DETECTION OF VERY EARLY STAGES OF DECAY IN WESTERN HEMLOCK WOOD USING ACOUSTIC EMISSIONS.

It is difficult to detect wood decay as early as 5 percent weight loss or less by conventional techniques. But monitoring the acoustic emissions (AEs) of western hemlock specimens in very early stages of decay and in bending stress indicated that even slightly decayed specimens will begin to emit AEs between loads of 4 percent and 32 percent of the failure load. Sound specimens will not begin to emit AEs until 50 percent of the failure load is reached. These results suggest that cumulative AE counts are a sensitive indicator of early decay in specimens stressed in bending.