Prediction of Oak Wood Mechanical Properties Based on the Statistical Exploitation of Vibrational Response

Abstract

aIn the European Union, timber is used in structural applications and must be graded with a Conformité Européene (CE) mark. To achieve standard, machine strength grading is used. A common technology for these machines is based on using the vibrational response of each wood board to estimate the timber modulus of elasticity and modulus of rupture. The first Eigen frequency is usually used to predict these mechanical properties. However, in heterogeneous wood species such as oak, this parameter is less correlated with mechanical properties. The current study proposes two new methods based on an extended exploitation of the vibrational response that predicts oak wood mechanical properties. The first method was based on the mechanical parameters deduced from several Eigen frequencies that were chosen with regards to a stepwise regression. The second method was based on the full vibrational spectrum and used a partial least squares method. The first method slightly improved the prediction of the modulus of elasticity compared with the first Eigen frequency in edgewise transversal vibration. Both methods significantly improved the prediction of the modulus of rupture.

Performance of strength grading methods based on fibre orientation and axial resonance frequency applied to Norway spruce (Picea abies L.), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and European oak (Quercus petraea (Matt.) Liebl./Quercus robur L.)

“…The relationship between ρ 12% and f m,h for the oak sample is also extremely low, R 2 = 0.03. Both of these results are consistent with findings of Faydi et al (2017) who conducted a study on dynamic properties of oak.…”

“…Data of a sample of European oak came from a second research project, which started in 2014 and finished in 2017. The study is presented in details in Faydi (2017), and a part of the results of the study are published in Faydi et al (2017). Boards of European oak came from a single sawmill located in the Burgundy region, and which gets its supply from this region.…”

Variation and serial correlation of modulus of elasticity between and within European oak boards (Quercus robur and Q. petraea)

“…For hardwoods, limited literature data can be found on the relationship between E t,0,glob and ρ glob . In a recent study on French oak boards an R-value of 0.30 was obtained (Faydi et al 2017), somewhat lower than in this study. For a mixed dataset of beech, oak, and ash laminations, an R-value of 0.40 was reported (Frühwald and Schickhofer 2005).…”

“…With regard to the representativity of the investigated oak material in terms of density, a very good agreement with the results of two comprehensive investigations (Glos and Lederer 2000;Faydi et al 2017) on oak from different growth regions can be stated. The first mentioned study on bending of 340 unseasoned oak scantlings (growth region south-west Germany, forest district of Herrenberg), cut primarily from second and third length segments of logs harvested in thinning operations, was conducted with different cross-sections (in mm) from 40 × 80 to 60 × 180.…”

Estimating the Residual Operating Life of Wooden Structures in High Humidity Conditions

“…As compared with other approaches to the estimation of wooden structures' durability (Chaouch, 2011;Faydi et al, 2017;Hannouz, 2014;Khrulyov, 1981;Köhler, 2006;Lamov, 1999;Perret, 2017), this method is quite interesting as it used regression analysis, which can be applied to any structures and operating conditions.…”