A multi-level load spectrum compilation method, storage medium, and automobile stabilizer bar equivalent bench durability test method

Abstract

The present invention relates to a multi-level load spectrum compilation method, a storage medium, and an equivalent bench durability test method for an automobile stabilizer bar. The steps of the multi-level load spectrum compilation method and the automobile stabilizer bar equivalent bench durability test method are as follows: establish a multi-body dynamics model of the entire vehicle and a digital model of the road surface, and obtain a time-domain spectrum of the load at the connection point between the stabilizer bar and the subframe during a road cycle; process the time-domain spectrum to obtain a multi-level spectrum of the single-piece bench load of the stabilizer bar; judge the equivalence of the multi-level spectrum and the time-domain spectrum in terms of fatigue loss, and then convert the multi-level spectrum of the single-piece stabilizer bar into a multi-level spectrum of the suspension system containing the stabilizer bar, substitute it into the suspension system bench test framework for testing, and verify the durability and reliability performance of the stabilizer bar during the service cycle. The present invention uses tools such as multi-body dynamics and finite element analysis software to obtain a single-piece bench multi-level load spectrum equivalent to the single-piece road load spectrum of the automobile stabilizer bar, thereby effectively improving the efficiency and accuracy of the automobile stabilizer bar durability test.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile component fatigue testing, and in particular to a multi-level load spectrum compilation method, a storage medium, and an automobile stabilizer bar equivalent bench durability test method. Background Art

[0002] Structural reliability is a key performance indicator for automobiles. During vehicle use, stabilizer bars are among the components most susceptible to fatigue failure. Therefore, to ensure structural reliability, extensive fatigue testing of stabilizer bars is required.

[0003] Fatigue testing of stabilizer bars primarily involves on-road testing and indoor bench testing. Road testing suffers from long cycles, high costs, and poor repeatability, limiting its widespread use in automotive R&D and validation. Bench testing, with its short cycles, low costs, and repeatability, complements road testing. However, given the randomness and complexity of road load spectra, designing a robust bench load spectrum and integrating it into the bench test system for accurate verification presents a challenge.

[0004] Stabilizer bar bench tests can be categorized into three types based on the load amplitude: uniform amplitude loading, multi-amplitude loading, and random spectrum loading. Random spectrum testing, however, requires high bench facilities and is difficult to implement. While uniform amplitude loading is simple and intuitive to design and widely used, it differs significantly from the actual loading conditions of the stabilizer bar. Multi-amplitude loading, while more closely resembling the actual loading conditions of the stabilizer bar, also presents a greater degree of design freedom and is difficult to control.

[0005] CN 111735645 A discloses a bench test method with equal amplitude loading, which is representative of this type of technical means. This method collects the strain-time curve of a specific part of the stabilizer bar during the road test, substitutes it into the fatigue damage mathematical model to calculate the road spectrum damage value. Next, the method uses simulation methods to iteratively select the bench load so that the bench stabilizer bar presents a damage condition similar to the road spectrum. This method is a forward development method for a stabilizer bar equivalent bench test, avoiding the blind reliance on empirical values ​​in previous production practices of such technologies. However, the test method mentioned in this method involves attaching strain rosettes to the stabilizer bar. Due to the structural limitations of the stabilizer bar and its connecting parts, it is often difficult to attach strain rosettes to the key fatigue parts of the stabilizer bar, which directly affects the pertinence of the subsequent bench strain benchmarking and easily leads to erroneous bench load design results.

[0006] Furthermore, based on actual production practices, building a bench test system with a single stabilizer bar can easily lead to issues with the actuator's degrees of freedom. Specifically, the stabilizer bar is connected to the subframe via a complex kinematic mechanism, the motion of which is not yet fully understood. Simply constraining the stabilizer bar end with an actuator during bench testing can easily introduce unexpected load constraints, affecting the accuracy of test results. Summary of the Invention

[0007] The purpose of the present invention is to provide a multi-level load spectrum compilation method, a storage medium and an equivalent bench durability test method for an automobile stabilizer bar, so as to obtain a bench multi-level load spectrum of a single automobile stabilizer bar, and convert the bench multi-level load spectrum of the single stabilizer bar into a bench multi-level load spectrum of a suspension system for testing, thereby improving the accuracy of the automobile stabilizer bar durability test.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A multi-level load spectrum compilation method includes the following steps:

[0010] S1. Based on the vehicle structure information and road surface information, a multi-body dynamics model of the vehicle and a digital model of the road surface are established, and the load time-domain spectrum at the connection point between the stabilizer bar and the subframe, i.e., the road load time-domain spectrum of the stabilizer bar alone, is calculated.

[0011] S2. Processing the load time domain spectrum to form a difference time domain spectrum; performing rain flow decomposition on the difference time domain spectrum to obtain a multi-level spectrum of the stabilizer bar;

[0012] S3. Determine whether the load time-domain spectrum and the test bench multi-level spectrum are equivalent in terms of fatigue loss; if so, determine that the test bench multi-level spectrum of this stabilizer bar single piece meets the set requirements; if not, adjust the test bench multi-level spectrum until the test bench multi-level spectrum and the load time-domain spectrum are equivalent in terms of fatigue loss.

[0013] Preferably, in said S1, specifically: establishing a multi-body dynamics model of the whole vehicle and a digital model of the road surface in a multi-body dynamics software according to the vehicle structure information and the road surface information;

[0014] In multibody dynamics software, dynamic simulation of the entire road driving process is carried out based on the vehicle structure and road surface topography. At each time step of the driving process simulation, the six-directional load values ​​at the connection point between the stabilizer bar and the subframe at the corresponding moment are obtained. These six-directional load values ​​are the road load time-domain spectrum of the stabilizer bar alone. The stabilizer bar and the subframe have two connection points, located at the left and right ends of the stabilizer bar, respectively, so two sets of load time-domain spectra are obtained.

[0015] Multibody dynamics (MBD) is a mechanical analysis that predicts the motion of one or more interconnected entities based on the forces acting on them. The results of the dynamics analysis are based on the motion of the entities or the interactions between them. In contrast to multi-flexible body dynamics (MFBD), MBD is a mechanical analysis of rigid body motion.

[0016] Preferably, in said S2, specifically: in the two sets of load time domain spectra, select the load component along the vertical direction of the vehicle coordinate space, and make a difference between the two sets of load components at corresponding time steps to form a difference time domain spectrum;

[0017] Perform rain flow decomposition on the difference time domain spectrum to obtain a scattered point set of the difference; divide the scattered point set into multiple load intervals according to the set interval width, and use half of the sum of the upper and lower bounds of each load interval as the representative amplitude of the load interval to form a representative amplitude-hit count statistical table;

[0018] At the same time, a finite element model of the stabilizer bar was established in the finite element analysis software. The representative amplitudes of each load interval were applied to the loading points on both sides of the stabilizer bar finite element model in a "different directions, once in the positive and negative directions" manner. The single damage value I1 was calculated. The number of hits in the load interval was regarded as the cycle number. The product of the single damage I1 and the cycle number was calculated as the total fatigue damage value I2 of the stabilizer bar in the load interval.

[0019] In order to improve the efficiency of subsequent tests, it is necessary to compress the above multiple load intervals into several load interval blocks, specifically:

[0020] The load interval set is sorted by amplitude and continuously divided into multiple load interval blocks according to the set standard. Each load interval block contains several load intervals with adjacent amplitudes. The total damage value I2 of all load intervals in each load interval block is added to obtain the total damage value I3 of each load interval block.

[0021] Half of the sum of the upper and lower bounds of each load interval block is taken as the representative amplitude of the load interval block. The representative amplitude of each load interval block is applied to the loading points on both sides of the stabilizer bar finite element model in a "different directions, once in positive and negative directions" manner. The single fatigue damage value I4 caused by the load amplitude of the load interval block to the stabilizer bar is calculated, and the ratio of the total damage value I3 of the load interval block to the single fatigue damage value I4 of the load interval block is the reference cycle number of the load interval block; the list of representative amplitudes - reference cycle numbers of multiple load interval blocks finally obtained is the multi-level spectrum of the rig for the stabilizer bar.

[0022] Preferably, in said S3, the specific method for judging whether the load time-domain spectrum and the bench multi-level spectrum are equivalent in terms of fatigue loss is: respectively substituting the load time-domain spectrum and the bench multi-level spectrum into the finite element calculation framework, and respectively calculating and obtaining the road fatigue damage results and the bench fatigue damage results of the stabilizer bar single piece; when the two are similar in distribution morphology, the positions of the maximum damage value points are close, and the ratio of the maximum damage values ​​of the two is between 0.9 and 1.1, then it is judged that the bench multi-level spectrum and the load time-domain spectrum are equivalent;

[0023] In fact, according to the movement characteristics of the stabilizer bar during vehicle use, the "distribution morphology similarity" and "close position of the maximum damage value point" are easily satisfied, which is proved as follows:

[0024] During the actual design process, analysis of the stabilizer bar's motion characteristics during vehicle operation under 21 road conditions involved revealed that: Firstly, due to the stabilizer bar's connection to the subframe, the stabilizer bar is not subject to vertical rotational torque during vehicle operation, and due to the vehicle structure, the stabilizer bar is also not subject to lateral, lateral, and lateral tensile (compressive) forces. Secondly, due to the degree of freedom of the stabilizer bar bushing, the stabilizer bar cannot withstand lateral rotational torque, otherwise it would rotate freely. Therefore, the only fatigue-inducing force in the stabilizer bar during operation is the bending force. When the two ends are subjected to vertical, lateral loads, the stabilizer bar's centroid remains fixed relative to the bushing. The bushing, the end near the bushing, and the stabilizer bar's midsection together form a three-point bending structure. When the two ends are cyclically loaded in alternating directions, specific locations within the stabilizer bar experience cyclical tensile-compressive stresses, inducing fatigue response. Therefore, it can be concluded that the fatigue damage morphology and location of the maximum damage point caused by applying vertical, lateral loads at the stabilizer bar-subframe connection points are similar to those observed in the stabilizer bar road spectrum. When judging the equivalence of the stabilizer bar multi-level spectrum and the time domain spectrum, it is only necessary to judge the ratio of the maximum damage values ​​of the two.

[0025] Preferably, in said S3, it has been proved through experiments that when the bench multi-level spectrum and the load time-domain spectrum of a single stabilizer bar are not equivalent in terms of fatigue loss, the equivalence requirement can be met by adjusting the reference number of cycles of the representative amplitudes of each level of the bench multi-level spectrum of the single stabilizer bar.

[0026] Preferably, the multi-body dynamics software includes RecurDyn and Adams, and the finite element analysis software includes Abaqus and Nastran. Among them, Adams, namely Automatic Dynamic Analysis of Mechanical Systems, is a virtual prototype analysis software developed by MSC Corporation of the United States; Abaqus software is a world-renowned finite element analysis software, and HKS Corporation (now Abaqus Corporation), founded in 1978 in Botha, Rhode Island, USA, is the creator of this software. The main task of Abaqus software is to perform analytical calculations of nonlinear finite element models. RecurDyn is the world's highest level multi-body dynamics analysis software. It is not only simple and fast to use, but also has complete functions and can provide the most complete solution for multi-body dynamics simulation. Among the many multi-body dynamics software today, RecurDyn is also the most advanced technical software.

[0027] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the multi-level load spectrum compilation method according to the present invention.

[0028] The present invention also provides a method for an equivalent bench durability test of an automobile stabilizer bar, comprising the following steps:

[0029] S1. Build a suspension system model including a stabilizer bar in finite element analysis software. Apply a series of loads, from small to large, to the external connection points of the suspension swing arm. The loading direction is the vertical direction of the vehicle coordinate space, with the left and right connection points facing opposite directions. Calculate the response force system at the connection point between the stabilizer bar and the subframe under each load, and develop a load correspondence between the stabilizer bar load and the suspension system load.

[0030] S2. Using the load correspondence between the stabilizer bar load and the suspension system load, the rig multi-level spectrum of the stabilizer bar obtained by the multi-level load spectrum compilation method of the present invention is converted into a multi-level spectrum of the external connection point of the suspension swing arm. The obtained multi-level spectrum of the external connection point of the swing arm and the reference cycle number of each level representative amplitude in the rig multi-level spectrum of the stabilizer bar together constitute the rig multi-level load spectrum of the suspension system.

[0031] S3. Substituting the bench multi-level load spectrum of the suspension system into the bench test framework of the suspension system including the stabilizer bar for bench testing can verify the durability and reliability performance of the stabilizer bar during the service life.

[0032] Since the suspension bench test has advantages over the stabilizer bar single-piece bench test in terms of degree of freedom control, and the stabilizer bar is easy to assemble and disassemble, we chose to build a suspension system to complete the final equivalent bench fatigue test of the stabilizer bar.

[0033] Beneficial effects of the present invention:

[0034] 1) The present invention's multi-level load spectrum compilation method for a test bench ensures high fidelity in the compression process of the stabilizer bar's road load time domain spectrum by fully utilizing the stabilizer bar's motion characteristics during use and rationally applying computational simulation techniques. This allows the equivalent test bench load to largely restore the fatigue-inducing properties of the road spectrum load on the stabilizer bar.

[0035] 2) The automobile stabilizer bar equivalent bench durability test method of the present invention converts the obtained bench multi-level spectrum of the stabilizer bar single piece into the bench multi-level load spectrum of the suspension system for durability testing, thereby fully utilizing the advantages of the suspension bench test at the operational level, avoiding the error risks that may be caused by the stabilizer bar single-piece bench test, improving the accuracy of the durability test, and having the advantages of low cost and high degree of automation. Its effect has been well responded to in long-term project practice, and has promotion and application value in the field of automobile parts fatigue testing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A flow chart of the method for compiling a multi-stage load spectrum and a durability test method for an equivalent test bench for an automobile stabilizer bar according to the present invention;

[0037] Figure 2 The multi-body dynamics model and the digital model of the road surface in Example 1;

[0038] Figure 3 This is the dynamic fatigue damage cloud diagram of the stabilizer bar;

[0039] Figure 4 This is the principle diagram of rainflow method statistics;

[0040] Figure 5 This is a schematic diagram of load merging and simplification;

[0041] Figure 6 This is the corresponding motion relationship diagram of the stabilizer bar-suspension system. DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art will readily appreciate the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the various details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are intended only to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0043] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0044] Example 1

[0045] like Figure 1 As shown, a method for compiling a multi-level load spectrum of an equivalent test bench for an automobile stabilizer bar includes the following steps:

[0046] S1. Based on the vehicle structure and road surface information, a multi-body dynamics model of the vehicle and a digital model of the road surface are established, and the load-time spectrum (referred to as the load-time spectrum, i.e., the road load spectrum of the stabilizer bar alone) at the connection point between the stabilizer bar and the subframe is calculated.

[0047] Specifically include:

[0048] S11. Based on the vehicle structure information and road surface information, a multi-body dynamics model of the vehicle including the stabilizer bar and a digital model of the road surface are established in the multi-body dynamics software Adams. The modeling results are as follows: Figure 2 As shown;

[0049] S12. In multibody dynamics software, conduct a dynamic simulation of the entire road driving process based on the vehicle structure (including physical parameters such as structural dimensions, mass, and center of mass) and road surface topography (road surface topography parameters). At each time step of the driving simulation, obtain the six-dimensional load values ​​at the connection point between the stabilizer bar and the subframe at the corresponding moment. These six-dimensional load values ​​are the road load time-domain spectrum of the stabilizer bar. The stabilizer bar and the subframe have two connection points, located at the left and right ends of the stabilizer bar, respectively, so two sets of load time-domain spectra are obtained.

[0050] S13. Using the two sets of load-time time-domain spectra, substitute them into the finite element calculation framework and use the dynamic fatigue method to solve the dynamic fatigue damage results (i.e., road fatigue damage results) of the stabilizer bar in this embodiment. The results are as follows: Figure 3 As shown, record its cloud shape, maximum damage point and maximum damage value for subsequent equivalent verification;

[0051] S2. Process the load time domain spectrum to form a difference time domain spectrum; perform rain flow decomposition on the difference time domain spectrum, bring the results of the rain flow decomposition into the stabilizer bar finite element model, and calculate the multi-level spectrum of the stabilizer bar;

[0052] Specifically include:

[0053] S21. For the two sets of load-time time domain spectra, the load components in the front and rear directions and the left and right directions of the vehicle are eliminated, and only the load component F in the Z direction is retained. Z (Z is the vertical direction of the vehicle coordinate system), at each time point, the two sets of load-time time domain spectra are subtracted to obtain the arithmetic difference-time curve;

[0054] S22. Use the rain flow method to decompose the arithmetic difference-time curve to obtain a series of amplitude scatter points;

[0055] Among them, the principle of rain flow method is as follows Figure 4 As shown, F of this embodiment Z The arithmetic difference-time curve contains 8 data points [P0, P1, P2, P3, P4, P5, P6, P7]. Starting from the first data point P0, we traverse the data points backwards and record the special data points. Here, the special data points recorded are required to be peak (valley) points, that is, they meet (P i-1 <P i ,P i >P i+1 ) or (P i-1 >P i ,P i <P i+1 ) i As the traversal progresses, when the number of recorded data points exceeds four, the data points at the end of the table are popped out according to the principle of "first in, first out" and the new data points are filled in at the beginning of the table, always maintaining the number of data points in the table = 4. )satisfy or When the output As the result amplitude, at the same time, the self to All points between (excluding or ).connect and Then, the data point traversal is restarted until all points are deleted. In this embodiment, [P2, P3, P4, P6] are the four points recorded in the table at a certain moment and meet the requirements. After outputting |P3-P4|, [P3, P4, P5] are deleted, and [P2, P6] are connected and the loop is restarted;

[0056] S23, after the rain flow method decomposition is completed, F Z The arithmetic difference-time curve is decomposed into a series of difference scatter points, which are then divided into multiple intervals according to the set interval width. Half of the sum of the upper and lower bounds of each interval is taken as the representative amplitude of the interval, forming a representative amplitude-hit count statistical table.

[0057] In this embodiment, Δk=200N is used as the set interval width, and the space formed by the entire difference scatter points is evenly divided into m load intervals. The quotient of the range ΔQ of all the difference scatter points and the set interval width Δk is m≡Δm / Δk as the number of intervals, that is, a series of difference scatter points are divided into m load intervals with 200N as the interval width. Then, the scatter points and the number of interval hits in each load interval are summarized, and half of the sum of the upper and lower bounds of each load interval is used as the representative amplitude of the interval to form a representative amplitude-hit number statistical table.

[0058] S24. Establish a stabilizer bar finite element model in the finite element analysis software Abaqus. In the finite element analysis software Abaqus, apply the representative amplitude of each load interval in S23 to the loading points on both sides of the stabilizer bar finite element model (i.e., the connection point between the stabilizer bar and the subframe) in a "different directions, once in both positive and negative directions" manner, and calculate the single damage value I1. The number of interval hits is the cycle number, and the product of the single damage I1 and the cycle number is calculated as the total fatigue damage value I2 of the stabilizer bar in the load interval; summarize the total damage results of each load interval in a pie chart, as shown in the attached figure. Figure 5 As shown in A, the arrangement order of each sector is the order of its amplitude, and the area size of the sector represents the total damage value of the load interval;

[0059] S25. Since the number of load intervals m is too large to be used as the load for the test, it is necessary to further merge them into load interval blocks. First, set the number of load interval blocks l. In this embodiment, l = 3. Then, m partitions are merged into l load interval blocks according to the principle of "nearby merging". In this embodiment, the load interval blocks obtained after merging the load intervals are as follows: Figure 5 As shown in B, sectors I, II, and III each represent a load interval block, and the sector area is equal to the sum of the sector areas of all load intervals contained in the load interval block, that is, the total damage value I3;

[0060] set up Figure 5 The total damage values ​​I3 of the three load interval blocks in B are [D I ,D II ,D III ], the representative amplitude of each load interval block is half of the sum of the upper and lower bounds of the load interval block, that is, [s I ,s II ,s III ], the representative amplitude of each load interval block is applied to the loading points on both sides of the stabilizer bar finite element model in a "different directions, one time in each direction" manner, and the fatigue damage value I4=[d I ,d II ,d III ], the total damage value of the load interval block I3=[DI ,D II ,D III ] and the single fatigue damage value of the load interval block I4=[d I ,d II ,d III ] is the reference cycle number of the load interval block [t I ,t II ,t III ], then the representative amplitudes of multiple load interval blocks [s I ,s II ,s III ] and the reference cycle number [t I ,t II ,t III ] together constitute the multi-level spectrum of the gantry of the stabilizer bar (in this embodiment, the three-level spectrum)

[0061] S3. Determine whether the test bench multi-level spectrum and the load time domain spectrum are equivalent in terms of fatigue loss. If so, determine that the test bench multi-level spectrum meets the set requirements. If not, adjust the test bench multi-level spectrum until it is equivalent to the load time domain spectrum in terms of fatigue loss.

[0062] Specifically, the test bench multi-level spectrum is brought into the stabilizer bar finite element model, and the fatigue damage results of the test bench multi-level spectrum are calculated using the dynamic fatigue method. The results are compared with the dynamic fatigue damage results in S13. If the ratio of the maximum damage values ​​of the two is between 0.9 and 1.1, the test bench multi-level spectrum and the load time domain spectrum are considered to be equivalent.

[0063] In fact, theoretical analysis shows that under normal road conditions, the damage distribution of the multi-level spectrum is always close to the damage of the load time domain spectrum in terms of morphology and the location of the maximum damage point. Therefore, the only factor affecting the equivalence is the proportional relationship of the maximum damage value. When the two do not meet the equivalence requirements, the reference cycle number [t I ,t II ,t III ], so that the ratio of the maximum damage values ​​of the two is within 0.9 to 1.1, the compilation of the equivalent spectrum can be completed, and the multi-level spectrum of the rig of the stabilizer bar can be output.

[0064] This embodiment further provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the multi-level load spectrum compilation method in this embodiment is implemented.

[0065] Example 2

[0066] Since the suspension system bench test has advantages over the stabilizer bar single-piece bench test in terms of degree of freedom control, and the stabilizer bar is easy to assemble and disassemble, the suspension system was chosen to complete the final equivalent bench fatigue test of the stabilizer bar.

[0067] A method for an equivalent bench durability test of an automobile stabilizer bar comprises the following steps:

[0068] S1. In the finite element analysis software Abaqus, a suspension system model including a stabilizer bar is established. A set of load amplitudes ranging from 0 to 10,000 N is applied to the outer connection points of the suspension swing arm, with load amplitudes at intervals of 500 N. The loading direction is the vertical direction in the vehicle coordinate space, and the loading direction is opposite at the right connection point. The response force system of the stabilizer bar and subframe connection points under each load is calculated to form a load correspondence between the stabilizer bar single-piece loading and the suspension system loading. In this embodiment, the corresponding motion relationship between the stabilizer bar and the suspension system is shown as follows: Figure 6 As shown;

[0069] S2. Using the load correspondence between the stabilizer bar single piece loading and the suspension system loading, the representative amplitudes of the three load interval blocks of the stabilizer bar obtained in Example 1 [s I ,s II ,s III ]Converted to the third level load amplitude of the swing arm external connection point Together with the corresponding reference cycle number [t I ,t II ,t III ] are output together as the bench multi-level load spectrum of the suspension system;

[0070] S3. Substituting the bench multi-level load spectrum of the suspension system into the bench test framework of the suspension system including the stabilizer bar for bench testing can verify the durability and reliability performance of the stabilizer bar during the service life.

[0071] In summary, the method for compiling an equivalent bench multi-level load spectrum and a durability test method for an automobile stabilizer bar of the present invention obtains the load time-domain spectrum of the connection point between the stabilizer bar and the subframe (i.e., the upper end of the stabilizer bar connecting rod) by using multi-body dynamics means and combining the usage characteristics of the stabilizer bar. The time-domain spectrum is then processed by mathematical means to compress the time-domain spectrum into several levels of load amplitudes and corresponding cycle times, thereby forming a stabilizer bar multi-level spectrum. Finite element calculation is used to verify the equivalence of the road spectrum and the multi-level spectrum of the stabilizer bar in terms of fatigue damage. The motion relationship between the stabilizer bar single piece and the entire suspension system is calibrated to convert the stabilizer bar single piece multi-level spectrum into the suspension system multi-level spectrum, thereby converting the stabilizer bar single piece road load time-domain spectrum into a bench multi-level load spectrum of the suspension system with strong equivalence. Finally, the test is completed by substituting it into the suspension bench durability test, and combined with the mechanical calculation function of the finite element, a more accurate bench test system can be designed. Stabilizer bar bench testing can be carried out on a large scale in the early stages of automobile development and verification, greatly improving the efficiency of automobile research and development. It has promotional and application value in the field of automobile component fatigue testing technology.

[0072] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for compiling a multi-level load spectrum, characterized in that: The following steps are involved: S1. Based on the vehicle structure and road surface information, a multi-body dynamics model of the vehicle and a digital model of the road surface are established, and the load time-domain spectrum at the connection point between the stabilizer bar and the subframe is calculated; S2. Processing the load time domain spectrum to form a difference time domain spectrum; performing rain flow decomposition on the difference time domain spectrum to obtain a multi-level spectrum of the stabilizing bar; S3. Determine whether the load time domain spectrum and the bench multi-level spectrum are equivalent in terms of fatigue loss; If yes, the rig multi-level spectrum of the stabilizer bar is determined to meet the set requirements; if not, the rig multi-level spectrum is adjusted until it is equivalent to the load time-domain spectrum in terms of fatigue loss; In the above S2, specifically, the load components along the vertical direction of the vehicle coordinate space are selected from the two sets of load time domain spectra, and the two sets of load components are subtracted at corresponding time steps to form a difference time domain spectrum; Perform rain flow decomposition on the difference time domain spectrum to obtain a scattered point set of the difference; divide the scattered point set into multiple load intervals according to the set interval width, and use half of the sum of the upper and lower bounds of each load interval as the representative amplitude of the load interval to form a representative amplitude-hit count statistical table; At the same time, a finite element model of the stabilizer bar was established in the finite element analysis software. The representative amplitude of each load interval was applied to the loading points on both sides of the stabilizer bar finite element model in a "different direction, once in the positive and once in the negative" manner. The single damage value I1 was calculated. The number of hits in the interval was defined as the number of cycles. The product of the single damage I1 and the number of cycles was calculated as the total fatigue damage value I2 of the stabilizer bar within the load interval. The load interval set is sorted by amplitude and continuously divided into multiple load interval blocks according to the set standard. Each load interval block contains several load intervals with adjacent amplitudes. The total damage value I2 of all load intervals in each load interval block is added to obtain the total damage value I3 of each load interval block. Taking half of the sum of the upper and lower bounds of each load interval block as the representative amplitude of the load interval block, the representative amplitude of each load interval block is applied to the loading points on both sides of the stabilizer bar finite element model in a "different direction, once in positive and reverse directions" manner, and the single fatigue damage value I4 caused by the load amplitude of the load interval block to the stabilizer bar is calculated. The ratio of the total damage value I3 of the load interval block to the single fatigue damage value I4 of the load interval block is the reference cycle number of the load interval block; the final list of representative amplitude-reference cycle number of multiple load interval blocks is the bench multi-level spectrum of the stabilizer bar single piece.

2. The multi-level load spectrum compilation method according to claim 1, characterized in that: In said S1, specifically: establishing a multi-body dynamics model of the whole vehicle and a digital model of the road surface in a multi-body dynamics software according to the vehicle structure information and the road surface information; In multibody dynamics software, dynamic simulation of the entire road driving process is carried out based on the vehicle structure and road surface topography. At each time step of the driving simulation, the six-directional load values ​​at the connection point between the stabilizer bar and the subframe at the corresponding moment are obtained. These six-directional load values ​​are the road load time-domain spectrum of the stabilizer bar alone. The stabilizer bar and the subframe have two connection points, located at the left and right ends of the stabilizer bar, respectively, so two sets of load time-domain spectra are obtained.

3. The multi-level load spectrum compilation method according to claim 1, characterized in that: In said S3, the specific method for judging whether the load time-domain spectrum and the bench multi-level spectrum are equivalent in terms of fatigue loss is: substituting the load time-domain spectrum and the bench multi-level spectrum into the finite element calculation framework respectively, and calculating the road fatigue damage results and the bench fatigue damage results of the stabilizer bar single piece respectively; when the ratio of the maximum damage values ​​of the two is between 0.9 and 1.1, it is judged that the bench multi-level spectrum and the load time-domain spectrum are equivalent.

4. The multi-level load spectrum compilation method according to claim 1, characterized in that: In said S3, the method for adjusting the gantry multi-level spectrum is: adjusting the reference cycle number of the representative amplitude of each level in the gantry multi-level spectrum.

5. The multi-level load spectrum compilation method according to claim 1, characterized in that: The multi-body dynamics software includes RecurDyn and Adams, and the finite element analysis software includes Abaqus and Nastran.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the multi-level load spectrum compilation method according to any one of claims 1 to 5 is implemented.

7. A vehicle stabilizer bar equivalent bench durability test method, characterized in that: The following steps are involved: S1. Build a suspension system model including a stabilizer bar in finite element analysis software. Apply a series of loads, from small to large, to the external connection points of the suspension swing arm. The loading direction is the vertical direction of the vehicle coordinate space, with the left and right connection points facing opposite directions. Calculate the response force system at the connection point between the stabilizer bar and the subframe under each load, and develop a load correspondence between the stabilizer bar load and the suspension system load. S2. Using the load correspondence between the stabilizer bar single-piece loading and the suspension system loading, the rig multi-level spectrum of the stabilizer bar single-piece obtained by the multi-level load spectrum compilation method described in any one of claims 1 to 5 is converted into a multi-level spectrum of the external connection point of the suspension swing arm, and the obtained multi-level spectrum of the external connection point of the swing arm and the reference cycle number of each level representative amplitude in the rig multi-level spectrum of the stabilizer bar single-piece jointly constitute the rig multi-level load spectrum of the suspension system; S3. Substituting the bench multi-level load spectrum of the suspension system into the bench test framework of the suspension system including the stabilizer bar for bench testing can verify the durability and reliability performance of the stabilizer bar during the service life.

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