## 1 Introduction
Based on the re-entrant honeycomb metamaterials, [PERSON] et al. [41] proposed a new type of re-entered negative Poisson's ratio metamaterial with rings instead of connection points, and the bandgap properties of the metamaterial were analyzed and optimized according to the mode theory. [PERSON] et al. [42] adopted the FEM to survey the band structure of a two-material triangular re-entrant honeycomb metamaterial with an adjustable thermal expansion coefficient. [PERSON] et al. [43] proposed an isotactic chiral metamaterial with a Thomson scattering-induced bandgap, which generated a broad bandgap in the low-frequency region. [PERSON] et al. [44] studied the vibration performance of three-dimensional reverse-chiral auxiliary metamaterial under quasistatic conditions through experiments and simulations, and the results showed that the metamaterial had a good performance in vibration suppression. [PERSON] et al. [45] introduced the concept of tacticity in spin-spin-coupled chiral phononic crystals. By aligning the centers of adjacent chiral structures in opposite directions, the nature of the coupling between the spins of the atoms in the chain was changed. Thus, it had a good vibration-suppression performance at a low frequency. These works show that low-frequency bandgaps can be achieved by reducing the local stiffness, increasing the local mass of the metamaterials or changing the arrangement of the unit structures. The superior properties of metamaterials with different structures are manifested in different aspects. Therefore, it is an innovative work to integrate two or more single-structural metamaterials to design a new metamaterial with the advantages of all single structures at the same time. In this work, we proposed a novel re-entrant honeycomb metamaterial based on the idea of assembly, which improved the load-bearing capacity of the metamaterial by introducing chiral structures into the conventional diamond structure. Moreover, circular rings were arranged at all the connecting nodes of the proposed metamaterial, and metal pins or particle damping were assembled into the rings to further optimize the overall stiffness of the metamaterial, and excellent bandgap properties in both the high- and low-frequency ranges were obtained. The bandgap properties of the metamaterials are figured by simulation method, and the influence of the design parameters (including the different sizes of the ring and pin, and the different materials of the pin) on the bandgap properties is also discussed to provide a bandgap adjustment method for meeting the different requirements in engineering applications. Meanwhile, with the different bandgaps of metamaterials generated from the above method, the vibration-suppression performance of the metamaterials was evaluated and compared by simulations and experiments, with a particular concern on the particle damping scheme. In addition, the static properties of the metamaterials, which affect the load-bearing capacity directly, are studied and validated by the combination method of the simulation and experiment. The rest of the paper is organized as follows. Section 2 describes the geometric structure and design ideas of the novel re-entrant honeycomb metamaterials. Section 3 shows the static properties of the proposed metamaterials and discusses the influence parameters. Section 4 investigates the bandgap properties of the proposed metamaterial and explores its adjustment methods. Section 5 verifies the vibration-isolation performance of the optimized metamaterials through simulation and experiment. Conclusions are given in Section 6.