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Bacterially infected wood, called wetwood, is often not visually apparent in logs or green lumber. When kiln-dried, lumber containing wetwood is prone to develop costly defects. The objective of this study was to determine the effectiveness of a stress wave nonde structive evaluation (NDE) technique to detect the presence of wetwood, thereby allow...
Contexts in source publication
Context 1
... trees were felled and bucked into 9-foot- (2.7-m-) long logs and hauled to FPL. As shown in Figure 1,6-inch-(140-mm-) long disks were cut from each end of each 9-foot log, leaving an 8-foot (2.4-m) log. Radial sections were cut from the log discs, wrapped in aluminum foil, and frozen. ...
Context 2
... pattern of wetwood formation in the tree is usually pyramidal, resulting from bacterial infections that start in the roots and lower trunk and progress upwards. Therefore, the presence of bacterial infection in the disks allowed us to "map" the likely location of bacterial infection in the log ( Figs. 1 and 2) and make a preliminary estimate of the amount of bacterial infection from the original location of the board in the log. Figure 2 illustrates how various combinations of normal and bacterial heartwood result when boards are sawed from logs. Table 1. ...
Citations
... However, symptoms are also observed in different parts of trees, including roots and leaves. Non-destructive methods to detect wetwood include measuring of time-of-transmission of mechanically or ultrasonically impacted stress waves (Ross et al., 1994;Kabir et al., 2006). ...
Bacterial diseases in woody plants are best characterized for ornamental and fruit trees and much less is known for forest trees. There are many diseases of forest trees whose etiology remains to be clarified and likely more bacterial diseases of forest trees will be discovered in the next few years. An overview of the main bacterial pathogens that cause diseases in forest and ornamental trees is described in this chapter and the general differences between fungal and bacterial diseases are outlined. For bacteria pathogenic to trees, six types of diseases are described: Bacterial blight diseases, represented by Erwinia amylovora, the fireblight disease; Bacterial wilt disease, represented by Ralstonia solanacearum species complex; root and stem galls of trees, represented by Agrobacterium tumefaciens; wetwood disease, caused by several bacterial genera like Clostridium, Bacillus, Enterobacter, Klebsiella, and Pseudomonas, Xanthomonas, and Pantoea; bacterial scorch disease represented by Xylella fastidiosa with all its subspecies; bacterial canker represented by Pseudomonas syringae with all its pathovars. Finally, the current diagnostic methods and specific issues related to bacteria detection, together with the main results of the scientific efforts and challenges in the genetic breeding to increase bacterial resistance of trees, are outlined.
... The determination of the material structure is based on the speed of the wave. Ross et al. (1994) used longitudinal stress wave NDE to detect the presence of wetwood. Oliveira et al. (2002) used stress wave NDE to predict the bending property of wood. ...
... After conditioning, the specimens were tested using a stress wave timer (Metrigard 239) by measuring the time transmission along the length of the wood, prior to conductive static bending tests, to determine their dynamic modulus of elasticity (MOE sw ). The tests were carried out according to Ross et al. (1994). In detail, the stress wave was induced in the wood by impact, and the transit time was measured with the stress wave timer. ...
Small wood specimens selected from six slash pine (Pinus elliottii) trees were inoculated with brown-rot and white-rot fungi and then evaluated for static modulus of elasticity (MOE) and dynamic MOE (MOEsw). The experimental variables studied included a brown-rot fungus (Gloeophyllum trabeum) and a white-rot fungus (Trametes versicolor) for six exposure periods (2, 4, 6, 8, 10, and 12 weeks). The MOEsw was tested by a stress wave timer prior to static bending and the results were compared via regression analyses. Regression analyses indicated good correlations between static MOE and MOEsw. The R² ranged from 0.66 to 0.80 for non-decayed, brown-rot, white-rot, and all the specimens.
... Chudnoff et al. (1984) reported similar results from experiments that utilized an ultrasonic measurement system and several hardwood and softwood species. Patton-Mallory and De Groot Static Bending, Transverse Vibration, and Longitudinal Stress Wave Nondestructive Evaluation Methods Elvery and Nwokoye (1970) Several 11 203-167 (62-51) - Red oak 12 302-226 (92-69) - Ihlseng (1878Ihlseng ( , 1879 Several -272-190 (83-58) - Gerhards (1978) Sitka spruce Southern Pine 10 9 170 (52) 197 (60) - Gerhards (1980) Douglas-fir 10 203 (62) - Gerhards (1982) Southern Pine 10 197-194 (60-59) - Rutherford (1987) Douglas-fir 12 -1,092-623 (333-190) Ross (1982) Douglas-fir --850-597 (259-182) Hoyle and Pellerin (1978) Douglas-fir 9 -1,073 (327) Pellerin et al. (1985) Southern Pine 9 200-170 (61-52) 613-1,594 (187-486) Soltis et al. (1992) Live oak 12 -613-1,594 (187-486) Ross et al. (1994) Northern red and white oak (1989) reported encouraging results from a fundamental study dealing with the application of acousto-ultrasonic techniques. Their results showed that energy loss parameters may provide useful additional information on early strength loss from incipient decay caused by brown-rot fungi. ...
... This fundamental signal is commonly called time of flight (TOF) (Li et al. 2012). Then, the single-ray velocity of a stress wave can be calculated, and it can be used to inspect the soundness of wood by measuring the velocity difference between the value and a reference value (Ross et al. 1994). Furthermore, once the multi-ray signals of a stress wave are measured, the horizontal distribution of the stress wave propagation velocity in wood can also be analyzed (Johnstone et al. 2010;Lin et al. 2011). ...
In this paper, a novel stress wave tomography method, using spatial interpolation and velocity compensation, is proposed for the detection of internal defects in wood, based on the measured time of flight data and the assumption that stress waves propagate in straight lines in the cross-sectional area of wood. First, an improved ellipse-based spatial interpolation method is proposed, which could be used to estimate the velocity value of a grid cell by the elliptic affected zones corresponding to the nearby velocity rays. Second, because of the anisotropic property of wood, a velocity compensation method was applied to obtain more accurate input data for spatial interpolation. Then, the internal graph of the cross-section of a wood trunk could be reconstructed by the proposed algorithm. Four wood samples, with different defects, were used to test the proposed tomography method in the experiment. The results showed that the proposed method performed well and was able to resist signal interference caused by the density variation of the defective area.
... There is no need to apply couple mixture between sensor and tested wood samples. Therefore, stress wave testing has been widely applied in wood defect judgments and measurement of wood mechanical properties [2][3][4][5]. ...
... It does not damage the measured wood, and no coupling agent is used between the sensor and the measured wood. Therefore, stress wave detection technology has been widely applied in the field of wood products industry, and many gratifying results have been achieved [4][5][6][7][8][9][10][11]. In this paper, the stress wave technique was used to test the impacts of wood defects of Korean pine wood samples. ...
... (3) The size of hole along the axis has great impact on the parameters and elastic modulus, which is positively correlated to propagation time and negatively correlated to velocity and elastic modulus. (4) The hole size at one end of the wood samples has no significant impact on the parameters and elastic modulus. This is probably due to stress wave may without passing through the hole. ...
The wood samples were tested by the technique of stress wave, and the testing results were analyzed by using the statistic software of SPSS. The results showed that the length, density and knots of wood, the sizes of holes and numbers of holes have significant influence on propagation parameters and dynamic modulus of elasticity. Under the same specifications, the propagation time of the stress wave was longer in the wood with holes than the perfect wood samples, and the time become longer with the increasing the sizes and numbers of holes. The studying results of this paper will provide a sound background for the application of stress-wave technique in detecting the inner defects of wood products and other wooden structures.
... It has been speculated that a wet-pocket is a consequence of bacterial contamination (Bauch et al. 1975;Ward and Zeikus 1980;Schink and Ward 1984). Wet-pockets can cause excessive honeycomb, ring shake and deep surface checks during kiln-drying (Ward and Groom 1983;Ross et al. 1994). Furthermore, due to the inherently low permeability and slow drying characteristics compared to normal heartwood (Ward 1986), drying lumber containing wet-pockets results in uneven final moisture content between and within boards, and also in long drying times (Kozlik and Ward 1981;Simpson 1991). ...
The potential of visible and near infrared (Vis-NIR) spectroscopy to distinguish wet-pockets from normal subalpine fir (Abies lasiocarpa Hook) wood was evaluated. Two specimen classes were used, namely, wood with more than half of the surfaces covered by wet-pockets
(WW), and wood completely free of wet-pockets (NW). A partial least square (PLS) regression model was derived and calibrated
to predict moisture content ranging from 0 to 210%, and its usefulness for moisture-based sorting of green lumber was assessed.
Samples were sorted into the two classes after Vis-NIR scanning via two models: (1) soft independent modeling of class analogy
(SIMCA) and (2) PLS discriminant analysis. The SIMCA model using second derivatives and wavelengths spanning 650 to 1150 nm
successfully classified 98% of WW and NW in the green state, while it resulted in misclassification of 96% of the specimens
after air-drying. The discriminant PLS model using wavelengths spanning 650–1150 nm, correctly classified WW and NW 96% in
the green state and 100% after air-drying, respectively. These results clearly demonstrate the applicability of Vis-NIR spectroscopy
to discriminate wet-pockets from normal wood.
... Gerhards (1974) showed that the stress wave speed are affected by such as moisture, temperature, grain angle and knot. A longitudinal stress wave and transverse vibration methods were developed for the estimation of modulus of the elasticity for lumber (Ross & Pellerin, 1991;Ross et al., , 1994. ...
... and found that relationship between the MOE of the logs and the lumber obtained from the logs is high. Another stress wave application approaches have been accomplished in degraded wood (Ross et al., 1994. Ross et al. (1994) found that the stress wave evaluation technique is effective to detect the presence of wet wood in red oak lumber. ...
... Another stress wave application approaches have been accomplished in degraded wood (Ross et al., 1994. Ross et al. (1994) found that the stress wave evaluation technique is effective to detect the presence of wet wood in red oak lumber. also found that the stress wave characteristics have a good coincidence with compressive strength values of biologically degraded wood. ...
Nondestructive evaluation (NDE) technique method using a resonance frequency mode was carried out for woodceramics made by different phenol resin impregnation ratios (40, 50, 60, 70%) for Broussonetia Kazinoki Sieb. Dynamic modulus of elasticity increased with increasing resin impregnation ratios. There was a close relationship between dynamic modulus of elasticity and static bending modulus of elasticity and between dynamic modulus of elasticity and MOR and between static bending modulus of elasticity and MOR. Therefore, the dynamic modulus of elasticity using resonance frequency mode is useful as a nondestructive evaluation method for predicting the MOR of woodceramics made by different impregnation ratios.
... exclusive permettant à la Bibliothèque nationale du Canada de reproduire, prêter, distribuer ou vendre des copies de cette thèse sous la forme de microfîche/fîlm, de reproduction sur papier ou sur format électronique. ..................................................................................................................... ...........74 (Ross et. al., 1994). The same problem has been found by the Canadian kilns all over the country, and this created a need for detailed research on wetwood distribution and properties. Because published comparisons o f moisture content (MC), specific gravity (SG) and shrinkage differences between wetwood and normal sapwood and heartwood are variable and inco ...
Physical, anatomical, chemical, and microbiological properties of wetwood in heartwood were compared with those of sapwood and normal heartwood in balsam fir (Abies balsamea (L.) Mill.). Wetwood found only in heartwood of balsam fir had significantly higher moisture content (MC) than normal heartwood but not significantly higher MC than sapwood. No differences in relative density or shrinkage properties were found among tissue types. Wetwood tissue needed longer times to dry to an equilibrium MC of 15%, not only because of its high initial MC, but also because of its lower moisture permeability (diffusion coefficient) in this particular MC range (from initial MC to 15% equilibrium MC). However, there were no significant differences in drying rates for the different tissues when drying from 15% MC to 8% MC. Anatomically, wetwood is similar to normal heartwood, and it has no distinctive characteristics except a greater frequency of bacteria. Energy dispersive X-ray analysis showed that all of the tissues contained the same inorganic elements. Both high-performance liquid chromatography and ash analysis showed that wetwood is chemically closer to normal heartwood than to sapwood. Wetwood was significantly more acidic than either normal heartwood or sapwood. A large number of bacterial genera were found in all three tissues, but there were no consistent or significant differences in bacterial presence or activity among tissue types.
... Owing to the technique limitations, not all the kernel parameters are detectable by direct measurement, but some of them can be achieved by the identifications based on experimental results. Stress wave technique is a nondestructive, economical and effective method for the identifications of structure and material properties [4][5][6][7] . In the traditional application of this technique, the stress wave transmitting in the object whose parameters to be tested is commonly generated by an external excitation and recorded by the sensor on the surface of the measured sample. ...
An experimental study of geometric characteristic identification of impacted object is presented by recording the stress waves inside the impacting projectile and then the effect of the geometric characteristics on the stress wave curves is analyzed. The discussions based on experimental results indicate that the geometric characteristics of the impacted object can be identified from the stress wave curves recorded by the gauges attached on the projectile surface.
