Active Fuzzy Control on Invisible Metamaterial Cloak in Elastic Thick Plate with Multiple Arbitrary Targets

Abstract Wave invisibility has great values in aerospace and military fields. In this work, a flexural wave metamaterial cloak is proposed for multiple arbitrary targets in elastic thick plate. The fuzzy proportional-integral-derivative (PID) active control is applied. The scattering field of flexural wave in thick plate is considered. Based on the wave function expansion method and Mindlin thick plate theory, the wave equation for infinite and arbitrary hole targets with their enveloping cloaks is derived. Both structure and material parameters are considered to discuss about the dynamic stress concentration, scattering amplitude, and scattering cross section (SCS) of the multiple targets. In addition, the cloaking device is designed to locate around every hole target, in which multiple layers with regularly arranged piezoelectric (PZT) patches are included. Every PZT patch is connected to the external active circuit with fuzzy PID control function. The theoretical and experimental results indicate that the present flexural cloak meets invisible requirements. Dynamic stress concentration, scattering amplitude, and scattering cross section of multiple targets are reduced by the cloaking configuration. Compared to the original structure without fuzzy PID active control, the invisible performance with the active cloak can be effectively enhanced.