Experimental investigation on periodic capsule barriers vibration isolation based on band gap theory

With the rapid development of rail transit, the associated vibration hazards have become increasingly severe. Traditional vibration isolation methods for the transmission paths each have limitations, highlighting the urgent need to explore novel approaches to vibration mitigation. The vibration reduction method of metamaterials based on bandgap theory has become the focus. Currently, experimental research on large-sized periodic metamaterials is still insufficient and poorly understood. This paper drew inspiration from nature and proposed the periodic capsule barriers vibration isolation technology. Firstly, the dynamic parameters were tested using an ultrasonic pulse system and an excitation system to obtain the BFGs. Secondly, experimental studies were conducted on different combinations of capsule barriers. Finally, the comparison and mechanism discussion were conducted on different evaluation indicators in both time and frequency domains. It is found that various periodic capsule barriers have vibration isolation effects in both time and frequency domains. The periodic capsule barriers filled with three rows of fast-hardening concrete can achieve targeted vibration isolation based on the bandgap theory. The vibration isolation effect of the capsule barriers composed of soft and stiff filling materials is better than that of single filling material. The findings can shed light on a better understanding of vibration isolation, and provide guidance for the engineering.