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Modulus of elasticity (MOE) of Douglas-fir ( Pseudotsuga menziesii) lumber loaded in parallel to grain tension was evaluated by nondestructive techniques (transverse vibration and longitudinal stress wave) and the results were correlated to the actual properties. Nondestructive parameters of specific gravity, wave frequency and attenuation and wave...
Citations
... There are several references in the literature regarding the effect of moisture content on measuring the bending MOEst with transverse vibration testing (França et al., 2018;Teixeira, 2016). In an experimental investigation of the moisture content effect on measurements of MOEd of wooden beams, were added extra weights (dead weights) distributed along the beam length to simulate the addition of free water (moisture content > fiber saturation point -FSP ≈ 30%) (Barrett & Hong, 2010). ...
Pinus forests are the second most planted in Brazil and the wood obtained from them is mainly used as structural elements in the civil construction sector. The Brazilian standard that deals with calculations of wooden structures projects recommends the use of wood in the range of 10% to 20% of moisture content. Thus, this study aimed to present an investigation about the influence of moisture content on the static modulus of elasticity (MOEst) of wooden beams by transverse vibration tests. The MOEst was evaluated by static bending tests and transverse vibration tests for various moisture content. The transverse vibration test was performed in a free condition using an accelerometer and an impulse hammer, and the dynamic modulus of elasticity (MOEd) was determined from the frequency of the first bending vibration mode. A total of 20 wooden beams were obtained from freshly cut Pinus spp. logs with initial high moisture content were used, with nominal dimensions of 5 cm × 10 cm × 200 cm (thickness × width × length). It was observed that the MOEd is also affected by moisture content according to the non-linear regression model. There were significant changes in the dynamic modulus of elasticity (MOEd) for the moisture contents (M) below 25% (near the fiber saturation point - FSP).
... Compared with other sawn timber, its main advantages are reflected in its low material variability and high overall mechanical properties of the structure (Wang and Dai 2013;Boccadoro et al. 2017;Schuler 2017). As an engineering structural material, its structural mechanical properties and reliability are notable (Xue 2013;Divino 2016;Nasir et al. 2019;Purba et al. 2019). ...
The vibrational frequency method was used to measure the elastic modulus of laminated veneer lumber (LVL), and the feasibility of using Weibull distribution to analyze the elastic modulus data of LVL was considered. Samples were randomly selected as test pieces at the factory. The sponge support structure was used to realize the free beam state, and the modal test results verified the accuracy of realizing the free beam. Under transient excitation, the elastic modulus of the specimen was obtained by testing the first-order bending frequency. The Weibull distribution fitting test, Weibull distribution K-S test, and normal distribution K-S test were used for the test data. The probability of LVL elastic modulus was calculated under a given value. The results showed that the LVL elastic modulus did not obey the two-parameter Weibull distribution (Eu=0). The LVL elastic modulus fit to the three-parameter Weibull distribution (Eu) was greater than half of the minimum test value and the normal distribution. When 9 GPa and 8 GPa were used as the setting values of Eu, the calculated probability value was relatively stable. At this time, Eu was 81% and 92% of the minimum elastic modulus 9.815 GPa. Therefore, it was recommended to use 80% to 90% of the minimum value of the measured data as the setting value of the position parameter Eu. The three-parameter Weibull distribution and the normal distribution calculated LVL elastic modulus have the same probability under the given value.
... In today's era of technology, non-destructive testing (NDT) methods are a better option than the conventional method for measuring wood properties. A number of NDT methods have been used to measure the mechanical properties of the wood of various species, such as the ultrasonic wave transmission velocity (Yang et al. 2008), stress wave velocity (Horacek et al. 2012), transverse vibration (Teixeira 2016), longitudinal vibration (Cheng and Hu 2011), tap tone sound velocity (Chiu et al. 2013), and transittime and resonance frequency (Lindstrom et al. 2009). Near-infrared (NIR) spectroscopy, which is an advanced NDT technology, also shows promise for the application, as transmitted or reflected spectra of electromagnetic waves ranging from 800 to 2500 nm have been used for the online or on-site measurement of various organic materials, such as agricultural products, foods, polymers, textiles, pharmaceuticals, and petrochemicals . ...
In this study, static bending measurements and online NIR spectra acquisitions were combined to construct modulus of elasticity (MOE) prediction model for sugi lumber. NIR spectra were acquired from tangential surface of sugi lumbers at a speed of 120 m min⁻¹ to assess its effectiveness in the wood industry. Cross-validation partial least squares regression (CV-PLSR) and test-set-validation partial least squares regression (TSV-PLSR) analyses were employed for analysing the data. The second derivative (2d) spectra with 19 smoothing points (Savitzky–Golay algorithm, second polynomial) gave the best result as spectral pre-processing treatment with the lowest root mean square error of cross-validation and the highest coefficient of determination for cross-validation based on the optimum number of latent variables as assessed from the minimum validation residual variance value in the CV-PLSR analysis. These 2d spectra were then used in the TSV-PLSR analysis for 100 repetitions to check the robustness of the calibration.
