A passenger car body comfort stiffness testing device and testing method thereof

Abstract

The present invention provides a passenger car body comfort stiffness test device and a test method thereof, the device comprising: a base plate assembly, the base plate assembly comprising first and second adjustment connection parts symmetrically arranged, the first and second adjustment connection parts comprising at least one connection hole, the base plate assembly being connected to the passenger car body surface through the connection hole; an excitation mounting seat fixedly connected to the base plate assembly. The present invention achieves that the excitation source and the body surface do not move relative to each other during the test process, thereby ensuring the accuracy of the data. Moreover, the present invention can standardize the test result evaluation method, and no longer uses the transfer function from the excitation to the response point as the basis for evaluation, but uses a scalar value as the test result.

Description

Technical Field

[0001] The invention relates to the field of automobile comfort stiffness testing, in particular to a passenger car body comfort stiffness testing device and a testing method thereof. Background Art

[0002] With the development of the automobile industry, people have higher expectations for comfort in addition to traditional safety and handling for passenger cars, so the requirements for the acoustics and vibration of the passenger compartment (body) are also constantly increasing. The body is the frame of the car, and the quality of the frame directly affects the acoustic and vibration levels. The assessment of body stiffness is an important part and a key indicator for evaluating the acoustic and vibration performance of the car.

[0003] At present, the main evaluation methods for vehicle body stiffness in the industry are dynamic stiffness and static stiffness. Among them, the schematic diagram of vehicle body static stiffness test is as follows Figure 1 The static stiffness test scenario is: fix the center position of the vehicle body, and apply a pair of equal and opposite force couples F / 2 on both sides. By measuring the strain of the vehicle body under the action of the known force couple, the rigidity of the vehicle body is calculated. Since the force is applied statically, the method of measuring the vehicle body stiffness is called the static stiffness test of the vehicle body.

[0004] In the static stiffness test, the loading force is static, that is, the excitation itself does not carry frequency information. This test method generally fixes the center position of the vehicle body and applies a pair of equal and opposite force couples on both sides of the vehicle body. The rigidity of the vehicle body is calculated by measuring the strain of the vehicle body under the action of a force couple of known size.

[0005] The test method for dynamic stiffness is to test the various free modes of the vehicle body in a free state. Static stiffness test can well evaluate the stiffness level of the vehicle body at 1 to 5 Hz, and dynamic stiffness test can well evaluate the stiffness level of the vehicle body after the first mode (generally greater than 20 Hz, 20 Hz is used as a reference in this article), but there is a lack of effective evaluation methods for the stiffness of the vehicle body between 5 and 20 Hz. At the same time, during the operation of the vehicle, the various modes of the chassis are generally between 10 Hz and 20 Hz, such as synchronous wheel hopping, asynchronous wheel hopping, etc.

[0006] In the existing evaluation methods, it is generally required that the first-order mode of the vehicle body is higher than the chassis mode, and the static stiffness of the vehicle body is used to characterize the vibration isolation level of the vehicle body when it is excited by various modes of the chassis. Although this evaluation method can roughly evaluate the vibration comfort of the vehicle body when it is excited by the chassis during driving, it is too rough. At the same time, it is difficult to unify the evaluation methods for dynamic stiffness and static stiffness because the test methods themselves are quite different. When testing the static stiffness of the vehicle body, the vehicle body has fixed constraints; when testing the dynamic stiffness of the vehicle body, the vehicle body has no constraints.

[0007] Currently, there is also a method of loading vertical (Z-direction) excitation at locations with greater rigidity at the bottom of the vehicle body, such as cross beams and longitudinal beams, and evaluating it through transfer functions. Figure 2 The figure shows a schematic diagram of the vehicle body beam plane plus excitation test. In this vehicle body beam plane plus excitation test scenario, the vehicle body is suspended by air springs, and a load is applied to the beam plane position of the vehicle body to measure the vehicle body rigidity. The schematic diagram shows a method of suspending a vehicle body by air springs, wherein the air springs and the vehicle body are attached at points A1 to A4, and applying a load to the beam plane position of the vehicle body to measure the vehicle body rigidity. As shown in the figure, the excitation points are placed at the front B1 position of the left longitudinal beam of the vehicle body and the rear B2 position of the right longitudinal beam, marked with black rectangular blocks. The characteristic of this method is that the excitation needs to be loaded at a plane position where the local stiffness of the vehicle body is large, generally speaking, the longitudinal beam plane position of the vehicle body.

[0008] The existing transfer function is calculated by dividing the test value of the test response point (such as the steering wheel, seat rail, etc., the specific response point is selected according to the requirements of the evaluation problem) by the excitation value of the excitation point. The defects of this evaluation method are as follows:

[0009] First, the load is located on the plane of the vehicle body. Although the rigidity is relatively large, the excitation point is not fixedly connected to the vehicle body. During the test, the excitation point is prone to slip, which will produce X- and Y-direction components, making the calculation of the transfer function no longer accurate because the excitation value is unstable.

[0010] Second, the repeatability of the test is relatively poor. The data of the same vehicle model in the same state may vary greatly when repeating the same test, which affects the credibility of the test data. Although this phenomenon can be appropriately improved by taking the average after multiple different tests, the credibility of the test data is still unsatisfactory. Therefore, even if the test cost is high, it is difficult to obtain relatively accurate test data.

[0011] Third, the selection of loading points is greatly affected by the actual structural design of the vehicle body. If the loading point is not located at the hard point of the vehicle body, it is even impossible to ensure that the loading position of the same model before and after the modification is consistent, which seriously affects the comparability of test data and its guiding significance for development, and is not conducive to the establishment of test standardization. It affects the ability to summarize the problems in vehicle development through test data of different models and guide the test purpose of the next generation of models, and reduces the economy and scalability of the test.

[0012] Fourth, the response points of the test are arranged and selected as needed for each test, and there is no comparability between different models, which further reduces the possibility of establishing test standardization.

[0013] Fifth, the comfort of the vehicle body cannot be characterized by a single numerical value, but must be expressed using different transfer functions, and the transfer functions are not comparable in different projects.

[0014] In view of the above problems, there is an urgent need for a comparable and repeatable method to test and compare the comfort stiffness of passenger car bodies. Summary of the invention

[0015] It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are exemplary and explanatory and are intended to provide further explanation of the disclosure.

[0016] In order to overcome the above problems, the present invention provides a passenger car body comfort stiffness test method, which uses a unified method to evaluate the entire low frequency band (1-100Hz), ensuring the consistency of the evaluation standard; at the same time, the excitation point can be connected to the body rigidity, and each model is loaded at the same body hard point position, ensuring the accuracy of the data, the repeatability of the test and the comparability between the models. Thereby reducing the test cost, reducing the necessity of repeated tests, and increasing the guiding significance of the test conclusions for development.

[0017] In order to solve the above technical problems, the present invention provides a passenger car body comfort stiffness testing device, which is characterized by comprising:

[0018] A floor assembly, the floor assembly comprising first and second adjustable connecting parts symmetrically arranged, the first and second adjustable connecting parts comprising at least one connecting hole, the floor assembly being connected to the body surface of the passenger vehicle through the connecting hole;

[0019] The excitation mounting seat is fixedly connected to the base plate assembly.

[0020] Preferably, the present invention further provides a passenger car body comfort stiffness testing device, characterized in that:

[0021] The base plate assembly includes a T-shaped rectangular steel plate, and the excitation mounting seat includes a solid cylinder, which is welded at the symmetric center of the T-shaped rectangular steel plate.

[0022] The present invention also provides a testing method using the above-mentioned testing device, characterized in that the testing method comprises:

[0023] Step 1: Test initialization;

[0024] Step 2: install K passenger car body comfort stiffness test devices at K response points and excitation points respectively, and install the combination of the exciter and the acceleration sensor on the excitation mounting seat of each test device respectively;

[0025] Step 3, obtaining K×K transfer functions of the acceleration sensors on the K test devices after the exciter on each test device emits an excitation:

[0026] Where: K er is the rth order equivalent stiffness, g r is the r-th order modal structural damping ratio, N is the degree of freedom, is the frequency ratio, N is a natural number greater than or equal to 6, and K is a natural number greater than or equal to 2;

[0027] The equivalent stiffness K identified by the transfer function er Used as a vehicle body comfort stiffness evaluation value.

[0028] Preferably, the present invention further provides a test method, characterized in that the r-th order modal structural damping ratio is determined by the half-power bandwidth:

[0029]

[0030] Where: a ,ω b is the circular frequency corresponding to the half-power point, and f a and f b is the corresponding frequency.

[0031] Preferably, the present invention further provides a testing method, characterized in that the testing method further comprises:

[0032] Step 4: Verify the validity of the test by calculating the spectral coherence function of the two transfer functions in each group, wherein the spectral coherence function formula is as follows:

[0033]

[0034] Among them, X and Y are two response points or excitation points, R xy is the spectral coherence function, S xx (ω) is the autospectrum of point X, S yy (ω) is the self-spectrum of point Y, S xy (ω) is the cross spectrum of points X and Y.

[0035] Preferably, the present invention further provides a testing method, characterized in that the testing method further comprises:

[0036] Step 5: Obtain the comfort stiffness value through the intersection of the curve of the M-order polynomial function and the Y-axis, wherein the polynomial function is expressed as:

[0037] Y=axM …+bx 9 +cx 8 +dx 7 +ex 6 +fx 5 +gx 4 +hx 3 +ix 2 +jx+k

[0038] Wherein, M is a natural number.

[0039] Preferably, the present invention further provides a testing method, characterized in that the K response points and excitation points include left and right front shock absorbers and vehicle body attachment points and left and right rear shock absorbers and vehicle body attachment points.

[0040] Preferably, the present invention further provides a testing method, characterized in that in the step three, the exciter provides white noise excitation of 1 to 100 Hz.

[0041] Preferably, the present invention further provides a testing method, characterized in that the initialization further comprises:

[0042] Establish the coordinate system and geometric model of the vehicle body comfort stiffness, and determine the coordinates of the measuring points;

[0043] Using air springs to suspend the vehicle body in a horizontal state;

[0044] Confirm the status of the vehicle body, including confirming whether the weighing accessories meet the test requirements and removing movable parts.

[0045] Compared with the prior art, the present invention has the following advantages:

[0046] The method of the present invention realizes that the excitation source and the body surface do not move relative to each other during the test process, thus ensuring the accuracy of the data. In addition, the present invention can standardize the test result evaluation method, no longer using the transfer function from the excitation to the response point as the basis for evaluation, but using a scalar value as the test result. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to preferred embodiments of the present disclosure, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numerals will be used in all drawings to represent the same or similar parts. In addition, although the terms used in the present disclosure are selected from well-known and commonly used terms, some of the terms mentioned in the present disclosure may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description herein. In addition, it is required to understand the present disclosure not only by the actual terms used, but also by the meaning implied by each term.

[0048] The above and other objects, features and advantages of the present invention will become apparent to those skilled in the art from the detailed description of the present invention with reference to the accompanying drawings below.

[0049] Figure 1 It is a schematic diagram of the traditional body static stiffness test;

[0050] Figure 2 This is a schematic diagram of the traditional body beam plane plus excitation test;

[0051] Figure 3 It is a schematic diagram of a vehicle body beam plane excitation test using the method of the present invention;

[0052] FIG4 is a structural diagram of parts of a comfort stiffness testing device used in the method of the present invention;

[0053] Figures 4a to 4c They are respectively a front view, a left view and a stereoscopic view of the test device used in the method of the present invention;

[0054] Figure 5 It is a schematic diagram of the test device combination in the application scenario of the method of the present invention;

[0055] Figure 6 Shown is a schematic diagram of the distribution of measuring points and excitation points of this test method;

[0056] Figure 7 The figure shows a schematic diagram of the test process of this test method;

[0057] Figure 8 1 is a schematic diagram showing the original test results of the transfer function of this test method;

[0058] Fig. 9 The figure shows a schematic diagram of the calculation results of comfort stiffness of this test method.

[0059] Reference numerals

[0060] 1 - Bottom plate assembly

[0061] 2 - Excitation mounting seat

[0062] 3-Adjustable steel plate

[0063] 31 - Bolt hole

[0064] 51, 52 - Connecting bolts

[0065] 6. Vibrator

[0066] 7 - Acceleration sensor DETAILED DESCRIPTION

[0067] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0068] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0069] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0070] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0071] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0072] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0073] Flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed accurately in order. On the contrary, various steps may be processed in reverse order or simultaneously. At the same time, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0074] Figure 3 The present invention is a schematic diagram of a vehicle body beam plane excitation test using the method of the present invention.

[0075] The excitation points B1 to B4 are marked with black rectangular blocks, and the black circles with white crosses within the air spring and body attachment points A1 to A4 are marked. The excitation points B1 to B4 are selected at the attachment points between the left and right front shock absorbers and the body and the attachment points between the left and right rear shock absorbers and the body. At this time, the body is suspended by the air spring, thus forming a free-free boundary condition. The height of the air spring should be adjusted to a uniform force state, and the body should be horizontal, and measured with a level ruler. This ensures that the rigidity of the body support system can be ignored in the test results.

[0076] Compared with the traditional test Figure 2 In comparison, the excitation points in the test method of the present invention are arranged at the attachment points between the left and right front shock absorbers and the vehicle body and the attachment points between the left and right rear shock absorbers and the vehicle body, a total of four points, such as Figure 3 The position marked by the black rectangle in the figure. This ensures that the excitation points are comparable between different models, making it easier to standardize the test method. At the same time, the body structures of different models vary greatly. In order to not only ensure the standardization of the test method, but also standardize the evaluation of the test results, the present invention also standardizes the test response points and arranges the response points at the same position as the excitation points, that is, at the left and right front shock absorbers and the body attachment points and the left and right rear shock absorbers and the body attachment points, a total of four points.

[0077] The excitation point refers to the point where the exciter 6 applies the excitation input, and the response point refers to the point where the acceleration sensor 7 measures. In this article, the excitation point and the response point can be understood as one point, that is, corresponding to any point in B1~B4. Although it is impossible to ensure that the two are placed at the same point in physical space, by placing the two points on the same plane of a fixture with great rigidity, the normalization of the excitation point and the response point is basically achieved. The attachment points A1~A4 refer to the installation points of the left and right front and rear shock absorbers 6 and the vehicle body on the vehicle body side.

[0078] Likewise, the design requires that the excitation point and the vehicle body are closely connected and do not shift to ensure the accuracy of the data. Therefore, in the test operation, the present invention uses a specially designed test device to perform the test.

[0079] The present invention adopts the hard points of the vehicle body as the response points, so that the selection of the response points can be standardized and not affected by the specific vehicle structure, thereby facilitating data comparison between different vehicle models. In addition, the hard points of the vehicle body are adopted as the excitation points, so that the selection of the excitation points can be standardized and not affected by the specific vehicle structure, thereby facilitating data comparison between different vehicle models.

[0080] The present invention uses a test device to make the excitation point and the response point actually located at the same position, thereby improving the accuracy of the test. In addition, the test device makes the excitation point and the response point actually located at the same position, so that the comfort stiffness value as the calculation result is not affected by different body structures when comparing different vehicle models, thereby increasing the credibility of the method for comparing different body structures.

[0081] Figures 4a to 4c This is a structural diagram of the components of the comfort stiffness testing device of the present invention. Figure 4a is its main view, Figure 4b yes Figure 4a The left view of Figure 4c It is a stereogram.

[0082] The comfort stiffness testing device comprises a bottom plate assembly 1 connected to the vehicle body surface and an excitation mounting seat 2.

[0083] The bottom plate assembly 1 is connected to the excitation mounting seat 2 by welding to ensure the rigidity requirement of the connection. The bottom plate assembly 1 further includes two left and right adjustment connection parts, thereby connecting the device to the vehicle body.

[0084] In a preferred embodiment, the adjustment connection portion adopts an adjustable steel plate 3, each adjustable steel plate 3 includes at least one connection hole. The adjustment connection portion shown in the figure adopts three connection holes. During testing, one of the connection holes is specifically selected according to the connection hole positions of different models of vehicle bodies to increase the versatility of the device.

[0085] Furthermore, since the connection holes on the vehicle body are fixed in position, it is considered to achieve adaptive connection with the vehicle body through the adjustable connection part on the test device.

[0086] In the preferred embodiment shown in the figure, the base plate assembly 1 adopts a T-shaped rectangular steel plate, the excitation mounting seat 2 is a solid cylinder, the solid cylindrical excitation mounting seat 2 is welded to the symmetry center of the T-shaped rectangular steel plate, and three bolt holes 31 are opened on the left and right sides of the T-shaped rectangular steel plate. Each installation only needs to use one bolt hole on the left and one bolt hole on the left to connect the test device to the vehicle body.

[0087] also, Figure 5 A schematic diagram of the test using the comfort stiffness test device shown in Figure 4 is given. It shows Figure 3 The working status of the 4 incentive points mentioned in. Figure 3The four excitation points mentioned in the figure have the same working state, and each excitation point includes a comfort stiffness test device (i.e., the parts structure diagram of the comfort stiffness test device including the excitation mounting seat 2 and the fixture bottom plate assembly 1 in FIG4 ). The comfort stiffness test device is connected to the shock absorber and the body attachment point on the body side through the two left and right connecting bolts 51 and 52 passing through the fixture bottom plate assembly 1, and the contact surface between the test device and the body is shown in the figure. The exciter 6 for applying excitation and the acceleration sensor 7 for testing response are installed on the excitation mounting seat 2 of the test device.

[0088] The test device is used for comfort stiffness tests on different vehicle models. By moving the adjustable steel plate 3 left and right, the bolt hole 31 on the appropriate adjustment steel plate 3 is selected, and the fixture is fixed to the vehicle body surface using one connecting bolt 51, 52 on the left and one on the right through the bolt hole 31 of the device. The comfort stiffness test device can be adaptively connected to the vehicle body surface with different hole spacings through the adjustable steel plate 3, so that one device can be used for comfort stiffness tests on different vehicle models, thereby expanding the use range of the device, improving the reuse rate and test efficiency, and reducing costs; the excitation mounting seat 2 is a cylinder. When performing a comfort stiffness test, the exciter 6 as the excitation source and the acceleration sensor 7 as the response point need to be fixed on the excitation mounting seat 2.

[0089] Next, combine Figure 5 The test process is specifically described with reference to the test device.

[0090] Step 1: Establish the coordinate system:

[0091] Set the rear of the vehicle to the +X direction, upward to the +Z direction, and rotate 90 degrees counterclockwise from the +X direction to the +Y direction.

[0092] Step 2: Establishment of test geometry model:

[0093] Determine the measurement point location, measure the measurement point coordinates, and establish the geometric model of the vehicle body comfort stiffness. Generally speaking, the measurement points are selected at the attachment points between the left and right front shock absorbers and the vehicle body and the attachment points between the left and right rear shock absorbers and the vehicle body, a total of four points. The specific locations are as follows: Figure 3 Middle B1~B4.

[0094] Step 3: Measuring point identification and numbering:

[0095] Usually the measuring points are arranged along the main frame of the vehicle body, a total of 8, such as Figure 6 Mark 1 to 8. Four of them are the exciter load loading points, and the other four are the acceleration measurement points at the corresponding positions. They are located at the installation holes of the front suspension shock absorber and the rear suspension shock absorber respectively. Measure the coordinates of the measuring points and record them. For similar models, use consistent measuring point positions as much as possible to facilitate data comparison.

[0096] Step 4: Car body suspension:

[0097] Use air springs to form free-free boundary conditions. The air springs are positioned as follows: Figure 3 As shown in A1 to A4. The air spring is arranged at the lifting position. The height of the air spring should be adjusted to a uniform stress state, and the vehicle body should be horizontal. It should be measured with a level ruler. If the level cannot be guaranteed, the inflation pressure of the air spring can be adjusted on the premise that the air spring is arranged in a reasonable position. Generally speaking, the inflation pressure of the four air springs should be kept consistent. More than four protective brackets are arranged under the vehicle body to prevent the vehicle body from accidentally falling and causing danger.

[0098] Step 5: Vehicle status confirmation:

[0099] Whether the accessories are in compliance with the test requirements, accessories not related to the vehicle body need to be removed. For a vehicle body with a sunroof, the movable part of the sunroof needs to be removed. Also avoid parts that may produce knocking sounds due to vehicle body vibration (for example, if there are loose parts, fix or remove them, add cushions between parts that knock against each other, etc.).

[0100] Step 6: Arrangement of the exciter 6 and pasting of the acceleration sensor 7:

[0101] Install the comfort stiffness test device in Figure 4 on Figure 3 The response points and excitation points B1 to B4 shown are the attachment points between the left and right front shock absorbers and the vehicle body and the attachment points between the left and right rear shock absorbers and the vehicle body. Figure 5 The arrangement shown is a vibration exciter 6 as an excitation, and an acceleration sensor 7 is installed as a test point.

[0102] Since the test excitation and response points are arranged symmetrically, the data can be cross-checked during the test process, which can easily eliminate inaccurate test results caused by equipment problems, which is impossible to achieve with traditional methods.

[0103] Step 7: Load stimulus for testing:

[0104] The test process is as follows Figure 7 As shown, the test method adopts the method of "multi-point excitation, multi-point vibration pickup".

[0105] The 4×4 excitation point×response point used in this preferred embodiment means that white noise excitation of, for example, 1 to 100 Hz is given to the four excitation points at the same time, and then the responses of the four response points are measured, so that 16 transfer functions can be obtained. That is, the transfer function from each excitation point to the four response points is measured, and there is one transfer function from each excitation point to each response point, so there are 16 transfer functions from the four excitation points to the four response points. By calculating these 16 transfer functions and their correlation, a vehicle body comfort stiffness value with a scalar value as the result can be finally obtained. This value can be used to evaluate the comfort stiffness of the vehicle body in the entire low-frequency band, and compare the results between different models.

[0106] The following is a detailed description of the method for obtaining relevant values ​​of comfort stiffness through transfer functions.

[0107] The body-in-white is a multi-degree-of-freedom system, assuming it has N degrees of freedom. For a system with N degrees of freedom, the modal frequency response transfer function of the response measured at point l and excited at point p can be expressed as:

[0108]

[0109] Where: K er is the rth order equivalent stiffness, g r is the r-th order modal structural damping ratio, is the frequency ratio, and N is a natural number greater than or equal to 6.

[0110] It can be seen from formula (1) that when the excitation frequency ω approaches the natural frequency of the r-th mode, this mode plays a dominant role. At this time, formula (1) can be written as:

[0111]

[0112] in: and They are the real and imaginary parts of the residual mode, respectively. Usually, they do not change much with ω, so on the real and imaginary frequency graphs, it is equivalent to shifting the coordinates by a constant, so it is also called the "residual flexibility line".

[0113] According to formula (2), the natural frequency of the system can be determined by the peak frequency corresponding to the imaginary frequency curve of the frequency response function. The damping ratio can be determined by the half-power bandwidth:

[0114]

[0115] Where: a ,ω b is the circular frequency corresponding to the half-power point, and f a and f b is the corresponding frequency.

[0116] Therefore, the equivalent stiffness of the system at the resonant frequency can be identified by the transfer function of the test system. In the technical solution of the present invention, the equivalent stiffness K identified by the transfer function er This is the evaluation value of comfort stiffness.

[0117] Next, data processing is carried out, which includes correlation analysis and data fitting.

[0118] In this preferred embodiment, 16 transfer functions are measured through testing. Since the excitation point positions and the response point positions are arranged perfectly, among these 16 transfer functions, 4 are origin responses, and the other 12 functions can be divided into 6 groups, with two functions in each group. The validity of the test can be verified by calculating the spectral coherence function of the two transfer functions in each group.

[0119] The formula of spectral coherence function is as follows:

[0120]

[0121] Where X and Y are two response points or excitation points, R xy is the spectral coherence function, S xx (ω) is the autospectrum of point X, S yy (ω) is the self-spectrum of point Y, S xy (ω) is the cross spectrum of points X and Y.

[0122] Data fitting started after correlation analysis.

[0123] According to experience, the curve to be fitted for solving the final comfort stiffness is generally a polynomial function, and can be fitted by a polynomial within tenth degree. The polynomial function expression is as follows:

[0124] Y=ax 10 +bx 9 +cx 8 +dx 7 +ex 6 +fx 5 +gx 4 +hx 3 +ix 2 +jx+k (5)

[0125] Finally, by solving the intersection of the fitted polynomial and the Y-axis, the comfort stiffness value can be obtained.

[0126] If the tenth-order polynomial still cannot fit the curve to be fitted well, a better fitting effect can be achieved by increasing the order of the polynomial.

[0127] Example 1

[0128] In a certain test, the 16 transfer functions obtained are as follows Figure 8 shown.

[0129] The excitation points (marked with A in the upper left corner of the figure) are numbered A1, A2, A3, A4; the response points (marked with S in the upper left corner of the figure) are numbered S5, S6, S7, S8. The 16 transfer functions refer to the transfer function from each excitation point to each response point. In the test of this embodiment, there are 4 excitation points and 4 response points, so there are 4X4=16 transfer functions in total.

[0130] For example, the 1st to 4th transfer functions in the following figure legend are the transfer functions from the first excitation point A1 to the 4 response points (S5, S6, S7, S8). The 5th to 8th transfer functions in the figure legend are the transfer functions from the first excitation point A2 to the 4 response points (S5, S6, S7, S8). The 9th to 12th transfer functions in the figure legend are the transfer functions from the first excitation point A3 to the 4 response points (S5, S6, S7, S8). The 13th to 16th transfer functions in the figure legend are the transfer functions from the first excitation point A4 to the 4 response points (S5, S6, S7, S8).

[0131] The four origin response functions in the transfer function are the transfer functions of A1 to S5, A2 to S6, A3 to S7, and A4 to S8. The remaining 12 transfer functions can be obtained into 6 groups through the reciprocal relationship between the excitation point and the response point, such as point x excitation point y response and point y excitation point x response.

[0132] After verifying the validity of the test data by calculating the correlation, the transfer function can be identified. Fig. 9 The curve shown is used, and the intersection of the curve and the Y-axis is obtained by fitting the data using a polynomial for the curve of the first main monotonic decreasing function in the original curve (generally the starting point is greater than 10Hz). The intersection value of the curve on the Y-axis is defined as the comfort stiffness of the vehicle.

[0133] Since the comfort stiffness obtained in the case is a scalar value, the purpose of defining the comfort stiffness of the vehicle body in the entire low-frequency band through a numerical quantitative method is achieved. In traditional methods, either only one numerical expression cannot be used for the entire low-frequency band, or different transfer functions can only be used instead of one numerical expression for the entire low-frequency band. And because the definition of the transfer function is consistent in the tests of different vehicle models, the comfort stiffness comparison between different vehicle models can be easily carried out, and the evaluation is no longer affected by the vehicle structure.

[0134] It should be noted that the technical idea of ​​the present invention is not limited to the scheme of the aforementioned embodiment. The embodiment provides a test method for Z-direction excitation and Z-direction response. For Z-direction excitation and X / Y-direction response, or X / Y-direction excitation and X / Y / Z-direction response; extending the test frequency band to the high frequency band, etc. are also within the protection scope of this patent. At the same time, the appearance of the test device base plate assembly and the excitation mounting seat can be designed as needed, and the intermediate adjustment system can also change the shape and adjustment method according to actual needs. These changes are all within the protection scope of this patent.

[0135] In summary, the testing method of the present invention has the following advantages:

[0136] First, the present invention can improve the accuracy of the test to the greatest extent, so that the excitation source and the body surface do not move relative to each other during the test, thus ensuring the accuracy of the data. In addition, the present invention can standardize the method for judging the test results, and no longer use the transfer function from the excitation to the response point as the basis for judgment, but use a scalar value as the test result.

[0137] Secondly, the present invention can define the comfort stiffness of the vehicle body in the entire low-frequency band through a numerical quantitative method. In traditional methods, either only one numerical expression can be used for the entire low-frequency band, or only different transfer functions can be used instead of one numerical expression for the entire low-frequency band.

[0138] Third, the present invention improves the repeatability of the test, reduces the need for the number of tests, and improves the credibility of the test. The present invention can achieve consistency between the excitation mode during the test and the load form during the vehicle driving process, thereby improving the representative significance of the test in reality.

[0139] Fourth, the present invention can define the contribution of comfort stiffness with a unified standard, because the definition of the transfer function in different vehicle model tests is consistent. It is convenient to compare the comfort stiffness of different vehicle models, and the evaluation is no longer affected by the vehicle model structure.

[0140] The basic concepts have been described above. Obviously, for those skilled in the art, the above invention disclosure is only used as an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0141] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0142] Some aspects of the present application may be performed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software may be referred to as "data blocks", "modules", "engines", "units", "components" or "systems". The processor may be one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, or combinations thereof. In addition, various aspects of the present application may be expressed as computer products located in one or more computer-readable media, which include computer-readable program codes. For example, computer-readable media may include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, tapes ...), optical disks (e.g., compact disks CDs, digital versatile disks DVDs ...), smart cards, and flash memory devices (e.g., cards, sticks, key drives ...).

[0143] A computer-readable medium may include a propagated data signal containing computer program code, such as in baseband or as part of a carrier wave. The propagated signal may have a variety of manifestations, including electromagnetic, optical, etc., or a suitable combination. A computer-readable medium may be any computer-readable medium other than a computer-readable storage medium, which may be connected to an instruction execution system, device or apparatus to communicate, propagate or transmit a program for use. The program code on the computer-readable medium may be propagated via any suitable medium, including radio, cable, fiber optic cable, radio frequency signal, or similar medium, or any combination of the above mediums.

[0144] The basic concepts have been described above. Obviously, for those skilled in the art, the above invention disclosure is only used as an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0145] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0146] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0147] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0148] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions may be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A test method, applicable to a passenger car body comfort stiffness test device, the passenger car body comfort stiffness test device comprising: A floor assembly, the floor assembly comprising first and second adjustable connecting parts symmetrically arranged, the first and second adjustable connecting parts comprising at least one connecting hole, the floor assembly being connected to the body surface of the passenger vehicle through the connecting hole; An excitation mounting seat, fixedly connected to the base plate assembly; The base plate assembly includes a T-shaped rectangular steel plate, and the excitation mounting seat includes a solid cylinder, and the solid cylinder is welded at the symmetric center of the T-shaped rectangular steel plate; Characterized in that the testing method comprises: Step 1: Test initialization; Step 2: install K passenger car body comfort stiffness test devices at K response points and excitation points respectively, and install a combination of an exciter and an acceleration sensor on the excitation mounting seat of each test device respectively; Step 3, obtaining K×K transfer functions of the acceleration sensors on the K test devices after the exciter on each test device emits an excitation: Where: K er is the rth order equivalent stiffness, g r is the r-th order modal structural damping ratio, N is the degree of freedom, is the frequency ratio, N is a natural number greater than or equal to 6, and K is a natural number greater than or equal to 2; The equivalent stiffness K identified by the transfer function er Used as a vehicle body comfort stiffness evaluation value.

2. The testing method according to claim 1, characterized in that: The r-th order modal structural damping ratio is determined by the half-power bandwidth: Where: a ,ω b is the circular frequency corresponding to the half-power point, and f a and f b is the corresponding frequency.

3. The testing method according to claim 2, characterized in that: The test method further comprises: Step 4: Verify the validity of the test by calculating the spectral coherence function of the two transfer functions in each group, wherein the spectral coherence function formula is as follows: Among them, X and Y are two response points or excitation points, R xy is the spectral coherence function, S xx (ω) is the autospectrum of point X, S yy (ω) is the self-spectrum of point Y, S xy (ω) is the cross spectrum of points X and Y.

4. The testing method according to claim 3, characterized in that: The test method further comprises: Step 5: Obtain the comfort stiffness evaluation value through the intersection of the curve of the M-order polynomial function and the Y-axis, wherein the polynomial function is expressed as: Y=ax M …+bx 9 +cx 8 +dx 7 +ex 6 +fx 5 +gx 4 +hx 3 +ix 2 + jx+k Wherein, M is a natural number.

5. The testing method according to claim 1, characterized in that: The K response points and excitation point positions include the attachment points between the left and right front shock absorbers and the vehicle body and the attachment points between the left and right rear shock absorbers and the vehicle body.

6. The testing method according to claim 1, characterized in that: In the step three, the exciter provides white noise excitation of 1 to 100 Hz.

7. The testing method according to claim 1, characterized in that: The initialization also includes: Establish the coordinate system and geometric model of the vehicle body comfort stiffness, and determine the coordinates of the measuring points; Using air springs to suspend the vehicle body in a horizontal state; Confirming the status of the vehicle body, including confirming whether the vehicle body parts meet the test requirements and removing removable parts.

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