The propagation of shock waves in granular or granular materials is important for determining the strength of earthquakes, determining the location of oil and gas tanks, designing acoustic insulation, and developing materials for powder compaction. Scientists used X-ray measurements and analyses to show that velocity scaling and dispersion in wave transmission are based on the location of the particles and the chains of forces between them. Time as a decrease in wave intensity, in turn, is caused only by the arrangement of particles. The study is published in the journal Proceedings of the National Academy of Sciences.
A new study by scientists provides a better understanding of how the small-scale structure of granular material is related to the behavior of waves propagating through them. This knowledge is fundamental for the study of seismic signals from landslides and earthquakes, for non-destructive soil assessment in civil engineering. In addition, this knowledge is useful for the manufacture of materials with the desired wave properties in materials science.
Structural and property relations of bulk materials are regulated by the arrangement of particles and the chains of forces between them. These relationships allow the creation of materials damping (damping) waves. Wave transmission in granular materials has been carefully studied and demonstrates unique features: power-law scaling of velocity, dispersion, and attenuation — a decrease in signal amplitude, electric current, or other vibrations.
Earlier studies from the late 1950s described “what” could happen to the material underlying wave propagation, but a new study provides an answer to the question “why”.
“A new experimental aspect of this work is the use of on-site X-ray measurements to obtain the packing structure, particle stresses and inter-particle forces in the entire granular material during the simultaneous measurement of ultrasound transmission. These measurements are the most accurate data set to date in the study of ultrasound, forces, and structures in granular materials”.
Ryan Hurley, Assistant Professor, Department of Engineering, Johns Hopkins School of Engineering
New experiments, along with supporting simulations, allow scientists to identify why the wave velocities in granular materials vary with pressure. Researchers also have the opportunity to quantify the effect of individual phenomena on a particle scale on the macroscopic behavior of waves.
The study provides new insights into the time and frequency domains of wave propagation, shedding light on the fundamental mechanisms that control wave velocities, dispersion, and attenuation in these systems.