Calibration of a combined XFEM and mode I cohesive zone model based on DIC measurements of cracks in structural scale wood composites

Ostapska, Katarzyna; Malo, Kjell Arne

doi:10.1016/j.compscitech.2020.108503

Cited by 13 publications

(5 citation statements)

References 28 publications

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“…The approach utilized full-eld deformation data history to obtain crack tip locations by analytical decomposition to various modal components of fracture that allowed adjustment of fracture characteristics. An extension of this approach towards creation of a calibrated numerical model re ecting nonlinear fracture phenomena was presented by the same authors later (Ostapska and Malo (2021). When searching for agreement with full-eld data, their optimization procedure allowed to vary not only elastic parameters, but also stress at initiation, crack propagation and softening functions.…”

Section: Introductionmentioning

confidence: 99%

Strain-based approach to characterize mode I crack propagation in Norway Spruce directly from optical data

Kunecký,

Hataj,

Jochman

et al. 2024

Preprint

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The paper focuses on assessment and utilization of strain-based criterion obtained using the digital image correlation in characterization of fracture behavior of Norway spruce wood. The study employed a single-edge notched beam loaded in three-point bending (SEN-TPB) to examine mode I at three anatomical directions of crack propagation (radial, tangential, tangential-radial - R, T and TR). The criterion is evaluated at the maximal load (Fmax), where the compliance-based beam method (CBBM) provides critical strain energy (Gc), which ensures the proper criteria representing equivalent crack length growth is described. The novel approach also enables one to determine the fracture process zone (FPZ) length using an algorithm which finds the onset of the nonlinear region. Uniqueness of the approach lies in processing a big set of optical data and simultaneous tracking of crack length on both sides of medium-size specimens. Results indicate that crack length is dependent on the anatomical direction, for instance in T direction the criterion ε1crit is 2.5e-3 producing crack length equal to ac =23.9 mm, whilst in R direction, the ε1crit is least and equals 1.3e-3 producing crack length of 22.1 mm. The highest ε1crit is attained in TR (on average ε1crit = 3.4e-3) and distance from the place where the crack started is 19.4 mm. Size of the non-linear region here attributed to FPZ length reaches the value of 38.4 mm in T, 30.1 mm in R and 36.3 mm in TR directions, respectively. The study presents a novel approach in characterization of fracture properties by coupling optical and energetical data and may find its usage in evaluation of other fracture modes.

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Section: Introductionmentioning

confidence: 99%

Strain-based approach to characterize mode I crack propagation in Norway Spruce directly from optical data

Kunecký,

Hataj,

Jochman

et al. 2024

Preprint

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“…Additional degrees of freedom and special displacement functions enable the consideration of discontinuities, such as cracks, within the now enriched finite elements, independent of the underlying mesh (Konopka et al 2017 ). XFEM was used to examine cracking in wood in various works, investigating bending of glued laminated timber (GLT) beams (Qiu et al 2014 ; Vida et al 2022 ), modeling brittle failure of wooden structures (Gebhardt and Kaliske 2020 ), finding optimal parameter values for numerical modeling of fracture using experiments as a basis (Ostapska and Malo 2021 ) or moisture-induced crack initiation and propagation of circular cross sections made of Anhui fir (Chen et al 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Prediction of moisture-induced cracks in wooden cross sections using finite element simulations

Brandstätter¹,

Autengruber²,

Lukacevic³

et al. 2023

Wood Sci Technol

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Wood absorbs and desorbs moisture due to its hygroscopic behavior, leading to moisture gradients in timber elements as well as swelling and shrinkage. These processes are constrained due to the orthotropic material properties of wood, leading to moisture-induced stresses, which can cause crack initiation and propagation. A significant amount of the damage in timber constructions indoors can be related to changes of the moisture content (MC). However, more information is needed about the correlation between moisture changes or gradients and specific damage characteristics, like crack depths. Thus, based on numerical simulations, the crack depth development within two solid timber and one glued laminated timber (GLT) cross section over time for different relative humidity (RH) reductions and initial MCs is analyzed. For this purpose, a multi-Fickian transport model is used to determine moisture fields, which are then used as loads in a subsequent stress simulation, where linear elastic material behavior is considered. An extended finite element approach, supported by a multisurface failure criterion defining the failure behavior, allows for the simulation of moisture-induced discrete cracking. Based on simulation results, correlations between potential maximum crack depths and moisture gradients in indoor climate conditions are derived, which enables the prediction of crack depths in wood. Finally, it is shown that the initial MC level significantly influences the maximum crack depth that can be expected.

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“…Such research is being developed in order to test the material properties of wood and its resistance to wood splitting (Ostapska and Malo 2021a, b); however, such methods cannot assess the influence of working tools on the processes of splitting wood. The procedure during the creation of such a research methodology is based on the results of the experiment (Ostapska and Malo 2021a), followed by recreating it under the conditions of numerical methods, for example the finite element method (FEM) (Ostapska and Malo 2021b), to support streamlined engineering methods for testing wood. Prediction of the cutting force is a basis for machine design and still a valid trend in science, especially in terms of designing innovative tools (Gochev et al 2018;Chuchala et al 2020;Wellenreiter et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Modelling the process of splitting wood and chipless cutting Pinus sylvestris L. wood in terms of designing the geometry of the tools and the driving force of the machine

et al. 2022

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The size of wood is reduced by splitting or chipless cutting whilst logging trees, limbing, or preparing wood to be a fuel, for example, or in order to improve the efficiency of wood drying processes. Low costs of wood processing are desirable in each of these processes. The article presents experimental and simulation tests run in ABAQUS software, which allow for an analysis of the geometry of cutting tools used during the splitting or chipless cutting of wood in order to determine the cutting force and driving force of the machine executing such a process. The tests involved wood of Pinus sylvestris L. (moisture content: 8.74% ± 0.1%) in four configurations (chipless cutting transverse to the fibres (90°–90°), splitting along the fibres (0°–90°), splitting radially to the grain (90°–0°) and splitting tangentially to the grain (90°–0°)). Analysis of the force and strength of the blade proved that an effective tip angle of the knife blade falls between 30° and 45°. The presented results also suggested that splitting wood along the fibres (0°–90°) is preferable in a machine process, while splitting tangentially and radially to the wood grain (90°–0°) is preferable when splitting wood using manual tools.

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Calibration of a combined XFEM and mode I cohesive zone model based on DIC measurements of cracks in structural scale wood composites

Cited by 13 publications

References 28 publications

Strain-based approach to characterize mode I crack propagation in Norway Spruce directly from optical data

Strain-based approach to characterize mode I crack propagation in Norway Spruce directly from optical data

Prediction of moisture-induced cracks in wooden cross sections using finite element simulations

Modelling the process of splitting wood and chipless cutting Pinus sylvestris L. wood in terms of designing the geometry of the tools and the driving force of the machine

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