Treesearch

This note presents theoretical analyses for determination of dimensions of structural sandwich of minimum weight that will have certain stiffness and load-carrying capabilities. Included is a brief discussion of the resultant minimum weight configurations.

This report gives information on the edgewise modulus of elasticity, stiffness, and shrinkage of 360 joists in three species, three grades, and two sizes, each species obtained from two sources. Each joist was evaluated nondestructively at four moisture content values ranging from the green condition to about 11 percent. Information is also given on specific gravity, strength ratio, hardness, and direction of the annual rings. The work showed a relation of modulus of elasticity to grade, with the highest grades having about the same value as that for clear wood. Increases of about 14...

This report summarizes the main points considered and the conclusions reached during the Symposium on Nondestructive Testing, October 7 to 9, 1963, at the Forest Products Laboratory. The purpose of this symposium was to bring research and industry leaders together to examine what is being done in nondestructive testing and discuss its applications to the wood products industries. Some 100 scientists, engineers, and industry leaders heard and discussed the possibilities of a wide range of scientific means for testing wood nondestructively--that is, without impairing the usefulness of the...

Nepal alder (Alnus nepalensis ) grown in Hawaii was evaluated for shrinkage, strength in bending, and hardness. This Hawaii-grown wood was comparable in bending strength to wood of the same species grown in Bengal, India, but was lower in modulus of elasticity and exhibited greater hardness and shrinkage. It was also harder than such Mainland species as aspen (Populus tremuloides ) and ponderosa pine (Pinus ponderosa) but softer than red alder (Alnus rubra). It was comparable in bending strength to aspen but was somewhat lower in modulus of elasticity. Shrinkage in radial and tangential...

During recent years considerable research and development work have been done on high-strength, durable adhesives for use in bonding metals. Much of this is also applicable for gluing wood to metal. The woodworking adhesives, such as animal, vegetable, casein, urea resin, phenol resin, and resorcinol resin, have not been found entirely suitable for this purpose. They usually are not elastic enough to distribute the stresses encountered in service when two dissimilar materials, such as wood and metal, are bonded together. Also, they generally do not adhere well to the surfaces of metals....

Various chemical treatments have been investigated at the Forest Products Laboratory for improving the compressive strength of linerboard exposed at high humidities and after water-soaking. Phenolic resins have been among the more promising chemicals studied, but they vary in performance. The low-condensed water-soluble phenolic resins have given some of the highest compressive strengths, but generally caused more embrittlement of the board, as noted by low tearing resistance and folding endurance. The medium-condensed phenolic resins gave only moderate increases in compressive strength...

This report discusses the screening of various adhesive and mastic systems for possible use in assembling lightweight wood containers. Results showed that dynamic tests of simulated box corners correlated reasonably well with rough handling evaluations of eight selected systems when used to assemble lightweight wood boxes made from a Group I container wood. Conventionally nailed specimens were used as the control. The impact tests, as well as the rough handling tests, showed that a system should exhibit a certain degree of resilience. Diagonal compression tests indicated that a system...

Evaluations of several mechanical and physical properties were conducted on specimens from five yagrumo hembra (Cecropia peltata) trees from Puerto Rico. With the exception of toughness and modulus of elasticity in both bending and compression parallel to grain, these specimens were lower in specific gravity and in strength properties than material reported previously. Although the specific gravity of the new material averaged about twice that of balsa, a wide range of specific gravity was evident and material at the lower part of the range could possibly be used as a substitute for balsa....

Angelique has for many years been incorrectly identified with the botanical name Dicorynia paraensis Benth. It differs from this species and from other described species of Dicorynia in the structure of the flowers and its restricted range of growth. Presently known as Dicorynia guianensis, angelique occurs only in French Guiana and Surinam. Dicorynia paraensis occurs along the Rio Negro and its tributaries in Brazil's Amazonas Territory. Aside from angelique, or basra locus as it is also known, the characteristics and properties of the various Dicorynia species are practically unknown at...

Methods of obtaining strength and elastic properties of plastic laminates reinforced with unwoven glass fibers were evaluated using the criteria of the strength values obtained and the failure characteristics observed. Variables investigated were specimen configuration and the manner of supporting and loading the specimens. Results of this investigation indicate that satisfactory tensile failures can be obtained by reinforcing the shank portion of the tension specimen with 1/32-inch sheet aluminum. Variation of tensile specimen geometry was inconclusive, with at least partial failures...