Influence of temperature on mechanical properties orthogonal to grain in some tropical hardwoods

In order to simulate the main mechanical phenomena during chip formation in veneer cutting, specific radial compression, RT shearing and RL fracture toughness tests were conducted on 10 tropical woods of specific gravity ranging from .27 to 1.18, until rupture or rather high strain level. Three kinds of criteria were measured in each type of test i.e. stiffness, strength and energetic criteria derived from the load- displacement curve. Tests were done on 3 replica at 12 temperatures ranging from 27°C to 80°C in the wet state. All the criteria were highly dependent on both specific gravity and temperature except for the fracture energy slightly influenced by wood temperature. Specific gravity influence can be expressed by relation like "Criteria = D", where D is the specific gravity. Values of the parameter = change from low value as 2/3 to high value like 2, depending on criteria and temperature. Temperature influence was clearly non linear with a typical main transition value ranging between 57°C and 65°C with rather small variability. Amplitude of the temperature effect between room temperature and 80°C depends on both specific gravity and type of criteria. Usually the ratio between maximum and minimum value ranges from 2 to 6, this ratio being higher for higher specific gravities. There are strong species effect on the different parameters apart from specific gravity. This can be a key to species selection for different uses as veneers, arch shaped woods. (Texte intégral