Visualization of the P-wave front

P-wave transit time was determined between the starter (position not changed) and receiver. The transit time was measured by the FAKOPP Microsecond Timer. Sample was an oak disk, moisture content: green. Step-by-step the receiver placed at all the grid point, and transit time was recorded. The grid size was 2 by 2 cm. A simple pendulum provided the uniform impact. After testing the intact oak disk an artificial hollow was made, to simulate the decay. The measured data was plotted in Excel surface plot. The image below shows the applied setup, where the material is beech, a hollow was made around the pith.

Beech disk with artifical hollow

P-wave propagation in oak, intact and hollow disk
grid size is 2x2 cm, time resolution: 20 microseconds

The oak disk, starter location is marked by the red point

P-wave front in LR plane

Material is spruce, dimension 24x72cm, grid size 4x4cm, time resolution is 20 microseconds

P-wave front around a knot

Material is spruce, dimension 10x41cm, grid size 1x1cm, time resolution is 3 microseconds