Tuning the Dissipation in Friction Dampers Excited by Depolarized Waves Across Patterned Surfaces

Recently, patterned surfaces (elastodynamic meta-surfaces) were shown to cause mechanical wave depolarization resulting in conversion of uniaxial waves to multiaxial vibrations. Frictional oscillators loaded in multiple directions provide more tailorable damping scheme when compared to uniaxially loaded equivalents. This paper utilizes wave depolarization properties of patterned surfaces in tuning frictional damping. In particular, two-dimensional (2D) motion achieved by anisotropic wave reflection and depolarization across patterned surfaces is exerted on a simple friction oscillator; and frictional energy dissipation is studied using the homogenization theory and mechanics of a simple friction oscillator under macro and microslip conditions. The degree of depolarization is shown to control the extent of frictional shakedown (no-dissipation) zones and magnitude of energy dissipation for different incident wave frequencies and amplitudes. Transmission of the depolarized waves from the patterned surface to the friction oscillator enables higher and more uniform frictional damping for broader loading conditions. Uniform damping facilitates predictive linear dynamic models, and tuning the magnitude of damping permits efficient and robust wave attenuation, and energy transfer and localization in dynamic applications. A discussion on modeling assumptions and practical utilization of this potential is also provided. The presented potential of tuning frictional dissipation from very low to high values by simple surface patterns suggests that more sophisticated surface patterns can be designed for spatially varying frequency-dependent wave attenuation.