Automotive vibration testing technology instrument technology

Automotive Vibration Testing Technology-Instrument Technology

From dashboard to tables and chairs, from airbag sensor to engine fuel pump, many parts of the interior of the car must be tested with precise vibration modes and amplitudes.

In some cases, vibration tests are used to verify that the car\'s various devices will not be damaged under normal road conditions. In other cases, vibration testing is used to identify annoying noises made by machinery.

In the vibration control industry, successfully developed digital signal processing technology can create a more realistic vibration environment in laboratories and production lines. production. Today, in addition to traditional methods of using random waves, sine waves and shock waves, vibration testingations have also added more complex methods, such as adding sine waves to random waves and replicating waveforms.

As the name suggests, random sine waves paint random vibrations with sine waves to form complex vibration shapes; the waveform reproduces the vibration to imitate the real vibration environment of the automobile. Sine wave random vibration combines multiple sine waves with broadband noise. Sinusoidal vibrations can be fixed or swept harmonic or non-harmonic vibrations, and the amplitude of the vibrations is variable over the entire frequency band. Random sinusoidal vibrations are a good test method for simulating the random vibrations of a car driving over changing road surfaces as engine speed increases or decreases.

Practical application

Random sinusoidal vibration and waveform replication methods are used to test cars, which can truly reproduce the real environment in which the car drives. . It is used as design verification and quality control.

·Dashboard

Many automobile manufacturers perform vibration tests on dashboard components to check for squeaks and rattles. This item is probably the biggest dissatisfaction among new car buyers and accounts for a large portion of the deposit.

For the test, a special vibrating table was built, which does not use fans, in order to create a quiet environment to check if there are any cracks and clicks in the dashboard vibrant. Since there is no ventilation or heat dissipation, only a short vibration test can be carried out when increasing thetemperature exceeds the operating temperature, then the test should be paused for a period of time to allow the equipment to cool.

With the exception of the vibration table, all instruments and equipment that can emit noise, including the vibration table controller, must be placed next to the test room. The remote control panel and display should hang above the test device so personnel can hear the noise and control the test process.

Used to examine vibration patterns of squeaks and clicks, which are made up of random waves. It consists of a sweeping sine wave and a multi-segment waveform representing the load. The vibration amplitude should be controlled within the rated experimental value during normal driving of the car. To avoid too much vibration. Repair the parts and tighten them properly.

InIn vibration testing, the operator plays a key role, for example by applying a sweeping sine wave to repeat the vibration pattern of the accelerated motor. At this point, multiple frequency sweeps can be added to detect abnormal noise. Since it is difficult to find the cause, the operator should stop the next operation of the dashboard and use dynamic methods to control the frequency and amplitude of vibration to check the real cause of the noise. Only in this way can the mechanism of noise generation be discovered. Many equipment manufacturers also use this method as a means of quality control.

When detecting crackles and clicks, a vibration experiment combining heating and sunlight is sometimes used. Some car manufacturers install an integrated test system with an electric vibrating table and a solar panelinstalled in a large temperature control room, and the operator adjusts the temperature, vibration mode and amplitude, and network in the central control center to detect noise.

Car Seats

Many car manufacturers have used high-tech vibration testing equipment to test for squeaky seats. Mount the seat on the tilt plate of the electro-hydraulic shaker. Use a dynamic signal analyzer to automatically check for noise and obtain the 1/3 octave spectrum. Instrument monitoring is used instead of manual detection. When the noise exceeds the preset level, the operator is informed.

Since a car seat is more sensitive to road vibrations, it is best to test the seat and its seat belt using a technology simulated road. Reproduction of real vibration waveformsinstead of traditional vibration methods can achieve better test results.

The pavement simulation uses a shaking table to reproduce the recorded historical conditions. Sometimes a device consisting of 4 or 6 vibrating tables is used to reproduce the environment in which the car wheels vibrate simultaneously. The use of cutting-edge signal processing technology and fast digital signal processors accurately simulates real-world vibration environments.

Previously, even simulating normal traffic conditions took less than an hour, but required a day of calculations. Today, a vibration controller can simulate historical road surface conditions indefinitely, without requiring hours or days of offline calculations. It is even possible to use several vibrating tables at the same time to carry out simulation tests.on several test points.

Mirror assembly

The stability test of the mirror assembly can be performed using a vibration table to simulate the vibrations of the road. The scattering of light beams reflected from mirrors is used to measure mirror vibrations and identify co-component vibrations that annoy car buyers.

Because the reflected beam is amplified twice by the rear view mirror, it has a lot of distortion in driving conditions. Small vibrations can blur the rearview mirror image. To find out the vibration frequency that causes the rearview mirror image to blur during testing, a sweeping sinusoidal vibration with controllable acceleration amplitude was used to apply it to the rearview mirror. A laser imaging system is used to monitor the mirror image and capture the resulting image when the mirror resonates. The program of the laser imaging system communicates with the vibration control system and stores the frequency, amplitude and other relevant parameters (time and date) of the vibrations.

Vibration testing can also be used to identify the natural vibration frequency of mirror components? Nature, using a hammer instrument to generate vibrations instead of a controlled vibrating table.

The vibration test process for automotive mirror manufacturers\' mirror components consists of: using the impact test method to identify the mirror\'s resonant frequency and potential structural defects caused by engine vibration; Use a dynamic signal analyzer to test the reaction of the manufactured product to impact, the resonant frequency of the manufactured product is measured and compared to the preset spectrum. This allows automatic quality checkingof the product during manufacturing.

Oil injection pump

The oil injection pump is subjected to the combined vibration environment of the body assembly of pump with the road surface and the engine. The sinusoidal vibration representing the engine vibration is superimposed on the background of random vibrations, which correctly simulates the vibration of the road surface and accurately simulates the vibration state of the road surface. Coupled with the use of multiple sinusoidal harmonics to simulate motor vibrations, this is a very effective loss to the real situation. The sound you hear from the shaker is the same as a real car on the road.

In order to imitate the oil injection pump actually installed on the engine, the oil injection pump is fixed with the clamp on the vibrating table and then the vibration test is carried out. Since the fixture itself also adds to thehe complexity of the inspection, its mechanical resonance adds additional amplitude to the movement of the transverse axis, therefore a technique called notching is used to impose the limit.

The maximum allowable amplitude of random and sinusoidal vibrations depends on the limiting spectrum, the amplitude of each sinusoidal harmonic and the additional energy spectral density of the random vibrations. During the test, the acceleration measured in the direction of the transverse axis must not exceed the limiting frequency spectrum. This limit can be avoided by reducing the frequency of the control signal. A notch appears on the ultimate control spectrum, indicating that this is a limiting spectrum.

Anti-collision sensor

The manufacturer of airbag anti-collision sensors tests each sensor by simulating instantaneous acceleration. The purpose of the test is to ensure that these sensors will not activate the airbags before reachingachieve a certain acceleration, and will immediately activate the airbags when the acceleration reaches a predetermined value.

Drive the vibration table to generate a half-sinusoidal acceleration pulse, or use the acceleration waveform recorded during the actual crash to simulate instantaneous acceleration. To verify that the action is effective with each impact, the sensor is attached to the test harness, controlled by vibration. It is monitored and controlled by the same computer program on the station.

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