WOOPS

(WOod OPtical Scope)

Title / Titre : Determination of the wood properties based on the light interaction : interpretation, measure and identification of the influencing mechanisms and parameters / Détermination des propriétés du bois par interaction lumineuse : interprétation, mesure et identification des mécanismes et des paramètres d'influence

Start date: 1/11/2021

Period: 3 years

Total budget:  128770 €

Collected budget / subvention :  128770 €

Funding: RBFC

Project bearer: LaBoMaP

Project coordinator : Stephane GIRARDON

Mots clés : Bois, Optique, Laser, Fibres, Propriétés, Ondes, Diffusion, Mesures

Keywords: Wood, Optic, Laser, Fibers, Properties, Waves, Diffusion, Measures

Abstract:

Wood is a one of basic construction materials for eco-friendly homes. It is essential for a sustainable development, while reducing the CO₂ emission. Despite its high heterogeneity, its usage is encouraged due to its interesting properties, mainly its lightness, rigidity and isolation. In order to control its natural variability and its mechanical properties, the determination of the fiber orientation is deeply required. It allows more optimized classification of veneers based on its properties (density, knottiness, …), which enables higher mechanical and esthetic properties of the engineered products (LVL, Plywood…).

Until now, experimental measurements are carried out based on the tracheid effect. It consists in applying a laser dot at the wood surface and measuring the light propagation, which depends on the fiber orientation (Figure 1). The lights propagate mainly following fiber direction and the spot light is transformed in an Ellipse.

Even though its interesting cost, the simplicity of its setting up, as well as the enabled development of mechanical and drying behavior models; the explanation of the phenomenon controlling the light propagation and the determination of the most influencing parameters are still, to our knowledge, not well documented in the literature. Therefore, further investigations are required to allow its understanding, deeply essential for the valorization of local woods with a low-quality.

The main purpose of this project is to investigate the real potential of adequately exploiting the fiber orientation measurements from scientific (diffusion, humidity, wall effect) and technical (local humidity, density, fiber orientation…) points of view. It is based on the skills of the two laboratories, LaBoMaP et FEMTO-ST, in the wood material and the optical measurements. The complementary technical platforms, the instrumented peeling line of LaBoMaP and the several optical devices of both laboratories, are also used to determine the most suitable conditions of the laser dot scanning method.

Figure 1 (a) Superposed views (radial-tangential plane) of fir specimen (Picea abies) (b) subjected to focused white light on its side part

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