Passive damping of truss vibration using preloaded joint backlash

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Passive damping of truss vibration using preloaded joint backlash

Onoda, J. / Sano, T. / Minesugi, K.

This paper proposes using preloaded backlashes to suppress the vibration of truss structures and clarifies the vibration suppression mechanism. With preloaded backlashes, a structure keeps its high stiffness and high static shape accuracy at low external loads and vibration levels. When the response of the structure exceeds a certain level, e.g., allowable level, the joints start slipping, introducing frictional damping and nonlinearity. This nonlinearity transfers energy from lower vibration modes to higher vibration modes. Because higher mode vibrations usually damp sooner, this nonlinear transfer of energy from lower to higher modes results in a quick damping of the entire vibration. Numerical simulations show that energy transfer between the modes drastically enhances the inherent damping capability of the structure. The resulting damping can be as large as that due to the frictional force at the backlashes, even when the inherent damping ratio of each mode is only 0.2 %. The simulation results demonstrate that frictional forces and enhanced inherent damping both suppress vibrations and that they are particularly effective in combination.