Development of Testing Platform and Comparison Studies for Wood Nondestructive Testing

Jian Li,Yiming Fang,Xiongwei Lou,Hailin Feng,Jiyong Tang

doi:10.1155/2016/6279869

Abstract

Stress wave based techniques have been developed for evaluating the quality of the wooden materials nondestructively. However the existing techniques have some shortcomings due to the significant variation of the wood properties and are now in need of updating. There are also stress wave based instruments which have been widely used for nondestructive testing of wood. But most of them are inflexible and unsuitable for the tentative studies. This paper proposed and implemented a wood nondestructive testing platform based on NI virtual instrument. Three wood nondestructive testing methods, including peak time interval measurement, cross-correlation, and spectrum analysis, were also tested on this platform with serious decay sample, early decay sample, and defect-free sample. The results show that new methods can be verified easily and the researches of wood nondestructive testing will be accelerated with the designed platform.

Highlights

Wood nondestructive testing technology can predict the wood internal condition without destruction and has been utilized to detect the mechanical properties of standing trees [1] or the decay and holes of wood [2]
Transmitted signal Received signal degree of the defect. It took about 45 μs for stress wave to travel in the defect-free sample and approximately 3 times longer to travel in the sample with early defect
With the Labview code of the spectrum analysis, we transformed the signal recorded on the received sensor into frequency domain

Summary

Introduction

Wood nondestructive testing technology can predict the wood internal condition without destruction and has been utilized to detect the mechanical properties of standing trees [1] or the decay and holes of wood [2]. Many wood nondestructive testing techniques have been studied, such as X-ray detection [3], ultrasonic [4], mechanical stress [5], and acoustic emission [6]. Li et al investigated the stress wave velocity pattern in the cross sections of black cherry trees and employed this pattern to detect the internal defect [9]. All of the above work have proven the effectiveness of stress wave technique for the detection of wood defect

Methods

Results

Conclusion