Dynamic displacement control error of multifunction and all-electric rheometer

A new multi-function and all-electric rheometer (MAR) is designed by the authors. A sine vibration displacement is superimposed on the steady-state displacement of the piston in parallel. In order to study the dynamic displacement control error of MAR, its frequency and amplitude was obtained through decomposing the measured resultant displacement into steady-state displacement and the dynamic displacement, and transforming the time-domain signal into frequency-domain presentation. The results show that both the frequency and amplitude control errors of MAR are small enough for the test requirement. However, the repeatability of measured values of amplitude is not as well as the frequency. And they are always smaller than the set values. The mean values of amplitude relative errors are about 2%, so it may be a useful way to set the amplitude 2% higher than the wanted values. The relative errors of amplitude in 5 Hz are slightly larger than the errors in the other cases. It may caused by the reason that 5 Hz is closed to the lower limitation of the vibration table rated frequency.