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Research article - Peer-reviewed, 2020

Creep in oak material from the Vasa ship: verification of linear viscoelasticity and identification of stress thresholds

Afshar, R.; Cheylan, M.; Almkvist, G.; Ahlgren, A.; Gamstedt, E. K.


Creep deformation is a general problem for large wooden structures, and in particular for shipwrecks in museums. In this study, experimental creep data on the wooden cubic samples from the Vasa ship have been analysed to confirm the linearity of the viscoelastic response in the directions where creep was detectable (T and R directions). Isochronous stress-strain curves were derived for relevant uniaxial compressive stresses within reasonable time spans. These curves and the associated creep compliance values justify that it is reasonable to assume a linear viscoelastic behaviour within the tested ranges, given the high degree of general variability. Furthermore, the creep curves were fitted with a one-dimensional standard linear solid model, and although the rheological parameters show a fair amount of scatter, they are candidates as input parameters in a numerical model to predict creep deformations. The isochronous stress-strain relationships were used to define a creep threshold stress below which only negligible creep is expected. These thresholds ranges were 0.3-0.5 MPa in the R direction and 0.05-0.2 MPa in the T direction.

Published in

European Journal of Wood and Wood Products
2020, volume: 78, number: 6, pages: 1095-1103
Publisher: SPRINGER

Authors' information

Afshar, R.
Uppsala Univ
Cheylan, M.
Ecole Natl Super Mecan and Microtech
Almkvist, Gunnar
Swedish University of Agricultural Sciences, Department of Molecular Sciences
Ahlgren, A.
Vasa Museum
Gamstedt, E. K.
Uppsala Univ

UKÄ Subject classification

Wood Science

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