Vibration analysis of a blood processor centrifuge with anti-twister mechanism

This paper deals with the vibration analysis of a blood processor centrifuge with an anti-twister mechanism. Blood processors that employ anti-twister mechanisms are becoming increasingly popular because they cause relatively less damage to the blood than the conventional ones, which employ rotating seals. Knowledge of the vibration response of the device in its operating regime is important for trouble-free operation. A simple, three-degree-of-freedom, lumped-parameter, torsional-mode model is presented here. This model was used to analyse an existing blood processor. On comparing experimental and analytical values, it was found that the fundamental frequency as predicted analytically is within 19 per cent of the experimental value; the predicted second harmonic is about 28 per cent higher than the experimental one. Thus the proposed model predicts the fundamental frequency with reasonable accuracy. In design, the goal is to keep the operating frequency of the device sufficiently above the fundamental frequency to avoid resonance problems.