Modeling and experimental study of a honeycomb beam filled with damping particles

Honeycomb sandwich laminates which are the basic structural element of spacecraft have inherently low damping. In this paper, we propose to improve the damping characteristics of such structures by adding damping particles in the cells of the honeycomb. This paper presents modeling of a cantilever beam constructed with honeycomb structure with the hexagonal honeycomb cells, filled with particles. The beam is subjected to external dynamic loads and the interactions of damping particles with the walls of the cells and its overall effect on the frequency response function (FRF) and the damping of the beam are obtained. The discrete-element-method (DEM) is used to model the dynamics of the particles in conjunction with the governing equations of motion of the beam and the cell-walls. The particle-particle and particle-wall impact is modeled using Hertz's non-linear dissipative contact model for normal component and Coulomb's laws of friction for tangential component. Contiguous block of cells near the tip of the cantilever beam were filled with the damping particles and the beam was excited with a random signal near the fixed end. The damping and transfer functions obtained experimentally are compared to those obtained from the mathematical model and they are found to match very well. Further the model was used to study the effect of fill fraction, mass ratio, and the level of excitation signal on transfer function. Depending on the mass ratio and fill fraction, significant reductions in vibration levels are observed.