Accession Number : AD0668487

Title :   DYNAMIC PROPERTIES OF SMALL, CLEAR SPECIMENS OF STRUCTURAL-GRADE TIMBER.

Descriptive Note : Technical rept. 1 Jul 65-30 Jun 67,

Corporate Author : NAVAL CIVIL ENGINEERING LAB PORT HUENEME CALIF

Personal Author(s) : Keeton,John R.

Report Date : APR 1968

Pagination or Media Count : 64

Abstract : About 300 static and 1,100 dynamic tests were made on small, clear specimens of Douglas fir (coast type). Green specimens and dry specimens were tested in shear parallel to the grain, bending, compression parallel to the grain, and compression perpendicular to the grain. Green specimens showed increases in dynamic strength values over static strength values, with the exception of modulus of elasticity in bending. Dry specimens showed increases in dynamic strengths over static strengths in shear, compression parallel to the grain, and compression perpendicular to the grain. In bending, the strength of dry specimens was drastically reduced at the higher rates of dynamic loading. In bending tests on green specimens, the modulus of rupture at speeds (or strain rates) corresponding to impact and blast loading was a maximum of 54% greater than the MOR at static speeds. On the basis of these results, it was concluded that conventional increased strength allowances for impact loading are excessive by as much as 46%. (Author)

Descriptors :   (*WOOD, MECHANICAL PROPERTIES), BENDING, MODULUS OF ELASTICITY, SHEAR STRESSES, COMPRESSIVE PROPERTIES, LOADS(FORCES), IMPACT SHOCK, FLEXURAL STRENGTH, TREES, DRYING, STRUCTURAL PROPERTIES, THICKNESS, STANDARDS, CLASSIFICATION, TABLES(DATA), RUPTURE, TEST METHODS, SPECIFICATIONS

Subject Categories : Forestry
      Wood, Paper and Related Forestry Products
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE