Four beam types were tested in a pilot study to investigate the feasibility of using 2 by 4 lumber and structural particleboard in 16-foot garage headers. This study compares the performance of each beam type with a double 2 by 12 header, a beam used in house construction for framing a 16-foot garage opening. The study beams, 16 feet 6 inches long and 16 inches deep, were of the ″I″ type cross section using flanges of stress-graded 2 by 4 lumber and webs of one of four materials: plywood; underlayment particleboard; large-flake, phenolic-bonded aspen board; and a urea-bonded mixed-hardwood board. Each beam was nailed-glued at all contact surfaces between the 2 by 4 materials and web stock.
The Forest Products Laboratory (FPL) has promoted healthy forests and forest-based economies since 1901 through the efficient, sustainable use of American wood resources. Early research priorities at the FPL focused on timber testing, wood preservation, wood-based distillates, wood technology, pulp and paper, and wood chemistry. Fourteen scientists and six assistants were initially supported by a total of $28,000 per year. The FPL focused on characterizing the fundamental properties of wood and on wood products utilization. Determining mechanical properties of North American woods and wood products led to practical applications for under-valued species found on National Forest and private lands. Wood preservation, another focus of early FPL research, often aimed to educate industrial wood consumers such as architects and railroad and mining engineers in the ways of efficient utilization. FPL researchers in the Durability & Wood Protection unit are developing new, environmentally preferable wood preservation technologies, including formulations free of toxic metals.
An analysis of hardwood lumber consumption found that demand has changed dramatically over the past four decades as a result of material substitution, changes in construction and remodeling product markets, and globalization. In 1963 furniture producers consumed 36 percent of the hardwood lumber used by domestic manufacturers. Producers of hardwood construction and remodeling (CR) products accounted for an additional 32 percent of hardwood lumber consumption with the bulk of this volume being consumed by manufacturers of hardwood flooring. Between 1967 and 1982 hardwood lumber consumption by furniture producers remained relatively constant. By contrast, lumber demand by CR product manufacturers declined by 33 percent as carpeting was substituted for wood flooring. However, this decline in demand was countered by increased production of pallets and crossties, which accounted for 41 percent of hardwood lumber consumption by 1982. In the 1980s and 1990s overall hardwood lumber consumption surged because of increased lumber use by pallet and CR product manufacturers. Since the late 1990s furniture imports have increased while domestic furniture production has declined, thus furniture manufacturers accounted for only 18 percent of domestic hardwood lumber consumption by 2002. By contrast, consumption by the hardwood millwork, cabinet, and flooring sectors have continued to increase, partially offsetting the decreased consumption by the domestic furniture industry.
This paper examines changes in sawmill concentration and hardwood lumber production for Tennessee between 1979 and 2005. In 1979, only 2 percent of the lumber manufactured in Tennessee was produced by very large mills with capacities of 10 million board feet (MMBF) or more annually. By 2005, such mills produced more than 43 percent of the lumber, generally following an "expand or exit" model of industry concentration. The greatest change in sawmill concentration, however, occurred in the eastern region of Tennessee, where very large mills accounted for 61 percent of the production in 2005 compared to 0 percent in 1979. Construction of mills in eastern Tennessee seems to have been facilitated by relatively low delivered log prices and improved highway systems. Such changes seem to follow a different model of industry concentration, one that occurred during the timber boom of the early 20th century -if timber can be economically transported it will be "severed and sawn." Since 2005 there has been a decline in demand for higher grades of hardwood lumber and large increases in energy costs. This combination could influence the future size, location, operational objectives, and the industrial concentration of sawmills in Tennessee and other eastern hardwood states.
The Global Forest Products Model was used to project international forest sector developments, conditional on the latest RPA Timber Assessment of future domestic changes in the United States. While the United States, Japan, and Europe were predicted to remain major importers of forest products out to 2030, the rapid economic growth of China would make it the world’s largest market for raw wood, and intermediate and final forest products.Mexico and the Republic ofKoreawould also become important markets for solid wood and fiber products. The U.S. share of global exports of industrial roundwood and other paper and paperboard were predicted to increase out to 2030. In competition with the United States, itwas predicted that Finland, Austria, Latvia, Chile, and New Zealand would increase their share of global sawnwood exports, and Austria and the Republic of Korea would emerge as exporters of printing and writing paper.
Environmental accumulation of preservative adjacent to a chromated copper arsenate (type C)-treated wetland boardwalk was evaluated. The site is considered a realistic "worst case" because of the large volume of treated wood, low current speeds, high annual rainfall, and environmental sensitivity. Soil and sediment samples were collected before construction and 0.5, 2, 5.5, 11, 24, 60, and 131 months (11 y) after construction and analyzed for total chromium, copper, and arsenic concentrations. This article updates the findings after 11 years of exposure. Environmental concentrations varied with time, with proximity to the treated wood, and between riparian and aquatic locations. Concentrations of leached components in the soil developed slowly, were greatest at the 60-month sampling, and declined at the 131-month inspection. Soil samples with elevated levels of copper and chromium were confined to directly under the drip line of the boardwalk, and arsenic appeared to be limited to within 0.3 m (1 ft) of the structure. Concentrations of leached components in the sediments increased more quickly than those in the soil and tended to reach maximum or near maximum levels within the first year. However, concentrations of arsenic and copper in sediments directly under the walkway reached maximum levels after 60 months, before declining at the 131-month sampling. Elevated concentrations of copper, chromium, and arsenic were occasionally found in sediments as much as 3 m (10 ft) from the boardwalk.
Consumers choose products based on various tangible and intangible attributes. Previous research has shown that there is a difference between appearance-based and word-based evaluations ofwood species. However, little research has been done on how this difference affects consumer choice. This study examined how the presence or absence of a species name affects a cabinet door's popularity in the Pacific Northwest (including Alaska). The results showed significant difference between appearance-based and species name-based preferences for cabinet doors. For example, respondents chose cherry and red oak cabinet doors more often when the doors were labeled with the species name than when they were not labeled. In contrast, red alder was chosen less often when the doors were labeled with the species name. This suggests that certain species names should be emphasized in cabinet door marketing while others should be avoided. Age and income demographic segments are analyzed and managerial implications are discussed.
Using information from 204 individuals with an active interest in home building and/or furnishing, this study surveys consumers and purchasing agents and reports their reaction to terms used to describe forest products from southeast Alaska. Regarding terms used to describe the trees or forest products, while 67 percent of the respondents would purchase products from old growth trees, purchasing agents were more likely to refuse to purchase products from old growth forests (negative response from 12 percent of consumers vs. 29 percent for purchasing agents). Eighty-eight percent of respondents reacted positively to purchasing products from trees grown under sustainable yield management. Twenty-eight percent of respondents reacted negatively to the term national forest, while the term Tongass received the highest level of uncertainty. When asked if they would purchase products made from trees cut from a forest of concern to either environmental or preservationist groups, respondents showed polarity with approximately equal yes (38 to 46%) and no (43 to 46%) responses. It was concluded that respondents had an overall positive view of Alaska forest products.
The deterioration of heartwood from live and dead Alaska yellow-cedar trees was evaluated by exposing ministakes in soils at field sites in Alaska and Mississippi for 2 and 4 year intervals. Southern yellow pine sapwood served as a control. The vastly greater deterioration, as measured by weight loss, in Mississippi compared to Alaska (60 and 10 percent after 4 years, respec- tively) was attributed to warmer temperatures, a longer growing season, and perhaps the presence of termites. The wood from Alaska yellow-cedar trees dead 26 years did not differ in deterioration from the wood from live cedar trees, but wood from cedar trees dead 81 years experienced an intermediate deterioration between these classes and the pine controls. Slow changes in heartwood chemistry following tree death probably explain these differences for Alaska yellow-cedar. The results from this and several related studies indicate that heartwood from dead Alaska yellow-cedar trees is suitable for many indoor and outdoor applications long after tree death, but wood from live or dead cedar trees does not perform particularly well in contact with soil.
Birch lumber is often characterized by a high degree of knots, bark pockets, heartwood, and other features which force sawmill owners to decide whether to edge and trim boards to produce standard grade lumber vs. proprietary grade character-marked lumber. In addition, the edging strategies used with irregularly shaped flitches can greatly influence cut-stock recovery. To investigate this recovery, 143 kiln-dried 4/4 birch flitches were obtained from a sawmill in south-central Alaska and evaluated by a National Hardwood Lumber Association (NHLA) grader for board grade and lumber tally. Each flitch was marked by the lumber grader, indicating where the board would be edged to produce NHLA grade lumber in a production setting. The flitches were transported from Alaska to Oregon State University where they were scanned to produce digital board data. These data were then processed with the computer simulation program CORY (Computerized Optimization of Recoverable Yield) to estimate the cut-stock yield for various levels of edging severity and sound feature (character mark) inclusion. Four edging strategies were evaluated, ranging from unedged (least severe) to wane-free (most severe). As expected, cutting area recoveries and cutting yields were reduced as edging severity was increased. In many cases, however, these differences were minimal. Cutting yields for clear parts were 21.1, 23.7, 26.2, and 27.1 percent for wane-free, actual, light, and unedged strategies, respectively. Cutting yields for parts that included sound character features increased by more than double to 44.0, 49.0, 52.7, and 54.0 percent for wane-free, actual, light, and unedged strategies, respectively. These results indicate that finding value-added alternatives for this character-marked birch might prove profitable for some Alaskan sawmills that also produce secondary products such as cabinets and furniture or supply cuttings to these manufacturers.
The effects of aligning fibers and of their placement within the fiber mat on strength, elastic modulus, and dimensional stability of high-density, dry-formed hardboard were investigated. This approach was taken to produce hardboards with increase strength for use as structural components. Four sets of oriented fiber configurations and one set of random-formed control boards 3/16 in. thick were prepared from aspen and from Douglas-fir.
This paper uses a previously developed theoretical simulation model to investigate the influence of orientation level of strands as measured by percent alignment (PA), and shelling ratio (SR) (weight percentage of the face layer) on modulus of elasticity (MOE) of oriented strandboard (OSB). As expected, improving PA increases MOE-parallel and decreases MOE-perpendicular, but the decrease of MOE-perpendicular levels off after PA exceeds approximately 50 percent. Increasing SR improves MOE-parallel and decreases MOE-perpendicular, but the change of MOE is negligible after SR reaches approximately 0.7. This paper also shows that orientation level and use of different species in the core only have minimal influence on MOE. Use of MOE-ratio (MOE-parallel/MOE-perpendicular) to estimate PA in the face of three-layer commercial OSB is also discussed.
Oriented Strandboard (OSB) is a versatile engineered material because the orientation of the strands and the shelling ratio (a measure of weight percentage of the face layer) can be easily changed to modify its properties. This paper reports a model investigation on the influence of orientation level of the strands as measured by percent alignment (PA) and shelling ratio (SR) on linear expansion (LE) of OSB. In general, reduction of LE in one direction is achieved at the expense of LE in the other direction. There is, however, an exception. The analysis showed that if PA is equal in both the face and core layers, increasing PA decreases LE in both directions at the same time if SR is around 0.5. This paper also discusses the LE ratio (LE-Perpendicular/LE-Parallel) in relation to PA and SR. The interdependence of PA in the face, PA in the core, and SR is graphically presented for the control of LE ratio. The ramification of incorporating large amount of fines in the core of OSB, a popular practice in the industry, is also discussed.
The primary objective of this project was to develop baseline treatment time data for a hot water bath treatment to meet IPPC phytosanitation regulations for wood packaging material. A second objective was to determine if 100 percent borate penetration could be demonstrated and, if so, the amount of time needed. Pallet-sized material of green red and white oak and yellow-poplar was used. In a worst-case scenario of frozen stringers, the internal temperature requirement was attained on average in 96 minutes. Complete penetration of the borate (as disodium octaborate tetrahydrate-Timbor) was obtained in 24 hours or less.
Amish-made furniture sector maintains its competitiveness during the decline of the US. wood furniture manufacturing industry. Amish-made furniture is an emerging manufacturing sector. More of Amish furniture manufacturers operates at Holmes County, Ohio. It is believed that Amish are only half of the county's population and with 3 percent of Amish employed in the wood sector by 1977, the number increased to 14 percent. Amish furniture sector apply many aspects of competitiveness for the survival of domestic manufacturers with quality craftsmanship and solid wood construction. Amish-made furniture retail stores provides semi-customization, allowing consumers to choose from different species that includes oak, cherry, maple, pine, and walnut. Amish manufacturers presents clustering for short lead times for product customization. Amish manufacturers offers consumers several option on retail floors and enables consumers to buy matching pieces at a later date.
Recycled newsprint (ONP) and dry process aspen fiber were combined with styrene maleic anhydride (SMA) copolymers containing either 7 or 14 percent maleic anhydride. The fiber-filled SMA composites were equivalent or superior to unfilled SMA in strength, stiffness, and notched Izod impact strength. ONP performed surprisingly well as a filler. Unnotched Izod impact strengths for filled polymers were lower than for unfilled polymers. Water sorption was similar among fillers, and was small compared with solid wood.
I.,urnber was sawn Sro~n 150 suppressed-growth ponderosa pine trees, 6 to 16 inches in diameter, harvested near Flagstaff, Arizona. 'l'lris paper presents grade recover and properlies li)r clry 2 by 4's sawn from the logs and graded by a variety of stritclural glading syslerns. Flexural properties met or exceeded those listed in the National Design Specification. When graded as Light Flairling 43 percent of the 2 by 3's made Standard and Better arid as Stmctuial Light Framing, 34 percent made No. 2 and-better. Cb'a~p was the biggest factor limiting grade yield. About 7 percent of the lun~bcr would ~nake a rriachine stress-rated (MSR) lurnber grade of 1450f. bur xith no established market such productio~i is not recomniended. If graded as laminating stock, about 8 percent of the lumber qualified as 1.3 or better. A cornparison of the results froni this study wilh those from a con~paizion study indicates that appearance grades ofl'er the highest vali~e alternative tbl- luinber produced from this resource. Poadams;i pine (PNms po,,rrili,rrta. I..) is ow of the most
This study shows that 1- one-half -inch kiln-dried, surfaced, dimension lumber may shrink in thickness by up to 0. 24 inch. Based on the frequency of occurrence in laboratory tests, these defects can be expected to develop in up to almost 30 percent of each kiln charge. Attention is drawn to the possible adverse effects of these defects on the acceptance of the species group for dimension lumber. More rigorous moisture-content metering is suggested, preferably with an in-line continuous meter, so that wet pockets may be detected.
A high-temperature schedule suitable for drying mixed trembling aspen and balsam poplar, according to grade requirements for maximum moisture content and with acceptably low degrade, was developed in a small laboratory kiln and confirmed in a semicommercial steam kiln. Drying temperatures of 250 degree F dry bulb and 180 degree F wet bulb, with an 18-hour period of high humidity for dissipation of wet pockets, will result in a total drying time of about 96 hours.
Live and Around sawing were compared for the processing of aspen poplar into 1-inch boards and dimension stock. Volume and value yields were obtained from 544 merchantable 8-foot logs. Two types of Live sawing provided lumber and dimension stock yields equal or superior to Around sawing for all log grades.
Both the disadvantages and advantages of aspen pallet lumber are enumerated. The results of tests are presented on the ultimate impact torsional and shear resistance and the torsional rigidity and shear stiffness of aspen pallet deckboard-stringer joints as well as the static stiffness and impact rigidity of 48- by 40-inch aspen pallets.
Some guidelines for the manufacture of aspen particleboard using sulfuric-acid-treated spent sulfite liquor binder were established. The performance of the binder was evaluated against three independent variables: acidity, binder content, and board density. Forty-eight boards were made with binders of 6. 4, 8. 1, 9. 8, and 11. 5 percent acid equivalent, and with 4, 6, 8, and 10 percent binder.
The objective of the pilot study described was to investigate the effects of panel construction and particle size on linear dimensional stability of aspen veneered particleboards. Linear expansion (LE) was measured in both the length and cross panel directions. Minimizing cross panel direction LE of structural type veneered particleboards can be an important consideration in many applications.
Phenolic bonded wafer-type particleboards were made at densities of 38, 43, and 48 lb. /ft. **3 from pure aspen, paper birch, and tamarack and from seven mixtures of the three. Aspen and tamarack were superior raw materials at the lower densities. The strength properties of all mixtures were good for the high-density class.
The schedules are recommended for use in direct-fired kilns having fully automatic cam-control equipment. Using a 20 degree F depression in the initial stages, the vents are held shut keeping the humidity high and the likelihood of degrade low. The schedule also provides for a larger proportion of drying to occur at lower temperatures.
Experimental aspen waferboards, bonded with liquid or powdered phenol-formaldehyde resins and treated by various methods with a wide selection of preservatives, were tested for fungal resistance in accelerated laboratory trials. Mold growth on the surface as well as weight and strength losses due to the actions of decay fungi were determined. Testing of board strength after decay in high and moderate hazard exposure conditions required modification of decay tests used for solid wood. A range of protection was noted with no preservative system exceeding the efficacy of the inorganic salt formulations. Averaged over all treatments, strength loss and weight loss are well correlated.
A method has been developed for straightening 8-foot-long 2- by 4-inch studs of Northern aspen which develop excessive crook during kiln-drying. Studs are steamed for 3 hours, then a load is applied at midlength to deflect them in the direction opposite to their crook, by an amount equal to two to three times the amount of crook. Stress relaxation takes place for a given length of time; then the load is removed, and the studs are allowed to recover. Equations are presented to allow calculation of the time required for stress relaxation when the deflection is arbitrarily selected.
Drying times were greatly reduced for both 1- and 2-inch-thick aspen lumber by predrilling green boards perpendicular to the grain and parallel to the wide drying surface. The uniformity of final moisture content was also significantly improved.
In many parts of the world, efforts are being made to recycle chromated copper arsenate (CCA)-treated materials. While positive steps have been taken to identify CCA-treated lumber in the waste stream, little has been done to find a fast and accurate means to ascertain the level of preservative that exists in the lumber. The ability of the laser induced breakdown spectroscopy (LIBS) technique to determine the level of residual CCA preservative in reclaimed decking was assessed in this experimental pilot study. Control specimens at treatment levels of 0, 2.5, 3.7, 8.5, and 11.8 kg of CCA preservative per m 3 of material (kg/m3) were analyzed to create a series of regression-fitted calibration lines. The most appropriate re gression analysis with data reduction procedures were determined and subsequently used to comparatively predict the level of residual preservative relative to reclaimed decking lumber. Three different deck boards were investigated varying in age from 10, 18, and 25 years, and the remaining amount of preservative in the reclaimed specimens was verified using x-ray fluorescence. The current study revealed that LIBS possesses the potential to measure a threshold value of preservative, so that a reclaimed piece of lumber could be classified for an appropriate application that corresponds to its level of preservative retention. A more in-depth study is warranted to more fully evaluate the LIBS technique with greater certainty.
An aging electricity distribution system and reduced availability of naturally durable tropical hardwoods in Australia will combine in the next decade to produce a major shortage of poles. One approach to mitigating this shortage is to utilize lower durability species and improve the penetration of preservatives into the refractory heartwood by introducing additional pretreatment processes. A potential method for improving preservative penetration in the critical ground-line zone is through-boring. This process, in which holes are drilled through the pole perpendicular to the grain in the ground-line zone, is widely used in the western United States for treatment of Douglas-fir and may be Suitable for many Australian wood species. The potential for improving heartwood penetration in eucalypts with alkaline-copper-quaternary (ACQ) compound was assessed on heartwood specimens from four species (Eucalyptus cloeziana F.Muell., E. grandis W.Hill ex Maiden, E. obliqua L'Her. and E. pellita F.Muell.) and Lophostemon confertus (R.Br.) Peter G.Wilson & J.T.Wateril). Longitudinal ACQ penetration was extremely shallow in L. confertus and only slightly better in E. cloeziana. Longitudinal penetration was good in both E. obliqua and E. pellita, although there was some variation in treatment results with length of pressure period. The results suggest that through-boring might be a reasonable approach for achieving heartwood penetration in some Eucalyptus species, although further studies are required to assess additional treatment schedules and to determine the effects of the process oil flexural properties of the poles.
Laboratory phenol-formaldehyde (PF) bonded waferboards (3% powdered PF) and flakeboards (6% liquid PF) were manufactured from 100 percent healthy balsam fir; 100 percent 3-month, 1-year, and 2-year-dead balsam fir; 100 percent healthy aspen; and from 50-50 percent combinations of aspen with each balsam fir type. Statistical comparisons of strength properties showed that the panels containing the balsam fir raw material types were superior to the 100 percent aspen panels in more cases than they were inferior. In other words, balsam fir, either alive or dead, has definite potential as a complete or supplemental raw material for waferboard and flakeboard.
Bark plays a critical role in the life of a tree when it is standing. Once the tree is felled, however, bark has minimal value and may be a net financial loss to the forest industry. Because of bark’s limited worth, logs are often bought and sold based on under bark measurements. Removing bark in the forest is generally very difficult, so over bark measurements are often made and converted to under bark using a bark thickness model. This study investigated the effect of six bark thickness models on the predicted volume and value recovery obtained during the log bucking process. The results indicate that the type of bark thickness model used is of lesser importance than obtaining the correct model coefficients. This study investigated the effect of using a bark thickness model developed for a different species or using data from the same species but a different site. Using the wrong species coefficients for the chosen model can result in 34 percent of the logs being out-of-specification, volume estimates being incorrect, and a loss of value to the forest owner of up to 11 percent. The results show that, for the stands in this study, 2 to 5 percent value gains could be achieved simply by using stand-specific bark thickness coefficients.
Detailed data on average specific gravities of secondary phloem, outer bark, total bark, and last formed sapwood are presented for seven species; specific gravities of samples were found to differ within some species and also to differ among many of species studied; observations of bark structure showed that specific gravity of secondary phloem by species increases as distribution of sclerenchyma increases.
Tables were prepared to show the relative amount of bark in each of the tree components, the concentration and range of 12 chemical elements in the bark of each tree component, the proportion of each of the chemical elements in the bark of that element in the complete tree, and the proportion of each element in the bark as compared to the wood and bark of the merchantable bole.
The behavior of the subterranean termite Reticulitermes flavipes Kollar (Isoptera: Rhinotermitidae) when applying ultrasonic fields under three single frequencies (100, 500, and 1000 kHz), in order to establish the conditions to create a physical barrier to their action, using 1 by 4 by 10 cm wood stick probes adapted from the European norm EN118. The three frequencies inhibited feeding while the acoustic field was kept active, with a lesser feeding rate at 500 kHz, and a greater mortality at 1000 kHz. These results demonstrate that ultrasound affects the physiology and behavior of R. flavipes.
Wormholes, stain, and decay in fire-damaged and fire-killed trees are causing rapid loss of value, and, to a lesser extent, volume when processed into wood products. Ponderosa pine trees killed in the Warner Mountain fire (southern Oregon) were found to be infested with wood-boring insects that were causing large amounts of massed wormholes and associated blue stain fungi as soon as 3 months after the fire. A sawmill recovery study was conducted on 44 control logs and 119 "wormy" logs ranging in small-end diameter from 6 to 37 in (15 to 94 cm) to determine if there was any measurable merchantable volume loss in the fire-killed trees as a result of massed wormholes. No lumber volume was lost owing to worm-generated defect. Both the control and wormy logs averaged 78 percent in green cubic volume recovery. There was a significant drop in average value of $258/MBF lumber tally (2005 prices) from the control to the wormy log sample. In this study, value loss occurred primarily because of the presence of blue stain in lumber that would otherwise have produced the higher value Factory grades (e.g., Shop, Moulding). Almost 80 percent of the lumber volume sawn from the control logs was in the higher value Factory grades whereas only 17 percent of the lumber from wormy logs received these grades. About 52 percent of the lumber produced from wormy logs was graded as lower value Dimension lumber as compared to 18 percent of the control being assigned under that grading system. Value loss increased with log diameter. The primary recommendation from these results is that loss should be handled in the valuation (appraisal) process rather than the measurement (scaling) process.
An early focus on structural use of processed rather than round timber resulted in an underestimation of the structural advantages of retaining the natural form of small-diameter round timber. In the round and tapered form, timbers are not susceptible to the strength-reducing effects of diving grain and exposed juvenile wood. Fiber continuity around knots on the surface of a debarked log rarely exhibits the stress concentration and fracture propagation commonly seen in disrupted grain around knots in lumber. Symmetry of material properties about the centroidal axis in a round timber improves the efficacy of standard section property equations derived for uniform isotropic materials. Ignoring these benefits and comparing the strength of round and processed timbers solely on the basis of section property, the round section has from two to four times the bending load design capacity of any standard-sized processed timber that could be sawn from it.
This study investigated fatigue strength properties of T-type, two-pin moment-resisting dowel joints subjected to constant and stepped cyclic bending loads. Red oak, yellow-poplar, plywood, aspen Engineered Strand Lumber (ESL), and particleboard were tested in the construction of joints. Regression of M-N data (moment versus log number of cycles to failure) of each joint material type subjected to constant cyclic bending loads resulted in linear equations for M-N curves. Fatigue life of dowel joints subjected to a given stepped cyclic bending schedule can be predicted with the Palmgren-Miner rule based on their M-N curves. Joints constructed of particleboard had significantly lower fatigue life than joints of red oak, yellow-poplar, plywood, and ESL. No evidence of significant differences existed in fatigue life among joints constructed of red oak, yellow-poplar, plywood, and ESL, but results of static bending tests showed significant differences in bending strength among them. Joint resistance to fatigue failure should be taken into account in strength design of furniture frames that are subjected to repeated loading.
A quantitative model is presented for evaluating the effects of incising on the bending strength and stiffness of structural dimension lumber. This model is based on the premise that bending strength and stiffness are reduced when lumber is incised, and the extent of this reduction is related to the reduction in moment of inertia of the bending members. Measurements of voids and damage caused by incisor teeth showed that actual incision depth was not always equal to nominal depth. For lumber with 660 incisions/ft2, the actual depth of the incisions was approximately equal to the targeted nominal depth. However, for lumber with 800 incisions/ft2, the actual depth of the incisions was approximately 65 percent of the targeted nominal depth. The amount of damaged wood below the incision was found to extend 1.38 to 2.18 times the depth of the void left by the incising process. Using these data as input, the reduced moment of inertia model predicted lumber bending strength loss resulting from incising to within 7 percent accuracy, on average. To predict lumber bending stiffness loss resulting from incising, a complementary virtual work method was used, which resulted in predictions that were accurate to within 1 percent, on average. It was then showed that bending strength and stiffness losses can be calculated for lumber of various sizes. Currently, the National Design Specification (NDS) publishes a single reduction factor for bending strength, which is applied to all sizes of structural lumber and to all incising densities, up to the maximum allowed. This factor is overly conservative for large members and does not account for various types of incisor tooth dimensions and incision densities. The reduced section modulus model presented here would provide the much needed adjustment to current NDS incising factors.
The purpose of this study was to determine the effects of two press-drying treatments on the static bending properties of plantation-grown, No. 2 grade, 2 by 4 loblolly pine lumber. Specimens were divided into groups containing primarily juvenile wood or primarily mature wood. The groups were subjected to three drying method-temperature/pressure combinations: (1) kiln-drying at 116 degrees C (240 degrees), (2) press-drying at 172 or 345 kPa (25 or 50 psi), and (3) press-drying at 177 or 210 degrees C (350 or 410 degrees). Modulus of rupture (MOR), modulus of elasticity (MOE), work to maximum load (WML), and specific gravity (SG) were determined. The results showed no change in SG in relationship to press-dry treatment and no practical differences in both MOE and MOR between press-dried and kiln-dried specimens. The only significant change was a decrease in work to maximum load with press-drying at 345 kPa and 210 degrees C (50 psi and 410 degrees), which was detectable only in the higher quality pieces. The results suggest that loblolly pine properties are far more affected by the presence of juvenile wood and the inherent defects associated with the No. 2 grade than by press-dry treatment. Further work is needed to determine the influence of press-drying on the SG of full-size lumber. We expect that any effects will be most noticeable in higher quality pieces.
Extensive biomass resources exist throughout the Western United States, and estimates vary depending on land ownership, size distribution of biomass, accessibility of biomass, and frequency of harvesting or thinning operations. The Western Governor's Association has adopted a resolution to examine the feasibility of developing 30 gigawatts of clean and diverse energy by 2015, of which half is believed to have been obtained from biomass. The National fire Plan (NFP) was developed in August 2000 with the aim of actively responding to severe wildland fires and their impacts to communities while ensuring sufficient firefighting capacity for the future. Other federal initiatives to stimulate biomass utilization includes The Healthy Forest Restoration Act (HFRA) of 2003, where a framework is provided to improve the structure and health of overstocked, small-diameter stands while reducing the complexity of environmental analysis.
The paper surveys federal research concerned with developing fuels from
biomass. Biomass production studies deal with the growing, harvesting,
and collection of agricultural, feedlot, and forestry residues. Biomass
conversion procedures involve biological techniques (aerobic digestion,
acid hydrolysis, enzyme hydrolysis, biophysics) and thermochemical
techniques (pyrolysis and hydrogasification) as well as direct
combustion. Field crops and tree crops considered potential feedstocks
for conversion to fuels are listed. The use of kelp is examined. Waste
utilization, which could involve manure, agricultural crop and food
wastes, logging and wood manufacturing residues, or urban solid wastes,
is discussed. The research and development implementation strategy is
described with attention to research categorization and the scheduling
of research projects.
Exciting new opportunities are emerging for sustainably meeting many global energy needs and simultaneously creating high-value bio-based consumer and construction products from wood, forest and agricultural residues, and other bio-based materials. In addition to traditional value-added bio-based products, such as lumber, paper, paperboard, and composites, opportunities are now on the horizon for biorefining to produce electricity, transportation fuels, chemical feedstocks, syngas, and nanocrystalline cellulose. In the near future, nanocrystalline cellulose, produced as a high-value by-product from the blorefining process, could likely compete with carbon fiber for use in innovative high-strength biocomposites. The holistic view of how to achieve both traditional and new high-value materials with enhanced performance properties from renewable resources Is called Integrated Biomass Technologies. This concept promotes the use of sustainable, bio-based, environmentally neutral (or even beneficial) technologies to meet global demands for building and materials end uses, chemicals, and energy. This concept provides a systematic approach for maximizing value, performance, resource sustainability, and improving profitability in the agriculture and forest products industries.
Particleboard and flakeboard panels were fabricated from remediated CCA-treated southern yellow pine. Treated wood, flaked or comminuted into particles, was remediated in 12-kg batches using oxalic acid extraction, followed by bioleaching with the metal-tolerant bacterium Bacillus licheniformis. Remediation resulted in removal of 80 percent Cu, 71 percent Cr, and 89 percent As for the particulate material and 83 percent Cu, 86 percent Cr, and 95 percent As for the flaked material. Particleboard and flakeboard panels were evaluated for modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond (IB) strength. Particleboard made from remediated material with 10 percent urea-formaldehyde resin showed an 18 percent reduction in MOE, 47 percent reduction in MOR, and 37 percent reduction in IB strength compared to comparable panels made from untreated wood. Flakeboard prepared from remediated material with 5 percent phenol-formaldehyde resin showed insignificant differences in MOE and MOR, and a 16 percent increase in IB strength compared to panels consisting of untreated wood. Properties of remediated particleboard were significantly diminished compared to those of panels made with untreated wood. MOR and MOE of remediated flakeboard were comparable to that of untreated material, but IB strength was increased. Flake geometry and type of resin, as well as differences in surface area and metal removal between the two wood geometries, may all account for variations in panel properties.
This study examined the effects of a compatibilizer on the wettability of birch plywood and polyolefins. The compatabilizer was a low molecular weight emulsion type maleated polypropylene (MAPP), Epolene E-43. The polyolefins investigated included low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and polypropylene (PP). For E-43 treated wood surfaces, contact angles among four wetting liquids were in the order of phenol formaldehyde (PF) > urea formaldehyde (UF) > isocyanate (ISO) > distilled water. Contact angles increased upon addition of E-43, then decreased as concentrations further increased for UF, PF, and ISO. Among the three polyolefin polymers, the contact angles of PP, either wetting with various concentration of E-43 or with various wetting liquids, showed the highest value but was less sensitive to changes in E-43 concentration. For all four wetting liquids, their contact angle ratings for different plastic types all followed the sequences of PP > LLDPE > LDPE and distilled water > UF > PF > ISO.