Accession Number : ADA140608

Title :   Effect of Mechanical Stress on the Dielectric Properties of Wood,

Corporate Author : FOREST PRODUCTS LAB MADISON WI

Personal Author(s) : James,W L

PDF Url : ADA140608

Report Date : Apr 1984

Pagination or Media Count : 20

Abstract : The effect of mechanical stress parallel to the electric field on the polarizability (dielectric constant) and equivalent parallel conductance of wood was studied as a possible means for monitoring drying stresses. For electric and mechanical stress parallel to the grain, the effect was observable in wood that was moisture equilibrated at 65 percent relative humidity or greater, but was rather small and variable and drifted considerably with time. For stresses perpendicular to the grain, the effect was nearly nonexistent when the mechanical stress was no greater than the proportional limit. The effect also was essentially nonexistent for wood at moisture content lower than about 7%. The effect was generally larger at lower frequencies and was practically negligible at frequencies as high as 100 kHz. These results indicate that dielectric measurements are not feasible as a measure of mechanical stress in wood.

Descriptors :   *Lumber, Moisture, Drying, Stresses, Compression, Tension, Dielectric properties, Electrical conductivity

Subject Categories : Wood, Paper and Related Forestry Products

Distribution Statement : APPROVED FOR PUBLIC RELEASE