Wood NDT-2000 Session V.: Inspection of structure and structural components
Development of an Electrical Impedance Spectrometer for the Analysis of Wood Transverse Moisture Gradient
Tiitta M., Savolainen T. Research Scientist, Dept. of Applied Physics, University of Kuopio, P.O.Box 1627, FIN-70211 Kuopio, Finland Lappalainen T. Research Scientist, VTT Energy, P.O.Box 1603, FIN-40101 Jyväskylä, Finland
ABSTRACT
A low cost impedance spectrometer prototype was developed for wood transverse moisture gradient analysis. The measurement of electrical impedance spectrum is based on a sine wave analysis using frequencies below 5 MHz. The equipment consists of portable PC with accumulator and electronics connected to the hand held probe with coaxial and power cables. The equipment can be easily transferred using small case. Because of the accumulators, no external electricity is needed and thus field measurements can be done. In the measurement, the parallel flat electrodes are pressed against the wood specimen. The method is based on modeling the electrical impedance of wood at the surface and below and using model parameters to estimate the moisture gradient. The equipment and the method have been tested using many types of uniform, desorption and absorption gradients. Timber and log specimes from spruce, pine, and birch have been used.
Publication Source: Proceedings of the 12th International Symposium on Nondestructive Testing of Wood University of Western Hungary, Sopron, 13-15 September 2000, ISBN 963 7180 88 5 Publisher: University of Western Hungary, H 9400 Sopron, P.O.Box 132, FAX: +36 99 311 103
