Experimental investigation of unbound nodes identification for metallic sandwich panels with truss core

Experimental investigation of metallic pyramidal sandwich panels with truss core in the cases of different extent and location of unbound nodes damages are conducted and a baseline-free damage identification method based on flexible matrix, gapped smoothing method and Teager energy operator is used. The influences of sensor density and Teager energy operator on the damage identification are also discussed. Moreover, a 0-1 unbound nodes identification method is also proposed to capture the shape and size of the unbound nodes damage zone. The results show that the proposed baseline-free method could identify the unbound nodes damage of metallic sandwich panels with truss core effectively. Increasing sensor density is beneficial for damage identification, and there is a critical sensor density for the identification of unbound nodes damage. Teager energy operator plays a very important role in suppressing fluctuations and singularities caused by non-damage factors, such as boundary condition, noise and shaker. The identified damage zone obtained by the 0-1 method is in accordance with the actual damage zone.