Vibration control of shadow-mask with tension gradient using multiple dynamic absorber

Damping wires have been used to reduce the vibration of the shadow-mask of a large-size cathode-ray-tube (CRT). However, because the wires are very thin and are equipped on the surface of the shadow-mask, they have some limitations. Specifically, difficulty in their construction is typically encountered and they create a shadow on the screen of the CRT when applied to the shadow-mask. In this work, a multiple dynamic absorber (MDA) is introduced to effectively reduce vibration of the shadow-mask and circumvents the aforementioned limitations. The design method of the MDA is developed based on the theory of a simple dynamic absorber, because the shadow-mask has well separated and locally deformed vibration modes. The design of the dynamic absorber should involve the specification of three parameters: mass, damping ratio, and tuning frequency. In order to determine the design criteria of the MDA, a sensitivity analysis of these three parameters is executed using a finite element (FE) model of the shadow-mask. The MDA designed via the proposed method is applied to the shadow-mask and tested numerically and experimentally in order to assess its vibration reduction efficiency.