Objectif THE C.T.F.T. HAS DEVELOPED A SPECIAL MACHINE TO MEASURE, BY CUTTING LONGITUDINAL PIECES THE SPATIAL DISTRIBUTION OF THE LONGITUDINAL STRESS COMPONENT. THE METHOD WAS TESTED ON SOME BEECH LOGS IN FRANCE, THEN TRANSFERRED TO FRENCH GUYANA. THE REASON IS THAT THE TROPICAL FOREST OF GUYANA GIVES MANY VERY INTERESTING SPECIES WITH HIGH LEVEL OF INTERNAL STRESSES. THIS FOREST REPRESENTS AN IMPORTANT POTENTIAL SUPPLY FOR THE EUROPEAN COMMUNITIES. MOREOVER, IN SPITE OF ITS LOCALIZATION IN SOUTH-AMERICA, THE COUNTRY BELONGS TO THE EUROPEAN ECONOMIC ZONE. FOR THESE DIFFERENT REASONS, THE C.T.F.T. IS ENGAGED IN A STUDY PROGRAM OF THE MORE INTERESTING SPECIES OF GUYANA. THE OBJECTIVE IS TO ACQUIRE THE BEST KNOWLEDGE OF THE INTERNAL STRESSES GENESIS WITH THE POSSIBILITY TO TRANSFER AND TO APPLY THESE RESULTS TO EUROPEAN SPECIES WITH AS CONSEQUENCE AN IMPROVEMENT OF YIELD AND LUMBER QUALITY. IN THE PAST, STUDIES OF THE INFLUENCE OF GROWTH STRESSES ON THE DIFFERENT ASPECTS OF WOOD BEHAVIOUR HAVE BEEN LIMITED, AS MOST LABORATORIES WERE SUPPLIED WITH TEST PIECES FOR WHICH THE GROWTH STRESS PARAMETER REMAINED UNKNOWN. PRESENTLY, THE SITUATION IS DIFFERENT AS THE DETERMINATION OF GROWTH STRESS DISTRIBUTION IN THE LOGS COLLECTED IN THE LABORATORIES IS INSTALLED AS A PERMANENT TASK IN THE TEST MATERIAL PREPARATION PROTOCOL. THE PROGRAMME IS DIVISED IN THREE PARTS: - WOOD ANATOMY : IMPROVEMENT OF THE METHOD USED TO MEASURE THE MICROFIBERS ANGLE IN ORDER TO DETERMINE THE RELATIONSHIP BETWEEN GROWTH STRESS LEVEL, LONGITUDINAL SHRINKAGE AND THAT ANGLE. - PHYSICAL PROPERTIES: MEASUREMENT OF THE LONGITUDINAL SHRINKAGE. THE TEST PIECE SIZES WILL BE CHOSEN TO ELIMINATE THE INFLUENCE OF TRANSVERSAL SHRINKAGE. COMPLEMENTARY STUDIES OF SHRINKAGES UNDER STRESS AND CONSEQUENCE ON THE INTERNAL STRESSES DURING DRYING. - MECHANICAL PROPERTIES : DEVELOPMENT OF A METHOD TO MEASURE THE MORE SIGNIFICANT ELEMENTS OF WOOD RHEOLOGY (YOUNG'S MODULUS, POISSON'S COEFFICIENT, EVENTUALLY SHEARING MODULUS). THE ARRANGEMENT WILL BE MICROCOMPUTER CONTROLLED TO ALLOW A LARGE NUMBER OF REPETITIONS AND A CONTINUOUS CONTROL OF THE MEASURE RELIABILITY. Programme(s) PRE-RAWMAT 2C - Research and development programme (EEC) in the raw materials sector, 1982-1985 Thème(s) Data not available Appel à propositions Data not available Régime de financement Data not available Coordinateur Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD) Contribution de l’UE Aucune donnée Adresse 45 bis avenue de la Belle Gabrielle 94736 Nogent-sur-Marne France Voir sur la carte Coût total Aucune donnée
