Monitoring Acoustic Emissions to Predict Modulus of Rupture of Finger-Joints from Tropical African Hardwoods


  • Joshua Ayarkwa
  • Yoshihiko Hirashima
  • Kosei Ando
  • Yasutoshi Sasaki


Acoustic emission, finger-joints, tropical African hardwood, modulus of rupture


The acoustic emission patterns generated from bending tests of finger-joints from three tropical African hardwoods, Obeche (Triplochiton scleroxylon), Makore (Tieghemella heckelii), and Moabi (Baillonella toxisperma) were evaluated to determine the possibility of using them to predict finger-joint modulus of rupture.

The patterns of acoustic emissions generated from the bending tests were observed to differ, depending on the type of finger profile and wood species. The regression coefficient of the regression of cumulative acoustic emission count on applied stress squared also varied with the profile and species type. When modulus of rupture was correlated with this regression coefficient, for stresses applied up to 50% of mean ultimate strength, the logarithmic regression model developed could predict modulus of rupture of the finger-joints accurately to ±10%. ±12%, and ±21% for Obeche, Makore, and Moabi, respectively. The models developed also seemed sensitive to the quality of the finger-joints from the three tropical African hardwoods.

The results of the study gave an indication that this acoustic emission monitoring procedure could be useful for nondestructively predicting modulus of rupture of finger-joints from the three tropical African hardwoods.


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