Treesearch

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...

“This report presents curves of coefficients and formulas for use in calculating the buckling of flat panels of sandwich construction under edgewise compressive loads. The curves were derived for sandwich panels having one facing of either of two orthotropic materials, the other facing of an isotropic material; both facings of orthotropic material; both facings of isotropic material; and cores of orthotropic or isotropic material. Parameters are chosen so that facings may be of different thicknesses and so that isotropic facings can also be of different isotropic materials. Curves were...

A major loss sustained by small mills results from inaccurately cut lumber. Such lumber sells only at reduced prices and encounters stiffer sales resistance than lumber from the more accurately cutting band mills. A less apparent loss is the excessive loss of material that results from inaccurate cutting.

Veneer, plywood, and flakeboard specimens were subjected to various humidity conditions. Physical and elastic properties of the veneer were determined and the influence of these properties on the movement of plywood and flakeboards fabricated of like material was evaluated, The linear movement of the plywood and flakeboards was closely related to the longitudinal-to-grain movement of the veneer.

Experimental work was undertaken to investigate the extent and magnitude of deterioration that can occur in typical plywood-to-lumber glue joints subjected to stresses resulting from changes in the moisture content of the wood, and to compare the performance of a somewhat flexible or deformable adhesive to that of a rigid adhesive in these joints. Results showed that the degradation of lumber-to-plywood joints can be very severe as a result of one cycle from 80° F. and 30 percent relative humidity, to 80° F. and 97 percent relative humidity, returning to a low moisture condition. Failure...

From the earliest days of exploration and colonization in tropical America, Spanish-cedar has been one of the most important timber trees of the area. The wood became an article for the export trade during the 1800’s when the cigar industry demanded the use of Spanish-cedar for packing cigars. These fragrant boxes were commonplace before rising costs in the 1930’s finally forced the cigar industry to turn to paperboard or less expensive containers manufactured from soft native lumber. Spanish-cedar remains to this day as one of the most valued trees for local use in Latin America. In the...

Shrinkage, specific gravity, and hardness of two shipments of silk-oak (Grevillea robusta) from Hawaii were evaluated to provide basic information pertinent to the use of the wood for cabinet and furniture purposes. The wood resembles Hawaii-grown shamel ash (Fraxinus uhdei ) in the properties evaluated. Shrinkage compares well with that of black cherry, silver maple, or red lauan. Side hardness of green wood considerably exceeds that of black cherry and paper birch, but that of air-dry wood is closely comparable to that of those two Mainland species. End hardness of green wood compares...

Tear tests made on low-finish bond paper and a 42-pound linerboard showed that the tear resistance, the degree of spreading of the plies, and the deviation from a straight line of failure increased with the increase in the number of plies tested. Tests on plies of aluminum foil indicated this degree of variation due to multiplicity of plies lay not in the tester but in the type of material being tested. With foil, no increase in tear resistance per ply accompanied the increase in the number of plies tested. But when the aluminum foil plies were separated by bulking and tested, results...