Takahisa Nakai, Hiroyuki Yamamoto
Properties of piezoelectric voltage considering the microscopic structure of wood cell walls
The combined effects of the grain-angle (?) and the microfibril angle (MFA) on the piezoelectric voltage (P) are discussed for a wood specimen subjected to unidirectional stress. The fiber axis of the specimen investigated was not parallel to the loading direction. A theoretical discussion is provided concerning fundamental elastic equations that predict the elastic strain field in the crystalline cellulose microfibril (CMF). It was assumed that an ideal wood specimen could be represented by a multi-tracheid model consisting mainly of the middle layer of the secondary wall. Experimental results revealed that plots of the piezoelectric voltage (P) versus the grain angle (?) show concave curves with a maximum at ?=45°, regardless of MFA in the specimen. A similar tendency was obtained for the relationship predicted between the average shear strain along the CMF and ?. The results indicate that generation of a shear strain in the CMF positively contributes to the piezoelectric effect in wood.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 61, 01/2007
Pages: 95 - 100
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