Study on wood fracture parallel to the grains based on fractal geometry

Compact tension specimens were used to determine the mode I (opening crack) fracture toughness of bamboo scrimber, a bio-based product for engineering applications. The influence of thickness and grain mode were investigated, and the extended finite element method (XFEM) was used to simulate the fracture behavior of bamboo scrimber. The results showed that all of the specimens failed in a brittle way. There were no significant differences in fracture toughness among specimens with different thicknesses; however, the grain mode did have a significant effect. The average fracture toughness KIC for T-L and R-L grain modes of bamboo scrimber were 54.32 MPa·mm1/2 and 47.91 MPa·mm1/2, respectively, where the letter “L” represents the longitudinal direction, “R” represents the stack direction, and “T” represents the flattened tangential direction. Based on the results, compact tension specimens with a thickness of 10 mm are recommended to measure the mode I fracture toughness of bamboo scrimber. Furthermore, XFEM was confirmed as a useful tool to investigate the fracture behavior of bamboo scrimber.

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“…6(b). This was similar to wood (Wu et al 2012); however, it was very easy to separate the two parts artificially.…”

Section: Failure Modementioning

confidence: 80%

Determination and simulation of the mode I fracture toughness of bamboo scrimber

Gong

Zhong

et al. 2019

BioRes

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“…The main steps for calculating fractal dimensions of cracks using photos of failure samples were as followings: (1) the photos of cracks in front and left views, as well as photos of fracture surfaces of CT samples were transferred to grayscale images with a resolution of 600 dpi in TIF format; then (2) the box dimension method was applied to calculate fractal dimensions of these grayscale images through using Fraclab 2.2 toolbox (INRIA, France) built in the Matlab R2014a (MathWorks, Natick, MA, USA); and (3) the specific settings were that box sizes ranged from 1/2048 to 1/2, and the relationship between box sizes and corresponding numbers of box was fitted by linear logarithmic least square regression method as shown in Equation (1). The slop, D, of the fitting line was the fractal dimension [35,36]. Figure 4 shows an example for calculating fractal dimensions, which indicates that the fractal dimension is 1.332.…”

Section: Calculating Methods Of Fractal Dimentionsmentioning

confidence: 99%

Characterizing Mode I Fracture Behaviors of Wood Using Compact Tension in Selected System Crack Propagation

Liu

2021

Forests

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The fracture behaviors of four wood species commonly used in wood products were characterized when subjected to compact tension (CT) load in radial-longitudinal (RL) system crack propagation. Meanwhile, the failure modes of evaluated CT samples were compared and analyzed using the fractal dimension method. The results showed that wood species had a significant effect on fracture characteristic values, including maximum fracture load, critical stress intensity factor and fracture energy. These characteristic values changed in the same way, i.e., beech wood CT samples obtained the maximum characteristic values, followed by ash, okoume, and poplar in descending order. The fracture behaviors of all wood species evaluated can be described by combining linear and exponential fitting equations at the crack initial stage and evolution stage, respectively. Linear positive proportional relationships were observed between fracture characteristic values and fractal dimensions calculated using cracks in front and left views of CT samples. However, the relationships between fracture characteristic values and fractal dimensions calculated using fracture surfaces were negative. The fractal dimensions of cracks in front view of CT samples could be a better indicator used to predict critical stress intensity factor and fracture energy, which had greater correlation coefficients beyond 0.95.

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“…In recent years, scientists and engineers have been looking for inspiration to create new, original structures with better properties. Among the many interesting trends, the attempts to apply structures called fractals in various fields of technology are remarkable [ 3 , 4 , 5 ]. These are mathematical structures discovered and described by Mandelbrot in the 1970s.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis, Optimization, and Multi-Criteria Design of Vacuum Insulated Glass Composite Panels

et al. 2023

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The subject of this study is Vacuum Insulated Glass (VIG) panels, which consist of two glass panes with an evacuated space and evenly distributed micro-support pillars between them. The deflection of panes towards the centre of the structure caused by atmospheric pressure is a mechanical problem that occurs in this type of structure. The aim of this study was to extend previous research on the optimal arrangement of support pillars in terms of eigenfrequencies and dynamics to include aesthetic aspects. Using Abaqus/CAE v2017 software, a large number of numerical models were created and subjected to a comprehensive multi-criteria analysis. Fractal analysis was employed to automatically assess the aesthetics of the proposed solutions. The study presents theoretical solutions that could be implemented in industrial production. The presented study shows that it is possible to effectively extend the criteria for optimizing the arrangement of pillars with new design criteria. Most studies focus on pillar placement, amount, or shape in terms of panes thermal or mechanical properties. Due to the increasing number of VIG panels applications in places exposed to external vibrations, other design criteria for VIG panels are also required and are provided by the following study.

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Study on wood fracture parallel to the grains based on fractal geometry

Cited by 7 publications

References 17 publications

Determination and simulation of the mode I fracture toughness of bamboo scrimber

Determination and simulation of the mode I fracture toughness of bamboo scrimber

Characterizing Mode I Fracture Behaviors of Wood Using Compact Tension in Selected System Crack Propagation

Numerical Analysis, Optimization, and Multi-Criteria Design of Vacuum Insulated Glass Composite Panels

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