ELASTIC WAVE PROPAGATION CHARACTERISTICS OF DENSITY GRADIENT CYLINDRICAL SHELL CHAINS

Uniform cylindrical shell chains can control elastic wave transmission, and introducing density gradient may further improve the ability of waveform control. The propagation behavior of elastic waves in the density gradient cylindrical shell chains was studied by developing a mesoscale finite element model and a continuum-based model. By equivalent the density gradient cylindrical shell chain to a variable density elastic rod, the governing equation of the density gradient chains under a stress pulse excitation was established. Based on the Laplace integral transformation and considering the linear density distribution in the rod, the analytical solution of the equation was obtained. Compared with the meso-finite element simulation results, it is found that the analytical solution can well predict the force evolution trend of the graded cylindrical shell chain under the excitation of a triangular stress pulse. The results show that the peak force in the positive gradient chain gradually increases with the wave propagation, while that of the negative gradient chain gradually decreases with the wave propagation. The peak force at the support end of the negative gradient chain is smaller than that of the uniform chain, while that of the positive gradient chain is greater than that of the uniform one. So the waveform control ability of the density gradient cylindrical shell chains is better than the uniform chain. The linear density gradient parameter has great influence on the waveform control ability of the density gradient cylindrical shell chains. The peak force transmitted to the support end increases with the increase of the density gradient parameter, and thus the density gradient cylindrical shell chain can control the stress pulse in a wider range. The theoretical model and its analytical solution provide a theoretical basis for studying the stress wave propagation law and revealing the force regulation mechanism of the graded cylindrical shell chains.