Treesearch

Flakeboards made with uniform densities throughout their thickness and different degrees of flake alignment were used to establish relationships between bending, tension, and compression values of modulus of elasticity or modulus of rupture (or stress to maximum load) and the variables of specific gravity and flake alignment. An equation using sonic velocity as an indicator of alignment was developed that describes the relations over a broad range with a high degree of confidence. Bending stiffness of boards having a density gradient were predicted within approximately ± 20% using the...

A simple and durable exterior natural finish developed at the Forest Products Laboratory is described. The finish is classified as a semi-transparent oil-base penetrating stain that effectively retains much of the natural grain and texture of wood when exposed to the weather. The directions for preparation are included as are the recommendations for application to both smooth and rough wood surfaces.

The applicability of using the oxygen index test (ASTM D 2863-76) to obtain an indication of the relative flammability of fire-retardant- treated wood products was investigated. The oxygen index is the minimum percentage oxygen that is required to maintain flaming combustion of a specimen under specified laboratory conditions. Within the plastics industry, the test is used in research and development and in quality control. Since the oxygen index test offers a single numerical value and requires relatively small specimens, it was desirable to determine its applicability to wood products....

Crossties were made by the Press-Lam process, in which logs are peeled into veneers, dried, and glued into billets in a continuous procedure. Billets were made from 8.5-foot-long veneers and from 4-foot-long veneers, cut into final product dimensions, and treated with preservative. In laboratory tests, bending strength and stiffness of the Press-Lam ties were found to exceed those of solid- sawn red oak crossties; shear strength was only adequate. Tie wear tests showed low surface wear for laminated ties, comparable to the performance of solid specimens. Results of spike driving tests,...

This report presents information needed for design and construction of energy-efficient light-frame wood structures. The opening section discusses improving the thermal performance of a house by careful planning and design. A second section of the report provides technical information on the thermal properties of construction materials, and on the basic engineering design principles applicable to light-frame wood structures. Moisture condensation problems are discussed in relation to the effects of increased building insulation and more effective air leakage control.

A model of present-day computer-controlled sawmilling technology is modified for the manufacture of any desired width of EGAR dimension lumber from small logs. EGAR lumber is manufactured via headrig production of 2-inch-thick flitches which are in turn dried, edged full width, edge-glued, and gang-novelty-ripped to wide widths (EGAR). The EGAR system is compared to the unmodified version of the same computer-controlled sawmill. Both systems appear to be good investment opportunities; however, the 12 to 13 percent increase in lumber recovery gained by the EGAR system does not justify the...

Determining optimum distribution of fiber through rational design of corrugated fiberboard could result in significant reductions in fiber required to meet end-use conditions, with subsequent reductions in price pressure and extension of the softwood timber supply. A theory of thin plates under large deformations is developed that is both kinematically and physically nonlinear. This theory is used to analyze the strength of a singlewall fiberboard element which modeled as a composite plate structure. Either an elastic-type instability or a compression failure mode is allowed. The results...

The effects of water soaking on the bending strength and stiffness of laminated timber were determined by deriving wet-dry ratios for these properties. Values for these ratios, when compared to currently recommended wet use factors, confirm the value now used for modulus of rupture. For modulus of elasticity, the reduction due to water soaking was found to be less than that now recommended. Results will be useful to organizations preparing design standards for heavy timbers subject to potentially high moisture contents.

Procedures have been recommended–such as in the National Design Specification–for design of bolted joints in wood members where the side members are thicker or thinner than half the main member thickness. However, these recommendations have had no experimental verification up to now. The same is true for joints with other than three members. This study experimentally verified present rules for handling three-member and multiple-member joints, but found that present rules for two-member joints were inadequate.

Achrouteria pomifera Eyma, the sole representative of the genus for almost 40 years, is distinguished from the world Sapotaceae by the very large silica particles which occur in the wood rays. Anatomically, two groups (species) may be distinguished on the basis of vessel member length and parenchyma seriation. A second species, A. durifructa described in 1974, differs significantly in several respects and may have been doubtfully placed in this genus.