Tailor metamaterial bandgaps with bending, folding and twisting for the non-vibration ship pump base

• Bandgap tailoring methods can effectively adjust and generate elastic wave bandgaps, such as bending, folding, and twisting operations on the negative Poisson's ratio star-shaped metamaterial (NPRSM) unit cell. • The bending operation has created a new complete bandgap and expanded the directional bandgap in the low-frequency region. The folding operation, meanwhile, has been observed to lead to the widening of the directional bandgaps in the high-frequency region. The twisting operation generates and expands directional bandgaps in the middle-frequency regions. • Using the bandgap tailoring method, the vibration level difference between the metamaterial pump base and the conventional base is >30 dB at 517.95 Hz - 668.36 Hz and 916.98 Hz - 965.03 Hz, with a weight reduction of 36.19 % to the conventional pump base. Applying distinctive designs to mechanical metamaterials is an effective way to achieve bandgap generation, widening and movement. In this paper, the bandgaps of metamaterials are tailored through the unique design of bending, folding, and twisting units and applied to the vibration-damping design of a marine water pump base. It is found that the bending operation generates a new complete bandgap and significantly enlarges the directional bandgap in the low-frequency region; the folding operation expands the directional bandgap in the high-frequency region; and the twisting operation generates and broadens the directional bandgap in the mid-frequency region. The application of the negative Poisson's ratio star-shaped metamaterial (NPRSM) cell, with a 60° bending angle, to vibration damping in a metamaterial ship pump base is presented. The new base achieved vibration attenuation of 43.435 dB and 60.282 dB over the bandgap ranges of 517.95 Hz - 668.36 Hz and 916.98 Hz - 965.03 Hz, respectively. In addition, the weight of the new base was reduced by 36.19 % compared to the conventional pump base, which is merely capable of bearing loads. This study provides an innovative design method for broadband vibration isolation and demonstrates the promising future of mechanical metamaterials in practical engineering applications.