Simulating the rotary-cutting of a softwood : modelling the variations of the veneer properties and the consequences on the plywood quality
1999
Bos, Frédéric | Chiorescu, Sorin | Constant, Thiéry | Jaeger, Marc | Mothe, Frédéric | Thibaut, Bernard
The product quality delivered as a final output by the growth and wood quality modelling software is usually based only upon the grading of structural timber products. Therefore, the economical value of a forest resource may increase significantly if a part of the volume is dedicated to the rotary cutting industry. In view to improve the efficiency of the growth and wood quality model, our final objective is to evaluate the amount of raw material which should be dedicated to veneering process and to assess the quality of the expected products (plywood or LVL). Starting from a "virtual tree" delivered by the growth models, the first step will be to simulate the rotary cutting process in view to deliver "virtual veneers". This step includes a geometrical transformation and a simulation of the peeling process. The key point will now be to merge both tools for delivering a database of fully described sheets of veneers including the thickness variations into the cutting pattern. The quality of a "virtual plywood" assembled from the "virtual veneers" may be assessed by numerical tools. We are focused on two main board properties: mechanical elastic design and dimensional stability. At the present stage, most of the necessary tools and models are on a good way and have already been employed despite the fact that their integration and validation are not still achieved. Another part of the work is a very first tentative of simulating and validating experimentally the dimensional stability of Douglas fir plywood as a function of the inner heterogeneity variation of the veneers. The predicted deformation is largely overestimated, and a new study is now to be engaged to improve the model
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