Numerical And Experimental Study On Two-dimensional Solid/Fluid Phononic Crystals In The Application Of Vibration Isolation And Wave Guidance

Phononic crystal is a new functional material consisting of two or more elastic materials with periodic distributions. The frequency ranges in which elastic waves are forbidden to propagate in any direction are called complete forbidden gaps or band gaps, while those in which elastic waves can propagate are called pass bands. The existence of band gaps of phononic crystals suggests wide applications in seismic resistance and vibration isolation of structures. In the present paper, wave transmission in the two-dimensional fluid-solid phononic crystals with perfect periods, point defect or linear defects are investigated in detail by using numerical simulation method and experimental method. The transmission spectra and the acoustic pressure distributions are displayed, and the feasibility of vibration isolation, seismic resistance and wave guidance based on the characteristics of phononic crystals are discussed.1.Wave transmission in the two-dimensional fluid-solid phononic crystals with perfect periods is simulated by using ABAQUS finite element software, and the associated experiments are carried out by the impulse-response technique. It can be seen that the experimental results are in good coincidence with those of numerical simulation for the steel/water phononic crystal with square lattice. The first band gap of concrete/water phononic crystal with a larger lattice is around 10Hz, which is of great practical significance. The propagation of elastic waves can be controlled by designing phononic crystals with band gaps covering the frequency of elastic waves, so that we can achieve the purpose of seismic resistence and vibration isolation.2. Wave transmission in the two-dimensional fluid-solid phononic crystals with point defects is simulated by using ABAQUS finite element software, and the associated experiments are carried out by the impulse-response technique. It can be seen that the experimental results are in coincidence with numerical simulation results both for the single point defect and multi-point defects. The sound pressure distributions show that the presence of point defects would lead to the vibration localization around the point defect for a certain frequency in the band gaps.3. Wave transmission in the two-dimensional fluid-solid phononic crystal with linear defects is simulated by using ABAQUS finite element software, and the associated experiments are carried out by the impulse-response technique. It can be seen that the experimental results coincide with numerical simulation results to some extent for straight, bend and branching linear defects respectively. When the linear defects are introduced in the phononic crystal, the propagation of elastic waves is constrained along the defects, and the band gap in perfect periods becomes into pass band. The path of linear defects and the distribution of scatters have a great influence on elastic wave propagation. Straight linear defects have good performance in wave guidance; while branching linear defects can separate elastic waves with different frequencies.The investigation shows that the propagation of elastic waves can be well controlled by introducing different forms of linear defects.