Multi DOF High Frequency Vibration Test System
Developing a high-frequency multi-axis vibration system for small objects (Electronic cards, sensor etc.) involves combining mechanical, electrical, and control engineering principles to create a reliable and effective testing platform.
A High-Frequency Vibration Test System is designed to subject objects or structures to controlled vibrational forces, simulating real-world conditions or testing for durability and performance under specific frequency ranges. These systems are used across various industries, including aerospace, automotive, electronics, and structural engineering to simulate and test the response of structures or products to vibrations.
Furthermore, the degree of freedom related to this topic has a vital role. Multi-axis systems typically offer control over multiple degrees of freedom. A degree of freedom represents an independent direction in which the system can move or vibrate. For comprehensive testing, a 3-axis (cartesian coordinate system parameters: x, y, z), Quadri-axial or 6-axis (x, y, z, pitch, roll and yaw) system may be used. Below are two multi-axis vibration test systems of S.E.R.E.M.E. Their core activity is the design and delivery of vibration, acoustic and shock test facilities. In this sector, SEREME’s main segment is the high-end segment, which often leads to customized testing facilities.
Figure 1: Quadri-Axial System
Figure 2: 6 Axis System
Objective & Scope
The test facility of the vibration test systems is designed to simulate the real-world operating conditions and to evaluate the response of the objects or structures to vibrations. The specific tests chosen to depend on the goals of the characterization and the characteristics of the material or product being studied. System characterization is essential to provide an overview of the objects’ natural frequencies, damping parameters, and structural mode shapes. By using those parameters, it is possible to use them into Finite Element analytical models as well and it enables users to validation or optimization of their products.
These test systems are handy and easy to use for diversified field of use. Those systems are used to clarify the characteristics of materials or products that under test (DUT). These tests provide valuable information by using Multiple Input Multiple Output (MIMO) measurement channels for design, manufacturing, quality control and research and development purposes.
Figure 3: 6 Axis Vibration Test System
Figure 4: Quadri-Axis Test System
A multi-axis test configurations of S.E.R.E.M.E is shown above. To execute characterization
tests with these vibration test systems, measurement and control accelerometers are used. To do
so, the content of certain concepts and equipment are explained.
MIMO measurement techniques are proven and well-established methods for collecting frequency response function “FRF” [g2/Hz] data sets which contains the modal parameters (Natural frequencies, damping ratios, mode shapes) of the related structure. They offer some distinct advantages for the measurement and extraction of basic modal parameters especially while testing larger structures.
The main idea behind the MDOF vibration system working principle and the MIMO notion is explained so far. However, to execute characterization test with those kind of vibration systems there are some required equipments such as controllers with multiple measurement channels.
Controller refers to a device or system that is used to apply forces or excitations to a structure in order to study its dynamic characteristics, specifically its natural frequencies, mode shapes, and damping ratios as mentioned. They play crucial role in modal testing and characterization test where the aim is to identify the modal parameters of a structure. Moreover, they are responsible for generating and applying these excitations which could be in the form of impact hammers, shakers, or other devices that induce vibrations in the structure. The responses are then measured using sensors like accelerometers or displacement transducers.
Test Profiles
There are some essential parameters (Test Profile, Weight and Dimensions) while executing vibration analyses and the test profile is one of the most important parameters on this subject. The test profiles are used to simulate the vibration energy observed on each unique system and those systems can be used to adapt certain standards (such as military standards etc.) The decision to select the ideal profile to perform a vibration test should depend on the environment and the goal of the test program.
i. Sinusoidal or Sine vibration testing
ii. Random vibration testing
iii. Sine on Random (SOR)
iv. Random on Random (ROR)
In real life situations, vibrations are usually in random form and the brief explanation of the random vibration testing involves running of vibration energy at all frequencies over a specified range on a device under test (DUT) simultaneously. This is the most effective application when the test is based on actual field measurements of the specific environment where a product will be operated. On a random vibration power spectral density plot, the acceleration amplitude is scaled on the y-axis in units of g2/Hz and the x-axis in units of frequency (Hz).
Figure 5: Random Test Profile
Due to the process of conducting random vibration testing and the statistical nature of random data, random vibration testing is most suited for vibration qualification tests. Using an accelerometer or multiple accelerometers to capture the in-situ vibration environment, a random power spectral density plot can be created.
Below are some results with the 6-axis system vibration test system configuration which is executed in line with the regulation of MIL-STD-810H Figure 514.8C-15. Category 9 – Helicopter vibration exposure.
In summary, when selecting a High-Frequency Vibration Test System, it’s crucial to consider the specific requirements of your application, including the frequency range, amplitude, and the type of vibrations your specimens will encounter. It’s also advisable to work with experienced suppliers or consultants who can help tailor the system to your needs and provide ongoing support.
Last but not least, the characterization tests by using vibration test systems play a crucial role in understanding and optimizing the properties of materials across diversified industries, from ensuring product quality to advancing scientific research and development. Those vibration test systems have vital role in safety so that to verify the system has appropriate safety features and complies with relevant standards and regulations.
Technical Specifications S.E.R.E.M.E Products
The technical specifications of the aforementioned vibration test systems are given below.
Figure 6: Quadri-Axis System
Figure 7: 6-Axis System