Functional features of ZETLAB shaker controllers
Before buying a new system, our customers often face the issue of selecting a system with the best possible combination of price, quality and functional range. Today the market of instruments offers a wide range of highly competitive systems. In order to help you, we have prepared the list of the most frequently asked questions related to operation of the shaker controllers by ZETLAB Company.
The first question is to deal with demonstration of the shaker controller’s operation.
Is it possible for you to demonstrate operation of your shaker controller and its functional features?
Yes, it is possible to demonstrate operation of the system both at the office of our Company and in the premises of the Customer (within the territory of Moscow district). In addition to that, you can also view our video lessons demonstrating operation of our shaker controllers.
How many channels does the shaker controller have, and how many channels can be used for control of system’s operation?
Shaker controllers ZET017-U4 and ZET017-U8 have 4 and 8 channels respectively. VCS ZET024 and VCS ZET028 are also available in configurations with 4 and 8 channels. In order to increase the number of channels, the basic configuration of the system includes the option of devices synchronization by PTP 1588 interface.
In the case if you have 4 shaker controllers ZET 017-U8 with synchronization option, you can actually use up to 32 channels. New versions of VCS ZET024 and ZET028 allow to increase the number of measurement channels up to 128.
The delivery scope of shaker controllers includes ZETLAB VIBRO software. The programs Sinusoidal vibration and Random vibration allow to use all the available channel as control channels. The programs Classical shock and Vibrational shock allow to use only one control channel.
What is the operational frequency range of the VCS? Is it possible to use the VCS for tests performance at the frequency of 1Hz?
Operational frequency range of the VCS is from 3Hz up to 10000Hz for accelerometers. In the range from 1Hz up to 16Hz the VCS is to be used with displacement transducers (eddy-current, and optical transducers) in the program Sinusoidal vibration.
What dynamic range is generated by the VCS? What dynamic range is required for tests performance?
The dynamic range for sine vibration testing is 80 dB, 60 dB for random vibration (for ZET017-U series). For the VCS of ZET 024 and ZET 028 series, the dynamic range of control signal for sine vibration is 105 dB, and 80 dB for random vibration.
Most of the tests are conducted in the range of 1-100g. Acceleration levels below 1 g do not affect the specimen, while acceleration over 100g can only be produced by powerful electrodynamic shakers. Interval of 1-100g is only 40 dB. Thus, the specified dynamic range is sufficient for tests performance.
Is it possible to use the VCS with a shaker, that has vacuum-tube amplifier?
It is possible in the case if the amplifier has an input for connection of external generator. If the output has BNC connection, there should be no issues. If the output is of a different type, then it will be necessary to make a special cable.
In the case if shaker controller ZET 017-U is connected to an amplifier, one have to observe the requirements of the connection scheme. In the case if the amplifier and the shaker controller have different ground connection levels, which will lead to a considerable interfereance preventing the tests performance and damaging the equipment. It is ncessary to check the grounding connections with the use of curcuit analyzer.
Is it possible to combine SoS and SoR tests on one and the same graph?
Yes, it is possible. ZETLAB VIBRO software allows to set the following combined test modes: Sine-on-Random, Random-on-Random, Sine-on-Sine, Sine-on-Random-on-Random.
Does the program “Sinusoidal vibration” allow to set testing profiles at a fixed frequency?
Yes, it is possible. To do that, it is necessary to set two points with identical frequency and amplitude. In this case, the sweep rate will have zero value for the speicifed interval. In the case if you need to avoid vibration at the intermediate frequencies, you have to set a point for each of the frequencies, and one additional point with the same frequency and smaller amplitude. An example of setting the profile can be viewed in the document “Operator manual”, which is suplied together with the system.
Is it possible to search for the resonance frequencies of the specimen using the VCS?
For the purpose of the resonance frequencies search, you can use the VCS software programs.
The programs “Sinusoidal vibration” and “Random vibration” allow to maintain constant levels of acceleration and acceleration spectral density. The “Report” key activates the report window displaying the transfer characteristic graph. The transfer characteristic graph displayed in the VCS software is the reverse graph from the AFR, i.e., the gap in the transfer characteristic graph corresponds to the resonance frequency, and the peak value of the transfer characteristic corresponds to the anti-resonance frequency. The programs allow to save the transfer characteristic value to the test report.
The programs “Classical shock” and “Vibrational shock” are used for measurement of AFR and phase-frequency response before actual test performance and allow to view the relevant graphs. At these graphs, resonance and anti-resonances are indicated by peak amplitudes and rapid shifts of phases at π/2. You can also copy these graphs to the clipboard (use the combination CTRL+C or C to copy the image, and CTRL+N or N to copy the values table).
Is it possible to do the following: measure the AFR of the shaker without the specimen, then measure the AFR with the specimen, reveal the resonance frequencies of the specimen, and then to maintain these resonance frequencies at the set parameters of vibration testing for the required amount of time?
Yes, it is possible. You have to measure the AFR using the task-specific programs available in the “Metrology” section. Then you have to calculate the test profile parameters and to enter it in the program (for instance, in the Generator: sinusoidal vibration program).
Latest versions of the VCS have an additional mode of software operation: Resonance search, track and dwell (RSTD).
It is quite often, that the test requirements imply that the user has to maintain constant peak-to-peak amplitude of the oscillations. In such cases, normally the following issues arise:
Does the VCS allow to maintain constant peak-to-peak amplitude of the oscillations? At the screenshots displayed on your web-site I have seen three options: RMS, amplitude, and peak values. Am I right to think that the peak-to-peak amplitude is represented by the peak amplitude?
Yes, the program in question allows to maintain constant amplitude of oscillations by displacement (it is important to specify the particular physical value to be controlled, since in the course of vibration testing, such parameters as displacement, velocity, and acceleration are to be controlled).
“RMS” and “Amplitude” are the two available methods of the control parameters measurements. All types of vibration testing are controlled based on the acceleration value. In order to prevent possible confusion in the names of the measurement methods, they are termed as “Effective” and “Envelope curve”.