Let’s explore additional espects by delving into the auxiliary technical indicators, providing a deeper understanding beyond the core vibration functionalities and technical specifications.
a) Stability of vibration parameters S
The stability of vibration parameters refers to the change in vibration output parameters (frequency, displacement, speed, acceleration) with the vibration time history, usually expressed as a percentage “%” value.
In vibration tests, the more stable the vibration parameters are, the more credible and effective the test results are.
b)Vibration waveform distortion degree Y
The smaller the waveform distortion of the shaking table, the more conducive it is to the waveform reproduction of sinusoidal vibration and the improvement of the accuracy of frequency sweep vibration. It is also conducive to the reproduction and simulation of transient waveforms and “spectrum” in random vibration and shock tests.
c) The first-order resonant frequency ω of the vibration table The first-order resonant frequency of the vibrating table refers to the basic natural frequency of the mass-spring system composed of the moving parts of the vibrating table and its suspension and support structures in the no-load state. The higher the value of this parameter, the more advantageous it is for the user to perform vibration tests.
d) Fixed vibration accuracy table for sweep frequency vibration
e) The dynamic range alarm test of the vibration test system During the vibration testing, due to the resonance of the sub-vibration table, fixture and test piece assembly, in the open-loop state, the measured acceleration-frequency response characteristics of the control point will have many steeply rising convex peaks and sudden depressions. During closed-loop control, the vibration control system must have the ability to compensate and flatten the steep changes in acceleration between “peaks and valleys” (referred to as voltage control capability) to meet the fixed vibration accuracy requirements of sweep frequency vibration, and is also conducive to the vibration power spectrum and Reproducible simulation of shock response spectrum. This ability to define the “peak-to-valleys” voltage control of the vibration table system is the dynamic range of the vibration test system.
The dynamic range of the vibration test system cannot be regarded as the same as the dynamic range of the vibration test control system itself. The former index is also related to the background noise of the vibration table body and the power amplifier. The dynamic range of the control system only directly connects its output and input ports, and detects the ratio of the maximum output of the control system itself to the background electrical noise, which has nothing to do with the working conditions of the vibration table and power amplifier.
f) Shaking table acceleration signal-to-noise ratio M
The acceleration signal-to-noise ratio of the shaking table refers to the ratio of the highest output acceleration to the lowest output acceleration under the no-load state of the shaking table. This indicator indicates the relationship between the highest acceleration output of the shaking table and the background noise. The higher this index is, the higher the dynamic range of the vibration test system will be, and it will also help improve the distortion of the waveform, and will be more conducive to the reproduction and simulation of random vibration signals and shock signals.
g) Vibration table transverse vibration T
The lateral vibration of the vibrating table refers to the percentage of the maximum vibration amplitude (displacement, acceleration) in the plane perpendicular to the main vibration direction and the vibration amplitude in the main vibration direction, usually expressed as a percentage “%” value.
h) Vibration table acceleration uniformity N Vibration table acceleration uniformity refers to the non-uniformity of the vibration acceleration output of each point on the vibration table in the no-load state. The calculation is based on the maximum of the acceleration of each point on the table and the acceleration of the center point of the table. The ratio of the difference to the acceleration of the center point, expressed as a percentage “%”.
i) Offset load capacity The eccentric load capacity refers to the degree to which the center of gravity (i.e., the center of mass) of the test piece installed on the vibration table is not allowed to coincide with the central axis of the vibration table. This type of vibration table is usually marked with “eccentric moment” (N·m or kN·m). ability.
j) Magnetic leakage on the working table
Table magnetic leakage refers to the intensity (T) of the magnetic leakage magnetic field generated above the central axis of the vibration table (that is, the position of the test piece during the vibration test) when the vibration table is working.