Determination of Young’s and shear moduli of common yew and Norway spruce by means of ultrasonic waves

Abstract

Despite the exceptional position of yew among the gymnosperms concerning its elastomechanical properties, no reference values for its elastic constants apart from the longitudinal Young's modulus have been available from literature so far. Hence, this study's objective was to determine the Young's moduli E L , E R and E T and the shear moduli G LR , G LT and G RT of yew wood. For that purpose, we measured the ultrasound velocities of longitudinal and transversal waves applied to small cubic specimens and derived the elastic constants from the results. The tests were carried out at varying wood moisture contents and were applied to spruce specimens as well in order to put the results into perspective. Results indicate that E L is in the same order of magnitude for both species, which means that a high-density wood species like yew does not inevitably have to have a high longitudinal Young's modulus. For the transverse Young's moduli of yew, however, we obtained 1.5-2 times, for the shear moduli even 3-6 times higher values compared to spruce. The variation of moisture content primarily revealed differences between both species concerning the shear modulus of the RT plane. We concluded that anatomical features such as the microfibril angle, the high ray percentage

Impact of Thermal Modification of Spruce Wood on Screw Direct Withdrawal Load Resistance

“…Their research confirmed the fact that the higher the wood moisture, the lower the screw direct withdrawal load resistance. This dependence is also confirmed by Keunecke et al (2007) and Hübner et al (2010) who have identified the highest screw direct withdrawal load resistance in the radial plane (tangential direction) of wood. On the other hand, Ferah (1991) identified higher values of screw direct withdrawal load resistance in the radial direction in seven different wood types.…”

Módulos de rigidez dinámicos de siete maderas mexicanas determinados por vibraciones en torsión

“…When the parameters are derived from dynamic tests, the experimental parameters to be determined in the test pieces are the frequency (Yoshihara, 2012a) or the speed of the wavelength (Keunecke, Sonderegger, Pereteanu, Lüthi, & Niemz, 2007). The experimental results are pondered by the density of the wood, its temperature, the content of humidity at the moment of the test (Gorišek & Straže, 2013;Hernández, Passarini, & Koubaa, 2014) and by the anisotropy directions in which the test pieces were aligned (Brémaud et al, 2011).…”

“…Regarding the modulus of rigidity, some authors such as Naruse (2003); Keunecke et al (2007); Yoshihara (2012b); Ozyhar, Hering, Sanabria, and Niemz (2013); Kránitz, Deublein, and Niemz (2014) ;Nadir, Nagarajan, and Midhun (2014) and Sotomayor (2015) have reported data from several types of wood. The information on the modulus of elasticity determined through non-destructive methods and quality indexes of Mexican wood is lacking, with the exception of Sotomayor-Castellanos, GuridiGómez, and García-Moreno (2010).…”

“…Cuando los parámetros son derivados de pruebas dinámicas, los parámetros experimentales a determinar en las probetas son la frecuencia (Yoshihara, 2012a) o la velocidad de onda (Keunecke, Sonderegger, Pereteanu, Lüthi, & Niemz, 2007). Los resultados experimentales son ponderados por la densidad de la madera, su temperatura, el contenido de humedad al momento del ensayo (Gorišek & Straže, 2013;Hernández, Passarini, & Koubaa, 2014) y por las direcciones de anisotropía en que las probetas están alineadas (Brémaud et al, 2011).…”

Wood elastic characterization from a single sample by resonant ultrasound spectroscopy

“…Fast measurements can be obtained by using different techniques based on ultrasonic (or acoustic) wave propagations in direct contact [3,4] or in a coupling medium (e.g., water) with a protective coating if dry wood properties have to be measured [5,6]. These techniques allow the determination of the diagonal terms of the elastic tensor on a unique parallelepipedic sample [7] but, except in some cases with a polyhedral [8] or spherical samples [6,9], they usually require other samples, and/or coupling with other kind of measurements, for the determination of off-diagonal terms [10,11,12,13,14].…”