An assessment of the feasibility of ultrasound as a defect detector in lumber
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Herman van Dyk
Abstract
This study investigated the limitations of certain attributes for use in detecting internal defects using ultrasonic methods in spruce dimension lumber. Wave propagation in the radial direction and the effect of induced defects on ultrasonic wave characteristics were examined. Ultrasonic velocity, a parameter often applied, was found to be ineffective due to changes in wavelength and frequency when large defects were present. Amplitude, peak frequency magnitude and the area under the frequency spectra showed statistically significant differences between clear and defect-bearing samples, but among-sample variation was found to be too high because of localized density differences and microstructure, so that these methods were not consistently reliable. When sound intensity level was calculated, the variation among samples decreased and distinctions could be made between clear and defect-bearing wood, both within and among the samples tested. Certain attributes of the frequency spectra also showed clear changes with the introduction of defects.
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Articles in the same Issue
- Chemical changes in silver birch (Betula pendula Roth) wood caused by hydrogen peroxide bleaching and monitored by color measurement (CIELab) and UV-Vis, FTIR and UVRR spectroscopy
- Hydrophobisation and densification of wood by different chemical treatments
- Functionalisation of wood by reaction with 3-isocyanatopropyltriethoxysilane: Grafting and hydrolysis of the triethoxysilane end groups
- Isolation and fractionation of lignosulfonates by amine extraction and ultrafiltration: A comparative study
- Bioactive phenolic substances in industrially important tree species. Part 4: Identification of two new 7-hydroxy divanillyl butyrolactol lignans in some spruce, fir, and pine species
- Characterization of physiological functions of sapwood IV: Formation and accumulation of lignans in sapwood of Cryptomeria japonica (L.f.) D. Don after felling
- X-ray scattering studies of thermally modified Scots pine (Pinus sylvestris L.)
- Differences in acoustic velocity by resonance and transit-time methods in an anisotropic laminated wood medium
- Parallel-plate rheology of latex films bonded to wood
- An assessment of the feasibility of ultrasound as a defect detector in lumber
- Vibrational properties of green wood in high-temperature water vapor
- The stiffness modulus in Norway spruce as a function of year ring
- Strain analysis in bulk forming of wood
- Decay fungi from playground wood products in service using 28S rDNA sequence analysis
- Effect of climatic variables on chromated copper arsenate (CCA) leaching during above-ground exposure
- Protic ionic liquids with organic anion as wood preservative
