Influence of bonding glues on the vibration of piezoelectric fans

Vibration characteristics of piezoelectric fans are investigated experimentally and theoretically in the present work. The proposed 2-D lumped-mass model with a variable air damping factor describes the motion of piezoelectric fans qualitatively and predicts the vibration amplitude of fan tip in the upper limit where the glue thickness equals zero. According to this mathematical model, the numerical results show that the vibration amplitude of fan tip linearly increases with the applied voltage without any air loading. The vibration amplitude decreases with the presence of air loading. The reduction in vibration amplitude becomes more pronounced as the applied voltage increases. Physically, the presence of glue layer contributes to the piezoceramic stiffness and the structural damping of the vibration system. For the same glue (Young's modulus), the vibration amplitude increases with decreasing glue thickness due to the reduction in piezoceramic stiffness. However, the vibration amplitude increases with the Young's modulus of glues at the same thickness for the problem of interest. This fact implies that the structural damping induced by the glue layer considerably outweighs its additional stiffness onto the piezoceramic patch; thereby the influence of types of bonding glues on the vibration of piezoelectric fans should be seriously taken into account.