Nondestructive Characterization of Dry Heat-Treated Fir (Abies Alba Mill.) Timber in View of Possible Structural Use

Straže, Aleš; Fajdiga, Gorazd; Gospodarič, Bojan

doi:10.3390/f9120776

Cited by 11 publications

(6 citation statements)

References 45 publications

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“…Each beam was composed of five lamellas free of anomalies and finger joints. The dynamic modulus of elasticity of the lamellas was determined with the vibration resonance method, using transverse and longitudinal excitement, as presented in Straže et al [27]. For the execution of this method, the density of the material (ρ) must be known, and this was determined by weighing the lamellas (m), measuring them in all dimensions (to determine the volume V), and calculating it using the equation ρ = m/V.…”

Section: Four-point Bending Testmentioning

confidence: 99%

Bonding Performance of Melamine–Urea–Formaldehyde and Polyurethane Adhesives for Laminated Hybrid Beams and Their Selected Mechanical Properties

Fašalek,

Straže,

Šega

et al. 2023

Buildings

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Beech (Fagus Sylvatica L.) is a prevalent tree species in Slovenia and is suitable for manufacturing glulam beams. However, beech wood has certain limitations that can potentially be mitigated by combining it with Norway spruce (Picea abies (L.) Karst.) wood to create hybrid beams. This study aimed to determine the bonding performance of commonly used melamine–urea–formaldehyde and polyurethane adhesives for these hybrid beams. Moreover, how varying the proportion of beech wood in a hybrid beam affects its mechanical properties was examined. Shear and delamination tests (method B) were conducted, and EN 14080:2013 requirements were met in all cases. The four-point bending tests of the beams showed that hybrid beams containing 20% of beech wood in the cross-sectional height on each side of the neutral axis exhibited a similar modulus of elasticity values as pure beech beams, but their strength was not equally improved. Hybrid beams with 11% of beech wood did not show any improvement in bending stiffness or strength compared to pure spruce beams. It was noted that the presence of beech wood in a hybrid beam can influence its failure mode. Furthermore, analytical calculations showed that a symmetrical lay-up is preferable to an asymmetrical one to increase the effective modulus of elasticity.

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Section: Four-point Bending Testmentioning

confidence: 99%

Bonding Performance of Melamine–Urea–Formaldehyde and Polyurethane Adhesives for Laminated Hybrid Beams and Their Selected Mechanical Properties

Fašalek,

Straže,

Šega

et al. 2023

Buildings

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“…In the case of 7 mm drill bit, the resulting model for estimating the MC of the specimen for all three species, using dr7 w /dr7 0 as an independent variable, is shown in Equation (5), where MC S is the MC of the specimen (%); dr7 w is the wet mass of the filter filled with drilling residue extracted with the 7 mm drill bit (g), and dr7 0 is the dry mass of the filter filled with oven-dried drilling residue (g). The StE of the estimate indicates that the standard deviation of the residues is 3.53% MC.…”

Section: Mcsmentioning

confidence: 99%

“…Non-destructive testing (NDT) is widely used in the assessment of existing timber structures for wood damage evaluation (internal defects and biological degradation), and for the estimation of the wood mechanical properties [1,2] due to the fact that these techniques are easy to use, dependable and accurate [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Wood Density and Moisture Content Estimation by Drilling Chips Extraction Technique

et al. 2020

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The novelty of this study is the development of an accurate wood moisture content (MC) estimation method based on a relatively brand-new, non-destructive testing technique (drilling chips extraction). The method is especially important in the assessment of existing timber structures, where non-destructive testing (NDT) results are affected by wood MC and should be adjusted to a reference MC, usually 12%. In the assessment of timber structures, it is not possible to determine MC by oven drying method and this should be estimated. Electrical resistance and capacitance are the conventional methods used for MC estimation. This research work aims to present an accurate MC estimation method based on the drilling chips extraction technique. For that, 99 specimens (90 × 65 × 38 mm3) from three softwood and hardwood species covering a wide range of densities (from 355 to 978 kg m−3) were tested after conditioning at five different MCs (5%, 10%, 15%, 20%, 25%). The Wood Extractor device based on the drilling chips extraction technique was used. The mass of the chips collected (drilling residue) from each drill was recorded. The results show that the MC of the chips extracted was statistically significantly different than the MC of the specimen and cannot be directly used as MC determination. However, the chips MC can be used as an estimator of specimen MC with high determination coefficients (R2 from 71% to 86%). As the main result, models to estimate density directly adjusted to a reference 12% MC from the wet and dry mass of chips extracted were developed with an R2 of 98%. In sum, the drilling chips extractor is a dependable and straightforward method to estimate MC and density from only one measurement. Density adjusted to a reference 12% MC can be directly estimated from a single model.

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“…During the research of its properties, static and fatigue bending tests were performed on beam-like specimens with the same geometry, but different properties (i.e., density, processing lot and orientation of the load with respect to the growth rings). Since a characterisation of the static properties of the material was previously published by Fajdiga et al [17][18][19][20], the main focus in this paper is an evaluation of the fatigue properties of spruce. Nevertheless, a statistical analysis is also performed for the static data to show the difference between the static and fatigue behaviours of the wood.…”

Section: Introductionmentioning

confidence: 99%

Statistical Modelling of the Fatigue Bending Strength of Norway Spruce Wood

Klemenc

Fajdiga

2022

Materials

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When wood is used as a structural material, the fact that it is a highly inhomogeneous material, which significantly affects its static and fatigue properties, presents a major challenge to engineers. In this paper, a novel approach to modelling the fatigue-life properties of wood is presented. In the model, the common inverse-power-law relationship between the structural amplitude loads and the corresponding number of load cycles to failure is augmented with the influence of the wood’s mass density, the loading direction and the processing lot. The model is based on the two-parametric conditional Weibull’s probability density function with a constant shape parameter and a scale parameter that is a function of the previously mentioned parameters. The proposed approach was validated using the example of experimental static and fatigue-strength data from spruce beams. It turned out that the newly presented model is capable of adequately replicating the spruce’s S-N curves with a scatter, despite the relatively scarce amount of experimental data, which came from different production lots that were loaded in different directions and had a significant variation in density. Based on the experimental data, the statistical model predicts that the lower density wood has better fatigue strength.

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Nondestructive Characterization of Dry Heat-Treated Fir (Abies Alba Mill.) Timber in View of Possible Structural Use

Cited by 11 publications

References 45 publications

Bonding Performance of Melamine–Urea–Formaldehyde and Polyurethane Adhesives for Laminated Hybrid Beams and Their Selected Mechanical Properties

Bonding Performance of Melamine–Urea–Formaldehyde and Polyurethane Adhesives for Laminated Hybrid Beams and Their Selected Mechanical Properties

Wood Density and Moisture Content Estimation by Drilling Chips Extraction Technique

Statistical Modelling of the Fatigue Bending Strength of Norway Spruce Wood

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