Experimental study of frictional interfaces using solitary waves in 1-D monoatomic granular crystals

This research addresses critical challenges in understanding the complex mechanics in frictional interfaces. Interfaces in machinery subjected to vibrations are difficult to study due to limited experimental data on contact states like stick, slip, and separation. To address this, we exploit solitary waves in granular crystals as a novel method to monitor friction in vibrating surfaces. Solitary waves exist in nonlinear media and are highly sensitive to contact mechanics due to their localized point contact and short interaction timescales. Their sensitivity to boundary conditions, short interaction timescales, and localized point contact suggest the potential for nondestructive evaluation of friction, offering advantages over conventional ultrasonic techniques. This study focuses on effects of vibrating frictional interface at the boundary of a chain of rigid spheres and its impact on solitary wave speed. The experiment demands precise control and measurements to address the challenges by solitary waves' sensitivity to contact variations. Experimental results show measurable changes in solitary wave speed during stick, slip, and the evolution of contact parameters by wear, above the noise floor, demonstrating the potential for nondestructive evaluation. Anticipated outcomes include deeper understanding of interfacial mechanics, new characterization tools, and innovative acoustic metamaterials, with implications for industrial and naval applications.