CN110442973B - Durability testing method and system for key parts of vehicle and storage medium - Google Patents
Durability testing method and system for key parts of vehicle and storage medium Download PDFInfo
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Abstract
The invention discloses a method for testing the durability of a key part of a vehicle, which judges the durability of the key part of the vehicle by compiling a block boundary spectrum and comprises the following steps: s1, analyzing and verifying the virtual strain through strain acquisition and load extraction; and S2, when the virtual strain result passes the verification, compiling the block boundary spectrum of the bench test of the automobile key parts. According to the invention, through the benchmarking of the virtual strain signal and the real strain signal, the accuracy of extracting the part load and the rationality of simplifying the rack constraint mode and the loading mode can be checked and confirmed, and the correct precondition foundation of the subsequent boundary spectrum equivalent work is ensured; the method performs real fatigue life equivalence through the actual maximum damage position under the working condition of the part test field, and improves the goodness of fit of the damage results of the bench test and the test field real vehicle test.
Description
Technical Field
The invention relates to the technical field of automobiles, in particular to a method and a system for testing the durability of key parts of a vehicle and a storage medium.
Background
The durability of the vehicle is listed as a very important basic performance in the development stage of the vehicle because of the direct relation to the service life of the vehicle and the driving safety. The performance of the whole vehicle level is mainly limited by the durability of each part of the vehicle, especially some key parts bearing alternating loads. Therefore, in the development process of the whole vehicle, in order to ensure that the durability of the whole vehicle meets the design requirements, the durability of key parts must be fully verified.
The bench test and the road test are two main means for investigating the durability of the parts. The bench endurance test has the characteristics of high efficiency, low cost and real damage, and is particularly suitable for the design verification and optimization of parts in the early stage. The boundary loads of bench tests are generally classified into three categories: random boundary spectra, constant amplitude boundary spectra, block boundary spectra. The stochastic boundary spectrum is derived from real signals acquired by a real vehicle in a test field, is closest to the actual working condition and can take the effect of load frequency on endurance performance into consideration, but has high requirements on equipment and long period, and is generally difficult to apply to endurance test equipment at a component level. The Hengfu boundary spectrum is the simplest, but the influence generated by the load amplitude change is completely ignored, and the test precision is rough. The block boundary spectrum is an input mode integrating the advantages of the two methods, can reproduce a road test failure mode, reflects the use characteristics of parts more truly, and has higher precision and is widely used.
The method mainly comprises the steps of adopting a unified virtual S-N curve to perform pseudo-damage equivalence on external loads of the parts, estimating the maximum damage position of the parts in advance by experience, and performing damage equivalence after arranging strain gauges at the position to directly measure real strain.
The pseudo damage in the first method is not actual damage, only the relation between the external load size and the fatigue damage of the part is simply considered, but the influence of the real structure and real material characteristics of the part on the load response and damage is completely ignored, and even if the pseudo damage is completely equivalent, the real damage of the part can not be guaranteed to be equivalent; in the second method, equivalence is carried out based on the real strain of the measuring points, the method can only ensure that damage values of the positions of the measuring points with strain gauges are equivalent, but whether the positions of the measuring points selected by experience are the maximum real damage points is uncertain, usually the maximum damage position cannot be accurately predicted before the real load is collected, so that a leak of the maximum damage position of a non-zero part at the patch position exists, which can cause the equivalent but ineffectiveness of the positions of the measuring points.
The methods do not necessarily ensure the equivalence of failure positions and damage values of the bench test, and the compilation of the bench test boundary spectrum is based on the premise of correct external load and reasonable bench constraint and loading mode, but the prior art does not have a verification method for the failure positions and the damage values of the bench test.
Disclosure of Invention
The invention mainly aims to provide a method, a system and a storage medium for testing the durability of key parts of a vehicle, aiming at solving the problems that the prior art can not ensure the equivalence of failure positions and damage values of a bench test, and the compilation of a bench test boundary spectrum can not be carried out on the premise of correct external load, reasonable bench constraint and loading modes and the factors such as various loads-time and the like are not fully considered.
In order to achieve the purpose, the invention provides a method for testing the durability of a key part of a vehicle, which judges the durability of the key part of the vehicle by compiling a block boundary spectrum and comprises the following steps:
s1, analyzing and verifying the virtual strain through strain acquisition and load extraction;
and S2, when the virtual strain result passes the verification, compiling the block boundary spectrum of the bench test of the automobile key parts.
Further, the step S1 specifically includes:
s11, strain signal acquisition and part test field load extraction: determining the position of a strain calibration standard, collecting a strain signal under a test field and acquiring the test field load of the part;
s12, simplifying and verifying gantry boundary conditions: and simplifying the constraint and loading modes of the parts in the bench test according to the stress characteristics of the parts and the conditions of the test equipment, extracting the virtual strain of the parts subjected to the simplified boundary conditions by adopting the extracted load, and performing benchmarking with the real strain at the same position acquired by the real vehicle so as to verify whether the virtual strain is consistent with the real strain.
Preferably, the step S2 specifically includes:
s21: the position of the maximum damage hot spot of the unidirectional load: determining the virtual strain inosculation, performing EN fatigue analysis under the unidirectional load, and extracting the position of the maximum hot spot of the damage under the action of the unidirectional load;
s22: extracting the maximum main strain of the hot spot position, performing local strain fatigue calculation on the hot spot position, and outputting a damage-strain amplitude-strain mean matrix;
s23, mapping the damage-strain amplitude-strain mean matrix into a damage-load amplitude-load mean matrix, grading the damage-load amplitude-load mean three-dimensional matrix according to load amplitude, and accumulating interval damage in each amplitude interval range;
s24: selecting a representative load of each interval, and calculating the damage of a single cycle under the load level; according to the damage equivalence principle, the loading times required when equivalent becomes a representative load in each interval are converted, and then a one-way load block boundary spectrum of the part can be compiled;
s25: and calculating and verifying the durability of the key parts of the vehicle through the equivalent load total damage.
Further, the step S25 is specifically: and (3) carrying out equivalence on loads in other directions, and verifying the comprehensive damage judgment durability under the comprehensive action of equivalent loads in all directions, namely repeating the steps S21-S24, carrying out benchmarking verification on the equivalent total damage under the loading of equivalent loads in all directions and the real total damage under the action of real loads in all directions, and after the verification is passed, carrying out bench test and judging the durability of the key parts of the vehicle.
Further, the specific way of extracting the maximum principal strain of the hot spot position in step S22 is as follows: extracting virtual right-angle strain roses aiming at the hot spot position under the unidirectional load, and synthesizing three-direction strain-time courses of 0 degree, 45 degrees and 90 degrees into a maximum main strain-time course:
further, in the step S22, local strain fatigue calculation is performed on the hot spot position, and a specific manner of outputting the damage-strain amplitude-strain mean matrix is as follows:
neuber correction is carried out on the main strain with the maximum absolute value, a strain loading and unloading path is obtained by combining a cyclic stress-strain curve equation and a hysteresis loop equation, rain flow circulation of a local strain process is analyzed, and finally the corresponding relation of damage under each cycle, strain amplitude and strain mean value and the total damage of a hot spot position are obtained;
εAbsMaxPrincipalthe local stress strain corresponding to the first loading process in the process is calculated by a cyclic stress strain curve equation:
wherein epsilona: amplitude of strain
σa: stress amplitude
E: modulus of elasticity
K': coefficient of circulating intensity
n': cyclic strain hardening index
Kt: the theoretical stress concentration coefficient of the material is,
εAbsMaxPrincipalcalculating the stress strain variation quantity of the local stress strain corresponding to other loading processes in the process through a stress-strain response hysteresis loop equation, and then deducing the local stress strain at the end of the last loading process to obtain:
Δεi+1: the strain range of the (i + 1) th loading history;
Δσi+1: stress range of the (i + 1) th loading history;
εi: strain amplitude at the end of the ith loading history;
σi: stress amplitude at the end of the ith loading history;
determining the strain amplitude ε of each steady-state loopaAnd mean stress σmAnd calculating the damage and total damage generated by each steady-state loop
σ′f: fatigue strength coefficient;
b: a fatigue strength index;
ε′f: fatigue ductility coefficient;
c: fatigue ductility index.
Further, the manner of acquiring the load of the part test field in step S11 is as follows: the random load of parts when the whole vehicle runs on a test field is directly acquired through virtual iteration indirect reproduction of a dynamic model or through strain gauge calibration.
In addition, in order to achieve the above object, the present invention further provides a durability testing system for a key part of a vehicle, the system comprising the following modules:
the strain signal and load extraction module comprises: the device is used for determining the position of a strain calibration target, acquiring a strain signal under a test field and acquiring the test field load of the part;
simplify and verify gantry boundary module: simplifying the constraint and loading modes of the parts in the bench test according to the stress characteristics of the parts and the conditions of test equipment, extracting the virtual strain of the parts subjected to the simplified boundary conditions by adopting the extracted load, and performing benchmarking with the same-position real strain acquired by a real vehicle so as to determine whether the virtual strain is consistent;
the acquisition module of the maximum damage hot spot position of the unidirectional load: determining the EN fatigue analysis under the unidirectional load after the virtual strain is coincided, and extracting the position of the maximum hot spot of the damage under the action of the unidirectional load;
a maximum principal strain module for extracting the hot spot position: the device is used for carrying out local strain fatigue calculation on the hot spot position and outputting a damage-strain amplitude-strain mean matrix;
mapping and one-way load equivalent compiling module: the system comprises a damage-strain amplitude-strain mean matrix, a load amplitude-load mean matrix and a load amplitude-load mean matrix, wherein the damage-strain amplitude-strain mean matrix is mapped into the damage-load amplitude-load mean matrix, the damage-load amplitude-load mean three-dimensional matrix is classified according to the load amplitude, and interval damage in each amplitude interval range is accumulated; selecting a representative load of each interval, and calculating the damage of a single cycle under the load level; according to the damage equivalence principle, the loading times required when equivalent becomes a representative load in each interval are converted, and then a one-way load block boundary spectrum of the part can be compiled;
the multidirectional load equivalent compiling and verifying module comprises: the system is used for carrying out equivalence on loads in other directions, verifying and determining the durability of key parts of the vehicle, carrying out benchmarking verification on equivalent total damage under the loading of equivalent loads in all directions and real total damage under the action of real loads in all directions, and carrying out bench test and judging the durability of the key parts of the vehicle after the verification is passed.
In addition, in order to achieve the above object, the present invention further provides a storage medium having stored thereon an endurance test program of a vehicle critical component, the endurance test of the vehicle critical component being executed by a processor to implement the steps of the endurance test method of the vehicle critical component as described above.
According to the technical scheme, the accuracy of extracting the part load and the rationality of simplifying a rack constraint mode and a loading mode can be checked and confirmed through the benchmarking of the virtual strain signal and the real strain signal, and the correct precondition foundation of the subsequent boundary spectrum equivalent work is ensured; (2) the method performs real fatigue life equivalence through the actual maximum damage position under the working condition of the part test field, and improves the goodness of fit of the damage results of the bench test and the test field real vehicle test. (3) The method extracts the virtual right-angle strain rosettes aiming at the hot spot position under the unidirectional load, and synthesizes the three-direction strain-time courses of 0 degree, 45 degrees and 90 degrees into the maximum main strain-time course, thereby improving the accuracy of the test process.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a flowchart of a method for testing durability of a key part of a vehicle according to embodiment 1;
FIG. 2 is a graph of a damage-load amplitude-load mean distribution of critical vehicle components using the test method of the present invention;
FIG. 3 is a schematic diagram showing the comparison between the equivalent total damage of the key parts of the vehicle under the loading of equivalent load in all directions and the real total damage of the key parts of the vehicle under the action of real load in all directions by using the endurance testing method of the present invention;
fig. 4 is a schematic structural diagram of an endurance testing system for key components of a vehicle in embodiment 2.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" appearing throughout includes three juxtapositions, exemplified by "A and/or B" including either A or B or both A and B. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
At present, when the durability of a vehicle is measured by compiling a key part block boundary spectrum of the vehicle in the prior art, two methods are mainly used, firstly, a unified virtual S-N curve is adopted to perform pseudo-damage equivalence on external loads of the part, secondly, the maximum damage position of the part is evaluated in advance by experience, and damage equivalence is performed after real strain is directly measured by arranging a strain gauge at the position. The pseudo damage in the first method is not actual damage, only the relation between the external load size and the fatigue damage of the part is simply considered, but the influence of the real structure and real material characteristics of the part on the load response and damage is completely ignored, and even if the pseudo damage is completely equivalent, the real damage of the part can not be guaranteed to be equivalent; in the second method, equivalence is carried out based on the real strain of the measuring points, the method can only ensure that damage values of the positions of the measuring points with strain gauges are equivalent, but whether the positions of the measuring points selected by experience are the maximum real damage points is uncertain, usually the maximum damage position cannot be accurately predicted before the real load is collected, so that a leak of the maximum damage position of a non-zero part at the patch position exists, which can cause the equivalent but ineffectiveness of the positions of the measuring points. The methods do not necessarily ensure the equivalence of failure positions and damage values of the bench test, and the compilation of the bench test boundary spectrum is based on the premise of correct external load and reasonable bench constraint and loading mode, but the prior art does not have a verification method for the failure positions and the damage values of the bench test.
In view of the above, the invention provides a method, a system and a storage medium for testing the durability of key parts of a vehicle, and aims to solve the problems that the prior art cannot ensure the equivalence of failure positions and damage values of a bench test, and the compilation of a bench test boundary spectrum cannot be premised on correct external loads, reasonable bench constraints and loading modes, and factors such as various loads-time and the like are not fully considered.
Example 1
To achieve the above object, see fig. 1: the embodiment provides a method for testing the durability of a key part of a vehicle, which judges the durability of the key part of the vehicle through compiling a block boundary spectrum and comprises the following steps:
s1, analyzing and verifying the virtual strain through strain acquisition and load extraction; the step S1 specifically includes:
s11, strain signal acquisition and part test field load extraction: determining the position of a strain calibration standard, collecting a strain signal under a test field and acquiring the test field load of the part;
it should be noted that, the manner of acquiring the test field load of the component in step S11 may be indirect reproduction through virtual iteration of a dynamic model or direct acquisition of the random load of the component when the entire vehicle runs on the test field through strain gauge calibration.
S12, simplifying and verifying gantry boundary conditions: and simplifying the constraint and loading modes of the parts in the bench test according to the stress characteristics of the parts and the conditions of the test equipment, extracting the virtual strain of the parts subjected to the simplified boundary conditions by adopting the extracted load, and performing benchmarking with the real strain at the same position acquired by the real vehicle so as to verify whether the virtual strain is consistent with the real strain.
It should be noted that the matching is not required to be completely accurate, and there may be some error, for example, when the same position strain of the real vehicle is 0.340, and the virtual strain is extracted between 0.331 and 0.349, the matching can be determined.
It can be understood that after the virtual strain is matched, the accuracy of load extraction and the rationality of boundary condition simplification are ensured, and the correct precondition basis of the subsequent boundary spectrum equivalent work is ensured.
And S2, when the virtual strain result passes the verification, compiling the block boundary spectrum of the bench test of the automobile key parts.
The step S2 specifically includes:
s21: the position of the maximum damage hot spot of the unidirectional load: determining the virtual strain inosculation, performing EN fatigue analysis under the unidirectional load, and extracting the position of the maximum hot spot of the damage under the action of the unidirectional load;
it should be noted that, in this embodiment, real fatigue life equivalence is performed through the actual maximum damage position under the zero component test field working condition, so that the goodness of fit of the damage results of the bench test and the test field actual vehicle test is improved.
S22: extracting the maximum main strain of the hot spot position, performing local strain fatigue calculation on the hot spot position, and outputting a damage-strain amplitude-strain mean matrix;
the specific way of extracting the maximum principal strain of the hot spot position in step S22 is as follows: extracting virtual right-angle strain roses aiming at the hot spot position under the unidirectional load, and synthesizing three-direction strain-time courses of 0 degree, 45 degrees and 90 degrees into a maximum main strain-time course:
in the step S22, the local strain fatigue calculation is performed on the hot spot position, and the specific way of outputting the damage-strain amplitude-strain mean matrix is as follows:
neuber correction is carried out on the main strain with the maximum absolute value, a strain loading and unloading path is obtained by combining a cyclic stress-strain curve equation and a hysteresis loop equation, rain flow circulation of a local strain process is analyzed, and finally the corresponding relation of damage under each cycle, strain amplitude and strain mean value and the total damage of a hot spot position are obtained;
εAbsMaxPrincipalthe local stress strain corresponding to the first loading process in the process is calculated by a cyclic stress strain curve equation:
wherein epsilona: amplitude of strain
σa: stress amplitude
E: modulus of elasticity
K': coefficient of circulating intensity
n': cyclic strain hardening index
Kt: the theoretical stress concentration coefficient of the material is,
εAbsMaxPrincipalcalculating the stress strain variation quantity of the local stress strain corresponding to other loading processes in the process through a stress-strain response hysteresis loop equation, and then deducing the local stress strain at the end of the last loading process to obtain:
Δεi+1: the strain range of the (i + 1) th loading history;
Δσi+1: stress range of the (i + 1) th loading history;
εi: strain at end of ith loading historyA web;
σi: stress amplitude at the end of the ith loading history;
determining the strain amplitude ε of each steady-state loopaAnd mean stress σmAnd calculating the damage and total damage generated by each steady-state loop
σ′f: fatigue strength coefficient;
b: a fatigue strength index;
ε′f: fatigue ductility coefficient;
c: fatigue ductility index.
S23, mapping the damage-strain amplitude-strain mean matrix into a damage-load amplitude-load mean matrix, grading the damage-load amplitude-load mean three-dimensional matrix according to load amplitude, accumulating interval damage in each amplitude interval range, and showing a damage-load amplitude-load mean distribution diagram of the key parts of the vehicle by adopting the testing method of the invention as shown in figure 2;
s24: selecting a representative load of each interval, and calculating the damage of a single cycle under the load level; according to the damage equivalence principle, the loading times required when equivalent becomes a representative load in each interval are converted, and then a one-way load block boundary spectrum of the part can be compiled;
s25: calculating and verifying the durability of the key parts of the vehicle through the total damage of the equivalent load: the loads in other directions are equivalent, the damage comprehensive judgment durability under the comprehensive action of the equivalent loads in all directions is verified, namely the steps S21-S24 are repeated, the equivalent total damage under the loading of the equivalent loads in all directions and the real total damage under the action of the real loads in all directions are verified, after the verification is passed, a bench test is carried out, and the durability of the key part of the vehicle is judged, see figure 3, which is a schematic diagram for comparing the equivalent total damage of the key part of the vehicle under the loading of the equivalent loads in all directions and the real total damage under the action of the real loads in all directions by adopting the durability testing method.
It can be understood that, in the embodiment, the virtual strain is analyzed and verified by performing strain acquisition and load extraction, when the verification is passed, the block boundary spectrum of the bench test of the key parts of the automobile is compiled, and then the durability of the key parts of the automobile is calculated through the total damage of the equivalent load, so that the test result is more accurate and reliable, and the reliability is higher.
Example 2
In addition, to achieve the above object, refer to fig. 4: the embodiment also provides a durability test system for the key parts of the vehicle, which comprises the following modules:
the strain signal and load extraction module comprises: the device is used for determining the position of a strain calibration target, acquiring a strain signal under a test field and acquiring the test field load of the part;
simplify and verify gantry boundary module: simplifying the constraint and loading modes of the parts in the bench test according to the stress characteristics of the parts and the conditions of test equipment, extracting the virtual strain of the parts subjected to the simplified boundary conditions by adopting the extracted load, and performing benchmarking with the same-position real strain acquired by a real vehicle so as to determine whether the virtual strain is consistent;
the acquisition module of the maximum damage hot spot position of the unidirectional load: determining the EN fatigue analysis under the unidirectional load after the virtual strain is coincided, and extracting the position of the maximum hot spot of the damage under the action of the unidirectional load;
a maximum principal strain module for extracting the hot spot position: the device is used for carrying out local strain fatigue calculation on the hot spot position and outputting a damage-strain amplitude-strain mean matrix;
mapping and one-way load equivalent compiling module: the system comprises a damage-strain amplitude-strain mean matrix, a load amplitude-load mean matrix and a load amplitude-load mean matrix, wherein the damage-strain amplitude-strain mean matrix is mapped into the damage-load amplitude-load mean matrix, the damage-load amplitude-load mean three-dimensional matrix is classified according to the load amplitude, and interval damage in each amplitude interval range is accumulated; selecting a representative load of each interval, and calculating the damage of a single cycle under the load level; according to the damage equivalence principle, the loading times required when equivalent becomes a representative load in each interval are converted, and then a one-way load block boundary spectrum of the part can be compiled;
the multidirectional load equivalent compiling and verifying module comprises: the system is used for carrying out equivalence on loads in other directions, verifying and determining the durability of key parts of the vehicle, carrying out benchmarking verification on equivalent total damage under the loading of equivalent loads in all directions and real total damage under the action of real loads in all directions, and carrying out bench test and judging the durability of the key parts of the vehicle after the verification is passed.
Example 3
In addition, in order to achieve the above object, the present embodiment also proposes a storage medium, on which an endurance test program of a vehicle critical component is stored, the endurance test of the vehicle critical component being executed by a processor to implement the steps of the endurance test method of the vehicle critical component as described above.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (e.g., a rom/ram, a magnetic disk, an optical disk) and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, an air conditioner, or a network device) to execute the method according to the embodiments of the present invention.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (5)
1. A durability test method for key parts of a vehicle judges the durability of the key parts of the vehicle by compiling a block boundary spectrum, and is characterized by comprising the following steps of:
s1, analyzing and verifying the virtual strain through strain acquisition and load extraction;
s2, when the virtual strain result passes the verification, compiling a block boundary spectrum of the automobile key part rack test;
the S1 specifically includes:
s11, strain signal acquisition and part test field load extraction: determining the position of a strain calibration standard, collecting a strain signal under a test field and acquiring the test field load of the part;
s12, simplifying and verifying gantry boundary conditions: simplifying the constraint and loading modes of the parts in the bench test according to the stress characteristics of the parts and the conditions of test equipment, extracting the virtual strain of the parts subjected to the simplified boundary conditions by adopting the extracted load, and performing benchmarking with the same-position real strain acquired by the real vehicle so as to verify whether the virtual strain is consistent;
the S2 specifically includes:
s21: the position of the maximum damage hot spot of the unidirectional load: after the virtual strain is determined to coincide, performing strain fatigue analysis under the unidirectional load, and extracting the position of the maximum hot spot of the damage under the action of the unidirectional load;
s22: extracting the maximum main strain of the hot spot position, performing local strain fatigue calculation on the hot spot position, and outputting a damage-strain amplitude-strain mean matrix;
s23, mapping the damage-strain amplitude-strain mean matrix into a damage-load amplitude-load mean matrix, grading the damage-load amplitude-load mean three-dimensional matrix according to load amplitude, and accumulating interval damage in each amplitude interval range;
s24: selecting a representative load of each interval, and calculating the damage of a single cycle under the load level; converting the loading times required when equivalent becomes a representative load in each interval according to a damage equivalence principle, and compiling a one-way load block boundary spectrum of the part;
s25: calculating and verifying the durability of key parts of the vehicle through the total damage of the equivalent load;
in the step S22, local strain fatigue calculation is performed on the hot spot position, and a specific manner of outputting the damage-strain amplitude-strain mean matrix is as follows:
neuber correction is carried out on the main strain with the maximum absolute value, a strain loading and unloading path is obtained by combining a cyclic stress-strain curve equation and a hysteresis loop equation, rain flow circulation of a local strain process is analyzed, and finally the corresponding relation of damage under each cycle, strain amplitude and strain mean value and the total damage of a hot spot position are obtained;
the local stress strain corresponding to the first loading process in the maximum main strain process is calculated by a cyclic stress-strain curve equation:
wherein epsilona: amplitude of strain
σa: stress amplitude
E: modulus of elasticity
K': coefficient of circulating intensity
n': cyclic strain hardening index
Kt: theoretical stress concentration coefficient
εAbsMaxPrincipal: maximum principal strain
ΔεAbsMaxPrincipal: maximum principal strain variation range
εAbsMaxPrincipalCalculating the stress strain variation quantity of the local stress strain corresponding to other loading processes in the process through a stress-strain response hysteresis loop equation, and then deducing the local stress strain at the end of the last loading process to obtain:
Δεi+1: the strain range of the (i + 1) th loading history;
Δσi+1: stress range of the (i + 1) th loading history;
εi: strain amplitude at the end of the ith loading history;
σi: stress amplitude at the end of the ith loading history;
sign: a sign function;
determining the strain amplitude ε of each steady-state loopaAnd mean stress σmAnd calculating the damage and total damage generated by each steady-state loop
Wherein epsilonmaxIs the maximum value of the strain amplitude, epsilonminIs the minimum value of the strain amplitude;
σmaxis the maximum stress value, σminIs the minimum stress value;
σ′f: fatigue strength coefficient;
b: a fatigue strength index;
ε′f: fatigue ductility coefficient;
c: fatigue ductility index;
n: the number of cycles;
σm: the average stress.
2. The method for testing the durability of the key part of the vehicle according to claim 1, wherein the step S25 is specifically as follows: and (3) carrying out equivalence on loads in directions other than the unidirectional load, and verifying the comprehensive damage judgment durability under the comprehensive action of each direction of equivalent load, namely repeating the steps S21-S24, carrying out benchmarking verification on the equivalent total damage under the load of each direction of equivalent load and the real total damage under the action of each direction of real load, and after the verification is passed, carrying out bench test and judging the durability of the key parts of the vehicle.
3. The method for testing the durability of the key part of the vehicle according to claim 1, wherein the specific manner for extracting the maximum principal strain at the hot spot position in S22 is as follows: extracting virtual right-angle strain roses aiming at the hot spot position under the unidirectional load, and synthesizing three-direction strain-time courses of 0 degree, 45 degrees and 90 degrees into a maximum main strain-time course:
wherein epsilonAbsMaxPrincipalIs the maximum principal strain, ε0°Strain in the 0 DEG direction, epsilon45°Strain in the direction of 45 ℃, ∈90°Refers to strain in the 90 ° direction.
4. The method for testing the durability of the key component of the vehicle according to claim 1, wherein the manner of obtaining the test field load of the component in S11 is as follows: the random load of parts when the whole vehicle runs on a test field is directly acquired through virtual iteration indirect reproduction of a dynamic model or through strain gauge calibration.
5. A storage medium having stored thereon an endurance testing program of a vehicle critical component, the endurance testing program of the vehicle critical component, when executed by a processor, implementing the steps of the endurance testing method of the vehicle critical component according to any one of claims 1 to 4.
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| CN111562107B (en) * | 2020-07-08 | 2021-11-23 | 江铃汽车股份有限公司 | Belt durability testing method and device for BSG system |
| CN111735645B (en) * | 2020-07-27 | 2021-09-10 | 东风汽车集团有限公司 | Load compilation method for durability test of automobile stabilizer bar rack |
| CN112229654B (en) * | 2020-09-30 | 2023-01-31 | 湖南行必达网联科技有限公司 | Plate spring test method, device, electronic equipment and computer readable medium |
| CN112378652A (en) * | 2020-11-10 | 2021-02-19 | 北京航空航天大学 | Method for analyzing service life of aviation membrane disc coupler |
| CN112685846B (en) * | 2020-12-02 | 2023-06-30 | 江苏徐工国重实验室科技有限公司 | Load spectrum acquisition test method and system |
| CN113970436B (en) * | 2021-11-12 | 2023-11-14 | 北京亿华通科技股份有限公司 | Fatigue performance testing method for fuel cell cantilever bracket |
| CN114048553B (en) * | 2022-01-13 | 2022-03-25 | 岚图汽车科技有限公司 | VPG load-based part durability DV test method, device and equipment |
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