High Damping Characteristics of an Elastomer Particle Damper

Abstract

Research testing has led to the development of an Elastomer Particle Damper (EPD), which can add considerable damping to a structure by directing the vibration to a set of interacting elastomer particles through a rigid connection. This vibration treatment presents highly nonlinear behavior that is strongly dependent on both the vibration amplitude and frequency. Curves of damping loss factor (DLF) of an EPD system with vertical motion as a function of frequency and acceleration are reported herein. The results show that the elastomer particle damper has two distinct damping regions. The first region is related to the fluidization state of the particles, as described in the literature, obtained when the damper is subjected to vertical acceleration close to 1 g and frequencies below 50 Hz. The second region presents high values of DLF to acceleration values lower than 1 g, and the frequency range is dependent upon the stiffness of the particles. A high degree of effectiveness is achieved when the working frequency of the elastomer particle dampers is tuned to a natural frequency of a plate and when they are strategically located at points having large displacement. The performance of EPDs was compared with that of a commercial constrained layer damping installed in an aircraft floor panel. The EPDs achieved an acceleration level attenuation in the aircraft floor panel similar to that of the commercial constrained layer damping system.

Efficiency of Particle Damping on Lightweight CFRP Structures

“…PD consists in enclosing particles (sand, metal powders, elastomer balls…) in a cavity that dissipate energy when they are excited. As it can be observed in Figure 1, the cavity can be bonded to the main structure [12,13] or integrated in the core of sandwich panels [14][15][16][17]. The dissipative mechanisms are very complex, as they consist in friction and inelastic collisions between particles, cavity walls and face-sheets.…”

“…This means that the response of these dampers depends on a large variety of parameters (particle geometry and material, filling ratio, cavity dimensions and material, particle-cavity coefficient of friction, etc.) that, although been studied [12,[15][16][17][18][19][20][21][22],…”

“…The slightly higher than gravity threshold can be explained by the fact that the particles have to overcome, besides gravity, frictional forces with the cavity before starting to have a relative motion with it. Some authors reported that dissipation at low accelerations occurred only due to the intrinsic Loss Factor of the particles, so in those cases dissipation could only be achieved by using elastomeric particles [12,18]. When the excitation is increased above the 1.2g value, convection rolls appear with frequency depending-shapes [25], due to the friction forces that the cavity exerts on the particle bed.…”

“…An alternative approach is a test experimental set-up permitting the direct measurement of the PD behavior, especially when it comes to studying their frequency and acceleration dependency. Placing the damper on a cantilever beam and measuring the Loss Factor via the Half-power Bandwidth Method was found to be too time consuming [12,15,22]. Another drawback of this method is the influence that the beam and clamping have on the dissipation measurements.…”

“…Another drawback of this method is the influence that the beam and clamping have on the dissipation measurements. The Power Input Method (PIM) was instead found to be the most convenient approach [12,20]. As it can be observed in Figure 6 (right), an impedance head was mounted on an electromagnetic shaker.…”