Monitoring acoustic emissions from finger-joints from tropical African hardwoods for predicting ultimate tensile strength

The patterns of acoustic emissions generated during tension test of finger-joints from three tropical African hardwoods, Obeche (Triplochiton scleroxylon), Makore (Tieghemella heckelii) and Moabi (Baillonella toxisperma) were evaluated to assess their potential usefulness for non-destructively predicting ultimate tensile strength. The acoustic emission patterns generated were observed to differ depending on the type of finger profile and the wood species. Regression coefficients from cumulative acoustic emission count versus applied stress squared functions also varied with the profile and species type. When ultimate tensile strength was correlated with these regression coefficients, for stresses applied up to 50 % of mean ultimate strength, the logarithmic regression model developed could predict finger-joint strength accurate to ±12 %, ±13 % and ±18 % for Obeche, Makore and Moabi, respectively. The model was also sensitive to the type of finger profile used for all three Tropical African hardwoods.
The results indicate that this acoustic emission monitoring procedure could be useful for non-destructively predicting ultimate tensile strength of finger-joints from the three tropical African hardwoods.