Observation of development of microcracks on wood surface caused by drying stresses

Antti Hanhijärvi, Paul Wahl, Jari Räsänen, Raimo Silvennoinen

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)

Abstract

Morén (1994) has suggested that during the early stages of the timber drying process, some damage, small cracks or “microcracks”, develop on the wood surface and this hypothesis has been shared by others (Hukka and Tarvainen 1997). However, the so-called microcracks have not been directly observed and the hypothesis is based on the observations of the cracking behaviour later during the drying process. Up to 50% difference in the final amount of visible cracks at the end of drying has been observed depending on the way the early warm-up stage is conducted (the actual drying stage being the same). It is suggested that something happens on the surface in the early stages that makes it more vulnerable to later developing cracks. A readily acceptable explanation is the appearance of small cracks on the surface, invisible to the naked eye, that act as initial flaws and later grow into visible cracks. The name “microcracks” has been attached to these cracks as opposed to visible “macrocracks”. The width limit for the visibility of cracks with the naked eye is approximately 0.1 mm (Wahl 1999), which may be used as a practical definition for the upper limit of “microcracks”. The goal of this work is to detect microcracks on wood surfaces and to verify the microcracking hypothesis and then to quantify it. For this purpose, a measurement technique was developed, its function verified as reported in (Wahl et al. 2001), and then applied for tests of microcracking. The results shown here concern wood surfaces examined during drying, and compare the amount of microcracking in various drying conditions.
Original languageEnglish
Pages (from-to)561-565
Number of pages5
JournalHolzforschung
Volume57
Issue number5
DOIs
Publication statusPublished - 2003
MoE publication typeA1 Journal article-refereed

Fingerprint

Microcracks
Wood
Drying
Cracks
Microcracking
Timber
Visibility
Defects

Cite this

Hanhijärvi, A., Wahl, P., Räsänen, J., & Silvennoinen, R. (2003). Observation of development of microcracks on wood surface caused by drying stresses. Holzforschung, 57(5), 561-565. https://doi.org/10.1515/HF.2003.083
Hanhijärvi, Antti ; Wahl, Paul ; Räsänen, Jari ; Silvennoinen, Raimo. / Observation of development of microcracks on wood surface caused by drying stresses. In: Holzforschung. 2003 ; Vol. 57, No. 5. pp. 561-565.
@article{8a4676073a65449a81ceba12974a6b9f,
title = "Observation of development of microcracks on wood surface caused by drying stresses",
abstract = "Mor{\'e}n (1994) has suggested that during the early stages of the timber drying process, some damage, small cracks or “microcracks”, develop on the wood surface and this hypothesis has been shared by others (Hukka and Tarvainen 1997). However, the so-called microcracks have not been directly observed and the hypothesis is based on the observations of the cracking behaviour later during the drying process. Up to 50{\%} difference in the final amount of visible cracks at the end of drying has been observed depending on the way the early warm-up stage is conducted (the actual drying stage being the same). It is suggested that something happens on the surface in the early stages that makes it more vulnerable to later developing cracks. A readily acceptable explanation is the appearance of small cracks on the surface, invisible to the naked eye, that act as initial flaws and later grow into visible cracks. The name “microcracks” has been attached to these cracks as opposed to visible “macrocracks”. The width limit for the visibility of cracks with the naked eye is approximately 0.1 mm (Wahl 1999), which may be used as a practical definition for the upper limit of “microcracks”. The goal of this work is to detect microcracks on wood surfaces and to verify the microcracking hypothesis and then to quantify it. For this purpose, a measurement technique was developed, its function verified as reported in (Wahl et al. 2001), and then applied for tests of microcracking. The results shown here concern wood surfaces examined during drying, and compare the amount of microcracking in various drying conditions.",
author = "Antti Hanhij{\"a}rvi and Paul Wahl and Jari R{\"a}s{\"a}nen and Raimo Silvennoinen",
year = "2003",
doi = "10.1515/HF.2003.083",
language = "English",
volume = "57",
pages = "561--565",
journal = "Holzforschung",
issn = "0018-3830",
publisher = "De Gruyter",
number = "5",

}

Hanhijärvi, A, Wahl, P, Räsänen, J & Silvennoinen, R 2003, 'Observation of development of microcracks on wood surface caused by drying stresses', Holzforschung, vol. 57, no. 5, pp. 561-565. https://doi.org/10.1515/HF.2003.083

Observation of development of microcracks on wood surface caused by drying stresses. / Hanhijärvi, Antti; Wahl, Paul; Räsänen, Jari; Silvennoinen, Raimo.

In: Holzforschung, Vol. 57, No. 5, 2003, p. 561-565.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Observation of development of microcracks on wood surface caused by drying stresses

AU - Hanhijärvi, Antti

AU - Wahl, Paul

AU - Räsänen, Jari

AU - Silvennoinen, Raimo

PY - 2003

Y1 - 2003

N2 - Morén (1994) has suggested that during the early stages of the timber drying process, some damage, small cracks or “microcracks”, develop on the wood surface and this hypothesis has been shared by others (Hukka and Tarvainen 1997). However, the so-called microcracks have not been directly observed and the hypothesis is based on the observations of the cracking behaviour later during the drying process. Up to 50% difference in the final amount of visible cracks at the end of drying has been observed depending on the way the early warm-up stage is conducted (the actual drying stage being the same). It is suggested that something happens on the surface in the early stages that makes it more vulnerable to later developing cracks. A readily acceptable explanation is the appearance of small cracks on the surface, invisible to the naked eye, that act as initial flaws and later grow into visible cracks. The name “microcracks” has been attached to these cracks as opposed to visible “macrocracks”. The width limit for the visibility of cracks with the naked eye is approximately 0.1 mm (Wahl 1999), which may be used as a practical definition for the upper limit of “microcracks”. The goal of this work is to detect microcracks on wood surfaces and to verify the microcracking hypothesis and then to quantify it. For this purpose, a measurement technique was developed, its function verified as reported in (Wahl et al. 2001), and then applied for tests of microcracking. The results shown here concern wood surfaces examined during drying, and compare the amount of microcracking in various drying conditions.

AB - Morén (1994) has suggested that during the early stages of the timber drying process, some damage, small cracks or “microcracks”, develop on the wood surface and this hypothesis has been shared by others (Hukka and Tarvainen 1997). However, the so-called microcracks have not been directly observed and the hypothesis is based on the observations of the cracking behaviour later during the drying process. Up to 50% difference in the final amount of visible cracks at the end of drying has been observed depending on the way the early warm-up stage is conducted (the actual drying stage being the same). It is suggested that something happens on the surface in the early stages that makes it more vulnerable to later developing cracks. A readily acceptable explanation is the appearance of small cracks on the surface, invisible to the naked eye, that act as initial flaws and later grow into visible cracks. The name “microcracks” has been attached to these cracks as opposed to visible “macrocracks”. The width limit for the visibility of cracks with the naked eye is approximately 0.1 mm (Wahl 1999), which may be used as a practical definition for the upper limit of “microcracks”. The goal of this work is to detect microcracks on wood surfaces and to verify the microcracking hypothesis and then to quantify it. For this purpose, a measurement technique was developed, its function verified as reported in (Wahl et al. 2001), and then applied for tests of microcracking. The results shown here concern wood surfaces examined during drying, and compare the amount of microcracking in various drying conditions.

U2 - 10.1515/HF.2003.083

DO - 10.1515/HF.2003.083

M3 - Article

VL - 57

SP - 561

EP - 565

JO - Holzforschung

JF - Holzforschung

SN - 0018-3830

IS - 5

ER -