A method for reducing the blade vibration of platform damper using the macro-micro slip model

By incorporating elastoplastic shear layer to characterize the dry friction contact, we present a macro-micro slip model for dry friction. Based on its first harmonics and equivalent linearization, the equivalent stiffness and damping which are defined as dry friction factors are studied. In addition, the spring-damper element containing two dry friction factors is introduced to model the dry friction force, and a finite element model for blade-blade (B-B) platform damper is set up. By using harmonic response analysis and iteration, the dynamical system is simulated. Influences of the key parameters in platform-damper design on reducing the blade vibration such as friction coefficient, normal force and external excitation are studied. Results indicate that after macro slip the equivalent stiffness and damping will decrease as the blade steady amplitude increases and that there is a range of normal load during which reduction effect of the blade's steady response under working frequency is satisfactory.