Speaker
Mikko Alava
(Aalto University, Espoo, Finland)
Description
Wood is a multi-scale material and exhibits a complex
mechanical response. We study the avalanches in small wood
samples in compression. Acoustic emission or crackling noise
in the deformation is similar to what is seen in rocks and
laboratory tests of porous, brittle materials. Both the
distribution of events energy and the waiting (silent) time
distribution follow power-laws. The stress-compressive
strain response exhibits the typical characteristics of wood
and other porous materials with clear signatures of the
localization of the compression deformation to "weak spots"
of, here, softwood layers. This can be directly identified
using Digital Image Correlation. Even though material
structure-dependent localization takes place, it does not
change the act that avalanche behavior is scalefree and
merely modifies the event rate of avalanches.
