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Nondestructive detection method of mechanical properties of standing timbers

A technology of non-destructive testing and standing trees, which is applied in the direction of wood testing, material inspection products, etc., and can solve problems such as narrow applicability

Active Publication Date: 2014-09-03
国际竹藤网络中心
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this model is a purely empirical model based on experimental measurements with narrow applicability, and a corresponding prediction model needs to be established for each tree species

Method used

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  • Nondestructive detection method of mechanical properties of standing timbers
  • Nondestructive detection method of mechanical properties of standing timbers
  • Nondestructive detection method of mechanical properties of standing timbers

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Experimental program
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Embodiment 1

[0030] The present invention is based on the multi-wall layer structure of wood cell wall, applies the stiffness prediction theory and classical laminate theory in the mesomechanics of composite materials, and combines the mechanical properties of the main components of the cell wall and the main characteristics of the wall layer structure to establish the longitudinal elastic modulus of the wood cell wall. Quantitative prediction model to measure the mechanical properties of standing trees, the specific process is as follows figure 1 shown, including:

[0031] Step S101, establishing the longitudinal elastic modulus E of the wood cell wall cell Theoretical model of computation:

[0032] E. cell =f(MFA);

[0033] (Refer to the specific content of the model: YU Yan, JIANG Ze-hui, TIAN Gen-lin. Size effect on longitudinal MOE of microtomed wood sections and relevanttheoretical explanation. Forestry Study in China, 2009, 11(4): 243-248)

[0034] When establishing the model, i...

Embodiment 2

[0068] Taking fir wood as the processing object, the processing is carried out according to the following steps:

[0069] Step 1, referring to Step 1 to Step 3 in Example 1 to establish a prediction model for the longitudinal modulus of elasticity of the cell wall of coniferous wood;

[0070] Step 2. After measuring the elastic modulus of the Chinese fir wood tensile national standard sample along the grain, intercept the effective part in the middle of the sample, select a long thin sheet non-standard sample with a thickness between 1mm and 3mm, and use X-ray Diffractometer to measure density and microfibril angle;

[0071] Step 3. Use 2 / 3 of the data set measured in step 2 for modeling, and directly substitute into the prediction model of the macroscopic longitudinal tensile elastic modulus E of wood:

[0072] E=a×(ρ / ρ cell )E cell +b

[0073] Obtain the coefficients a and b, and establish a prediction model for the longitudinal elastic modulus of Chinese fir based on na...

Embodiment 3

[0077] Take poplar tomentosa as the processing object, and proceed as follows:

[0078] Step 1, step 1 to step 3 in the reference embodiment 2 set up the predictive model of Populus tomentosa longitudinal modulus of elasticity;

[0079] Step 2, after measuring the modulus of elasticity of the poplar wood along the grain of the tensile national standard sample, the effective part in the middle of the sample is intercepted, and the X-ray diffractometer is used to measure the density and the microfibril angle;

[0080] Step 3. Use 2 / 3 of the data set measured in step 2 for modeling, and directly substitute into the prediction model of the macroscopic longitudinal tensile elastic modulus E of wood:

[0081] E=a×(ρ / ρ cell )E cell +b

[0082] The coefficients a and b are obtained, and the prediction model of the longitudinal elastic modulus of Populus tomentosa is established:

[0083] E = 1.2293 × ρ 1.5 ...

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Abstract

The invention discloses a nondestructive detection method of mechanical properties of standing timbers. The method comprises the following steps of: S1, establishing a prediction model Ecell of a longitudinal elastic modulus of a wood cell wall; S2, establishing a prediction model of a wood macroscopic longitudinal elastic tensile modulus E taking the air-dry density rho and a microfibril angle MFA of a mechanical sample as independent variables: E=a*( rho / rhocell) Ecell+b; S3, measuring the elastic tensile modulus of wood rift grains, the air-dry density and the MFA on the same one mechanical sample, putting the measured data into E and carrying out linear regression to obtain coefficients a and b, and completing the establishment of the wood macroscopic longitudinal elastic tensile modulus E; and S4, drilling the standing timbers to take a growth cone, detecting the air-dry density and the MFA of the growth cone from a pith to bark multipoint, and putting into the model E after the step S3 so as to obtain the predicted value and regularities of distribution of the longitudinal elastic modulus of the standing timbers. According to the nondestructive detection method, the nondestructive and accurate measurement to the mechanical properties of the standing timbers is realized.

Description

technical field [0001] The invention relates to the technical field of material performance detection, in particular to a method for non-destructive detection of the mechanical properties of living trees. Background technique [0002] Mechanical properties are an important evaluation parameter to describe the application of wood, and a key indicator to evaluate the effect of silvicultural cultivation. The traditional detection method of wood mechanical properties is to cut down the trees, make samples of specified size, and then directly measure them with a mechanical testing machine or use non-destructive testing techniques such as ultrasonic waves, stress waves and other technologies to measure indirectly. This detection method is costly and expensive. Inefficient and destructive. However, in the field of modern tree cultivation, there is an urgent need for a technology that can quickly and non-destructively evaluate the mechanical properties of a large area of ​​living t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N33/46
Inventor 费本华余雁张淑琴邢新婷
Owner 国际竹藤网络中心
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