The role of geometry precision in frequency-resonance method for non-destructive wood assessment – numerical case study on sugar maple

Tippner, Jan; Vojáčková, Barbora; Zlámal, Jan; Kolařĺk, Jaroslav; Paulić, Vinko; Funai, James T.

doi:10.1080/17480272.2022.2071166

Cited by 2 publications

(4 citation statements)

References 32 publications

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“…1. Similar to previous studies' findings [27,30,32], there was no significantly better correspondence to the experiment for either type of FEM. In the solid (scan-based) models, the possibilities associated with the wood material model definition [28,30] were not fully taken advantage of, as the data for concrete material properties (from species to specimen) are difficult to experimentally obtain, and the description of influence of factors (e.g., structure changes, moisture content) with property distribution, the full anisotropy, the non-linear nature, and similar factors are complex and were beyond the scope of this study.…”

Section: Experiments and Validationsupporting

confidence: 87%

“…The precisely extracted scanned shapes used in the details (stem junction) showed more agreement with the static response in the experiment than the cylinder-created geometry [30]. In a modal analysis, the model accuracy varied according to the type of mode shape [32]. In a dynamic analysis of the whole tree, the beam model provided the best prediction of the first natural frequency [27].…”

Section: Introductionmentioning

confidence: 88%

“…Furthermore, the bending moment is a useful and measurable parameter for static and dynamic analyses [22,25,26]. The emergence of tree structure (crown and stem) creation provides the option to apply, for example, (a) beam-shaped geometry based on directly measured and 3D scan-based parameters [20,27]; (b) solid geometry, which can be generated from a 3D scan by cylinders [28,29]; or (c) solid geometry, precisely extracted by Poisson surface reconstruction [30][31][32]. Solid geometry opens the possibility of implementing wood anisotropy and heterogeneously distributed properties [28].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Geometry Precision and Load Distribution on Branch Mechanical Response

Vojáčková

Tippner

Mařík

et al. 2023

Forests

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Tree risk assessment requires mechanical response studies, but simplification of the shape, material, or boundary conditions is necessary when dealing with such complex structures. To observe overall tree response, sub-structuring to several levels of detail can be used, enabled by recent developments in numerical methods and three-dimensional laser scanning (3D scan). This study aimed to determine an appropriate level of geometry and loading simplification allowed for high-order branches at the crown border, which is useful for the mechanical analysis of structured tree models. Four higher-order branches were pruned and experimentally tested by single-point loading. Beam and solid finite-element models (FEMs) were created based on measured geometric parameters and detailed 3D scans, respectively. The FEMs were used to analyze seven loading scenarios with force applied at (a) the center of gravity, (b) the top of side branches, (c) key discrete points, and (d) uniformly to the whole volume (to each finite element). Force was distributed by ratios weighted according to the mass, area, and diameter of side branches; or according to the mass of each finite element. The results showed no significant difference between the beam model and 3D scan-based model. The scenarios with finite elements’ mass-based force distribution deviated significantly from those of the other scenarios. The most simplified single-point loading caused a deviation in the deflection curve. The deviation of single-point loading in the case of the bending moment was related to force distribution ratios given by the branches architecture. Therefore, such loading simplification is not considered always appropriate. Consistency between the bending moment and branch deflection provided a representative mechanical response, recommended for further modeling of trees by sub-structuring.

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Section: Experiments and Validationsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Effect of Geometry Precision and Load Distribution on Branch Mechanical Response

Vojáčková

Tippner

Mařík

et al. 2023

Forests

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“…Due to their versatility, different NDT techniques are used nowadays to estimate the static mechanical properties of timber and standing trees [14][15][16]. Some of these methods are based on vibro-acoustic properties such as stress wave velocity or frequency of vibrations [17,18], including FRT, which describes a number of dynamic parameters simultaneously [19][20][21]. With FRT, engineering constants such as the longitudinal dynamic modulus of elasticity (E dyn ), dynamic shear modulus (G), Poisson ratios (v), and MOED can be determined based on the response of the tested specimen to dynamic loading [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Determination of the Static Bending Properties of Green Beech and Oak Wood by the Frequency Resonance Technique

Nop,

Cristini,

Zlámal

et al. 2024

Forests

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This article discusses the non-destructive evaluation of the mechanical properties of green wood. To estimate the dynamic flexural modulus of elasticity (MOED), a non-destructive test (NDT) method—the frequency resonance technique (FRT)—was used. A three-point bending test was carried out to determine the static bending properties as the bending modulus of elasticity (MOE), the modulus of rupture (MOR), and bending toughness (Aw). This article presents the results of a study comparing the correlations between the dynamic and static bending parameters of beech (Fagus sylvatica L.) and oak (Quercus robur L.) wood, which was further divided into heartwood and sapwood. These species were chosen as the most widespread representatives of diffuse-porous and ring-porous hardwoods. This study found statistically significant differences in most mechanical parameters between the two species, except for MOR. Among the investigated parameters, beech had higher values than oak (by 22.1% for MOED, 9.5% for MOE, and 12.1% for Aw). Furthermore, relevant correlations (R > |0.7|) were established between MOED and between some of the static flexural parameters. These correlations were stronger for beech, which due to its more homogeneous structure showed less data variability than the ring-porous oak.

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The role of geometry precision in frequency-resonance method for non-destructive wood assessment – numerical case study on sugar maple

Cited by 2 publications

References 32 publications

Effect of Geometry Precision and Load Distribution on Branch Mechanical Response

Effect of Geometry Precision and Load Distribution on Branch Mechanical Response

Determination of the Static Bending Properties of Green Beech and Oak Wood by the Frequency Resonance Technique

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