Attenuating acoustic pulse propagation in multilayered rods

Abstract

The problem of seismic activity and carrying out anti-seismic measures is extremely urgent at the present time. A large number of regions are more or less earthquake-prone and sometimes new regions, in which seismic activity has not been recorded before, fall into this category. Various methods of seismic load reduction are used to build new structures and support existing structures in these areas. The seismic load is transmitted to the structure through the foundation, therefore one of the effective ways to reduce it is to change the properties of the foundation. If instead of soil, which perfectly transmits impulses of seismic load, fill in a certain order with material that dampens these impulses - the desired effect can be achieved. The article analyzes the way of how one-dimensional pulse becomes attenuated in a multilayer rod. The layers in the rod are arranged in a periodical order and have contrasting acoustic properties. Numerical analysis is carried out using the finite element method. A pulse hitting the interface between the media undergoes multiple reflection and refraction, which causes damping in a purely mechanical system. The analysis shows that the larger the difference in acoustic properties between adjacent layers, the higher the attenuation of acoustical properties becomes.