Diversité des bois utilisés ou utilisables en facture d'instruments de musique. Étude expérimentale des propriétés vibratoires en direction axiale de types de bois contrastés en majorité tropicaux. Relations à des déterminants de microstructure et de composition chimique secondaire

摘要

This work aims at bringing a better knowledge of woods, mainly heavy tropical ones, used in instruments, and some proposals for a diversification in relation with difficulties in sustainable availability. It follows two complementary approaches: characterization of the diversity used or usable in musical instrument making (species, vibrational properties); study of microstructural and chemical (extractives) factors influencing the important properties. A database “woody species – uses in instruments” is drawn and started to be implemented with information about extra-European traditions in instrument making. Basic vibrational properties (specific Young's modulus and damping coefficient in the frequency range 200- 600Hz) in axial direction, equilibrium moisture content (at 20°C and 65% RH) and colour parameters CIELab and CIELCh are determined on 1400 probes of small dimensions covering 60 species and 70 wood types, including 70% of tropical woods. One half is provided by instrument makers, the other is pre-selected according to criteria linking mechanical, chemical and physical properties. The relationships between properties are analysed and the species are classified into similarity groups by multivariate analysis. Heartwood extractives are responsible for very low damping coefficients and moisture contents for the majority of the tropical woods under study. Simple predictive models are proposed that explain, on studied species, 85-90% of the observed variability in damping coefficients. Relationships between physico-mechanical properties and microfibril angle on normal and compression wood of 3 softwoods are globally in agreement with the literature but compression woods exhibit – at given specific modulus- lower damping than normal woods. Heartwoods of two species of Papilionaceae (Pterocarpus soyauxii Taub. ‘Padauk' et P. erinaceus Harms. ‘Senegal Rosewood') are compared in their native state and after being extracted in different solvents. The extractives from Padauk are –at given quantities- more efficient in reducing damping than those of Senegal Rosewood and conversely for moisture content. Hypothesis are formulated about possible mechanisms.