Vibration control in bolted joints with locally resonant metamaterials

Fundamental frequency vibrations generated by aero-engines can propagate through joint structures to the airframe, potentially causing significant damage to precision instruments and electronic equipment. This paper innovatively integrates the spiral resonant system (elastic wave manipulation capability) into the Hierarchical Diamond Honeycomb with Variable wall Thickness (HDH-VT) structure (lightweight and high-strength mechanical properties), designing a Locally Resonant Metamaterials - Bolted Joints (LRMs-BJ) to suppress the transmission of harmful vibrations from aero-engines to the airframe. First, an equivalent model of the spiral resonant system is developed, with a detailed analysis of the vibration reduction mechanism of the flexural wave bandgap and its tuning capabilities. Second, the vibration reduction characteristics of LRMs-BJs are investigated through finite element simulations and experiments, and the effects of various joint conditions on the vibration reduction frequency band of LRMs-BJs are analyzed. The results demonstrate that the spiral resonant system can produce bandgaps within the target frequency range, and modifying the structural parameters of the spiral elastic beam enables flexible low-frequency tuning of the bandgap. The LRMs-BJ exhibits significant vibration control within the vibration reduction frequency range. The effects of lap length, bolt arrangement direction, and preload on the position and width of the vibration reduction band are minimal, closely aligning with the bandgap of the spiral resonant system unit cell. The proposed LRMs-BJ is a multifunctional integration of metamaterials and honeycomb structures, broadening the application potential of metamaterials in vibration reduction for bolted joints.