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Growth Ring Orientation Effects in Transverse Softwood Fracture

In this study, the fracture mechanics of eastern spruce were characterized in relation to end-grain orientation. Compact tension-type specimens with small pre-formed cracks were prepared such that grain angle varied relative to the load axis. Specimens were loaded under crack mouth opening displacem...

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Autores principales: Belalpour Dastjerdi, Parinaz, Landis, Eric N.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8510428/
https://www.ncbi.nlm.nih.gov/pubmed/34640152
http://dx.doi.org/10.3390/ma14195755
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author Belalpour Dastjerdi, Parinaz
Landis, Eric N.
author_facet Belalpour Dastjerdi, Parinaz
Landis, Eric N.
author_sort Belalpour Dastjerdi, Parinaz
collection PubMed
description In this study, the fracture mechanics of eastern spruce were characterized in relation to end-grain orientation. Compact tension-type specimens with small pre-formed cracks were prepared such that grain angle varied relative to the load axis. Specimens were loaded under crack mouth opening displacement (CMOD) control as to maintain stable crack growth. Specimen fracture was characterized using both R-curve and bulk fracture energy approaches. The results showed that under a RT grain orientation, as well as grain deviations up to about 40 [Formula: see text] , cracks will follow a path of least resistance in an earlywood region. As the grain angle exceeds 40 [Formula: see text] , the crack will initially move macroscopically in the direction of maximum strain energy release rate, which extends in the direction of the pre-crack, but locally meanders through earlywood and latewood regions before settling once again in an earlywood region. At 45 [Formula: see text] , however, the macroscopic crack takes a turn and follows a straight radial path. The results further show that RT fracture is macroscopically stable, while TR fracture is unstable. None of the end-grain fracture orientations showed rising R-curve behavior, suggesting that there is not a traditional fracture process zone in this orientation.
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spelling pubmed-85104282021-10-13 Growth Ring Orientation Effects in Transverse Softwood Fracture Belalpour Dastjerdi, Parinaz Landis, Eric N. Materials (Basel) Article In this study, the fracture mechanics of eastern spruce were characterized in relation to end-grain orientation. Compact tension-type specimens with small pre-formed cracks were prepared such that grain angle varied relative to the load axis. Specimens were loaded under crack mouth opening displacement (CMOD) control as to maintain stable crack growth. Specimen fracture was characterized using both R-curve and bulk fracture energy approaches. The results showed that under a RT grain orientation, as well as grain deviations up to about 40 [Formula: see text] , cracks will follow a path of least resistance in an earlywood region. As the grain angle exceeds 40 [Formula: see text] , the crack will initially move macroscopically in the direction of maximum strain energy release rate, which extends in the direction of the pre-crack, but locally meanders through earlywood and latewood regions before settling once again in an earlywood region. At 45 [Formula: see text] , however, the macroscopic crack takes a turn and follows a straight radial path. The results further show that RT fracture is macroscopically stable, while TR fracture is unstable. None of the end-grain fracture orientations showed rising R-curve behavior, suggesting that there is not a traditional fracture process zone in this orientation. MDPI 2021-10-02 /pmc/articles/PMC8510428/ /pubmed/34640152 http://dx.doi.org/10.3390/ma14195755 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Belalpour Dastjerdi, Parinaz
Landis, Eric N.
Growth Ring Orientation Effects in Transverse Softwood Fracture
title Growth Ring Orientation Effects in Transverse Softwood Fracture
title_full Growth Ring Orientation Effects in Transverse Softwood Fracture
title_fullStr Growth Ring Orientation Effects in Transverse Softwood Fracture
title_full_unstemmed Growth Ring Orientation Effects in Transverse Softwood Fracture
title_short Growth Ring Orientation Effects in Transverse Softwood Fracture
title_sort growth ring orientation effects in transverse softwood fracture
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8510428/
https://www.ncbi.nlm.nih.gov/pubmed/34640152
http://dx.doi.org/10.3390/ma14195755
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