Experimental study on the possibility of detecting internal decay in standing Picea abies by blind impact response analysis
Author
Summary, in English
This paper considers detection of internal decay in standing trees of species Picea abies (L.) Karst. The novel approach is based on two-dimensional spatiotemporal modal analysis of a cross-section which is excited by the hand-made impact of a hammer. An array of accelerometers is distributed around the cross-section, and the resulting impact response is analysed. The temporal frequency for a special spatial mode-shape is used for comparisons on a tree-to-tree basis. The mechanical properties of wood are inherently variable as they are for most materials of biological origin. This leads to a scatter of the analysed parameters that hinders detection of decay based on the temporal frequencies alone. Using regression analysis, we show that by incorporating the additional information on a surface wave propagation velocity, the scatter of sound trees is significantly reduced. The performance of a detector rule which incorporates the frequency and the surface wave propagation velocity is investigated and found to be better than performance reported for visual tree examination. The analyses are based on the impact responses from 94 standing trees, with 66 sound and 28 in various stages of decay. The proposed technique is yet to be considered an experimental tool. Further research, e.g. on how the mechanical properties are influenced by various environmental factors, is needed before the technique can be applied operationally.
Department/s
- Mathematical Statistics
- Department of Electrical and Information Technology
- Statistical Signal Processing Group
Publishing year
2004
Language
English
Pages
179-192
Publication/Series
Forestry
Volume
77
Issue
3
Document type
Journal article
Publisher
Oxford University Press
Topic
- Forest Science
Status
Published
Research group
- Statistical Signal Processing Group
ISBN/ISSN/Other
- ISSN: 1464-3626