CN113702073A - Method and system for evaluating road load sensitivity of suspension system and electronic equipment - Google Patents
Method and system for evaluating road load sensitivity of suspension system and electronic equipment Download PDFInfo
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- CN113702073A CN113702073A CN202110861100.3A CN202110861100A CN113702073A CN 113702073 A CN113702073 A CN 113702073A CN 202110861100 A CN202110861100 A CN 202110861100A CN 113702073 A CN113702073 A CN 113702073A
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Abstract
The invention discloses an evaluation method for road load sensitivity of a suspension system, which comprises the following steps: acquiring a suspension reference main frequency of a test vehicle on a reference road surface; determining a suspension characteristic dominant frequency according to the acquired characteristic road load spectrum of the test vehicle on the characteristic road surface; determining a load sensitivity coefficient according to the suspension reference dominant frequency and the suspension characteristic dominant frequency; determining the road load sensitivity of the test vehicle on the characteristic road surface according to the load sensitivity coefficient and the load amplification coefficient; the load amplification coefficient is determined according to the characteristic road load spectrum when the load sensitivity coefficient is in a preset sensitive section; the reference road surface is a test road surface with preset road surface excitation, and the characteristic road surface is a test road surface for carrying out the whole vehicle road durability test on the test vehicle. The method improves the accuracy of the evaluation result and obviously improves the timeliness of the road load sensitivity analysis.
Description
Technical Field
The application relates to the technical field of vehicle endurance tests, in particular to a method and a system for evaluating road load sensitivity of a suspension system and electronic equipment.
Background
The vehicle durability test is a group of tests for examining the reliability of the whole vehicle, a system, a subsystem and parts, and the whole vehicle is usually subjected to the durability test in a special durability test field at present. When a vehicle carries out a durability test in a durability test field or carries out road load spectrum acquisition in the test field, a phenomenon that the load of some test road surfaces is suddenly amplified may occur, the load amplification condition is often caused by the sensitivity of some systems to the road surfaces, and if the problem is not processed, the road load spectrum data is subjected to excessive damage accumulation in a plurality of links of bench tests, CAE strength analysis, CAE fatigue analysis, load decomposition, actual vehicle durability and the like in the later period, so that the analysis is inaccurate and the over-design condition occurs, thereby causing unnecessary increase of the conditions such as cost, weight and the like in the development of a project.
The current methods for evaluating the road load sensitivity of the whole vehicle comprise a subjective evaluation method and an NVH vibration analysis method, wherein the subjective evaluation method is used for dynamically evaluating the running stability by actually measuring the vehicle by a driver, and comprises the following steps: the vehicle is accelerated to a set speed and drives into a characteristic road surface, and a driver subjectively senses through a seat, a steering wheel and a lower floor and subjectively evaluates the stability of the system. The subjective evaluation method has the disadvantages of large bias, different people, poor consistency and inaccuracy; and the stability of the whole vehicle can only be sensed, the local vibration cannot be sensed, the judgment on a certain system cannot be made, and no data support exists. The NVH vibration analysis method is to analyze the natural frequency of the parts through simulation software, and whether the frequency needs to be avoided or not, and comprises the following steps: establishing an analysis model, importing an intensity boundary, importing a vibration analysis module, and judging whether resonance exists. The NVH vibration analysis method has the problems that due to the fact that a simulation modeling means is adopted, a simulation model is different from a real vehicle, the model is limited by nodes, rubber pieces, damping pieces and elastic pieces, the data accuracy is not as good as expected, and the simulation method needs a large amount of time for modeling, collecting data, simulating simulation and result analysis, and the timeliness for judging the road load sensitivity is poor.
Disclosure of Invention
The invention provides an evaluation method, an evaluation system and electronic equipment for road load sensitivity of a suspension system, and aims to solve or partially solve the technical problems that the evaluation method for the road load sensitivity of a finished automobile or a suspension is poor in precision, poor in timeliness and low in efficiency when a finished automobile road endurance test is carried out at present.
To solve the above technical problem, according to an alternative embodiment of the present invention, there is provided a method for evaluating road load sensitivity of a suspension system, including:
acquiring a suspension reference main frequency of a test vehicle on a reference road surface;
determining a suspension characteristic dominant frequency according to the acquired characteristic road load spectrum of the test vehicle on the characteristic road surface;
determining a load sensitivity coefficient according to the suspension reference dominant frequency and the suspension characteristic dominant frequency;
determining the road load sensitivity of the test vehicle on the characteristic road surface according to the load sensitivity coefficient and the load amplification coefficient;
the load amplification coefficient is determined according to the characteristic road load spectrum when the load sensitivity coefficient is in a preset sensitive section; the reference road surface is a test road surface with preset road surface excitation, and the characteristic road surface is a test road surface for carrying out a whole vehicle road endurance test on the test vehicle; the characteristic road load spectrum is a load response time domain signal of the suspension system, which is obtained when the test vehicle carries out a whole vehicle road endurance test on the characteristic road surface.
Optionally, the acquiring a suspension reference main frequency of the test vehicle on a reference road surface includes:
acquiring a reference road load spectrum;
performing time-frequency transformation on the reference road load spectrum to obtain a first power spectral density;
determining the suspension reference main frequency according to the first power spectral density.
Optionally, the preset road excitation is white noise; before the acquiring of the reference road load spectrum, the evaluation method further includes:
acquiring the road surface unevenness information of each test road surface of the test field;
determining the reference road surface according to the road surface unevenness information; the reference road surface has the same road surface excitation characteristics as the white noise.
Optionally, the determining a suspension characteristic dominant frequency according to the obtained characteristic road load spectrum of the test vehicle on the characteristic road surface includes:
performing time-frequency transformation on the characteristic road load spectrum to obtain a second power spectral density;
determining the suspension characteristic dominant frequency from the second power spectral density.
Optionally, the method for determining the load amplification factor includes:
determining a static load ratio according to the static load of the front axle and the static load of the rear axle of the test vehicle;
obtaining a front axle dynamic load and a rear axle dynamic load according to the characteristic road load spectrum;
determining a dynamic load ratio according to the dynamic load of the front shaft and the dynamic load of the rear shaft;
and determining the load amplification factor according to the dynamic load ratio and the static load ratio.
Further, the determining the road load sensitivity of the test vehicle on the characteristic road surface according to the load sensitivity coefficient and the load amplification coefficient includes:
when the load sensitivity coefficient is in a preset sensitivity zone, determining the road load sensitivity according to the load amplification coefficient;
and when the load sensitivity coefficient is out of the preset sensitivity interval, determining the road load sensitivity as a first sensitivity.
Further, the determining the road load sensitivity according to the load amplification factor includes:
if the load amplification factor is larger than a first threshold value or the load amplification factor is smaller than a second threshold value, determining that the road load sensitivity is a second sensitivity; the second sensitivity is greater than the first sensitivity;
and if the load amplification factor is between the second threshold and the first threshold, determining the road load sensitivity as the first sensitivity.
According to another alternative embodiment of the present invention, there is provided a system for evaluating road load sensitivity of a suspension system, including:
the system comprises an acquisition module, a detection module and a control module, wherein the acquisition module is used for acquiring the suspension reference dominant frequency of a test vehicle on a reference road surface;
the first determination module is used for determining a suspension characteristic main frequency according to the acquired characteristic road load spectrum of the test vehicle on the characteristic road surface;
the second determining module is used for determining a load sensitivity coefficient according to the suspension reference dominant frequency and the suspension characteristic dominant frequency;
the evaluation module is used for determining the road load sensitivity of the test vehicle on the characteristic road surface according to the load sensitivity coefficient and the load amplification coefficient;
the load amplification coefficient is determined according to the characteristic road load spectrum when the load sensitivity coefficient is in a preset sensitive section; the reference road surface is a test road surface with preset road surface excitation, and the characteristic road surface is a test road surface for carrying out a whole vehicle road endurance test on the test vehicle; the characteristic road load spectrum is a load response time domain signal of the suspension system, which is obtained when the test vehicle carries out a whole vehicle road endurance test on the characteristic road surface.
Optionally, the evaluation module is configured to:
when the load sensitivity coefficient is in a preset sensitivity zone, determining the road load sensitivity according to the load amplification coefficient;
and when the load sensitivity coefficient is out of the preset sensitivity interval, determining the road load sensitivity as a first sensitivity.
According to yet another alternative embodiment of the present invention, there is provided an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the evaluation method according to any one of the preceding claims when executing the computer program.
Through one or more technical schemes of the invention, the invention has the following beneficial effects or advantages:
the invention provides an evaluation method of road load sensitivity of a suspension system, which is characterized in that based on the sensitivity of a vehicle to a road surface, the invention provides that actually measured road load spectrum data is utilized to determine a load sensitivity coefficient and a load amplification coefficient for evaluating the road load sensitivity; the method comprises the steps that a suspension reference main frequency which is used for driving a test vehicle on a reference road surface with preset road surface excitation and can represent the inherent vibration characteristic of a suspension system and a road load spectrum obtained by performing a whole vehicle road durability test on the test vehicle on a characteristic road surface are obtained to determine the suspension characteristic main frequency, and whether the phenomenon of same-frequency resonance occurs between the road surface excitation frequency and the system inherent frequency of the system in the current motion state can be accurately represented through a load sensitivity coefficient determined by the two main frequencies; if the obtained load sensitivity coefficient is in a preset sensitive region, indicating that same-frequency resonance occurs at the moment, then obtaining a system load amplification level, namely a load amplification coefficient, in the current endurance test motion state through the characteristic road load spectrum data, and judging the load sensitivity level of the vehicle on the road surface through the load amplification coefficient; based on the principle, whether the system damage occurring in the current motion state is accurate and reasonable or not can be accurately judged, whether the damage can be used as fatigue endurance to carry out damage accumulation or not can be accurately judged, and therefore the reasonability of a field road endurance test and the accuracy of data in a downstream development field can be accurately judged; compared with an NVH vibration analysis method, the scheme is based on the analysis of the measured data of the vehicle, so that the data precision is higher, and the time for acquiring the road load spectrum and the data analysis time are far shorter than the time required by modeling simulation; the subjective evaluation method needs to be repeatedly sensed on the characteristic road surface, and the judgment result has strong subjectivity, so that the evaluation result obtained by the scheme is more scientific and accurate; in general, the method and the device improve the accuracy of the evaluation result and obviously improve the timeliness of the road load sensitivity analysis. Thereby providing powerful data support for reliable and durable development.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a schematic flow diagram illustrating a method for assessing road load sensitivity of a suspension system according to one embodiment of the present invention;
FIG. 2 is a diagram illustrating an example of road surface irregularity information according to an embodiment of the present invention;
FIG. 3 illustrates a schematic diagram of converting a time domain signal of a reference road surface to a frequency domain signal according to one embodiment of the invention;
FIG. 4 shows a schematic diagram of converting a time domain signal of a characteristic road surface into a frequency domain signal according to one embodiment of the invention;
FIG. 5 shows a dominant frequency contrast diagram of a characteristic road surface and a reference road surface according to one embodiment of the invention;
FIG. 6 shows a schematic diagram illustrating the occurrence of load amplification according to one embodiment of the present invention;
FIG. 7 shows a schematic diagram of a system for assessing road load sensitivity of a suspension system according to one embodiment of the present invention.
Detailed Description
In order to make the present application more clearly understood by those skilled in the art to which the present application pertains, the following detailed description of the present application is made with reference to the accompanying drawings by way of specific embodiments. Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control. Unless otherwise specifically stated, various apparatuses and the like used in the present invention are either commercially available or can be prepared by existing methods.
Further research shows that based on the NVH vibration analysis method of simulation, the problem that whether resonance is favorable resonance or harmful resonance is not considered exists; the occurrence of resonance is generally attributed to parts, and the influence of a suspension system and road surface characteristics is not considered; and the influence of the load amplification factor is not considered; and generally not as a method in the development of endurance attributes.
In order to overcome the technical problems of poor precision, poor timeliness and low efficiency of the method for evaluating the road load sensitivity of the whole vehicle or the suspension system in the conventional whole vehicle road endurance test, the invention provides a method for evaluating the road load sensitivity of the suspension system, which has the following overall thought:
acquiring a suspension reference main frequency of a test vehicle on a reference road surface; determining a suspension characteristic dominant frequency according to the acquired characteristic road load spectrum of the test vehicle on the characteristic road surface; determining a load sensitivity coefficient according to the suspension reference dominant frequency and the suspension characteristic dominant frequency; determining the road load sensitivity of the test vehicle on the characteristic road surface according to the load sensitivity coefficient and the load amplification coefficient; the load amplification coefficient is determined according to the characteristic road load spectrum when the load sensitivity coefficient is in a preset sensitive section; the reference road surface is a test road surface with preset road surface excitation, and the characteristic road surface is a test road surface for carrying out a whole vehicle road endurance test on the test vehicle; the characteristic road load spectrum is a load response time domain signal of the suspension system, which is obtained when the test vehicle carries out a whole vehicle road endurance test on the characteristic road surface.
The method is based on the sensitivity of the vehicle to the road surface, and provides that the load sensitivity coefficient and the load amplification coefficient for evaluating the road load sensitivity are determined by using actually measured road load spectrum data; the method comprises the steps that a suspension reference main frequency which is used for driving a test vehicle on a reference road surface with preset road surface excitation and can represent the inherent vibration characteristic of a suspension system and a road load spectrum obtained by performing a whole vehicle road durability test on the test vehicle on a characteristic road surface are obtained to determine the suspension characteristic main frequency, and whether the phenomenon of same-frequency resonance occurs between the road surface excitation frequency and the system inherent frequency of the system in the current motion state can be accurately represented through a load sensitivity coefficient determined by the two main frequencies; if the obtained load sensitivity coefficient is in a preset sensitive region, indicating that same-frequency resonance occurs at the moment, then obtaining a system load amplification level, namely a load amplification coefficient, in the current endurance test motion state through the characteristic road load spectrum data, and judging the load sensitivity level of the vehicle on the road surface through the load amplification coefficient;
based on the principle, whether the system damage occurring in the current motion state is accurate and reasonable or not can be accurately judged, whether the damage can be used as fatigue endurance to carry out damage accumulation or not can be accurately judged, and therefore the reasonability of a field road endurance test and the accuracy of data in a downstream development field can be accurately judged; compared with an NVH vibration analysis method, the scheme is based on the analysis of the measured data of the vehicle, so that the data precision is higher, and the time for acquiring the road load spectrum and the data analysis time are far shorter than the time required by modeling simulation; the subjective evaluation method needs to be repeatedly sensed on the characteristic road surface, and the judgment result has strong subjectivity, so that the evaluation result obtained by the scheme is more scientific and accurate; in general, the data accuracy is improved, and meanwhile the timeliness of road load sensitivity analysis is obviously improved. Thereby providing powerful data support for reliable and durable development.
In the following, the above-described scheme is further explained with reference to specific embodiments:
in an alternative embodiment, the above scheme is applied to a road endurance test for a certain vehicle type, and some terms referred to in this embodiment are explained as follows:
a suspension system: the general term of all force transmission connecting devices between a frame (or a bearing type vehicle body) and an axle (or wheels) of an automobile;
resonance: a case where the physical system vibrates at a larger amplitude than other frequencies at a specific frequency;
load spectrum time domain signal: in the load spectrum data, the independent variable is time, namely the horizontal axis is time, and the vertical axis is the change of a signal; the dynamic signal x (t) is a function for describing the value of the signal at different moments;
load spectrum frequency domain signal: the argument is the frequency, i.e. the horizontal axis is the frequency and the vertical axis is the amplitude of the frequency signal, i.e. a spectrogram in general;
power spectral density: a physical quantity characterizing a power energy versus frequency relationship of the signal;
dominant frequency: the frequency corresponding to the main energy concentration point of the system response signal in the spectrogram;
reference road surface: the test field is provided with a test road surface with preset road surface excitation;
the characteristic road surface: a test pavement for carrying out a road durability test in a test field.
As shown in fig. 1, the steps of the method for evaluating road load sensitivity of a suspension system include:
s1: and acquiring the suspension reference main frequency of the test vehicle on the reference road surface.
As described above, the reference road surface is a test road surface having a preset road surface excitation, and the reference road surface is determined by the following method:
first, the preset (theoretical) excitation characteristics are determined:
according to the lagrangian equation, the suspension can be regarded as a multi-degree-of-freedom system, so that the following equation is obtained:
according to the equation, the damping C and the rigidity K in the system influence the transfer function characteristic of the system, so that when the transfer function characteristic of the system is determined, not any road surface excitation can be used as the input of the system. In this embodiment, a preset road excitation with an approximate wideband and a power spectral density that is distributed uniformly in the entire frequency domain and close to a constant is selected as an input to obtain the transfer function characteristic of the system. The road surface excitation meeting the requirement includes a white noise signal, a white noise-like signal and a pink noise signal, and if no specific description is given, the white noise is used as the preset road surface excitation in the embodiment. After the required theoretical road surface excitation is determined, a group of test road surfaces with the excitation characteristics are found from a test field, and the road surfaces are used as reference road surfaces capable of representing the characteristics of the suspension system. At present, a series of test roads built for tests in a vehicle endurance test field comprise a high-speed runway, a ramp, a comprehensive road, a twisted road, a stone road, a cobblestone road and the like.
Secondly, according to preset road surface excitation, determining a reference road surface with the excitation characteristics in a test field:
a method for determining a reference road surface includes driving a test vehicle on each test road surface in a test field to obtain a road load spectrum of the test vehicle on each road, namely a load response time domain signal, and determining road surface characteristics or road surface excitation corresponding to each test road surface by analyzing actual load response. The other mode is that the road surface unevenness information of each test road surface of the test field is obtained from a supplier for constructing the test field, and the reference road surface is determined according to the road surface unevenness information.
The road surface unevenness is schematically shown in fig. 2, and it can be seen that the road surface is characterized by the relationship between the height q of the road surface relative to the reference coordinate plane and the strike length I, i.e., the road surface unevenness. Using the formula:
Gq(n)＝Gq(n0)(n/n0)-w (2)
the power spectral density Gq (n) corresponding to the road surface unevenness can be obtained, relevant data of the road surface unevenness information of each test road surface can be provided when each large test field builds the test road surface at present, and after the relevant information of the test road surface of the test field is obtained, what test road surface has the preset road surface excitation characteristic required by the first step can be judged, so that the test road surface with the preset road surface excitation characteristic can be selected as a reference road surface to obtain the response characteristic of the suspension system.
After the reference road surface is determined, the test vehicle can be controlled to run on the reference road surface according to a preset speed, and a road load response time domain signal, namely a reference road load spectrum, of the test vehicle on the reference road surface is obtained; then, time-frequency transformation can be carried out on the reference road load spectrum by utilizing data processing software to obtain a first power spectral density; determining the suspension reference main frequency according to the first power spectral density. The road surface excitation of the reference road surface is wide frequency, the power spectral density is distributed uniformly and close to a constant in the whole frequency domain, so that the load response obtained at the time can represent the inherent characteristics of the test object, the power spectral density obtained by conversion can be equivalent to the power spectral density characteristics of the system, and the main frequency can be regarded as the main frequency of the system. The suspension reference main frequency can therefore be determined based on the power spectral density. The preset speed is set according to needs, can be the same driving speed as the endurance test, and can also be a driving speed different from the endurance test, and only after the test vehicle drives on the reference road surface, the corresponding road load spectrum can be obtained according to the road surface excitation.
Fig. 3 shows a process of converting a load response time domain signal of a reference road surface into a frequency domain signal by using nCode data analysis software to obtain a power spectral density, and after obtaining the power spectral density data, a suspension reference main frequency can be determined. Since the main frequency is the frequency corresponding to the main energy concentration point of the system response signal in the spectrogram, the frequency corresponding to the point with the highest energy can be determined as the suspension reference main frequency, which is denoted as f0。
S2: and determining the main frequency of the suspension characteristic according to the acquired characteristic road load spectrum of the test vehicle on the characteristic road surface.
Specifically, according to the industry specification or enterprise specification of the durability test of the whole vehicle road, a test vehicle is driven on a characteristic road surface according to the speed specified by the test, time domain signals of a load spectrum at a preset measuring point are measured through six force-sharing meters arranged at the preset measuring point, such as the positions of a left front shaft, a right front shaft, a left rear shaft, a right rear shaft and the like of a suspension system, and then according to the same data processing method as the road load spectrum of a reference road surface, as shown in fig. 4, time-frequency conversion is carried out on the characteristic road load spectrum to obtain a second power spectrum density; determining the suspension characteristic dominant frequency from the second power spectral density. The main frequency of the suspension characteristic is generally determined by taking a point of amplified load as a data object, for example, the position of a shaft head is taken as a data processing object when the load of a six-component force meter is amplified, and the main frequency of the suspension characteristic can be determined by taking the mode of looking at the shaft head under a spring and looking at a tower bag on the spring, and is recorded as fn。
S3: determining a load sensitivity coefficient according to the suspension reference dominant frequency and the suspension characteristic dominant frequency;
specifically, according to a ratio of the suspension characteristic dominant frequency to the suspension reference dominant frequency: f. ofn/f0Determining the load sensitivity coefficient S; the suspension characteristic dominant frequency may also be calculated from a ratio of the suspension reference dominant frequency to the suspension characteristic dominant frequency: f. of0/fnAnd determining the load sensitivity coefficient S. In the following description, unless otherwise specified, S is equal to fn/f0The description is given.
Alternatively, after obtaining the power spectral density of the reference road and the power spectral density of the characteristic road in step S3 according to step S1, the load sensitivity coefficient may be obtained by comparing and analyzing the two power spectral densities in the data processing software nCode, as shown in fig. 5.
After the load sensitivity coefficient is determined, the load sensitivity of the system is then evaluated using the load sensitivity coefficient:
and S4, determining the road load sensitivity of the test vehicle on the characteristic road surface according to the load sensitivity coefficient and the load amplification coefficient.
Specifically, when the load sensitivity coefficient is in a preset sensitive region, a load amplification coefficient needs to be determined according to the characteristic road load spectrum; and when the load sensitivity coefficient is out of the preset sensitivity interval, determining the road load sensitivity as a first sensitivity.
The preset sensitive interval here is a threshold interval representing the degree of stability of the suspension system under the speed excitation of the road endurance test. For load sensitivity coefficient S ═ fn/f0The preset interval determined by calibration is [0.95,1.05]]. If the load sensitivity coefficient is outside the preset sensitivity range, S<0.95 or S>1.05, which shows that the sensitivity is far from 1 at the moment, the suspension system tends to be stable under the current excitation, the current speed of the suspension system at the moment can be directly determined, and the road load sensitivity under the current characteristic road surface is the first sensitivity.
If the load sensitivity coefficient is in a preset sensitivity range: and when S is more than or equal to 0.95 and less than or equal to 1.05, the system sensitivity is close to 1 at the moment, the suspension system is likely to have a load amplification condition under the current excitation, the load amplification coefficient is calculated according to the road load spectrum at the moment, and the load amplification level is evaluated according to the load amplification coefficient. The high and low load amplification level will result in larger input data of subsequent tests or simulations, and result in over-design of subsequent processes due to overload conditions of actual endurance tests.
The determination method of the load amplification factor may be:
determining a static load ratio according to the static load of the front axle and the static load of the rear axle of the test vehicle; obtaining a front axle dynamic load and a rear axle dynamic load according to the characteristic road load spectrum; determining a dynamic load ratio according to the dynamic load of the front shaft and the dynamic load of the rear shaft; and determining the load amplification factor according to the dynamic load ratio and the static load ratio.
Specifically, the static load of the front axle and the static load of the rear axle of the vehicle can directly acquire the weighing data of the test vehicle in the preorder process, so that the static load data of the front axle and the rear axle can be acquired.
For the dynamic load, as described above, in performing the durability test of the entire vehicle, six-component force meters are provided at a plurality of measurement point positions of the suspension system to obtain a load spectrum at each measurement point position. For a two-axle vehicle, in this embodiment, measurement points are provided at least at the left wheel and the right wheel of the front axle and the left wheel and the right wheel of the rear axle of the suspension, so as to obtain a left front wheel dynamic load, a left rear wheel dynamic load, a right front wheel dynamic load and a right rear wheel dynamic load according to a characteristic road load spectrum obtained at each measurement point, obtain the front axle dynamic load according to the sum of the left front wheel dynamic load and the right front wheel dynamic load, and obtain the rear axle dynamic load according to the sum of the left rear wheel dynamic load and the right rear wheel dynamic load.
Next, the load amplification factor K is determined to be K1/K2 according to the dynamic load ratio K1 being front axle dynamic load/rear axle dynamic load and the static load ratio K2 being front axle static load/rear axle static load. Of course, calculation of the rear axle dynamic load/front axle dynamic load ratio K1 and the rear axle static load/front axle static load ratio K2 is also possible.
After the load amplification factor is calculated, the result shows that if the load amplification factor is larger than a first threshold value or the load amplification factor is smaller than a second threshold value, the road load sensitivity is determined to be a second sensitivity; and if the load amplification factor is between the second threshold and the first threshold, determining the road load sensitivity as the first sensitivity. Wherein the second sensitivity is greater than the first sensitivity; for example, the first sensitivity may be represented by a low sensitivity and the second sensitivity may be represented by a high sensitivity.
The value range of the first threshold is 1.08-1.2, preferably 1.1, determined by a large number of tests and data analysis; the value range of the second threshold is 0.8-0.9, preferably 0.9.
Fig. 6 shows a case where load amplification exists, and according to the road load spectrums of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel, corresponding wheel loads can be determined by combining the data processing software nCode, and the front axle dynamic load and the rear axle dynamic load can be calculated according to the wheel loads. The calculation result shows that the load has obvious amplification effect at the moment, so that the load spectrum data under the current speed excitation cannot be applied to subsequent design, and the calculation result also shows that the current speed excitation condition cannot be used for carrying out accumulation test in the road endurance test.
The preset range is [0.95,1.05], and the first threshold value is 1.1; the second threshold value is 0.9 as an example, according to the above scheme, the road load sensitivity level obtained after the endurance test is performed on the characteristic road surface by the evaluation vehicle at the preset speed as shown in table 1 is determined:
table 1 load response level evaluation table
After the evaluation result of the road load sensitivity level is obtained according to the scheme, a proper node import project is selected in the subsequent whole vehicle development process and is used as a delivery object with reliability attribute, and the method can be generally selected to be introduced in the stage of a naked vehicle to ensure the accuracy of a road spectrum and site endurance test.
In summary, the method provided by the present embodiment has the following advantages:
(1) the method adopts a mode of testing an actual vehicle to obtain actual measurement data of the vehicle, and the CAE simulation of the existing NVH vibration analysis method adopts a modeling means, so that the difference exists between a model and an actual vehicle, the model is limited by nodes, rubber pieces, damping pieces and elastic pieces, and the obtained data is far inferior to an evaluation result obtained according to the actual vehicle data in the aspect of precision; in addition, the method of the embodiment is based on actually measured road load spectrum data as support, and is more scientific and accurate than a method of subjectively evaluating perception removal depending on human subjectivity.
(2) The method has the characteristic of strong timeliness, because the collection of a group of load spectrum data for analysis only needs about one hour, and the collection of only one characteristic road surface only needs several minutes; the subjective evaluation needs to be repeatedly sensed on the road surface, the CAE method needs to be modeled, input data is prepared, a simulation result is waited, and the result data is analyzed, and both the two methods are time-consuming; the load sensitivity coefficient and the load amplification coefficient can be obtained in a few minutes through the existing data processing software, whether the sensitivity of the vehicle to the road surface meets the requirement or not can be quickly obtained through the two coefficients, the timeliness is far superior to other evaluation modes, and the time cost is effectively reduced.
(3) In the embodiment, two basic characterization parameters are provided for the sensitivity evaluation of a vehicle based on a road surface, namely a load sensitivity coefficient and a load amplification coefficient of the vehicle, which are obtained from actually measured road load spectrum data, are adopted to characterize the sensitivity of a system to the road surface, wherein the load sensitivity coefficient is obtained by comparing a main frequency in a characteristic road load spectrum power spectral density with a main frequency of a power spectral density of a reference road surface for characterizing the inherent vibration characteristic of the system; the load sensitivity coefficient can accurately represent whether the road surface excitation frequency and the system natural frequency of the system have the same-frequency resonance or not in the current motion state, meanwhile, the condition whether the system has load amplification or not and the load amplification level in the current motion state are obtained through an actual load spectrum, so that the load amplification coefficient is obtained, and the sensitivity level of the vehicle on the road surface can be judged through the load amplification coefficient and the load sensitivity coefficient. Based on the principle, whether system damage occurring in the current motion state is accurate and reasonable or not can be accurately judged, whether the damage can be accumulated as fatigue endurance or not can be judged, the reasonability of a site road endurance test and the accuracy of data in the downstream development field can be accurately judged, and powerful data support is provided for reliability endurance development.
Based on the same inventive concept of the previous embodiment, in another alternative embodiment, as shown in fig. 7, there is provided an evaluation system of road load sensitivity of a suspension system, including:
the system comprises an acquisition module 10, a detection module and a control module, wherein the acquisition module is used for acquiring suspension reference main frequency of a test vehicle on a reference road surface;
the first determining module 20 is configured to determine a suspension characteristic dominant frequency according to the acquired characteristic road load spectrum of the test vehicle on the characteristic road surface;
the second determining module 30 is configured to determine a load sensitivity coefficient according to the suspension reference dominant frequency and the suspension characteristic dominant frequency;
the evaluation module 40 is used for determining the road load sensitivity of the test vehicle on the characteristic road surface according to the load sensitivity coefficient and the load amplification coefficient;
the load amplification coefficient is determined according to the characteristic road load spectrum when the load sensitivity coefficient is in a preset sensitive section; the reference road surface is a test road surface with preset road surface excitation, and the characteristic road surface is a test road surface for carrying out a whole vehicle road endurance test on the test vehicle; the characteristic road load spectrum is a load response time domain signal of the suspension system, which is obtained when the test vehicle carries out a whole vehicle road endurance test on the characteristic road surface.
Optionally, the obtaining module 10 is configured to:
acquiring a reference road load spectrum;
performing time-frequency transformation on the reference road load spectrum to obtain a first power spectral density;
determining the suspension reference main frequency according to the first power spectral density.
Further, the preset road excitation is white noise; before the acquiring the reference road load spectrum, the acquiring module 10 is configured to:
acquiring the road surface unevenness information of each test road surface of the test field;
determining the reference road surface according to the road surface unevenness information; the reference road surface has the same road surface excitation characteristics as the white noise.
Optionally, the first determining module 20 is configured to:
performing time-frequency transformation on the characteristic road load spectrum to obtain a second power spectral density;
determining the suspension characteristic dominant frequency from the second power spectral density.
Optionally, the method for determining the load amplification factor includes:
determining a static load ratio according to the static load of the front axle and the static load of the rear axle of the test vehicle;
obtaining a front axle dynamic load and a rear axle dynamic load according to the characteristic road load spectrum;
determining a dynamic load ratio according to the dynamic load of the front shaft and the dynamic load of the rear shaft;
and determining the load amplification factor according to the dynamic load ratio and the static load ratio.
Further, the evaluation module 40 is configured to:
when the load sensitivity coefficient is in a preset sensitivity zone, determining the road load sensitivity according to the load amplification coefficient;
and when the load sensitivity coefficient is out of the preset sensitivity interval, determining the road load sensitivity as a first sensitivity.
Further, the evaluation module 40 is configured to:
if the load amplification factor is larger than a first threshold value or the load amplification factor is smaller than a second threshold value, determining that the road load sensitivity is a second sensitivity; the second sensitivity is greater than the first sensitivity;
and if the load amplification factor is between the second threshold and the first threshold, determining the road load sensitivity as the first sensitivity.
Based on the same inventive concept as the previous embodiments, the present invention further provides an electronic device, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the evaluation method of any one of the previous embodiments when executing the computer program.
In one exemplary embodiment, the invention may provide the following advantages or benefits:
the invention provides an evaluation method, an evaluation system and electronic equipment for road load sensitivity of a suspension system, which are used for determining a load sensitivity coefficient and a load amplification coefficient for evaluating the road load sensitivity by utilizing road load spectrum data measured actually based on the sensitivity of a vehicle to a road surface; the method comprises the steps that a suspension reference main frequency which is used for driving a test vehicle on a reference road surface with preset road surface excitation and can represent the inherent vibration characteristic of a suspension system and a road load spectrum obtained by performing a whole vehicle road durability test on the test vehicle on a characteristic road surface are obtained to determine the suspension characteristic main frequency, and whether the phenomenon of same-frequency resonance occurs between the road surface excitation frequency and the system inherent frequency of the system in the current motion state can be accurately represented through a load sensitivity coefficient determined by the two main frequencies; if the obtained load sensitivity coefficient is in a preset sensitive region, indicating that same-frequency resonance occurs at the moment, then obtaining a system load amplification level, namely a load amplification coefficient, in the current endurance test motion state through the characteristic road load spectrum data, and judging the load sensitivity level of the vehicle on the road surface through the load amplification coefficient;
based on the principle, whether the system damage occurring in the current motion state is accurate and reasonable or not can be accurately judged, whether the damage can be used as fatigue endurance to carry out damage accumulation or not can be accurately judged, and therefore the reasonability of a field road endurance test and the accuracy of data in a downstream development field can be accurately judged; compared with an NVH vibration analysis method, the scheme is based on the analysis of the measured data of the vehicle, so that the data precision is higher, and the time for acquiring the road load spectrum and the data analysis time are far shorter than the time required by modeling simulation; the subjective evaluation method needs to be repeatedly sensed on the characteristic road surface, and the judgment result has strong subjectivity, so that the evaluation result obtained by the scheme is more scientific and accurate; in general, the method and the device improve the accuracy of the evaluation result and obviously improve the timeliness of the road load sensitivity analysis. Thereby providing powerful data support for reliable and durable development.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Claims (10)
1. A method of evaluating road load sensitivity of a suspension system, the method comprising:
acquiring a suspension reference main frequency of a test vehicle on a reference road surface;
determining a suspension characteristic dominant frequency according to the acquired characteristic road load spectrum of the test vehicle on the characteristic road surface;
determining a load sensitivity coefficient according to the suspension reference dominant frequency and the suspension characteristic dominant frequency;
determining the road load sensitivity of the test vehicle on the characteristic road surface according to the load sensitivity coefficient and the load amplification coefficient;
the load amplification coefficient is determined according to the characteristic road load spectrum when the load sensitivity coefficient is in a preset sensitive section; the reference road surface is a test road surface with preset road surface excitation, and the characteristic road surface is a test road surface for carrying out a whole vehicle road endurance test on the test vehicle; the characteristic road load spectrum is a load response time domain signal of the suspension system, which is obtained when the test vehicle carries out a whole vehicle road endurance test on the characteristic road surface.
2. The evaluation method of claim 1, wherein the obtaining of the suspension reference dominant frequency of the test vehicle on the reference road surface comprises:
acquiring a reference road load spectrum;
performing time-frequency transformation on the reference road load spectrum to obtain a first power spectral density;
determining the suspension reference main frequency according to the first power spectral density.
3. The evaluation method according to claim 2, wherein the preset road surface excitation is white noise; before the acquiring of the reference road load spectrum, the evaluation method further includes:
acquiring the road surface unevenness information of each test road surface of the test field;
determining the reference road surface according to the road surface unevenness information; the reference road surface has the same road surface excitation characteristics as the white noise.
4. The evaluation method of claim 1, wherein determining a suspension characteristic dominant frequency from the acquired characteristic road load spectrum of the test vehicle on the characteristic road surface comprises:
performing time-frequency transformation on the characteristic road load spectrum to obtain a second power spectral density;
determining the suspension characteristic dominant frequency from the second power spectral density.
5. The evaluation method according to claim 1, wherein the load amplification factor is determined by:
determining a static load ratio according to the static load of the front axle and the static load of the rear axle of the test vehicle;
obtaining a front axle dynamic load and a rear axle dynamic load according to the characteristic road load spectrum;
determining a dynamic load ratio according to the dynamic load of the front shaft and the dynamic load of the rear shaft;
and determining the load amplification factor according to the dynamic load ratio and the static load ratio.
6. The evaluation method of claim 5, wherein said determining the road load sensitivity of the test vehicle on the characteristic road surface based on the load sensitivity coefficient and the load amplification coefficient comprises:
when the load sensitivity coefficient is in a preset sensitivity zone, determining the road load sensitivity according to the load amplification coefficient;
and when the load sensitivity coefficient is out of the preset sensitivity interval, determining the road load sensitivity as a first sensitivity.
7. The evaluation method of claim 6, wherein said determining said road load sensitivity based on said load magnification factor comprises:
if the load amplification factor is larger than a first threshold value or the load amplification factor is smaller than a second threshold value, determining that the road load sensitivity is a second sensitivity; the second sensitivity is greater than the first sensitivity;
and if the load amplification factor is between the second threshold and the first threshold, determining the road load sensitivity as the first sensitivity.
8. An evaluation system of road load sensitivity of a suspension system, the evaluation system comprising:
the system comprises an acquisition module, a detection module and a control module, wherein the acquisition module is used for acquiring the suspension reference dominant frequency of a test vehicle on a reference road surface;
the first determination module is used for determining a suspension characteristic main frequency according to the acquired characteristic road load spectrum of the test vehicle on the characteristic road surface;
the second determining module is used for determining a load sensitivity coefficient according to the suspension reference dominant frequency and the suspension characteristic dominant frequency;
the evaluation module is used for determining the road load sensitivity of the test vehicle on the characteristic road surface according to the load sensitivity coefficient and the load amplification coefficient;
the load amplification coefficient is determined according to the characteristic road load spectrum when the load sensitivity coefficient is in a preset sensitive section; the reference road surface is a test road surface with preset road surface excitation, and the characteristic road surface is a test road surface for carrying out a whole vehicle road endurance test on the test vehicle; the characteristic road load spectrum is a load response time domain signal of the suspension system, which is obtained when the test vehicle carries out a whole vehicle road endurance test on the characteristic road surface.
9. The evaluation system of claim 8, wherein the evaluation module is to:
when the load sensitivity coefficient is in a preset sensitivity zone, determining the road load sensitivity according to the load amplification coefficient;
and when the load sensitivity coefficient is out of the preset sensitivity interval, determining the road load sensitivity as a first sensitivity.
10. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the evaluation method according to any of claims 1 to 7 when executing the computer program.
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