ACOUSTIC-EMISSION RELATED TO INSTANTANEOUS STRAIN IN TASMANIAN EUCALYPT TIMBER DURING SEASONING

Acoustic Emission (AE) was measured in 30 mm-thick backsawn and quarte rsawn Tasmanian Oak (Eucalyptus regnans F. muell) boards drying at tem peratures in the vicinity of 20-degrees-C. By varying the diffusion co efficient used in a non-linear drying simulation program, calculated h alf-thickness moisture profiles were matched to measured profiles in a sample board. Once the measured and calculated drying behaviour was s atisfactorily matched, the AE measured in an endmatched board closely followed the surface instantaneous strain calculated with the program. The AE activity increased once the surface instantaneous strain attai ned the proportional limit. The AE is not simply related to drying tem perature or humidity but rather to a complex interaction between the t wo parameters.