Accurate finite element modelling of knots and related fibre deviations in structural timber

Saad, Khaled; Lengyel, András

doi:10.1016/j.jksues.2022.01.005

Cited by 5 publications

(10 citation statements)

References 20 publications

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“…Knots in structural wood are regarded as a significant issue. When detected in the tension zone, they tend to lower the stiffness and ultimate capacity of wood components [190]. Knots were represented as openings in some numerical studies.…”

Section: Knot Represented By Openingsmentioning

confidence: 99%

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Strengthening Timber Structural Members with CFRP and GFRP: A State-of-the-Art Review

Saad

Lengyel

2022

Polymers

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The application of fibre-reinforced polymers (FRP) for strengthening timber structures has proven its efficiency in enhancing load-bearing capacity and, in some cases, the stiffness of structural elements, thus providing cost-effective and competitive alternatives both in new design and retrofitting existing historical buildings. Over the last few decades, several reinforcing materials and techniques evolved, and considerable progress was made in numerical modelling, especially using the finite element method. As this field of research has become extensive and diversified, as well as numerous contradicting results have emerged, a thorough review is necessary. This manuscript covers the topics of historical preliminaries, reinforcing with carbon and glass fibre composites, bond characteristics, main reinforcing techniques, modelling of knots, and the effects of the fibre waviness on the composite behaviour. A detailed overview is given on the experimental and numerical investigation of mechanics of strengthened beams. A one-of-a-kind table that compares the stiffness improvement observed in several studies with analytical estimates. Attention is drawn to a number of challenges that have arisen, e.g., the moderate stiffness enhancement, composite-to-wood interface, modelling of knots, and strengthening of defected timber members. This paper can be used as a starting point for future research and engineering projects.

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Section: Knot Represented By Openingsmentioning

confidence: 99%

“…The precision of knot modelling was demonstrated to be dependent on accurate pith modelling. [190] opening/solid variable 30-40 up to 62…”

Section: Knot Represented By a Cone Or A Cylindermentioning

confidence: 99%

Strengthening Timber Structural Members with CFRP and GFRP: A State-of-the-Art Review

Saad

Lengyel

2022

Polymers

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“…The material properties applied for this specific study were adopted based on the literature. For complete description, see [35].…”

Section: Timber Beam Properties Considered For Numerical Simulationmentioning

confidence: 99%

“…An experimental study on six timber beams was evaluated for the validation of the computational model ( [35]), see Table 1. The tested beams were sawn from Norway spruce wood.…”

Section: Experimental Procedures and Validation Of The Numerical Modelmentioning

confidence: 99%

“…The existence of knots influences the global and local fibre orientation, which affects the mechanical behaviour of the timber element. The load-deflection curves obtained in the four-point bending tests ( [35]) serve as a basis for the validation of the numerical model. The model considers linearly elastic and perfectly plastic behaviour in compression and unlimited tension capacity, assuming no plasticity in tension.…”

Section: Experimental Procedures and Validation Of The Numerical Modelmentioning

confidence: 99%

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A parametric investigation of the influence of knots on the flexural behaviour of wood beams

Saad

Lengyel

2022

Preprint

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The presence of knots significantly influences the mechanical behaviour of timber. This research presents a parametric finite element analysis of the effect of knot characteristics on the flexural capacity of wood beams. Parameters include knot radius, longitudinal and vertical positions, length, and diving angle. The generation of the FE model is based on a technique developed in a previous research stage, and bending tests on a set of beams were employed for the validation. The numerical model accurately recreates the three-dimensional geometry of the knot and related fibre deviations. The capacity of the beams under bending is evaluated via the Tsai--Wu failure criterion. Findings reveal that the presence of knots in the tension zone leads to an early tensile failure and insufficient utilization of compression capacity. The decrease of bending capacity may rise to 39\%, and the knot inclination may positively or negatively influence the behaviour depending on the diving angle.

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Comparison of classical beam theory and finite element modelling of timber from fibre orientation data according to knot position and loading type

Pot,

Duriot,

Girardon

et al. 2024

Eur. J. Wood Prod.

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Accurate finite element modelling of knots and related fibre deviations in structural timber

Cited by 5 publications

References 20 publications

Strengthening Timber Structural Members with CFRP and GFRP: A State-of-the-Art Review

Strengthening Timber Structural Members with CFRP and GFRP: A State-of-the-Art Review

A parametric investigation of the influence of knots on the flexural behaviour of wood beams

Comparison of classical beam theory and finite element modelling of timber from fibre orientation data according to knot position and loading type

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