Non-Destructive Assessment of the Dynamic Elasticity Modulus of Eucalyptus nitens Timber Boards

Abstract

Eucalyptus nitens is a fast-growing wood species with a relevant presence in countries like Australia and Chile. The sustainable construction goals have driven the search of structural applications for Eucalyptus nitens; however, this process has been complicated due to the defects usually presented in these timber boards. This study aims to evaluate the dynamic elasticity modulus (Exd) of Eucalyptus nitens timber boards through non-destructive vibration-based tests. Thirty-six timber boards with different levels of knots and cracks were instrumented and tested in a simply supported condition by measuring longitudinal and transverse vibrations. In the first stage, the Exd was calculated globally through simplified normative formulas. Then, in a second stage, the local variability of the Exd was estimated using operational modal analysis (OMA), finite element numerical simulations (FEM), and regional sensitivity analysis (RSA). The positive correlation found between the global static modulus of elasticity and Exd suggests that non-destructive techniques could be used as a reliable and fast alternative for the assessment of bending stiffness. Finally, the proposed method to estimate the local variability of Exdt based on the combination of OMA, FEM, and RSA techniques was useful to improve the structural selection process of timber boards for lightweight social housing floors.

Non-Destructive Assessment of the Elastic Properties of Low-Grade CLT Panels

“…This technique allows the estimation of some unknown properties of a system, which are expressed as input parameters in a numerical model, from the measurement of other system properties by experimental tests. In the specific context of timber structures, the authors recently applied this methodology to study the local variability of the elastic properties of timber beams [31]. Based on the above, a two-phase methodology was implemented, as shown in Figure 7, and the two phases are described in detail below.…”

“…Combining these dynamic properties into a single objective function and a single threshold value is challenging because it is necessary to harmonize properties with very different dimensions and magnitudes. Sometimes it is possible to define a series of weighting factors that allow normalizing the different objective function components [31]; however, this process is tedious and indirectly increases the number of unknown parameters. Therefore, in the present work, it is proposed to apply three objective functions Y (X) using both the frequencies and the modal shapes of the CLT panels.…”

Measurement and Analysis of the Vibration Responses of Piano Soundboards with Different Structures

“…Ege separated the nonlinearity of the resonance board from that of the excitation device and measured them [ 18 ]. Opazo-Vega proposed a non-destructive method for measuring local variations [ 19 ]. Ou D. proposed an inherent frequency optimization method for plate structures based on the finite element method and genetic algorithm [ 20 ].…”