## 5 Conclusions  
A parallel polyurea integration method was proposed to effectively enhance the damping properties of metal lattice structures, thereby achieving superior vibration isolation and shock attenuation capabilities. The metal lattice structure was used for load-bearing capacity while incorporating parallel polyurea viscoelastic elements used for enhanced damping and energy dissipation. A novel vibration isolation system featuring this metal lattice-polyurea parallel composite structure was designed, with its corresponding theoretical model developed. Comprehensive analyses were conducted to evaluate the system's damping characteristics, vibration isolation performance, and shock mitigation capability. The experimental setup of the metal lattice-polyurea parallel composite structure vibration isolation system was built and verified through semi-sinusoidal shock tests and swept-frequency tests. Both theoretical and experimental results demonstrate that, compared with the metal lattice structure, the damping performance of the composite structure is improved significantly. Under shock excitation, the maximum peak value of the shock response of the composite structure with the introduction of the polyurea damping structure decreases, while the decay rate of the shock response is accelerated. Thus, the shock resistance effect is enhanced. Under swept-frequency excitation, the peak response of the composite structure significantly decreases, while the natural frequency remains unchanged, demonstrating better vibration isolation performance.  
This study offers a novel approach to enhancing the damping performance of metal lattice structure vibration isolation systems, improving their shock resistance and vibration isolation effectiveness. It also provides insights for the future development of vibration isolators suitable for conditions with high radiation, constrained spaces, large load-bearing  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Type**} & \multicolumn{2}{c}{**Theoretical Results**} & \multicolumn{2}{c}{**Experimental Results**} \\  & \(\xi\) & \(c\)/(N\(\cdot\)s/m) & \(\xi\) & \(c\)/(N\(\cdot\)s/m) \\ \hline LS & - & - & 0.0093 & 486.98 \\ CS-6 mm & 0.0243 & 1286.98 & 0.0154 & 807.03 \\ CS-8 mm & 0.0318 & 1686.98 & 0.0190 & 995.47 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Damping performance of the three vibration isolation systems under sweep-frequency excitation.  
capacity, low stiffness, and improved damping performance. In addition, there is a potential application in vibration isolation for steel domes by introducing metal lattice-polyurea parallel composite structures between the steel dome and its lower supporting structure.  
Conceptualization, Z.C. and J.C.; methodology, Z.C.; software, Z.C. and Y.Z. ([PERSON]); validation, J.C. and X.Z.; formal analysis, Z.C. and Y.Z. ([PERSON]); investigation, Z.C. and Y.Z. ([PERSON]); resources, J.C. and X.Z.; data curation, Z.C.; writing--original draft preparation, Z.C.; writing--review and editing, Z.C., X.Z. and J.C.; visualization, Z.C. and X.Z.; supervision, J.C. and X.Z.; project administration, J.C., Y.Z. ([PERSON]) and X.Z.; funding acquisition, J.C. and Y.Z. ([PERSON]). All authors have read and agreed to the published version of the manuscript.  
This research work is supported by the CGN-HIT Advanced Nuclear and New Energy Research Institute (Grant No. CGN-HIT202215), the National Science Foundation of China (Grant No. 52405586), the China Postdoctoral Science Foundation (Grant No. 2023M740942), and the New Era-Longjiang Excellent Master and Ph.D. Thesis Funding Project (Grant No. IJYXL2023-034).  
Not applicable.  
All data that support the findings of this study are included within this article.  
The authors declare no conflicts of interest.