Experimental Testing and Numerical Evaluation of the Strain-softening Behavior of Birch Using a Cross-validation Calibration Approach
Jonasson, Johannes LU ; Danielsson, Henrik LU
and Serrano, Erik
LU
(2023)
3rd ECCOMAS Thematic Conference on Computational Methodsin Wood Mechanics - from Material Properties to Timber Structures
p.125-126
- Abstract
- Softwood species are the most commonly used species in structural applications in north-
ern Europe. However, in the last couple of years, utilization of hardwoods has gathered
increased momentum, and different hardwood species, such as birch, have even been uti-
lized in cross laminated timber and glued laminated timber [1]. In general hardwoods
show an increase in strength and stiffness as compared to softwoods. However, the in-
crease in fracture toughness is less pronounced, and, consequently, increased brittleness
can be expected.
Many structural failures stem from introducing a new material, where the behavior is not
completely understood or characterized [2]. Consequently, ahead of using a material... (More) - Softwood species are the most commonly used species in structural applications in north-
ern Europe. However, in the last couple of years, utilization of hardwoods has gathered
increased momentum, and different hardwood species, such as birch, have even been uti-
lized in cross laminated timber and glued laminated timber [1]. In general hardwoods
show an increase in strength and stiffness as compared to softwoods. However, the in-
crease in fracture toughness is less pronounced, and, consequently, increased brittleness
can be expected.
Many structural failures stem from introducing a new material, where the behavior is not
completely understood or characterized [2]. Consequently, ahead of using a material with
increased brittleness in structural applications, such as birch, understanding and char-
acterizing the failure and/or fracture behavior is highly important. Research regarding
mechanical behavior of birch has previously been carried out in e.g [3], where sawn birch
timber boards were examined under compression loading, both parallel and perpendicular
to the grain.
The aim of the present work is to characterize the fracture behavior of birch in tension
perpendicular to grain. The experimental work to evaluate the fracture energy has been
carried out according to the standardized Nordtest method [4], where a single edge notched
beam (SENB) is loaded in three-point-bending. Softwood structural timber of class C24
was used as a reference.
In addition to the experimental investigations, numerical evaluations were carried out
with several finite element models, both two- and three-dimensional, corresponding to
the experimental set-up. Crack propagation was modeled along a predefined crack path
where the strain-softening behavior was modeled by discrete nonlinear springs with intial
length equal to zero, see Figure 1. Bi-linear, tri-linear and linear-exponential curves of
the stress (σ) versus deformation (δ) response were used to model the strain-softening
behavior. All types of stress-deformation curves were then evaluated and calibrated after
the experimental results with a cross-validation calibration approach (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/31c72a58-0674-4720-bcb3-bc23e521f059
- author
- Jonasson, Johannes
LU
; Danielsson, Henrik
LU
and Serrano, Erik
LU
- organization
- publishing date
- 2023
- type
- Contribution to conference
- publication status
- published
- subject
- pages
- 125 - 126
- conference name
- 3rd ECCOMAS Thematic Conference on Computational Methods<br/>in Wood Mechanics - from Material Properties to Timber Structures<br/>
- conference location
- Dresden, Germany
- conference dates
- 2023-09-05 - 2023-09-08
- language
- English
- LU publication?
- yes
- id
- 31c72a58-0674-4720-bcb3-bc23e521f059
- alternative location
- https://congressarchive.cimne.com/compwood_2023/assets/book_of_abstracts_compwood_2023.pdf
- date added to LUP
- 2024-03-01 15:28:17
- date last changed
- 2024-03-06 11:43:30
@misc{31c72a58-0674-4720-bcb3-bc23e521f059,
abstract = {{Softwood species are the most commonly used species in structural applications in north-<br/>ern Europe. However, in the last couple of years, utilization of hardwoods has gathered<br/>increased momentum, and different hardwood species, such as birch, have even been uti-<br/>lized in cross laminated timber and glued laminated timber [1]. In general hardwoods<br/>show an increase in strength and stiffness as compared to softwoods. However, the in-<br/>crease in fracture toughness is less pronounced, and, consequently, increased brittleness<br/>can be expected.<br/>Many structural failures stem from introducing a new material, where the behavior is not<br/>completely understood or characterized [2]. Consequently, ahead of using a material with<br/>increased brittleness in structural applications, such as birch, understanding and char-<br/>acterizing the failure and/or fracture behavior is highly important. Research regarding<br/>mechanical behavior of birch has previously been carried out in e.g [3], where sawn birch<br/>timber boards were examined under compression loading, both parallel and perpendicular<br/>to the grain.<br/>The aim of the present work is to characterize the fracture behavior of birch in tension<br/>perpendicular to grain. The experimental work to evaluate the fracture energy has been<br/>carried out according to the standardized Nordtest method [4], where a single edge notched<br/>beam (SENB) is loaded in three-point-bending. Softwood structural timber of class C24<br/>was used as a reference.<br/>In addition to the experimental investigations, numerical evaluations were carried out<br/>with several finite element models, both two- and three-dimensional, corresponding to<br/>the experimental set-up. Crack propagation was modeled along a predefined crack path<br/>where the strain-softening behavior was modeled by discrete nonlinear springs with intial<br/>length equal to zero, see Figure 1. Bi-linear, tri-linear and linear-exponential curves of<br/>the stress (σ) versus deformation (δ) response were used to model the strain-softening<br/>behavior. All types of stress-deformation curves were then evaluated and calibrated after<br/>the experimental results with a cross-validation calibration approach}},
author = {{Jonasson, Johannes and Danielsson, Henrik and Serrano, Erik}},
language = {{eng}},
pages = {{125--126}},
title = {{Experimental Testing and Numerical Evaluation of the Strain-softening Behavior of Birch Using a Cross-validation Calibration Approach}},
url = {{https://congressarchive.cimne.com/compwood_2023/assets/book_of_abstracts_compwood_2023.pdf}},
year = {{2023}},
}