Improved self-sensing harsh-impact absorber merging compression-torsion metamaterial with active magnetorheological effects

Abstract

Obtaining Efficient buffering and energy absorption under harsh impact is critical for research areas such as military, aviation, and vehicle. As a candidate solution, magnetorheological (MR) materials, capable of flexibly regulating damping and stiffness by through external magnetic field to prevent system resonance, face limitations in their energy absorption efficiency due to significant deformation under harsh impacts. To address this, the unique mechanical properties of mechanical metamaterials, exemplified by compression-torsion metamaterial (CTM), offer a promising strategy. Inspired by the energy absorption of myocardial torsion, we propose an innovative MRE/MRF absorber merged CTM. The layered structure, where the external CTM layer drives the torsional deformation of the internal MRE/MRF layer, can synergistically modulate the elastic modulus and shear modulus, thereby enhancing the energy absorption efficiency. Through theoretical analysis and simulations, optimal geometric parameters of CTM were determined, achieving a torsional absorption ratio of 21.64 %. Under simulated continuous vibration on a small-scale vibro-stand, the natural frequency was shifted from 32 Hz to 65 Hz, and the vibration acceleration attenuation rate reached 75.5 %, after applying the magnetic field. To achieve vibration identification under harsh impact, a direct current triboelectric nanogenerator (DC-TENG) sensor based on torsional deformation is designed in the interface gap between the two layers. In large-size vibro-stand tests simulating harsh impact (1-6 g), the DC-TENG sensor triggered a high voltage signal during instantaneous torsional deformation (a≥3 g), enabling magnetic field modulation and achieving an impact energy absorption efficiency of 48 %. Finally, the practical utility of this absorber was further illustrated in the context of the unmanned aerial vehicle (UAV) forced landing, where its installation increased the safe forced landing height of the UAV by 33 % (from 60 cm to 80 cm), while maintaining an impact energy absorption efficiency of 40 %. This study presents a viable solution for improving impact buffering and energy absorption in challenging environments.