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Found 1 result for A. Opazo-Vega
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. 2021 Jan 7;14(2):269.
doi: 10.3390/ma14020269.

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

Alexander Opazo-Vega  1   2 , Víctor Rosales-Garcés  3 , Claudio Oyarzo-Vera  2
Affiliations

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

Alexander Opazo-Vega et al. Materials (Basel). .

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.

Keywords: hardwoods; model updating; operational modal analysis; regional sensitivity analysis.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Lateral view of the central third and transversal section of: (a) Timber board #33, (b) timber board #28, and (c) timber board # 10.
Figure 2
Figure 2
Longitudinal vibration test set up.
Figure 3
Figure 3
Transverse vibration test set up.
Figure 4
Figure 4
Static bending test set up.
Figure 5
Figure 5
Logical diagram of Exdt local variability estimation.
Figure 6
Figure 6
Theoretical first three resonant vertical vibration modes: (a) First mode, (b) second mode, and (c) third mode.
Figure 6
Figure 6
Theoretical first three resonant vertical vibration modes: (a) First mode, (b) second mode, and (c) third mode.
Figure 7
Figure 7
Numerical model of timber boards.
Figure 8
Figure 8
Regression analysis for: (a) Ex versus Exdl; (b) Ex versus Exdt. The red fitted lines show the predicted Ex for any Exdl or Exdt value. The blue dashes lines show the 95% prediction interval.
Figure 9
Figure 9
Vibrational response for the timber board #33 measured in the central accelerometer.
Figure 10
Figure 10
(a) Singular values diagram for lumber board #33 (Enhanced Frequency Domain Decomposition (EFDD) method); (b) stabilization diagram for lumber board #33 (Stochastic Subspace Identification (SSI) method). Adapted from ARTeMIS Modal Pro [38].
Figure 11
Figure 11
Graphical comparison between the experimental modal shapes obtained by EFDD and SSI methods in: (a) Timber board #20—first mode; (b) timber board #20—third mode; (c) timber board #28—first mode; (d) timber board #28—third mode.
Figure 12
Figure 12
Scatter plots of the output samples (Y function) against the four input factors located in the central third of the timber board # 33 (Exdt in zones 5 to 8). The green and red dots represent the sets B (behavioral) and NB (non-behavioral), respectively.
Figure 13
Figure 13
Cumulative Distributions Functions (CDFs) of the four input factors located in the central third of the timber board # 33 (Exdt in zones 5 to 8) for the output metric (Y function). The green and red curves represent the sets B (behavioral) and NB (non-behavioral), respectively.
Figure 14
Figure 14
Boxplots of the four input factors located in the central third of the timber board # 33 (Exdt in zones 5 to 8) for B sets. The pictures show the back and front of the lumber board in zones 5 to 8.
Figure 15
Figure 15
Scatter plots of the output samples (Y function) against the four input factors located in the central third of the timber board # 19 (Exdt in zones 5 to 8). The green and red dots represent the sets B (behavioral) and NB (non-behavioral), respectively.
Figure 16
Figure 16
Cumulative Distributions Functions (CDFs) of the four input factors located in the central third of the timber board # 19 (Exdt in zones 5 to 8) for the output metric (Y function). The green and red curves represent the sets B (behavioral) and NB (non-behavioral), respectively.
Figure 17
Figure 17
Boxplots of the four input factors located in the central third of the lumber board # 19 (Exdt in zones 5 to 8) for B sets. The pictures show the back and front of the timber board in zones 5 to 8.
Figure 18
Figure 18
Scatter plots of the output samples (Y function) against the four input factors located in the central third of the timber board # 28 (Exdt in zones 5 to 8). The green and red dots represent the sets B (behavioral) and NB (non-behavioral), respectively.
Figure 19
Figure 19
Cumulative Distributions Functions (CDFs) of the four input factors located in the central third of the timber board # 28 (Exdt in zones 5 to 8) for the output metric (Y function). The green and red curves represent the sets B (behavioral) and NB (non-behavioral), respectively.
Figure 20
Figure 20
Boxplots of the four input factors located in the central third of the timber board # 28 (Exdt in zones 5 to 8) for B sets. The pictures show the back and front of the lumber board in zones 5 to 8.
Figure 21
Figure 21
Defect visualization in the central third of the eight timber boards that met the current global serviceability criterion but not the proposed new local criterion.
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