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Method for measuring propagation time of stress wave in wood and nondestructive test system

A travel time, non-destructive testing technology, applied in the direction of using sonic/ultrasonic/infrasonic waves to analyze solids, can solve the problem of non-destructive rapid detection and continuous detection, etc., to improve detection efficiency and accuracy, reduce errors, improve The effect of precision and reliability

Inactive Publication Date: 2012-02-01
ZHEJIANG FORESTRY UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since traditional wood testing mostly uses manual methods, and even wood samples have to be destroyed before testing, these testing methods can no longer meet the needs of non-destructive rapid testing and continuous testing in wood production.

Method used

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  • Method for measuring propagation time of stress wave in wood and nondestructive test system
  • Method for measuring propagation time of stress wave in wood and nondestructive test system
  • Method for measuring propagation time of stress wave in wood and nondestructive test system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] Example 1 (see figure 1 )

[0049] In the first step, two screws are embedded in the wood sample 1 to be tested, the start sensor 4 is connected with the start screw and the pulse hammer 5, the end sensor 2 is connected with the terminal screw, and the data cable and the detection system ( That is, the signal processing part 3) in the figure is connected.

[0050] The second step is to turn on the power switch of the detection system and set up the test environment. Including wood species, test sequence number, test sequence length (i.e. number of moving average items), wood density, distance between sensors (distance between screws), etc. After the test environment is set up, the system proceeds to the test waiting stage.

[0051] In the third step, the tester uses a pulse hammer to hit the screw at the start end to generate a stress wave that propagates inside the wood (the arrow in the figure indicates the direction of propagation). The start sensor collects the...

Embodiment 2

[0052] Example 2 (see figure 2 )

[0053] In order to accurately locate the internal defects of wood, it is necessary to perform multiple measurements on the wood sample from multiple directions to obtain test results from different directions, so as to more accurately determine the position and degree of defects within the wood. figure 2 represents the cross-section of the tested wood, where a, b, c, d, e, f Respectively represent six detection points (3 start sensors and 3 end sensors are respectively installed), and the central part 7 in the figure represents internal decay. The user conducts inspections from 9 directions in turn to obtain different stress wave propagation velocities and wood elastic modulus. According to these measurement results, the size and location of wood internal defects can be determined more accurately.

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Abstract

The invention relates to a method for measuring the propagation time of a stress wave in wood and a nondestructive test system for wood, and the method and system provided by the invention aims at judging whether a defect exists in the wood according to the measured propagation speed of the stress wave. The characteristics of high measurement accuracy, high efficiency and no radiation are required. The nondestructive detection system for wood is required to have the characteristics of high speed, strong antijamming capability and relatively high detection accuracy. The technical scheme is as follows: the method for measuring the propagation time of the stress wave in the wood comprises the following steps: 1) determining six detection points around the cross section of the detected wood to form 9 detection paths, and inputting a stress wave signal acquired by each detection path into a processing circuit; 2) knocking the end surface of one end of the wood by use of a pulse hammer so as to produce propagation of the stress wave; and 3) processing the measured data sequence according to a sliding average algorithm by virtue of a microcontroller. The nondestructive detection system for the wood using stress wave comprises a signal acquisition part, a signal processing part and the microcontroller which are electrically turned on in turn.

Description

technical field [0001] The invention relates to a measurement method and a detection system, in particular to a method for measuring the propagation time of a stress wave in wood and a stress wave wood non-destructive detection system. Background technique [0002] Wood is a renewable natural resource with the longest history of human use. With the progress of society, people's requirements for production and quality of life have improved, and the demand for wood has gradually increased. Fully and effectively utilizing timber resources to maximize economic and social benefits is a subject of common concern and continuous research by forestry researchers from all over the world. Because most of the traditional wood detection methods are manual, and even the wood samples have to be destroyed before detection, so these detection methods can no longer meet the needs of non-destructive rapid detection and continuous detection in wood production. In recent years, with the develo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/07
Inventor 李光辉
Owner ZHEJIANG FORESTRY UNIVERSITY
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