The Study Of Stress Wave Nondestructive Testing Of Wood Based On Spectral Analysis And Influencing Factors

The wood non-destructive testing technology is a kind of new non-destructive testingtechnology using in wood testing. It is particularly important in improving timber utilization. Ithas been widely concerned that distinguishing types of defects accurately. Due to the impact offactors such as moisture content and temperature, there are some unstable and indistinguishablebetween the early and mid-rot decay and other problems.To solve these problems, this paper studied and discussed through a series of tests. Theproblem that nondestructive testing techniques can not accurately distinguish between degrees ofdecayed wood-based spectral analysis problems are analyzed through wood resonance testing. Todetermine the extent of wood decay were subdivided. Through the health of wood samples andspecimens containing wood decay experiments, the effect and variation of the stress waveresonant frequency spectrum causing by moisture content and temperature has been analyzed.The following findings has got through the analysis and discussion of the study content:(1)The resonance frequency range of wood decay parts has been divided based on previousresearch. It enriched the dividing of timber corresponding resonance frequency band（600～800Hz） in different healthy conditions. To use this technology, we can determine the decaydecadent.(2)The stress spectrum wave resonant frequency decreased with increasing moisture contentgradually no matter healthy wood or decadent wood. When the moisture content is below the fibersaturation point, stress wave spectrum resonant frequency declined relatively large with themoisture content decrease, otherwise declined relatively little. And the effect of the resonantfrequency of high-frequency part is greater than the resonance frequency of low-frequency part. hefit goodness of linear regression model between moisture stress wave spectrum and resonancefrequency relatively high. The correlation coefficient (R2) were higher than0.93.(3)When the moisture content is below the fiber saturation point, the stress wave spectrumresonant frequency decreased gradually with increasing temperature, but the decline was notdramatic. When the temperature is below zero degrees Celsius, stress wave spectrum resonancefrequency decreases relatively large with temperature varies. When the temperature is above zero degrees Celsius, stress wave spectrum resonance frequency decreases relatively flat withtemperature varies. And this variation is irrelevant with the existence of timber decadent.