A pilot plant apparatus was built to electrostatically spray phenolic resin on strands. To evaluate the resin distribution on these strands, an image analysis method was developed. The experimental conditions in this study made it difficult to compare electrostatic treatments to control (non- electrostatic) treatments. Although not statistically significant, there were notable differences between these treatments which indicate that electrostatic resin application may improve panel properties and is therefore worth further investigation. First of all, the electrostatic treatment produced panels with a 10% higher internal bond than the control. Secondly, the resin distribution results show that the electrostatic spray, on average, covered a 30% greater area of the strands than the control even though both treatments applied resin at the 2% resin solids level. Further experiments using alternative test procedures are planned to compare electrostatic treatments to control treatments that simulate industrial conditions.
Wood failure evaluation is the key criterion for predicting the long-term durability of plywood. At present, the conventional visual method for plywood wood failure evaluation is slow and subjective. Even experienced evaluators can show significant differences in their evaluations on the same plywood specimen and an individual evaluator can make different wood failure estimates on the same specimen at different times. Differences among evaluators can be as high as 50% for some samples. Evaluations can be influenced by room lighting, the wood species, sample treatment, and readings from prior samples. An automatic wood failure evaluation system using image analysis techniques could potentially be programmed to consider all the variables and respond with consistent wood failure values regardless of the experience level of the machine operator. This report describes the results of a one-year project in which a system for automatic plywood wood failure determination was investigated. A color optical imaging system was assembled and the preliminary work of compiling suitable algorithms was completed with promising results. The imaging system was 100% effective in reproducing individual sample values. Samples were sorted according to plywood type and test method to develop appropriate program algorithms for each category. The wood failure program was then further developed to automatically detect wood species and test method, thus avoiding the need for specimen separation prior to evaluation. Based on nearly 1200 samples in four categories, the differences in average values of wood failure between human evaluation and machine vision were found to be less than plus or minus 5%. In addition, a minimum of 85% of individual machine readings fell in the plus or minus 15% range of deviation expected of human wood failure readers. The imaging system was more accurate for light-colored specimens (i.e., Canadian Softwood Plywood) than darker-colored specimens (i.e., Douglas fir ) and for specimens where resin had been applied by spray. In order to make the imaging system more reliable and robust, the algorithm parameters now need to be fine-tuned based on a larger sample database.
A report on the results of tests on the feasibility of using ceramics for saw blade tips. The major factors determining whether it is practical to use ceramics are the physical attachment of the tip to the blade, the inherent brittleness of the material and its wear characteristics.
Les auteurs définissent la qualité du bois en fonction de ses emplois, puis décrivent l'anatomie et la croissance du bois en regard de ses caractéristiques microscopiques et macroscopiques telles qu'observées en coupe transversale. Les exigences liées aux emplois sont énoncées selon les différentes classes de bois. Diverses caractéristiques déterminant la qualité du bois sont présentées et leurs conséquences pratiques pour la transformation du bois et les produits sont expliquées. Ces caractéristiques sont: la densité du bois, les variations de la densité, la répartition des bois juvénile et adulte, la proportion de duramen et d'aubier, la longueur des fibres, l'orientation des microfibrilles, le bois de compression, les noeuds, le grain ou la texture, le fil et les substances extractibles. Enfin, les auteurs traitent de la possibilité de modifier les paramètres de croissance de l'arbre et la qualité du bois grâce à un contrôle de la densité du peuplement. Les forestiers sont invités à prendre en considération les répercussions des travaux sylvicoles propres à chaque station.
Samples of western hemlock [Tsuga heterophylla (Raf.) Sarg.] and western red cedar [Thuja plicata Donn] trees completely submerged standing in a fresh water reservoir for approximately 24 years were examined in terms of relative wood density, extractives content in cedar and mechanical properties of small clear specimens. Due to diameter limitations in the sample material, test results for modulus of elasticity (MOE) in compression parallel-to-the-grain were found to be unreliable, but could be expected to compare to published values in a like manner as other test results. Based on the results of tests for wood density, extractives content and strength properties of small clears, the sound wood quality of submerged western hemlock and western red cedar is comparable to that of these species in general. Mitigating these favourable results, however, were the low proportion of sound logs recovered, external checking of log surfaces, and fine shake observed in red cedar which could have a negative impact on appearance grades. Definite determination of submerged wood quality would require sawing of logs, and evaluation of lumber yield and properties, and long-term tests for durability of the red cedar.
A concept for a wood frame construction system suitable for medium-rise buildings and/or buildings with large openings has been developed and patented. The system is composed of prefabricated column modules and continuous beams that can be cut to size at a manufacturing plant. Column modules, a primary feature of the system, have four standardized configurations depending on the configuration of the beams they are supporting. Each column module has at least two full-module-height vertical members spaced apart and diagonally-braced with wood and steel to provide lateral resistance to wind and earthquake forces. The column modules are placed at optimum plan spacings to support large-span continuous beams prefabricated with engineered composite products. A goal of this research was to prove the principle that the modular column assembly as originally patented can carry loads of a magnitude that could be expected in service. It was apparent from load-testing the patented design, however, that many shortcomings exist. In some cases this design could not meet test case load values expected in service, and could not sustain high design load levels for very long without softening. The patented design, in spite of reasonable ductility and good elastic recovery, also lacked the stiffness necessary to resist light horizontal loadings such as daily winds. As a result of many difficulties identified with this patented prototype, a second-generation column module design (with preliminary modeling analysis in hand) is awaiting consideration for construction and testing. The key to the success of this building system lies with the correct design of the column module to render appropriate horizontal racking and vertical load-carrying performance. It is recommended that the results of this research be pursued further to address some of the shortcomings found during the testing of this first patented prototype specimen. This proposed work should include finalizing examination of the racking test data of the original column module design, finalizing the modeling of a second generation prototype that addresses the shortcomings of the original design, and constructing and testing a second-generation prototype design. The aim is to deliver a viable system (with supporting data) to any potential collaborator for commercial considerations. This work should be complete and a final report submitted by 31, August 1997.
Conversion factors in comparative and standardized units are proposed for Eastern Canada forest products industry data. Information on wood measurement, wood properties and wood products are the most common "missing links" in the calculation of wood consumption and wood product yield. In this research, Forintek was commissioned to improve the accuracy and usefulness of OMNR'S Forest Industry Mill Information System (FIMIS) database. This publication contains information specific to the resource sizes, species, technologies and units used by the lumber and composite board industries in Ontario, Quebec, New Brunswick, Nova Scotia and Newfoundland. The resulting forest products industry statistics respond to industry, research and government who need to convert performance data into units and ratios.
A prediction model for long term creep and creep-rupture behavior of OSB was developed by the late Senior Research Scientist, Dr. L. Palka at Forintek Canada Corporation, Vancouver, BC, Canada. By using one minute destructive ramp load test results, the "Palka Model" allows the prediction of time-to-failure and time-dependent creep deformations under given sustained loads. Verification testing of the model was performed on time-to-failure at the 75% sustained load level and on creep deformation behavior at the 25% and 50% levels. The verification tests gave encouraging results which showed a reasonable agreement between the test results and the Palka Model predictions. The Palka Model is recommended for use as a first approximation prediction tool for long term creep behavior of OSB. The model prediction technique appears ideal to assist in product development decisions and also in evaluation of load duration and creep factors in timber design codes.