TY - JOUR
T1 - Deformation of wood slice in fire
T2 - Interactions between heterogeneous chemistry and thermomechanical stress
AU - Wang, Supan
AU - Ding, Pengfei
AU - Lin, Shaorun
AU - Huang, Xinyan
AU - Usmani, Asif
N1 - Funding Information:
This work is supported by NSFC ( 51706095 , 51876183 ), Natural Science Foundation of Jiangsu Province of China ( BK20171001 ), China Postdoctoral Science Foundation ( 2017M611798 ), HK PolyU (BE-04), and the opening Fund of SKLFS ( HZ2017-KF09 , HZ2019-KF02 ).
Publisher Copyright:
© 2020 The Combustion Institute.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/10/21
Y1 - 2020/10/21
N2 - Wood is a common flammable material in the building fire and the dominant fuel in the wildland fire. In this work, disc wood slices were examined under irradiation to characterize the smoldering burning and the corresponding deformation behaviors. Due to interactions between chemical reactions and thermomechanical stresses, four successive deformation stages were observed and hypothesized: (I) drying shrinkage to ∪ shape, (II) irradiation-driven thermal expansion to ∩ shape, (III) pyrolysis shrinkage to ∪ shape, and (IV) oxidation-driven thermal expansion to ∩ shape. For these 5-15 mm thick samples, the degree and occurrence of these deformation stages are sensitive to the aspect ratio (i.e. D/δ). Increasing the slice thickness decreases the deformation in the first three stages but increases the deformation of the fourth stage. These experimental observations are qualitatively reproduced by a 2-D finite-element numerical model, coupling 3-step heterogeneous kinetics with a thermomechanical solver. Modeling results further verified the underlying heterogeneous processes (dehydration, pyrolysis, and oxidation) and thermomechanical stresses (thermal expansion and pre-stress) for each deformation stage. This study helps understand the influence of burning processes on the deformation of wood and the failure of timber structures.
AB - Wood is a common flammable material in the building fire and the dominant fuel in the wildland fire. In this work, disc wood slices were examined under irradiation to characterize the smoldering burning and the corresponding deformation behaviors. Due to interactions between chemical reactions and thermomechanical stresses, four successive deformation stages were observed and hypothesized: (I) drying shrinkage to ∪ shape, (II) irradiation-driven thermal expansion to ∩ shape, (III) pyrolysis shrinkage to ∪ shape, and (IV) oxidation-driven thermal expansion to ∩ shape. For these 5-15 mm thick samples, the degree and occurrence of these deformation stages are sensitive to the aspect ratio (i.e. D/δ). Increasing the slice thickness decreases the deformation in the first three stages but increases the deformation of the fourth stage. These experimental observations are qualitatively reproduced by a 2-D finite-element numerical model, coupling 3-step heterogeneous kinetics with a thermomechanical solver. Modeling results further verified the underlying heterogeneous processes (dehydration, pyrolysis, and oxidation) and thermomechanical stresses (thermal expansion and pre-stress) for each deformation stage. This study helps understand the influence of burning processes on the deformation of wood and the failure of timber structures.
KW - Charring
KW - Finite element analysis
KW - Smoldering
KW - Thermal expansion
KW - Timber
UR - http://www.scopus.com/inward/record.url?scp=85097410798&partnerID=8YFLogxK
U2 - 10.1016/j.proci.2020.08.060
DO - 10.1016/j.proci.2020.08.060
M3 - Journal article
AN - SCOPUS:85097410798
SN - 1540-7489
VL - 38
SP - 5081
EP - 5090
JO - Proceedings of the Combustion Institute
JF - Proceedings of the Combustion Institute
IS - 3
ER -