UC San Diego

Strongly nonlinear waves were investigated experimentally, numerically and ana- lytically in two-mass and one mass systems. Experimental setups consist of one dimen- sional assembly of elastic stainless steel spheres or cylinders with different masses layered alternatively. When such assembly is not compressed, the sound speed is zero therefore creating a new state called “sonic vacuum”. Such systems does not supports sound waves but strongly nonlinear solitary waves can propagate in it. Band-gap phenomenon was observed and discussed for strongly nonlinear and nonlinear quasi-harmonic excitations in two-mass systems.

Formation and transformation of short, strongly nonlinear stress pulses were investigated in granular systems with different mass ratios, but with the same contact. Dissipation in the system with mass ratio close to 1 was faster than in the system with mass ratio 0.55. This is contrary to the expected behavior of corresponding non dissipative systems.

Striker impact generates a single solitary wave or a train of solitary waves depend- ing on the mass ratio between the striker and the particle mass inside the chain. Imaginary scenarios of striker interacting with a single mass, that’s called “effective mass”, will be discussed to model the striker interaction with a collective of particles. This approach is based on two conservation laws. It satisfactorily predicts the upper estimate for the linear momenta, energies and amplitudes in the train of solitary wave in far field depending on the relative mass of the striker and particles in the chain.