_i}(ω) and the suspension bush vehicle-body side input force F of the i-th transmission path_iAcceleration-force transfer function VTF between (omega)_i(ω)；

Step A2: in the test of the ith transmission path, the acceleration a of the suspension bush on the vehicle body side is acquired_i(ω) and the suspension bush vehicle-body side input force F of the i-th transmission path_iAcceleration-force transfer function IPI between (omega)_i(ω)；

Step A3: according to the acceleration-force transfer function VTF_i(ω) and the acceleration-force transfer function IPI_i(ω) deriving and calculating the acceleration a of the i-th transmission path on the vehicle body side of the suspension liner_i(ω) acceleration a of the vehicle body response point_{12_i}(ω) the acceleration-acceleration transfer function ATF_i(ω)；

Where ω is the angular frequency, i is the path number, i is 1, 2, 3.. n, and n is the number of transmission paths.

5. The method for analyzing structural vibration of a vehicle based on separation of an acceleration transmission path according to claim 4, wherein said step A3 includes:

the acceleration-force transfer function VTF_i(ω) divided by the acceleration-force transfer function IPI_i(ω) obtaining said acceleration-acceleration transfer function ATF_i(ω)。

6. The method for analyzing structural vibrations of a vehicle based on separation of an acceleration transfer path as recited in claim 1, wherein in said third step, the ATF is performed according to the acceleration-acceleration transfer function_i(ω) and acceleration a of the suspension bush on the vehicle body side_{b_i}(ω) calculating the acceleration a transmitted through each of the transmission paths_{p_i}(ω) includes:

acceleration a of the suspension bush on the vehicle body side_{b_i}(ω) times the acceleration-acceleration transfer function ATF_i(ω) obtaining the acceleration a transmitted by each of said transmission paths_{p_i}(ω)。

7. The method for analyzing structural vibration of a split vehicle based on acceleration transmission path as claimed in claim 1, wherein in said step four, the acceleration a of the vehicle body response point under the entire vehicle operating condition is calculated_c(ω) includes:

acceleration a transmitted by each transmission path_{p_i}(omega) in the frequency domain, the acceleration a of the vehicle body response point is obtained by superposition synthesis calculation_c(ω)。

8. The method for analyzing structural vibration of a vehicle based on separation of acceleration transmission paths according to claim 7, wherein in the fourth step, the contribution a of each transmission path under the whole vehicle operating condition is calculated_{con_i}(ω) includes:

acceleration a transmitted according to the transmission path_{p_i}(ω) and the acceleration a of the vehicle body response point_c(ω) calculating the contribution amount a of each of the transmission paths_{con_i}(ω)。

9. The method for analyzing structural vibration of a decoupled vehicle based on an acceleration transmission path according to claim 1, wherein in the second step, a test is performed by using a vibration exciter method or a force hammer method.

10. The method for analyzing structural vibration of a vehicle based on separation of an acceleration transmission path according to claim 1, wherein in the third step, the method further comprises: under the working condition of the whole vehicle, acquiring the acceleration a of the vehicle body response point₀(ω) for the acceleration a of the vehicle body response point calculated in the fourth step_c(ω) verification was performed.