Treesearch

The goal of this research was to develop nondestructive evaluation (NDE) technology to enhance mechanical stress rating of lumber. An ultrasonic NDE technique was developed that is sensitive to grain angle and edge knots in lumber - two primary determinants of lumber strength. The presence of edge knots increased the acoustic wave travel time and selectively attenuated the higher frequency ultrasonic energy. NDE measurements and tension tests were performed on 200 pieces of nominal 50 × 150 mm Southern Pine lumber. Statistical models were developed from localized stress wave indices to...

In studies on wood strength, researchers sometimes replace experimental unit allocation via random sampling with allocation via sorts based on nondestructive measurements of strength predictors such as modulus of elasticity and specific gravity. This report documents TT, a computer program that implements recently published methods to increase the sensitivity of such bpredictor sortc experiments. The report consists of annotated keyboard sessions and computer output from runs of TT.

The presentations at this symposium discussed concepts of ecosystem management and sustainability as viewed by various levels of government and private land managers. The theme was to integrate ecology, silviculture, forest operations, wood products, and economics to find ways to develop healthy sustainable ecosystems under financially sound management practices. Speakers discussed ways to manage disturbance to create landscapes with the desired level of diversity and resilience to fire, disease, and insects. Others identified technical aspects of improving the options for producing wood...

This report describes 52 taxa of North American softwoods, which are organized alphabetically by genus. Descriptions include scientific name, trade name, distribution, tree characteristics, wood characteristics (e.g., general, weight, mechanical properties, drying, shrinkage, working properties, durability, preservation, uses, and toxicity), and additional sources of information. Data were compiled from existing literature, mostly from research done at the U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, Wisconsin.

Structural and nonstructural panels have been the fastest growing sector among wood products for the past two decades. The recent spate of plant construction and drop in product prices indicate slower growth and consolidation in the next 2 years. Growth in demand is unlikely to catch up with projected capacities until the next century, unless attrition of some existing capacity reduces industry growth. Among structural panels, costs of production are lowest for oriented strandboard, but there is a wide range among plants. Plywood costs are lowest in the U.S. South and highest in the West....

Longitudinal stress wave and transverse vibration nondestructive testing (NDT) techniques have proven to be accurate means of evaluating the quality of wood based products. Researchers have found strong relationships between stress wave and transverse vibration parameters (e.g., wave velocity and modulus of elasticity predicted using NDT measurements) with the actual static bending properties (e.g., modulus of elasticity from static bending tests) of d y as well as green wood based materials. Therefore, these techniques may be used to presort or grade structural wood prior to drying,...

The numerical solution to the frequency equation for the transverse vibration of a simple beam with symmetric overhang is found. The numerical results converge to the analytical solutions for the two limiting cases of a beam with no overhang and a beam with no span and agree with the case in which the supports are at the nodal points of a freely vibrating beam. An approximation to the solution of the frequency equation for beams with small overhang is presented and compared to the numerical solution. This simple yet accurate approximation is most useful to determine a beamas flexural...

This study reviewed the literature on experimental and analytical research for the connection of wood members using multiple laterally loaded bolts. From this, the influence of geometric factors were ascertained, such as staggered and aligned fasteners, optimum fastener configurations, row factors and length-to-diameter bolt ratios, spacing, end and edge distances, and the effect of mixed types and sizes of fasteners and eccentric loading. Areas of additional research needed on multiple-bolted joints in wood members are identified.

Wood-plastic composites are becoming more important as a material that fulfills recycling needs. In this study, fire performance tests were conducted on several compositions of wood and plastic materials using the Ohio State University rate of heat release apparatus. Test results included five-minute average heat release rate in kW/m2 (HRR avg) and maximum heat release rate in kW/m2 (HRR max). As expected, the general trend was an increase in the values of HRR avg and HRR max with increasing concentrations of polypropylene or high density polyethylene.

The repair and remodeling of residential units in the existing housing stock is an important market for wood products. Included are many, and varied repair and remodeling activities and projects, some of which require substantial amounts of wood products, some of which do not. Currently, about 24 percent of all lumber, 23 percent of all structural panels, 15 percent of all nonstructural panels, and lesser amounts of engineered wood products consumed in the United States are used for residential repair and remodeling. This market has become much more important in recent years as the...