Spatially networked architecture of locally resonant metamaterial for multi-frequency and multi-directional bandgap formation in pipes

Multi-directional vibrations in marine equipment pipeline systems severely threaten the safe and coordinated operation of multiple systems. Yet, the high spatial density of pipelines imposes stricter requirements on the compact and lightweight design of vibration absorbers. This paper proposes a topology design for multi-frequency resonant metamaterial pipes under limited space and additional mass constraints. Via a spatially networked array of local oscillators and equidistant cell arrangement, a spatially networked metamaterial (SNM) pipe is constructed to suppress multi-directional vibrations in both radial and longitudinal pipe modes. A finite element model of the SNM pipe was developed to obtain band structures, frequency-response curves, and insertion losses. Experimental validation of the pipe’s vibration performance confirmed both the simulation model and computational accuracy. Parametric analysis was performed on the pipe’s vibration attenuation characteristics in longitudinal and circumferential radial directions. It is found that unidirectional arrangement of SNM cells can generate multi-directional broadband gaps. Tuning SNM cell parameters enables multi-frequency bandgap coupling, broadening the vibration attenuation range and reducing overflow resonance peaks. Moreover, the spiral geometry of metamaterial cells preserves vibration attenuation performance while enabling circumferential bandgap coupling, thus expanding the operational bandwidth for vibration mitigation. This research presents innovative methodologies for the integrated control of multi-directional low-frequency broadband vibrations of pipes under complex engineering constraints in marine equipment.