Method for determining stress rosette attaching position when wood Poisson's ratio is dynamically measured

Abstract

The invention provides a method for determining a stress rosette attaching position when the wood Poisson's ratio is dynamically measured.By means of the method, when the Poisson's ratio is measured dynamically through a suspension arm plate in a first-order bending mode, the testing speed and testing precision can be increased.According to the method, the wood Poisson's ratio is dynamically measured through the cuboid suspension arm plate in the first-order bending mode, and the fixed end of the suspension arm plate serves as the original point; when the wood tangential section Poisson's ratio is measured, the x-axis direction is the wood texture direction, the y-axis direction is the wood tangential direction, stress rosette is attached to the tangential section as the x-y plane, the suspension arm plate has the size, in the x-axis direction, of length 1 and the size, in the y-axis direction, of width b, the attaching position x0 of a transverse stress gauge parallel to the y-axis direction on the x axis meets the equation of x0 / 1=0.4400-0.0982 rho+0.6939b / l, and rho is the wood density and has the unit of g / cm<3>.

Description

technical field [0001] The invention relates to a method for determining the sticking position of strain rosettes when using a cantilever plate to dynamically measure the Poisson's ratio of wood in a first-order bending mode. Background technique [0002] Wood can be regarded as an orthotropic material, and the material elastic constant in the principal direction is E L ,E R ,E T , G LR , G LT , G RT , μ LR , μ LT , μ RT , μ RL , μ TL and μ TR . Only three of the six Poisson's ratios are independent, namely μ LR , μ LT and μ RT or μ TR , and the other three Poisson's ratios can be calculated from the forward elastic modulus and these three Poisson's ratios by the flexibility matrix symmetry. In this way, wood has only nine independent principal elastic constants, namely three elastic moduli, three shear moduli, and three Poisson’s ratios (Tan Shouxia, Zhou Dingguo. 2007. Wood Industry Handbook. China Forestry Press; Sun Youfu. 1999. Timber Production Technol...

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Problems solved by technology

[0005] However, when using a cantilever plate to dynamically measure Poisson's ratio in the first-order bending mode, how to quickly determine the sticking position of the strain rosette for different types and shapes of wood, so as to improve the test speed and test accuracy, has not yet been published.

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