Influence of temperature on green mechanical properties of wood across the grain in relation to heating before veneer cutting

Beauchêne, Jacques; Thibaut, Bernard

Influence of temperature on green mechanical properties of wood across the grain in relation to heating before veneer cutting

2001

Beauchêne, Jacques | Thibaut, Bernard

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 cunducted on 10 tropical woods of specific gravity ranging from .27 to 1. 18, until rupture or rather high strain lever. Three kind of criteria were measured in each type of test ie stiffness, strength and energetic critera derived from the load-displacement curve. Tests were clone on 3 replica at 12 temperatures ranging from 27°C to 80°C in the wet stase. All the criteria were highly dependant 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 = B.T", where T is the temperature. The values of the parameter a 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. (Résumé d'auteur)

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