Fatigue reliability test method based on line actual measurement load spectrum

Abstract

The invention discloses a fatigue reliability testing method based on a line actual measurement load spectrum. The fatigue reliability testing method is used for testing the fatigue life of an automobile stabilizer bar welded through magnetic control rotating electric arc welding. Comprising the following steps: acquiring actually measured load spectrums of the automobile stabilizer bar under various load working conditions in real time through a sensor mounted on an automobile; building a stabilizer bar rack test platform; placing a to-be-tested stabilizer bar on the stabilizer bar rack test platform; all mounting points of the to-be-tested stabilizer bar are restrained and fixed by using a fixing and clamping device; performing a fatigue test on the stabilizer bar to be tested based on the actually measured load spectrum; recording the damage condition and the root-mean-square error of the to-be-tested stabilizer bar in the testing process; and according to the damage condition and the root-mean-square error, evaluating the fatigue life and reliability of the to-be-tested stabilizer bar. According to the method, the problem that a traditional one-dimensional single load spectrum compilation method cannot comprehensively simulate real working conditions is solved, and an important basis is provided for improving the safety and reliability of welding structural parts, especially automobile key parts.

Description

Technical Field

[0001] The present invention relates to the technical field of fatigue damage assessment, and more particularly to a fatigue reliability testing method based on a measured load spectrum of a circuit. Background Art

[0002] Pipe fittings are lightweight, rigid, and low-cost, and are widely used in the petrochemical and automotive industries. In the automotive industry, ductile iron (DCI) has higher strength and toughness than other grades of cast iron, and has a higher elongation. Generally, DCI (GGG40) and alloy steel (E355) are welded to produce automotive composite structural parts, such as automotive stabilizer bars and half-axles. However, due to the different physical properties and chemical compositions of the two base materials, two major problems are usually encountered during welding: (1) high-carbon martensitic structure is easily formed; (2) residual stress accumulates near the weld, which is prone to cracking. Therefore, welding DCI and alloy steel is extremely difficult. With the rapid development of the manufacturing industry, welding efficiency and quality have become important issues of general concern.

[0003] Magnetic rotary arc welding (MIAB) is a welding method that uses magnetic field force to drive the arc to rotate at high speed along the end face of the weldment, uniformly and quickly heating the weld end face to a molten state, and then quickly applying pressure to forge it to form a strong joint.

[0004] In the existing technology, fatigue testing of magnetically controlled rotary arc welded structures is done by compiling a one-dimensional single-item load spectrum. This method has the following limitations:

[0005] Simplification and simplicity: One-dimensional single-item load spectrum often only considers the stress or strain input in one direction, ignoring the impact of multi-dimensional and complex working conditions in practical applications.

[0006] Lack of real-time performance: These load spectra are usually based on historical data or standard test conditions and cannot reflect the actual load conditions of instantaneous changes in real use environments.

[0007] Inconsistent with actual conditions: Since the various random loads to which the vehicle is subjected during operation (such as vibration caused by road unevenness, lateral force during cornering, etc.) are complex and changeable, the traditional unidirectional loading mode is difficult to accurately simulate.

[0008] Therefore, how to overcome the problem that the traditional one-dimensional single-item load spectrum compilation method cannot fully simulate the actual working conditions is an urgent problem that technical personnel in this field need to solve. Summary of the Invention

[0009] In view of the above problems, the present invention provides a fatigue reliability testing method based on the measured load spectrum of the line, so as to at least solve some of the technical problems mentioned in the above background technology.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] The present invention provides a fatigue reliability testing method based on a line measured load spectrum, which is used to test the fatigue life of an automobile stabilizer bar welded by magnetically controlled rotary arc welding. The method comprises the following steps:

[0012] The sensors installed on the vehicle collect the measured load spectra of the vehicle stabilizer bar under various load conditions in real time;

[0013] Build a stabilizer bar test bench; place the stabilizer bar to be tested on the stabilizer bar test bench; and use a fixing clamping device to constrain and fix all the mounting points of the stabilizer bar to be tested;

[0014] Based on the measured load spectrum, a fatigue test is performed on the stabilizer bar to be tested; and damage conditions and root mean square error of the stabilizer bar to be tested during the test are recorded;

[0015] Based on the damage conditions and the root mean square error, the fatigue life and reliability of the stabilizer bar to be tested are evaluated.

[0016] Furthermore, the welding materials adopt ductile iron and alloy steel pipes of the same specifications.

[0017] Furthermore, the real-time acquisition of measured load spectra of the vehicle stabilizer bar under various load conditions specifically includes:

[0018] The axle force on the vehicle stabilizer bar under different load conditions is taken as the instantaneous random load;

[0019] The instantaneous random load of the vehicle stabilizer bar is collected and recorded in real time to form a measured load spectrum.

[0020] Furthermore, performing a fatigue test on the stabilizer bar to be tested based on the measured load spectrum specifically includes: using a hydraulic cylinder to apply the measured load spectrum in opposite Y and Z directions to both ends of the stabilizer bar to be tested.

[0021] Furthermore, a fatigue test is performed on the stabilizer bar to be tested for a preset number of cycles, each cycle corresponding to a preset number of working hours.

[0022] Furthermore, if the stabilizer bar to be tested does not break within a preset cycle period, it is determined that the fatigue life and reliability of the stabilizer bar to be tested meet the requirements.

[0023] Furthermore, it also includes:

[0024] Perform a bending test on the stabilizer bar after fatigue testing and record whether cracks appear at the weld;

[0025] If no cracks appear, the joint performance is judged to meet the requirements.

[0026] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a fatigue reliability testing method based on the measured load spectrum of the line, which has the following beneficial effects:

[0027] The present invention uses sensors installed on actual running vehicles to collect real load data of the stabilizer bar under various operating conditions, forming a load spectrum that can more accurately reflect the actual working environment.

[0028] The present invention uses a hydraulic cylinder to apply a measured load spectrum in opposite Y and Z directions to the transverse stabilizer bar, thereby simulating the actual stress state of the vehicle during operation, including the effects of forces in different directions and magnitudes.

[0029] The present invention ensures the validity and reliability of the test results by performing multiple cycles of fatigue tests on the test piece to evaluate its durability for long-term use.

[0030] The present invention not only focuses on whether there is fracture, but also checks whether there are cracks or defects in the weld through bending tests and other methods, comprehensively assessing the integrity and ductility of the joint and providing a more comprehensive performance evaluation.

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0033] Figure 1 A schematic flow chart of a fatigue reliability testing method based on a measured load spectrum of a circuit provided in an embodiment of the present invention.

[0034] Figure 2 The embodiment of the present invention provides the damage condition and RMS error trend of the stabilizer bar to be tested after fatigue testing. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] The embodiment of the present invention discloses a fatigue reliability test method based on a line measured load spectrum, which is used to test the fatigue life of an automobile stabilizer bar welded by magnetic rotary arc welding; the welding materials are ductile iron and alloy steel pipes of the same specifications; see Figure 1 As shown, the following steps are included:

[0037] S1. Using sensors installed on the vehicle, the measured load spectrum of the vehicle stabilizer bar under various load conditions is collected in real time;

[0038] S2. Build a stabilizer bar test bench; place the stabilizer bar to be tested on the stabilizer bar test bench; and use a fixing clamping device to constrain and fix all the mounting points of the stabilizer bar to be tested;

[0039] S3. Perform fatigue testing on the stabilizer bar under test based on the measured load spectrum; and record the damage and root mean square error of the stabilizer bar under test during the test;

[0040] S4. Evaluate the fatigue life and reliability of the stabilizer bar under test based on the damage condition and root mean square error.

[0041] The above-mentioned marks S1-S4 are only for the convenience of explanation and do not limit the execution order of each step. Next, each of the above-mentioned steps will be described respectively.

[0042] In the above step S1, the load spectrum of the vehicle stabilizer bar under various load conditions is collected in real time by using sensors installed on the vehicle;

[0043] Specifically, the axle force borne by the automobile stabilizer bar under different load conditions is used as the instantaneous random load; the instantaneous random load of the automobile stabilizer bar is collected and recorded in real time to form a measured load spectrum.

[0044] In the above step S2, a stabilizer bar bench test platform is constructed; the stabilizer bar to be tested is placed on the stabilizer bar bench test platform; and all the mounting points of the stabilizer bar to be tested are constrained and fixed using a fixing clamping device; ensuring that the actual load applied can simulate the wheel axle force under real driving conditions.

[0045] In the above step S3, based on the measured load spectrum obtained in the above step S1, a fatigue test is performed on the stabilizer bar to be tested; and the damage condition and root mean square error of the stabilizer bar to be tested during the test are recorded;

[0046] The fatigue test specifically includes: using a hydraulic cylinder to apply a measured load spectrum in opposite Y and Z directions at both ends of the stabilizer bar to be tested, so that the stabilizer bar to be tested is subjected to the same stress state as in the actual driving process.

[0047] In an embodiment of the present invention, a fatigue test of a preset number of cycles is performed on the stabilizer bar to be tested, each cycle corresponding to a preset number of working hours; for example, 645 cycles correspond to the required 300 working hours.

[0048] In the above step S4, the fatigue life and reliability of the stabilizer bar to be tested are evaluated based on the damage condition and the root mean square error (RMS);

[0049] Specifically, if the stabilizer bar to be tested does not break within the preset cycle period, it is determined that the fatigue life and reliability of the stabilizer bar to be tested meet the requirements. Figure 2 As shown in the figure, the tested stabilizer bar did not fracture after 1290 cycles, demonstrating excellent fatigue life results, demonstrating that the MIAB welded ductile iron and alloy steel stabilizer bar meets both design and practical requirements. Here, Fz rel.DMG represents the relative damage in the Z direction; Fy rel.DMG represents the relative damage in the Y direction; Fz RMSe represents the root mean square error in the Z direction; Fy RMSe represents the root mean square error in the Y direction; and target range represents the target range.

[0050] In another embodiment, the method further includes: performing a bending test on the stabilizer bar after the fatigue test, and recording whether cracks appear at the weld; if no cracks appear, it is determined that the joint performance meets the requirements.

[0051] In summary, the embodiments of the present invention provide a fatigue reliability testing method based on the measured load spectrum of the circuit, which overcomes the problem that the traditional one-dimensional single-item load spectrum compilation method cannot fully simulate the actual working conditions, and provides an important basis for improving the safety and reliability of welded structural parts, especially key automotive components.

[0052] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0053] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fatigue reliability testing method based on a measured load spectrum of a circuit, characterized in that: Used to test the fatigue life of automobile stabilizer bars welded by magnetic rotary arc welding; including the following steps: The sensors installed on the vehicle collect the measured load spectra of the vehicle stabilizer bar under various load conditions in real time; Build a stabilizer bar test bench; place the stabilizer bar to be tested on the stabilizer bar test bench; And use the fixing clamping device to constrain and fix all the installation points of the stabilizer bar to be tested; Based on the measured load spectrum, a fatigue test is performed on the stabilizer bar to be tested; and damage conditions and root mean square error of the stabilizer bar to be tested during the test are recorded; Based on the damage conditions and the root mean square error, the fatigue life and reliability of the stabilizer bar to be tested are evaluated.

2. A fatigue reliability testing method based on line measured load spectrum according to claim 1, characterized in that: The welding materials are ductile iron and alloy steel pipes of the same specifications.

3. The fatigue reliability testing method based on the measured load spectrum of the line according to claim 1 is characterized in that: The real-time acquisition of measured load spectra of the automobile stabilizer bar under various load conditions specifically includes: The axle force on the vehicle stabilizer bar under different load conditions is taken as the instantaneous random load; The instantaneous random load of the vehicle stabilizer bar is collected and recorded in real time to form a measured load spectrum.

4. A fatigue reliability testing method based on line measured load spectrum according to claim 1, characterized in that: The fatigue test is performed on the stabilizer bar to be tested based on the measured load spectrum, specifically comprising: using a hydraulic cylinder to apply the measured load spectrum in opposite Y and Z directions to both ends of the stabilizer bar to be tested.

5. The fatigue reliability testing method based on the measured load spectrum of the circuit according to claim 1 is characterized in that: The stabilizer bar under test is fatigue tested for a preset number of cycles, each cycle corresponding to a preset number of operating hours.

6. A fatigue reliability testing method based on line load spectrum according to claim 1, characterized in that: If the stabilizer bar to be tested does not break within the preset cycle period, it is determined that the fatigue life and reliability of the stabilizer bar to be tested meet the requirements.

7. The fatigue reliability testing method based on the measured load spectrum of the circuit according to claim 1 is characterized in that: Also includes: Perform a bending test on the stabilizer bar after fatigue testing and record whether cracks appear at the weld; If no cracks appear, the joint performance is judged to meet the requirements.

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