“…Accordingly, a wide class of new applications arise both in the aerospace and mechanical engineering fields, ranging from cloaking, 5 energy absorption, 6 coupling of distant structures, 7,8 wave control, 9,10 but also swarm dynamics. 11,12 In all these cases, the new features produce effects in terms of changes in wave stability, the emergence of negative group velocity, 13 superfast group and phase propagation 14,15 and band gaps. 16,17…”