%0 Thesis %1 1994PhDT.......206B %A Biernacki, J. M. %D 1994 %K Douglas_fir LVL OSB SEM acoustic adhesive bond bonding curing destructive gel_time glulam kissing laminated_veneer_lumber laminates microscopic oriented_strandboard particleboard pressure ultrasonic viscosity wood %T Acoustic Monitoring of Adhesive Bond Curing in Wood Laminates. %X Challenges in manufacturing of wood products, such as glulam, include difficulty in controlling bonding variables and assessing bond quality. This dissertation investigates an ultrasonic method as a means of monitoring of curing and assessing bond quality in wood laminates. The effect of curing on ultrasonic transmission was studied using specimens of clear Douglas-fir, 100 x 200 x 600 mm, with the adhesive bond in the center of the specimen. Monitoring was performed simultaneously at normal and angular (5 ^circ nominal) incidence to the bond plane. Acoustic measurements were supplemented with destructive cure monitoring, standard bond strength measurement, monitoring of bulk viscosity curing, gel time measurement, and microscopic (SEM) examination. Angular incidence gave greater sensitivity to bond quality and curing status than did normal incidence. Analysis of wave propagation showed that displacement for transmission at a small angle (on the order of 5^circ ) was nearly parallel to the bond, which seems to explain greater sensitivity of angular incidence. Experimental results showed that this method was effective in detection of curing phases, such as spread, penetration, and hardening, defective bonds, and the effect of clamping pressure. An ünloading effect", measured as a relative transmission reduction after the clamping load was released, was sensitive to defective bonds, including uncured (kissing), underspread, and uneven spread bonds. Thick bonds (0.5 and 1.0 mm) caused the greatest increase in transmission, since waves at start of curing were highly attenuated. In angular transmission, thick-bond curing curves showed a characteristic inflection, which may be used to identify thick bonds and measure the curing rate. The results of this dissertation could be utilized to develop commercial systems in glulam manufacturing, which could evaluate: (a) phase of and completion of curing (b) bond quality (c) optimum clamping pressure. Similar systems could also be developed to monitor lumber and panel products curing at high temperature, such as LVL (laminated veneer lumber), OSB (oriented strandboard) and particleboard.

@phdthesis{1994PhDT.......206B, abstract = {Challenges in manufacturing of wood products, such as glulam, include difficulty in controlling bonding variables and assessing bond quality. This dissertation investigates an ultrasonic method as a means of monitoring of curing and assessing bond quality in wood laminates. The effect of curing on ultrasonic transmission was studied using specimens of clear Douglas-fir, 100 x 200 x 600 mm, with the adhesive bond in the center of the specimen. Monitoring was performed simultaneously at normal and angular (5 ^circ nominal) incidence to the bond plane. Acoustic measurements were supplemented with destructive cure monitoring, standard bond strength measurement, monitoring of bulk viscosity curing, gel time measurement, and microscopic (SEM) examination. Angular incidence gave greater sensitivity to bond quality and curing status than did normal incidence. Analysis of wave propagation showed that displacement for transmission at a small angle (on the order of 5^circ ) was nearly parallel to the bond, which seems to explain greater sensitivity of angular incidence. Experimental results showed that this method was effective in detection of curing phases, such as spread, penetration, and hardening, defective bonds, and the effect of clamping pressure. An "unloading effect", measured as a relative transmission reduction after the clamping load was released, was sensitive to defective bonds, including uncured (kissing), underspread, and uneven spread bonds. Thick bonds (0.5 and 1.0 mm) caused the greatest increase in transmission, since waves at start of curing were highly attenuated. In angular transmission, thick-bond curing curves showed a characteristic inflection, which may be used to identify thick bonds and measure the curing rate. The results of this dissertation could be utilized to develop commercial systems in glulam manufacturing, which could evaluate: (a) phase of and completion of curing (b) bond quality (c) optimum clamping pressure. Similar systems could also be developed to monitor lumber and panel products curing at high temperature, such as LVL (laminated veneer lumber), OSB (oriented strandboard) and particleboard.}, added-at = {2008-05-17T02:43:22.000+0200}, adsnote = {Provided by the SAO/NASA Astrophysics Data System}, adsurl = {http://adsabs.harvard.edu/abs/1994PhDT.......206B}, author = {{Biernacki}, J. M.}, biburl = {https://www.bibsonomy.org/bibtex/243e0828559082561acb6ac205b45f616/thulefoth}, description = {Acoustic Monitoring of Adhesive Bond Curing in Wood Laminates.}, interhash = {91df9bd54c9fd71116e8a9fb989214e5}, intrahash = {43e0828559082561acb6ac205b45f616}, keywords = {Douglas_fir LVL OSB SEM acoustic adhesive bond bonding curing destructive gel_time glulam kissing laminated_veneer_lumber laminates microscopic oriented_strandboard particleboard pressure ultrasonic viscosity wood}, school = {UNIVERSITY OF CALIFORNIA, BERKELEY.}, timestamp = {2008-05-17T02:43:22.000+0200}, title = {{Acoustic Monitoring of Adhesive Bond Curing in Wood Laminates.}}, year = 1994 }