A compact quasi-zero-stiffness mechanical metamaterial based on truncated conical shells

As the demand for low-frequency and ultra-low-frequency vibration isolation in aerospace inspection and ultra-precision manufacturing grows exponentially, traditional vibration isolation strategies have been unable to satisfy these escalating needs due to their drawbacks such as a loose appearance, substantial dead weight, and elevated mechanical friction. Metamaterials, as artificially constructed periodic materials, have provided a promising solution to these above issues. In this paper, a novel compact one-dimensional quasi-zero-stiffness metamaterial with a tunable bandgap is presented, composed of a single unit centered on a truncated conical shell with a unique quasi-zero-stiffness structure. The monolithic quasi-zero-stiffness configuration significantly reduces the weight and size compared to conventional vibration isolation structures, ensuring high reliability with a minimum number of units and a compact form factor. A combination of theoretical analysis, finite element method and experiment is employed to investigate the vibration isolation properties of metamaterials comprehensively. Notably, the metamaterials designed in this paper can achieve vibration isolation at a very low frequency. Through the strategic application of pre-displacement, the entire bandgap can be systematically shifted to lower frequency ranges, which results in a reduction of the starting frequency to 15.01 Hz, marking a remarkable decrease of 46.6%. The novel proposed metamaterial, as detailed in this paper, can provide a reference for researchers involved in this field.