I. Simulation of Complex Electromagnetic Environments
Difficulty Analysis
- Diverse Interference Sources: There are numerous electronic devices inside a vehicle, such as the Engine Control Unit (ECU), in-vehicle entertainment systems, and various sensors. These devices generate electromagnetic interferences of different frequencies and intensities during operation. Meanwhile, there are also multiple electromagnetic interference sources in the external environment of the vehicle, like radio stations, mobile communication base stations, and the electronic equipment of nearby vehicles. It is extremely challenging to simulate such a complex electromagnetic environment to test the anti-interference ability of automotive electronic and electrical systems.
- Difficulty in Precise Simulation of Electromagnetic Coupling: The electronic devices inside the vehicle are connected by wire harnesses, and electromagnetic coupling will occur in the wire harnesses under the electromagnetic environment. This coupling causes interference signals to be transmitted among different lines, and the degree of coupling is affected by multiple factors such as the length, routing, shielding measures of the wire harnesses, and surrounding metal components. It is very difficult to precisely simulate this complex electromagnetic coupling process.
Solution Methods
- Construction of a Comprehensive Electromagnetic Interference Environment Testing Platform: Utilize multiple signal generators to simultaneously generate interference signals of different frequency bands and waveforms to simulate various electromagnetic interference sources inside and outside the vehicle. For example, use one signal generator to simulate the medium-frequency interference of radio stations and another to simulate the high-frequency interference of mobile communications. Moreover, the intensity, frequency, and phase of the signals can be adjusted to restore the actual electromagnetic environment more realistically.
- Adoption of Electromagnetic Coupling Modeling and Simulation Tools: With the help of professional electromagnetic simulation software, such as CST (Computer Simulation Technology) or ANSYS HFSS (High-Frequency Structure Simulator), model and analyze the electromagnetic coupling of vehicle wire harnesses. By establishing accurate three-dimensional models, including wire harnesses, electronic device housings, and vehicle body metal structures, calculate the electromagnetic coupling coefficients under different circumstances to provide a theoretical reference for testing, so as to better design test schemes and conduct electromagnetic compatibility tests in a targeted manner.
II. Long-Term Durability Testing under High Temperature and High Humidity Environments
Difficulty Analysis
- Long Testing Cycle: Automotive electronic and electrical equipment may experience several years or even more than a decade in actual use. It is difficult to simulate the impact of such a long period of high temperature and high humidity environments on the equipment in a short time. Moreover, many reliability problems will only manifest after a long period of accumulation, such as material aging, corrosion, and degradation of electrical performance.
- High Precision Requirements for Environmental Parameter Control: In high temperature and high humidity environments, slight fluctuations in temperature and humidity can have a significant impact on test results. For example, during moisture-proof performance testing, if the humidity is not controlled accurately, the test results may not truly reflect the equipment’s moisture-proof ability in the actual environment.
Solution Methods
- Optimization of Accelerated Life Testing Methods: Apply the Accelerated Life Testing (ALT) theory. Based on material characteristics and failure mechanisms, reasonably increase the temperature and humidity of the testing environment to shorten the testing cycle. However, it should be noted that the determination of the acceleration factor must be based on scientific theories and a large amount of experimental data to ensure that the test results after acceleration can truly reflect the service life of the equipment under normal use conditions. For example, use the Arrhenius equation to calculate the temperature acceleration factor and determine appropriate high-temperature testing conditions.
- Use of High-Precision Environmental Testing Equipment: Adopt advanced temperature and humidity control equipment, such as constant temperature and humidity test chambers equipped with high-precision sensors and feedback control systems. These equipment can precisely control the temperature (with an error within ±0.5 °C) and humidity (with an error within ±3% RH), and can monitor and record environmental parameters in real time to ensure the stability and consistency of the testing environment, thereby improving the accuracy of test results.
III. Simulation of Complex Vibration Conditions
Difficulty Analysis
- Complex Vibration Spectra: During driving, a vehicle will encounter various road conditions, such as smooth highways, bumpy dirt roads, and speed bumps. The vibration frequencies and amplitudes corresponding to each road condition are different. Moreover, factors such as the operation of the engine and tire imbalance will also generate additional vibrations. It is a difficulty in reliability testing to accurately simulate the vibration spectra of the vehicle under various working conditions.
- Multi-Axis Vibration Coupling Problem: Automotive electronic and electrical equipment will be subjected to vibrations from multiple directions (X, Y, Z axes) in actual use, and these vibrations will couple with each other, resulting in complex mechanical effects. For example, vibrations in one direction may cause resonance of the equipment in other directions. This multi-axis vibration coupling has a great impact on the reliability of the mechanical structure and electrical connections of the equipment, and it is relatively difficult to simulate this complex coupling vibration.
Solution Methods
- Establishment of Detailed Vibration Databases and Models: Collect vibration data of different vehicle models under various road conditions, and establish vibration spectrum models through data analysis. For example, install acceleration sensors on actual vehicles using a data acquisition system to record vibration signals of the vehicles under different driving speeds and road conditions, and then use signal processing software for spectrum analysis. Store these data in a database. During testing, the vibration spectrum parameters of the vibration test bench can be set according to the vehicle type and application scenario of the test object by retrieving the corresponding vibration spectrum from the database.
- Adoption of Multi-Axis Vibration Testing Systems: Use testing equipment that can simultaneously apply vibrations in multiple axes (X, Y, Z axes), and these equipment can simulate the coupling relationship between vibrations in different axes. By adjusting the frequency, amplitude, and phase difference of the vibrations in each axis, accurately simulate the complex vibration situation during the actual driving of the vehicle. Meanwhile, install multiple strain gauges and acceleration sensors on the equipment to monitor the stress and acceleration responses of the equipment under multi-axis vibrations in real time and detect potential reliability problems in a timely manner.
Post time: Nov-26-2024
