In mechanical metamaterials, large deformations can occur in systems which are topological from the point of view of linear waves. The interplay between such nonlinearities and topology affects... Show moreIn mechanical metamaterials, large deformations can occur in systems which are topological from the point of view of linear waves. The interplay between such nonlinearities and topology affects wave propagation. Beyond perfectly periodic systems, defects provide a way to modify and control the properties of metamaterials, and can also interact with both nonlinearities and the bulk topology. To investigate these, we explore the wave propagation in three mechanical models, i.e.~solitary waves in topological rotor chains, lattice waves in twisted kagome networks, and transverse shock waves in flexible strings. Show less