Study on Young's Modulus and Internal Friction of Wood in Relation to the Evaluation of Wood for Musical Instruments

Abstract

Young's modulus E and internal friction Q -1 in longitudinal (L) direction and specific gravity γ were measured for numerous specimens of 25 softwood species. There was a high correlation between Q -1/(E/γ) and E/γ, and the suitability of wood for musical instruments can be evaluated by using the value of E/γ. Furthermore, effects of grain angle in the longitudinal-radial plane on Young's modulus and internal friction of wood were investigated. From these results, it is concluded that the value of internal friction as well as Young's modulus of wood is determined in large part by microfibril angle in the S2 layer of tracheid against the L direction.

Relationships between anatomical and vibrational properties of wavy sycamore maple

“…Results from the vibrational measurements on all specimens show that, overall, the relationship between tanδ and E'/ρ of sycamore maple ( Figure 7) follows a trend similar to the "standard" relationship established on numerous species (Ono and Norimoto 1983;Brémaud et al 2012).…”

“…Nevertheless, sycamore maple plates under study tend to have low to very low ratios of anisotropy (Table 3), especially for the waviest ones, when compared to other hardwood species (Brémaud et al 2011). It is also determined that the tanδ L in more wavy wood is higher than the standard relationship (Ono & Norimoto 1983) which is followed by the less wavy specimens. It is suggested to conduct more research comparing the vibrational properties between wavy-figured wood with various kinds of anatomical features (either by extending the sampling on sycamore maple, or by including other species to allow more variations in the different types of cells), and maybe also to observe in parallel possible chemical variations as affecting factors (Longui et al 2012;Brémaud et al 2013).…”

“…this study with the "standard" relationship established on numerous species (Ono & Norimoto 1983;Brémaud et al 2012). Further analysis on local variations also shows that, along the trunk's radius, E' L /ρ tends to increase and tanδ L to decrease the further the wood is from the pith (Figure 8 (Brémaud 2012).…”

“…The measurement of vibrational properties of the specimens was conducted based on the principle of non-contact forced vibrations of free-free slender beams (Obataya et al 2000;Ono & Norimoto 1983) using a semi-automated device "Vybris" which was developed and manufactured in LMGC (Laboratoire de Mécanique et Génie Civil) in Montpellier, France (Brémaud 2006). For the measurement, the wood specimen was hung with silk threads, vibrated using an electromagnet facing a thin steel piece glued to one end of the sample, and the vibration was then recorded by a laser-triangulation sensor with the resolution (smallest measurable displacement or vibration amplitude) of 10 µm (Figure 3).…”

“…Acoustically speaking, properties that are important for instrument plates are density (ρ), Young's modulus (E'), specific modulus (E'/ρ, which is related to the sound speed V≈[ E'/ρ] 1/2 ), damping coefficient (tanδ), and their anisotropy between longitudinal (L) and radial (R) directions (Ono & Norimoto 1983;Obataya et al 2000;Bucur 2006). The woods used for back plates-like maple-are known to show different values of these properties than wood for topplates such as spruce (Yano et al 1992;Wegst 2006;Yoshikawa 2007).…”