Simultaneous non-destructive identification of multiple elastic and damping properties of spruce tonewood to improve grading
Résumé
The tonewoods used in musical instruments are finely selected and are subject to current and upcomingavailability issues. Wood grading assesses the quality of the tonewood and depends on both subjectiveand objective criteria. Traditionally, grading criteria based on mechanical properties consider mainlythe longitudinal direction. This paper investigates the elastic and damping properties of spruce woodused in the making of acoustical guitars and violins. In this context, the mechanical grading propertieswill be studied in multiple directions. A non-destructive vibrational characterisation method is used tosimultaneously identify at least six mechanical properties of wood and leads to the determination of theelastic and damping parameters of wood along the different material directions. The main objective isto quantify the variability of the mechanical properties in different material directions as a function ofthe grading attributed by the wood seller. The results show that material anisotropy decreases as thegrade decreases. This is attributed to strong increase of the specific elastic modulus in the radial directionand the specific shear modulus in longitudinal and radial plane. Moreover, grading seems to be assignedas a function of specific elasticity and loss factor in the longitudinal direction, which is tied in with thepreferences of instrument makers. Following the assumption that high specific modulus is desirable,the classification based on instrument makers choices can be improved for new grading criteria thatconsider directions than longitudinal. Moreover, the substitution of wood species and the proposal ofnew materials exhibiting equivalent elastic and damping properties can be proposed.
Domaines
Mécanique [physics]
Origine : Fichiers produits par l'(les) auteur(s)
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