Non-destructive evaluation of wood decay

Evaluation of wood decay is often prone to subjective assessment. Standard rating scales are based on human perception of decay, often in addition to weight loss measurements. Especially the assessment of graveyard specimens or other long term testing material that has to be monitored regularly on a non-destructive basis, is challenging. In this paper two techniques are presented that can deliver extra insight. The first technique is based on the analysis of the resonance frequencies of the material. It is very fast and only minimal sample manipulation is required. Instantaneously, an approximation of the modulus of elasticity (MOE) and damping are obtained that can be followed during degradation. The technique is applicable in the field. The second method requires an X-ray tomography scanner, but enables a three dimensional view on the internal structure of the sample and accompanying degradation. It is not applicable in the field but can give a very interesting view on possible degradation patterns. Both methods can not only assist in non-destructive assessment, but can possibly best serve as early decay detection techniques and give more insight into the rate and modes of degradation.

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