An invisibility cloak has been realized across various physical fields underpinned by metamaterials, but is demanding for delicate microstructures and thus suffers from a sensitive working frequency. In this Letter, we propose a metamaterial-free approach to design an invisibility cloak on an elastic beam. It is realized by bonding two miniature blocks and a shell without damaging the stiffness and strength of the beam. The blocks can isolate the invisible area by completely reflecting flexural waves. Meanwhile, the shell, with a varying thickness and optimized joints, ensures a perfect redirection of waves around the cloaked region by preserving both amplitudes and phases from 4.9 to 13.1 kHz. We numerically and experimentally verify its functionality and robustness against a change of the obstacle and the cloaking shell. This work presents the possibility for wave/energy flux manipulation in mechanical systems, circumventing the need of complex artificial structures.

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• Cloaking
• Continuum mechanics
• Elastic waves
• Transformation optics
• Wave scattering
• Acoustic metamaterials
• Elastic wave theory