Measurement Of The Smaller Poisson's Ratios And Related Compliances For Wood
Keywords:Poisson's ratio, compliance, Young's modulus, stress, strain
AbstractFew direct measurements have been made of strains in the longitudinal L direction of wood when uniaxial loading takes place in the radial, R, or tangential, T, directions because of the difficulty of making the small measurements involved. Improved accuracy in measurements of this type were achieved by using low modulus strain gages having little or no sensitivity perpendicular to the gage axis, by having low noise signals in connecting wires, by making strain measurements with a resolution of 107 inches per inch, and by having a proper loading device. Compliances from loadings made on different specimens representing a number of species were found to be correlated in that the strain in the L direction per unit of stress in the R or T direction was proportional to the strain per unit stress in the load direction (R or T). The best estimates that could be found for Poisson's ratios vTL and VRL were 0.030 and 0.043, respectively. For some reason basswood data from a single board did not seem to fit with the rest of the data.
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