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Feasibility of AE (Acoustic Emission) monitoring for the detection of the activities of wood-destroying insects
1992 - IRG/WP 92-2416
The feasibility of acoustic emission (AE) as a nondestructive testing method for the detection of the wood destroying insects was investigated. AEs were detected from the wood specimens under feeding attack of sugi bark borers or powder-post beetles. However, the feasible monitoring area of an AE sensor is influenced by the attenuation of AE amplitude, so that this could be a problem in the practical AE measurements, especially with wood specimens of higher moisture content.
Y Fujii, Y Imamura, E Shibata, M Noguchi


Nondestructive Evaluation of Oriented Strand Board Exposed to Decay Fungi
2002 - IRG/WP 02-20243
Stress wave nondestructive evaluation (NDE) technologies are being used in our laboratory to evaluate the performance properties of engineered wood. These techniques have proven useful in the inspection of timber structures to locate internal voids and decayed or deteriorated areas in large timbers. But no information exists concerning NDE and important properties of wood composites exposed to decay fungi. For our pilot study on several types of wood composites, we examined the relationship between nondestructive stress wave transmission, decay rate and the bending properties of OSB exposed to the brown-rot fungus, Gloeophyllum trabeum (MAD-617). The following measurements were taken: stress wave transmission time (pulse echo test method), static bending test (ASTM D3043-95), and decay (expressed as percent weight). Stress wave measurements correlated with strength loss and with increasing rate of fungal decay. Stress wave NDE has great potential as a method for inspection of wood composite load-bearing (in-service) structures, detection of decay in laboratory tests, assessment of chemical additives to improve wood composite durability, and prediction of long term composite performance.
B Illman, V W Yang, R J Ross, W J Nelson


Detection of feeding behaviour of termites using AE monitoring
1991 - IRG/WP 1514
Using acoustic emission (AE) monitoring, the feeding activity of the termite inhabiting a wood specimen was investigated. The amplitude and the rate of AE from the specimen of Coptotermes formosanus Shiraki was larger than that of Reticulitermes speratus Kolbe. The AE event rate was higher in the specimen with soldiers than without soldiers. The AE event rate decreased according to the resistance of wood specimens against termite attack.
Y Imamura, M Tokoro, M Owada, Y Fujii, M Noguchi


Feasibility of termite control using crushed cement-stabilized sludge (Polynite) as a physical barrier and acoustic emission (AE) monitoring
2000 - IRG/WP 00-10381
In Japan, the damages by the subterranean termites (Coptotermes formosanus Shiraki and Reticulitermes speratus Kolbe) are more common. Recently, the more attention is paid to the methods of the termite controls of less- or non-chemical. As one of the non- chemical treatment, physical barrier using particles as basalts 1) , granites, and gravels 2) were investigated in terms of its safety, cost effectiveness and duration of performance, and there were also examples that the physical barriers using some particles have been put to practical use in a few countries except in Japan. Ebeling and Pence showed that the relationship between particle size and termite body size is an important factor in controlling tunneling activity of subterranean termites, and the crushed volcanic cinders of 0.85-2.36 mm in diameter prevented R. hesperus from penetrating 3) . Tamashiro and co- workers indicated that the particles of particular sizes (1.70-2.40 mm in diameter) prevented C. formosanus from penetrating 4) . Su and co- workers investigated the penetration of the sand barrier consisting of crushed quartz rocks and fossilized coral by C. formosanus in laboratory- and field-testing 5, 6) . These results show that it is important to investigate the relationships between the size of termites and particles to evaluate the effects of the physical barrier using particles. On the other hand, in Japan surplus soils and sludge of sixty million tons per annum are discharged from construction sites. The recycle techniques using the surplus soils and sludge and the development of the market for these recycled products are the theme of importance. The crushed cement- stabilized sludge (Polynite) as one of the recycled products of surplus soils and sludge is one of the newly developed and recycled material. It is technically suitable for mass production, has grate cost effectiveness, and is easy to uniform the particle size. In this study, the feasibility of a physical barrier using Polynite uniformed the particle size for termite was examined in a laboratory testing. AE monitoring 7-13) as a method forthe detection of the penetration of termites into the Polynite barrier at an early stage was also investigated, for the application of Polynite barrier in the house.
Y Yanase, M Shibata, Y Fujii, S Okumura, K Iwamoto, T Nogiwa, T Yoshimura, Y Imamura


Detection of Acoustic Emission (AE) generated by termite attack in a wooden house
1999 - IRG/WP 99-20166
Recently, considerable attention has been paid to methods for termite control, which involves few or no chemicals. To reduce the amount of termiticide needed, it is necessary to detect termite attack in wood as early as possible. The feasibility of acoustic emission (AE) monitoring for the nondestructive detection of termite attack has been discussed previously. In this study, we propose some technical solution for the application of AE monitoring to practical control operations. Using a needle-type waveguide combined with an AE sensor (PZT sensor), AEs generated and propagated within floors and walls could be detected effectively. A 0.04 mm-thick sample of the piezoelectric polymer PVDF, which was inserted between the construction members of wooden houses, could detect Aes propagated both in such members and at joint surfaces, although PVDF film is less sensitive than a PZT sensor. The feasibility of using a portable AE detector as the input device for a total security system against termite attack in a house is also discussed.
Y Fujii, Y Yanase, T Yoshimura, Y Imamura, S Okumura, M Kozaki


Detection of termite attack in wood using AE monitoring
1990 - IRG/WP 2355
An acoustic emission (AE) monitoring method for detecting termite activity in wood was applied to lumber of 3 by 3 cm to 10 by 10 cm square, 1 m long. Furthermore, the propagation of AEs due to the feeding activities of termites in the specimens and the locations of AE sources were analyzed. Also discussed was the feasibility of the method applied to posts out in the field of subterranean termites. The results obtained from laboratory and field tests suggest that AE monitoring could be an effective non-destructive method to detect feeding activity of termites even in the incipient stages of the termite attack in wood.
Y Fujii, M Owada, M Noguchi, Y Imamura, M Tokoro


A Long-term Observation of Termite Activity in The Nest by Continuous Acoustic Emission (AE) Monitoring
2003 - IRG/WP 03-20280
In order to evaluate the influence of temperature on the termite activity, acoustic emission (AE) monitoring was applied to two nests of Coptotermes formosanus SHIRAKI; a nest in the stem of a standing tree and a nest in the underground of a wooden house, respectively. Temperature change in and around the nests were continuously measured for about one year using thermocouples at four points; the centre of the nest, the periphery of the nest, the environment around the nest, and the underground, respectively. AEs were detected at the centre of nest and underneath the nest sphere by using wave-guides inserted into the nest of the standing tree and at the centre of nest. AEs were also detected at the wooden construction member near the nest in the wooden house. The termites in the nests were periodically stimulated by rotating, drawing and sticking the wave-guides. The temperatures in the both nests varied from 5 to 35 °C during the experiment. The highest and the lowest temperatures were recorded in August and February, respectively. The highest AEs event rate was recorded when the temperature of the nest in the tree was between 30 and 35 °C and when the temperature of the nest under the house was above 25 °C. In winter, when the nest temperature was below 10 °C, no significant numbers of AE were detected. These findings clearly show that AE generation has a close relation to the termite activities, which are influenced by the temperature in the nest.
Y Yanase, Y Fujii, S Okumura, T Yoshimura, Y Imamura


Using AE monitoring for detecting economically important species of termites in California
1991 - IRG/WP 2375
Acoustic emission (AE) monitoring was conducted on wooden samples containing three economically important species of termites in California (dampwood termite, Zootermopsis nevadensis, Western drywood termite, Incisitermes minor, and Western subterranean termite, Reticulitermes hesperus). Laboratory AE studies included varying termite species, as well as 7 day studies exploring the periodicity of termite behavior. The results from the laboratory tests revealed significant differences in AE events between species, days, and sensors used. In a second study, the distance that AE signals could be detected in 2.6 m (8 ft.) long, 52 x 102 mm² (2 by 4 in.) wooden studs was also explored for the dampwood termite. Acoustic emission signals were detectable for up to 2.2 m in wood for dampwood termites. This study is compared with other investigations exploring the feasibility of using AE to detect termites.
V R Lewis, R L Lemaster, F C Beall, D L Wood


Detection of Termite Attack to Wood Stakes in a Monitoring Station Using Ceramic Gas Sensors and Acoustic Emission (AE) Sensor
2003 - IRG/WP 03-20271
To evaluate the termite activity in monitoring stations non-destructively, metabolic gas from termites and acoustic emission generated by feeding of termites were measured. Ten cylindrical stations with small wood stakes of Japanese red pine (Pinus densiflora) were buried around a house attacked by Coptotermes formosanus SHIRAKI. A sample air in the station was collected by sucking through a drilled hole of the station lid and analyzed using two types of ceramic gas sensors (odour- and hydrogen-selective sensors). Acoustic emissions (AEs) were detected by a PZT sensor attached to the cross section of one of the small stakes in the station. The concentrations of two components of the collected gas, odour and hydrogen, and AE event rate per 2 minutes were measured periodically from December 2001 to February 2003. The infestation activity in the station was also evaluated by visual inspection. In the early stage of the experiment, from the first to the third measurements, neither AEs nor significant level of the gas concentration was detected, and no termite was found in any stations. A higher gas concentration of odour and hydrogen and a larger number of AE events were detected since termites have invaded in the stations. These findings suggest that termite attack in the monitoring station can be evaluated by using two types of the gas sensors and AE sensor.
Y Yanase, Y Fujii, S Okumura, T Yoshimura, Y Imamura, T Maekawa, K Suzuki


Non-destructive stress wave measurement of decay and termite attack in experimental wood units
1986 - IRG/WP 2256
The purpose of this study was to determine if stress wave analysis could be used to monitor the degradation of wood specimens exposed to the brown-rot decay fungi (Gloeophyllum trabeum) and of wood specimens subjected to attack by subterranean termites. One hundred fifty 3/4 by 3/4 by 12 in. Southern pine specimens were used for exposure to brown-rot decay fungi and two hundred twenty-five 3/4 by 3/4 by 12 in. Southern pine specimens were used for attack by subterranean termites. Lots containing twenty five specimens each were subjected to either brown-rot decay fungi or monocultures of subterranean termites for various lengths of time in order to produce a gradient series of wood degradation. The specimens were then stress waved and statically tested to failure in compression. Stress wave modulus of elasticity and stress wave time provided useful correlation coefficients when used to estimate the ultimate compression stress of the degraded wood specimens. For the brown-rot decay specimens, a correlation coefficient of 0.892 was achieved using stress wave modulus of elasticity, as calculated with original specific gravity and exposed stress wave time values, to predict ultimate compression stress. Stress wave time by itself provided a correlation coefficient of 0.729. For the termite attacked specimens, correlation coefficients ranged from r = 0.90 for the control specimens, to r = 0.79 for the attacked specimens. In this case however, stress wave time by itself was not affected by the degradation of the wood due to the fact that the termites devoured the early wood but not the late wood of each annual ring. Changes in stress wave modulus of elasticity and stress wave time values reflected changes in ultimate compression stress values during early periods of decay. From the results it appears that stress wave analysis can be used to accurately monitor the strength degradation of wood specimens exposed to brown-rot decay fungi. Similar results were found in the termite attacked specimens with stress wave modulus of elasticity but not with stress wave time alone.
R F Pellerin, R C De Groot, G R Esenther


Future Directions Regarding Research on the Environmental Impacts of Preservative-Treated Wood: Environmental Impacts of Preservative-Treated Wood. February 8-11, 2004, FL, USA Workshop – Research Needs
2004 - IRG/WP 04-50222
This paper presents a series of documents that focus on research needs for potential future work focusing on the environmental impacts of preservative-treated wood. These documents were developed through a conference sponsored by the Florida Center for Environmental Solutions (FCES), located in Gainesville, Florida. The conference was held in Orlando, Florida, February 8 – 11, 2004 and the title of the conference was, “Environmental Impacts of Preservative-Treated Wood.” Approximately 150 people from 15 countries attended the conference. The “research needs” documents developed to date were summarized from: 1) feedback received from conference participants prior to the conference and 2) a two hour workshop held at the conclusion of the conference. A draft voting ballot has been prepared from these documents. This ballot is currently being reviewed by the FCES conference Technical Advisory Committee and a final ballot will be released in mid-April for a vote among the conference participants. A copy of the draft voting ballot is included at the end of this document. Results of the vote will be released at the 35th Annual IRG Meeting in Slovenia.
H M Solo-Gabriele, J D Schert, T G Townsend


New approaches to practical evaluation method of bio-degradation of wooden construction - Non-destructive detection of defects using radar technique
2000 - IRG/WP 00-20214
There have been a number of researches and developments on the techniques and apparatus for the nondestructive evaluation of the biological deterioration in wood and wooden constructions, such as decay or insect attack in house, public buildings or in historically important architectures. As for the detection of the decay in wood, techniques using sound in audible or in ultrasonic frequency ranges, stress waves, heat wave and X- ray have been investigated, where the changes in the physical properties expressed in the wave form were related to decay. The change in the velocity, the attenuation or the frequency spectrum of these physical energy waves can be associated with the decrease of the specific gravity or the structural change due to decay. Some mechanical properties such as the boring resistance and the elastic properties of wood surface could be an indicator of decay. The dielectric property of wood and its relation to decay is also useful. Miller et al. (1989) applied a radar technique to diagnosing of standing trees. However the techniques previously developed are not always feasible. One of the possible reasons is that these physical or mechanical properties change not only on decay but also on other factors, such as the water content or the grain direction in wood. In addition, sometimes the techniques are less practical, strictly not non- destructive or too expensive. In practical maintenance operation of wooden constructions, visual inspection together with sampling method plays an important roll, however a specialized training is needed for the operator to get the skill of the diagnosing. In this study, to establish a practical evaluation method of bio- degradation in wooden construction, scanning using a newly developed portable radar apparatus was investigated. By comparing the results with other methods, a more practical method to evaluate the bio-degradation in wood was proposed.
Y Fujii, Y Komatsu, Y Yanase, S Okumura, Y Imamura, M Tarumi, H Takiuchi, A Inai


Control of termite attack using a trapping method and acoustic emission (AE) monitoring a case study at an electric power plant
1997 - IRG/WP 97-10224
To prevent subterranean termites (Coptotermes formosanus Shiraki and Reticulitermes speratus Kolbe) from invading the buildings of an electric power plant and to control their attack, artificial traps were buried around the buildings. The attack of the termites in and around the traps was monitored by detecting acoustic emissions (AE) generated by the feeding behavior of the workers. The cylindrical artificial traps were 600 mm long and 300 mm in diameter, and consisted of pieces of Japanese red pine surrounded by slender polystyrene foam sticks. Termite inhabitation was observed in eight of the ten traps set, and particularly high levels were found in three traps. The traps were renewed every one or two months. The amount of termites inhabiting the traps decreased drastically after the first renewal, but varied only slightly over the following two and a half years. The amount of termites in the traps increased when the traps were not renewed. Termite activity was significantly restricted by installing artificial traps and no additional serious attacks were found in or around the buildings during the study period. AEs generated by feeding activities were monitored by piezoelectric AE sensors attached to the wooden sticks in the traps or to wooden bait stakes near the trap. The rate of AE events varied according to feeding activity which was associated with the number of termites in the trap and the temperature.
Y Fujii, Y Imamura, E Iwatsubo, S Yamamoto


Detection of termite attack in wood using acoustic emission
1989 - IRG/WP 2331
Acoustic emission (AE) is the elastic wave produced by the strain energy released in the process of fracture of a material and propagates through it. The object of this report is to detect AEs produced by the termite activities and to evaluate the possibility of using an AE monitoring test to nondestructively detect the termite attack in wood. It was revealed that AEs were detected from the specimens under termite-attack and the rate of AE events increased according to the number of the inhabiting termites. As no AE was detected from the specimens with soldiers only, it was assumed that workers should generate AEs through feeding activities. It was also revealed that the distribution of AE sources corresponded to that of the region attacked by termites in the specimen.
Y Fujii, M Noguchi, Y Imamura, M Tokoro


Underwater shock treatment for improvement of penetration of wood
2006 - IRG/WP 06-40325
Many of conifers including Beimatsu (Pseudotsuga menziesii Franco; Dougras fir, Oregon pine), Akamatsu (Pinus densiflora Sieb. et Zucc.; Japanese red pine), Dafurica Karamatsu (Larix gmelinii Gordon; Dahurica larch) and Karamatsu (Larix leptolepis GORDON; Japanese larch) generally contains the high moisture content. Although subjected to the drying process, it is difficult to be dried up completely so that a long time is necessary for conifers to be used as an architectural material. The bordered pit membrane on tracheids closes in the heartwood of conifers. For this reason, internal moisture is not able to go outside easily. And it makes difficult to saturate the wood preservatives to purpose of production of high value-added wood. In this paper, we developed an underwater shock wave technique to treat the pre-dried wood for the improvement the penetration of wood as well as be drying property by selectively fracturing the bordered pit membrane. The result indicates a very remarkable improvement on the penetration.
S Itoh, H Maehara, K Tanaka, T Echigo, K Morioka, E Shirai, K Nishimoto


Detection and Assessment Healthy Situation of Poulus Euphratica Oliv. with Stress Wave
2009 - IRG/WP 09-20415
The defects of tree trunk of Poulus euphratica Oliv were inspected by stress wave method and diagnosed with transmission time and velocity. The reference values of transmission time of unit length and velocity from stress wave were used to assess the healthy situation of tree trunk. The goal is provide fast inspecting technology and assessment method for the historic trees in China. The results shown: 1) Single-path method of stress wave is effective nondestructive method to diagnoses the defect of wood, but it can not effective assess wetwood in standing trees using the reference value of unit length transmission time (670 m/s )and average velocity (942 m/s), there would have more accurate assessment results if reference value be summarized from sound wood and used to diagnoses healthy situation of tree trunk; 2) Two directions testing of stress wave can not accurate diagnose the edge crack and small area decay in stem, multitude point test should be used to get more useful information of wood ; 3) the multitude point test from single-path stress wave shown that the trend of velocity of healthy tree trunk was increasing firstly with the angle increase and decreasing when the transmission angle more than 180o. There has a binomial formula relationship between velocity and transmission angle and the correlation coefficient arrived at 0.9942. This velocity trend of cross-section in healthy tree trunk and binomial formula can be used to diagnoses the defects of tree trunk.
Shanqing Liang, Nana Hu, Lanying Lin, Feng Fu


Stress wave and visual analysis of treated and non treated fence posts after 15 years in field test
2010 - IRG/WP 10-20449
Wood preservation may play an important role in protecting tropical rain forest. Basically, it can reduce pressure on natural resources by increasing wood durability. Field tests are conducted to simulate final use of woods under different environmental conditions. Visual analysis, non destructive testing, and non destructive evaluation techniques were applied to assess wood resistance and chemical preservative efficiency. In Brazil visual analysis is frequently applied in field tests while NDE (Non Destructive Evaluation) techniques have been very little used. We assessed the sound level of treated and non treated wooden fence posts after 15 years in field tests using stress wave and visual analysis techniques. We studied the following wood species: Eucalyptus saligna, Eucalyptus grandis, Pinus elliottii and Sclerolobium paniculatum. Additionally, two non-vacuum/pressure and one vacuum/pressure methods were used to impregnate the fence posts. Creosote, CCA, a mixture of creosote and used motor oil, and a formulation based on fluor chrome arsenate phenol were the chemicals applied. For each wood specie/chemical a combination of 10 samples was treated and other 10 samples for each wood species were used as control. The visual analysis and non destructive evaluation techniques were conducted according to the criteria proposed by the IUFRO. The stress wave timer Metriguard model 239A equipment was also used. These research results showed that the non-destructive analysis method using the stress wave timer device was an efficient alternative to rapidly measure sound level of the wooden fence posts in field test. The average velocity of wave propagation acquired by the stress wave timer was lower in decayed woods compared to sound ones. Also the average velocity of the wave propagation through the buried portion was lower than through the above ground portion of the wooden fence posts. The visual analysis and stress wave timer showed a good relationship as alternative approach to assess sound level of the fence posts in field test.
A Florian da Costa, R Faustino Teles, J Costa Gonçalves


Use of Acoustic Emission (AE) to detect activity of common European dry-woodboring insects: some practical considerations
2013 - IRG/WP 13-10803
Old house borer (Hylotrupes bajulus), Furniture beetle (Anobium punctatum), and Deathwatch beetle (Xestobium rufovillosum) are common dry-woodboring insects occurring throughout Europe. With the aim to prevent unnecessary use of biocidal products, to protect valuable wooden elements and objects from unwanted influences, and to have a more objective method, SHR has started to study the use of acoustic emission (AE) to assess activity of attack by these insects. This manuscript deals with the results of some experiments done in order to collect knowledge about the influence of (low) temperature or possible daily rhythms on the activity of the insects. Such knowledge is crucial for a trustworthy application of AE detection for European dry-woodboring insects in practice. Based on an 8-day-test with Hylotrupes with normal daily variation in temperature it is concluded that under these circumstances, temperature is the main influencing factor regarding insect activity. For individual larvae, phases of inactivity exist with a duration of up to 30 minutes. In practice, where probably more than one larva is present at one specific time, in the absence of AE events, measuring periods may need to be extended to at least these 30 minutes. With regard to minimum temperatures for detection, the insect species studied show small differences in behaviour at low temperature. Because the number of registered hits for all species shows a marked decrease at temperatures becoming lower than 10 °C, it is recommended that decisive assessments using AE for detection of activity of these dry-woodboring insects should be done at (wood) temperatures of 10 °C or higher.
J G M Creemers


Remote sensing for detection of termite infestations—Proof of Concept
2015 - IRG/WP 15-10846
This paper reports the results of a search to discover the most cost effective and robust method of detecting Reticulitermes flavipes infestations in structural members of remote bridges, homes and other wooden structures and transmitting these results to internet cloud storage thus obviating routine travel to these structures for periodic visual inspections. Duplicate stainless steel tanks were constructed for housing R. flavipes colonies and commodity size dimension lumber members. Overall, results indicated that the simplest and cheapest independent variables to measure and send were: temperature (ºC), relative humidity (% RH); dew point (DPºC) and wood moisture content (WPE %) using off-the-shelf commercially available sensor systems. Above ground termite bait stations were determined to be the best method of housing the various sensors to permit ease of subsequent baiting if any termite activity was detected. We conclude that it is feasible and cost effective to monitor valuable wooden structures, like historic covered bridges, against termite infestation and potential structural damage.
F Green III, R A Arango, C R Boardman, K J Bourne, J C Hermanson, R A Munson


Profiling fungal degradation of Scots pine sapwood by short wave infrared hyperspectral image analysis
2020 - IRG/WP 20-20667
Hyperspectral image analysis of Scots pine sapwood wood affected by decay fungi has been carried out as part of a Ph.D. thesis within the project Remote Inspection of Wooden Utility Poles (RIWUP). In a lab experiment, Petri-dishes with Scots pine sapwood samples on malt agar medium were infected with two types of decay fungi, a brown rot and a white rot. The wood samples were scanned with a HySpex SWIR-384 hyperspectral camera at different stages of decay progression to create a time series of short wave infrared hyperspectral measurements. The time series captures the wood-decay effect for a period of sixteen weeks. The primary variables in this experiment are mass loss and the recorded wood spectra. The correlation of the wood mass loss with the wood infrared spectra was performed with Partial Least Squares (PLS) regression. The preliminary analysis show that the change in the wood infrared spectra can largely be modelled by a single component for both the brown rot and the white rot decay processes.
A Jochemsen, G Alfredsen, I Burud


Comparison of AE-apparatus for detection of activity of Old house borer larvae, including reality check
2021 - IRG/WP 21-10981
As part of the German funded project ‘InsectDetect’ comparative measurements were done with three different Acoustic-Emission-(AE)-apparatus on 14 pine beams in order to assess presence of active attack by the Old house borer (Hylotrupes bajulus (L.)). In all beams active attack was measured, though in varying intensity. This was corroborated by completely dissecting 10 of the beams. All three AE-systems proved suitable to find active attack, although their results in terms of numbers of events are different even when used in the same situation. Therefore, it is important that the operator is familiar with the technical functioning of the system that is used in order to be able to interpret the results reliably. The dissection of the beams showed that there is also an element of chance in these measurements regarding proximity of sensors to gnawing larvae and temporal larval inactivity. Still, such measurements with these apparatuses can give an answer to the question whether active attack of wood-boring insects is present.
J Creemers, B Plinke, U Noldt