Wood and Fiber Science (E-Journal)
Not a member yet
2592 research outputs found
Sort by
A Lean Logistics Framework: A Case Study in the Wood Fiber Supply Chain
Full text linkThere are opportunities for improvement within the wood fiber supply chain. A significant amount of these opportunities are related to waste reduction. The body of literature focuses on what are the causes of waste and supply chain inefficiency. Conclusions suggest this is partially due to improper supply chain management and collaboration. There is a gap within the research regarding applications of lean tools in the wood fiber supply chain, especially tools that help suppliers and consumers work together to reduce waste. A value stream map (VSM) tool that focused on identifying lean waste in logistic operations was developed and applied. The VSM for the paper mill case study includes three processes: supplier, transportation to the wood yard, and receiving operations at the wood yard (consumer mill). Once the tool was applied, the following cost reductions were projected: the inbound logistics cost was reduced from 2.3 million and the inventory carrying cost was reduced from 79,600 annually. The possible annual savings reported totaled $320,000 approximately by the introduction of lean principles that reduce the waste in transportation and carrying cost.
TECHNICAL NOTE: POSITIVE EFFECTS OF DOUBLE-SIDED PROFILING ON THE CUPPING AND CHECKING OF ACQ-TREATED DOUGLAS FIR, WESTERN HEMLOCK AND WHITE SPRUCE DECKBOARDS EXPOSED TO NATURAL WEATHERING
Full text linkMachining grooves into the upper surface of wooden deckboards reduces undesirable checking that develops when deckboards are exposed to weather. But profiled boards cup more than unprofiled boards. We sought a solution to this problem and hypothesized that profiling both sides of boards would reduce the cupping of profiled boards. We tested the effects of profile type (Flat, single-, and double-sided profiles) and growth ring orientation (concave vs convex) on the cupping and checking of alkaline copper quaternary-treated deckboards made from Douglas fir, western hemlock, and white spruce. There were significant differences in the cupping of deckboards made from the three different wood species (Douglas fir<white spruce<western hemlock), and boards with concave growth ring orientations cupped significantly less than boards with convex growth ring orientations. Most importantly, our results show that double-sided profiling reduces the cupping of deckboards, irrespective of wood species, and growth ring orientations of deckboards. Double-sided profiling also significantly reduced checking of deckboards exposed to the weather. We conclude that profiling the underside or profiled deckboards to create a “balance” double-sided board is a simple solution to the problem of increased cupping that develops when profiled (single-sided) softwood deckboards are exposed to weather
DISTRIBUTIONS OF MOE AND MOR IN EIGHT MILL-RUN LUMBER POPULATIONS (FOUR MILLS AT TWO TIMES)
Full text linkTo evaluate the reliability of lumber structures, good models for the strength and stiffness distributions of visual and machine stress-rated (MSR) grades of lumber are necessary. Verrill and coworkers established theoretically and empirically that the strength properties of visual and MSR grades of lumber are not distributed as 2-parameter Weibulls. Instead, strength properties of grades of lumber must have “pseudo-truncated” distributions. To properly implement the pseudo-truncation theory (to correctly estimate the MOR and MOE distributions of graded subpopulations), one must know the MOE and MOR distributions of full (“mill-run”) lumber populations. Owens and coworkers investigated the mill-run distributions of MOE and MOR at each of four mills. They found that univariate mill-run MOE and MOR distributions are well-modeled by skew normal distributions or mixtures of normal distributions but not so well modeled by normal, lognormal, 2-parameter Weibull, or 3-parameter Weibull distributions. They noted that it was important to investigate whether these results were stable over time. In this article, to investigate stability over time, the authors extend the analyses of “summer” data sets performed by Owens et al to new mill-run “winter” data sets. The results show that normal, lognormal, 2-parameter Weibull and 3-parameter Weibull distributions continue to perform relatively poorly, and that skew normal distributions and mixtures of normal distributions continue to perform relatively well
DECAY OF BIRDSEYE SUGAR MAPLE (ACER SACCHARUM) AND CURLY RED MAPLE (ACER RUBRUM) FIGURED WOODS
Full text linkTwo figured woods, commonly known as birdseye maple (Acer saccharum, sugar maple) and curly maple (Acer rubrum, red maple), were exposed to brown rot and white rot fungi in a standard laboratory decay test and compared with unfigured wood of each species, respectively. For the birdseye maple, two levels of figure intensity were used: wood with heavy figure and wood with light figure. Heavily figured birdseye maple wood was decayed significantly less by the brown rot fungus Rhodonia placenta than unfigured maple wood or lightly figured maple wood. However, heavily figured birdseye maple wood was decayed significantly more by two white rot fungi, Trametes versicolor and Irpex lacteus, than unfigured maple wood but was not decayed significantly more than lightly figured wood. For both brown rot and white rot fungi, lightly figured birdseye maple wood did not decay significantly differently compared with unfigured wood. Likewise, there was no significant difference in decay between curly red maple wood and unfigured red maple wood for either brown rot or white rot fungi. Results suggest chemical or anatomical differences in the heavily figured birdseye sugar maple wood affect decay by brown rot and white rot fungi. These findings may be useful to hobbyists and woodworkers needing to protect wood or who partially decay wood to produce spalted wood for decorative purposes
AN EXPERIMENTAL STUDY ON FLEXURAL BEHAVIOR OF GLULAM BEAMS MADE OUT OF THERMALLY TREATED FAST-GROWING POPLAR LAMINAE
Full text linkIn this study, to improve the structural applications of glued laminated timber (glulam) in high RH environment according to its relatively lower MOE, fast-growing poplar laminae with a thickness of 35 mm were thermally treated at 20oC for 3.5 h. The effects of thermal treatment and RH in the surrounding environment on laminae strength class was conducted. Afterward, 12 full-scale same-grade composition glulam beams made out of untreated and thermally treated poplar laminae were prepared. The four-point bending tests were conducted to reveal the effects of laminae thermal treatment and RH in the surrounding environment on flexural properties of glulam beams with a span-depth ratio of 18. The results showed that the strength class of fast-growing poplar laminae was negatively related to RH in the surrounding condition, and thermal treatment can contribute to the increase in strength class. In 90% RH, strength class increased from untreated laminae ME7 to the heat-treated ME10, according to China standard. The relationship between bending properties of glulam beams and RH in the surrounding environment was negatively correlated, as well as thermal treatment, whereas MOE was improved significantly after thermally pretreated, especially in high RH. In 90% RH, MOE of glulam beams made of thermally pretreated laminae was 29.57% higher than the untreated beams with an MOR reduction of 8.82%. The results of characteristic load-deformation curves, characteristic load-strain curves, average extreme fiber strain, and the failure mode can support each other in this study. Industrial thermal treatment technology to laminae improved the MOE of glulam beams significantly in high RH with a reduction in MOR, and glulam beam made out of thermally treated fast-growing poplar laminae can be used in construction, but need checking in MOR or be used for a limited range of structural elements
Response of Self-Centering Mass Plywood Panel Shear Walls
Full text linkThe rocking behavior of self-centering mass plywood panel (MPP) walls was investigated with and without the use of supplementary energy dissipation systems. Two energy dissipation systems were tested. The first system used a kinematically expanding hysteretic damper (KE-HD), whereas the second system used slip friction connections (SFCs). The reviewed energy dissipating systems were used in a self-centering system comprising one unbonded posttensioned (PT) hold-down rod on each side of the MPP walls. The cyclic performance of the PT and the hybrid MPP specimens was investigated through a series of full-scale quasi-static cyclic tests. The test results demonstrated the viability of the investigated energy dissipaters in self-centering MPP rocking systems. Results further indicate that hybrid specimens with SFC dissipate more energy and provide higher strength than those with KE-HDs, however, with higher residual drift.
Salt Damage in Wood: Controlled Laboratory Exposures and Mechanical Property Measurements
Full text linkSalt damage in wood can be recognized by its stringy appearance and is frequently observed in wood used in maritime structures and buildings built near the ocean. Whereas salt-damaged wood is common, little is known about the mechanism by which salt water alters the wood structure. There is no information on the effects of salt damage on the mechanical properties of wood. In this study, a laboratory method for creating salt damage in other porous materials was applied to wood. Wood pillars were placed in a reservoir of 5 M NaCl and exposed to a 40% RH environment. Capillary action pulled the salt water to the upper part of the pillars which were dry. Large deposits of effloresced salts were observed. The changes in mechanical properties caused by the salt were measured by the high-energy multiple impact (HEMI) test. Salt damage caused a reduction in the resistance to impact milling (RIM) of 6.5%, and it was concluded that salt damage causes only minor effects on the strength of wood. The tests were not conclusive as the exact mechanism of salt damage in treated wood. However, diffusion of mineral ions through the cell wall was found to be a key step in the salt damage mechanism
Acoustic wave propagation in standing trees - Part 1. Numerical simulation
Full text linkThe use of acoustic waves for assessing wood properties in standing trees has been investigated extensively in recent years. Most studies were experimental in nature and limited to direct measurement of wave velocities in trees using a time-of-flight (TOF) method. How acoustic waves propagate in a tree trunk and how tree diameter, species, stand age, and juvenile wood affect wave propagation behavior in standing trees are not well understood. In this study, we examined propagation patterns of acoustic waves in a virtual tree trunk through numerical simulation using COMSOL Multiphysics® software (COMSOL, Inc., Burlington, MA). The simulation was based on the elastic theory of a solid medium with the assumption of an orthotropic material for a standing tree. Extensive acoustic measurements were conducted on green larch log samples to validate the simulation results. Our results showed that the wave front maps of the tree model from numerical simulations were consistent with those obtained through TOF measurements of the log samples, indicating that the simulation results were accurate and reliable. Wave propagation patterns of the tree model revealed that the side surface-generated acoustic wave expanded as a dilatational wave within a 0-to 1.2m transit distance, as the wave moved up along the tree model, the shape of the wave front gradually flattened and the wave eventually transformed into a quasi-plane wave from a 2.4-m transit distance