Unveiling solitonic collisions in mechanical metamaterials

Interactions between solitary waves are crucial for understanding nonlinear phenomena in systems such as optics, fluid dynamics, and mechanical metamaterials. Rarefaction solitary waves, in particular, offer insight into nonlinear wave dynamics in strain-softening media. Despite their proposed applications in waveguides and energy harvesting, key characteristics-particularly solitonic collisions-are not yet fully understood due to energy dissipation and the need for high-precision measurement techniques. In this work, we introduce an experimental platform for studying pure rarefaction solitons in a strain-softening lattice. Our results show that both symmetric and asymmetric collisions display elastic interactions and amplitude-dependent phase shifts. The experimentally observed dynamics, including soliton speed and phase shifts, closely match numerical simulations and analytical predictions based on the Boussinesq approximation. These findings not only validate our platform but also highlight the potential of mechanical rarefaction solitons for probing nonlinear wave interactions and advancing wave-based computing.