Tensile Strength Properties of Tropical Hardwoods in Structural Size Testing
In Malaysia, there is no research done on the tensile strength of structural size timber. The tension stress found in the Malaysian code of practice, MS 544: Part 2: 2001, was not determined directly and it was taken as 60% of the bending strength values of small clear specimens. This paper presents the results of the tensile test on structural size timber specimens from selected Malaysian Tropical hardwoods namely Kedondong (Canarium spp), Keruing (Dipterocarpus spp) and Bintangor (Calophyllum spp) under the strength group SG5. A special tensile grip was fabricated using the model suggested in ASTM D198 and the tests were also conducted according to ASTM D198. The tensile strength characteristics evaluated include tensile strength, modulus of elasticity and Poisson’s ratio, and the data were analyzed statistically. In this study it was found that the grade stresses for structural size specimens were higher than that published in the Malaysian code of practice. Index Term— tensile strength, structural size, Malaysian
Mechanics and Rheology of Wood
Elasticity means that deformations produced in a solid body by low stresses are completely recovered after unloading. The elastic properties are characteristic for solid bodies below a certain limit of stress; above this limit plastic deformations or failure will occur. Apparently the elastic limit is a rather arbitrary conception. In wood the influence of hygroscopic moisture is also important. Small elastic deformations imposed for a period of time may turn into plastic deformations. If deformations increase, structural wooden members may fail rapidly since there is no yielding of stresses as in steel. The relations between elastic deformations or strains and stresses within certain limits of stresses are therefore of great importance.
Über die rechnerische Auswertung von Verdrehungsmessungen an Holzstäben
ZusammenfassungEs wird gezeigt, daß man aus Verdrehungsmessungen an Holzstäben von quadratischem Querschnitte, wie sie kürzlich vonStamer undSieglerschmidt mitgeteilt wurden, durch ein stark konvergentes Näherungsverfahren die drei Gleitzahlen berechnen kann, die zu dem System der neun elastischen Konstanten gehören, durch welche die elastischen Verhältnisse beim Holz darstellbar sind.