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

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 cree...

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Bibliographic Details
Published in:European journal of wood and wood products Vol. 78; no. 6; pp. 1095 - 1103
Main Authors: Afshar, R., Cheylan, M., Almkvist, G., Ahlgren, A., Gamstedt, E. K.
Format: Journal Article
Language:English
Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2020
Springer Nature B.V
Subjects:
Biomedical and Life Sciences
Ceramics
Cold flow
Composites
Compressive properties
Creep strength
Deformation
Engineering Science with specialization in Solid Mechanics
Glass
Life Sciences
Linearity
Machines
Manufacturing
Mathematical models
Museums
Natural Materials
Numerical models
Numerical prediction
Original Article
Parameters
Processes
Rheological properties
Shipwrecks
Strain
Stress-strain curves
Stress-strain relationships
Teknisk fysik med inriktning mot hållfasthetslära
Threshold stress
Thresholds
Trävetenskap
Vasa oak
Viscoelasticity
wood
Wood Science
Wood Science & Technology
Wooden structures
ISSN:0018-3768, 1436-736X, 1436-736X
Online Access:Get full text
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Description
Summary: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.
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ISSN:0018-3768
1436-736X
1436-736X
DOI:10.1007/s00107-020-01566-1