44975
2018
eng
957
969
4
52
article
Springer
Berlin Heidelberg
1
--
--
--
Sorption surfaces and energies of untreated and thermally modified wood evaluated by means of excess surface work (ESW)
Water vapor sorption surface areas and sorption energies of untreated
and thermally modified Norway spruce [Picea abies (L.) Karst.], sycamore maple (Acer pseudoplatanus L.) and European ash (Fraxinus excelcior L.) were investigated by means of dynamic vapor sorption (DVS) measurements and excess surface work (ESW) evaluation method, respectively. Adsorption and desorption experiments in the hygroscopic range and desorption tests from water saturation were conducted.
Thermodynamically, ESW is the sum of the surface free energy and the isothermal isobaric work of sorption. From the amount adsorbed in the first Minimum a specific surface area similar to the BET surface area can be obtained. The results show that untreated spruce has a significantly higher specific water vapor Sorption surface and sorption energy compared to both hardwoods maple and ash. Thermal modification of the woods leads to a significant reduction of water vapor Sorption surface and sorption energy. The determined surface area and energy are higher in desorption direction than in adsorption direction, whereby the highest values in Desorption direction from water saturation, especially for maple and ash, were obtained.
The surface areas calculated by means of the ESW method are similar to the surface areas calculated by means of the BET method, particularly in adsorption direction.
Wood Science and Technology
10.1007/s00226-018-1021-2
1432-5225
0043-7719
05.07.2018
M. Zauer
Carsten Prinz
J. Adolphs
Franziska Emmerling
A. Wagenführ
eng
uncontrolled
Excess surface work
eng
uncontrolled
Dynamic vapor sorption
eng
uncontrolled
Wood
eng
uncontrolled
BET
Analytische Chemie
Ingenieurwissenschaften und zugeordnete Tätigkeiten
6 Materialchemie
6.3 Strukturanalytik
Material
Chemie und Prozesstechnik
Verlagsliteratur
Datei im Netzwerk der BAM verfügbar ("Closed Access")
51010
2020
eng
81
88
62 Part 1
13
bookpartcollection
Transilvania University Press, Brasov, Romania
Brasov
0
--
--
--
Acoustic Emission Analysis And Synchrotron-based Microtomography of glued shear strength samples from spruce wood
To better understanding the failure of adhesive joints tensile tests were carried out on miniature test specimens from Norway spruce in the synchrotron. Urea-formaldehyde resin was used as adhesive. e. For comparison purposes, tensile tests were carried out on solid wood and on bonded miniature tensile shear samples with acoustic emission. The acoustic emission signals of all the experiments occurred with classified pattern recognition. This resulted in two classes of signals for each two frequency peaks. One class consisted of the low-frequency and the other of the higher-frequency peak of higher intensity, but this was essentially independent from the structure (solid wood or plywood) and size scale of the test specimens. The influence of the adhesive layers was determined on wood test specimens on laboratory scale and on miniature test specimens with an adhesive layer and selected fiber orientations. This gave evidence that the sound emission signals from the failure of the adhesive layer presumably of the class with low frequency signals peak in the range of services can be assigned.
Bulletin of the Transilvania University of Braşov, Series II
10.31926/but.fwiafe.2020.13.62.1.7
false
true
P. Niemz
Franziska Baensch
A. J. Brunner
eng
uncontrolled
Wood
eng
uncontrolled
Bondline
eng
uncontrolled
In-situ test
eng
uncontrolled
Acoustic emission
eng
uncontrolled
Synchrotron tomography
Analytische Chemie
Ingenieurwissenschaften und zugeordnete Tätigkeiten
8 Zerstörungsfreie Prüfung
8.1 Sensorik, mess- und prüftechnische Verfahren
Material
Degradation von Werkstoffen
Chemie und Prozesstechnik
Datei im Netzwerk der BAM verfügbar ("Closed Access")
Graue Literatur
51517
2020
eng
poster
0
--
--
--
Heat Flux from Wood Filled Impact Limiter under Fire Conditions
Packages for the transport of high-level radioactive material must withstand severe hypothetical accidents. Regulatory test conditions shall cover these severe accident conditions and consist of mechanical tests and a following thermal test. To withstand the mechanical tests heavy weight packages are often designed with impact limiters consisting of wood encapsulated in steel sheets. The thermal test is defined precisely in the IAEA-regulations as a 30 minute fully engulfing 800 °C fire. After the fire phase a pre-damaged impact limiter might continue burning or smouldering and influence the cask thermal behaviour with its energy release. The energy transferred from the impact limiter to the cask is of importance for the safety of transport packages. A full-scale fire test with an impact limiter of 2.3 m in diameter and filled with spruce wood was designed and performed. The impact limiter continued burning for 3 days. Energy transfer and temperature measurements were performed.
9th International Scientific Conference - wood & fire safety 2020
Online meeting
02.11.2020
03.11.2020
false
true
Martin Feldkamp
eng
uncontrolled
Fre
eng
uncontrolled
Smouldering
eng
uncontrolled
Wood
Ingenieurwissenschaften und zugeordnete Tätigkeiten
3 Gefahrgutumschließungen; Energiespeicher
3.3 Sicherheit von Transportbehältern
Energie
Datei im Netzwerk der BAM verfügbar ("Closed Access")
Präsentation
Kerntechnische Entsorgung
41613
2017
eng
Article UNSP V007T07A037, 1
9
7
conferenceobject
ASME
1
--
--
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Development of a material model for the crush of spruce wood
Typical transport packages used in Germany are equipped with wooden impact limiting devices. In this paper we give an overview of the latest status regarding the development of a finite element material model for the crush of spruce wood. Although the crush of wood – mainly in longitudinal direction – is a phenomenon governed by macroscopic fracture and failure of wood fibres we smear fracture and failure mechanisms over the continuous voume. In first step we altered an existing LS-DYNA material model for foams, which considers an ellipse shaped yield surface written in terms of the first two stress invariants. The evolution of the yield surface in the existing model depends on the volumetric strain only. For the use with spruce wood, we modified the existing material model to consider the deviatoric strain for the evolution of the yield surface as well. This is in accordance with the results of crush tests with spruce wood specimens, where the crushing deformation was rather deviatoric for uniaxial stress states and rather volumetric for multiaxial stress states We rate the basic idea of this approach to be reasonable, though other problems exist regarding the shape of the yield surface and the assumption of isotropic material properties. Therefore we developed a new transversal isotropic material model with two main directions, which considers different yield curves according to the multiaxiality of the stress state via a multi-surface yield criterion and a non-associated flow rule. The results show the ability to reproduce the basic strength characteristics of spruce wood. Nevertheless, problems with regularization etc. show that additional investigations are necessary.
Proceedings of ASME PVP 2017
978-0-7918-5802-8
ASME PVP 2017
Waikaloa, HY, USA
16.07.2017
20.07.2017
08.02.2018
Martin Neumann
Germar Eisenacher
Thorsten Schönfelder
Frank Wille
eng
uncontrolled
Chrush
eng
uncontrolled
Spruce
eng
uncontrolled
Wood
eng
uncontrolled
FEM
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Angewandte Physik
Datei im Netzwerk der BAM verfügbar ("Closed Access")
Graue Literatur
41617
2017
eng
poster
0
--
--
--
Development of a material model for the crush of spruce wood
Typical transport packages used in Germany are equipped with wooden impact limiting devices. In this paper we give an overview of the latest status regarding the development of a finite element material model for the crush of spruce wood. Although the crush of wood – mainly in longitudinal direction – is a phenomenon governed by macroscopic fracture and failure of wood fibres we smear fracture and failure mechanisms over the continuous voume. In first step we altered an existing LS-DYNA material model for foams, which considers an ellipse shaped yield surface written in terms of the first two stress invariants. The evolution of the yield surface in the existing model depends on the volumetric strain only. For the use with spruce wood, we modified the existing material model to consider the deviatoric strain for the evolution of the yield surface as well. This is in accordance with the results of crush tests with spruce wood specimens, where the crushing deformation was rather deviatoric for uniaxial stress states and rather volumetric for multiaxial stress states We rate the basic idea of this approach to be reasonable, though other problems exist regarding the shape of the yield surface and the assumption of isotropic material properties. Therefore we developed a new transversal isotropic material model with two main directions, which considers different yield curves according to the multiaxiality of the stress state via a multi-surface yield criterion and a non-associated flow rule. The results show the ability to reproduce the basic strength characteristics of spruce wood. Nevertheless, problems with regularization etc. show that additional investigations are necessary.
ASME PVP 2017
Waikaloa, HY, USA
16.07.2017
20.07.2017
Martin Neumann
eng
uncontrolled
Crush
eng
uncontrolled
Wood
eng
uncontrolled
Spruce
eng
uncontrolled
FEM
Ingenieurwissenschaften und zugeordnete Tätigkeiten
Angewandte Physik
Datei im Netzwerk der BAM verfügbar ("Closed Access")
Präsentation
58001
2023
eng
1
32
7
18
article
PLOS
San Francisco, California, US
1
--
--
--
A double-pointed wooden throwing stick from Schöningen, Germany: Results and new insights from a multianalytical study
The site of Schöningen (Germany), dated to ca. 300,000 years ago, yielded the earliest large-scale record of humanly-made wooden tools. These include wooden spears and shorter double-pointed sticks, discovered in association with herbivores that were hunted and butchered along a lakeshore. Wooden tools have not been systematically analysed to the same standard as other Palaeolithic technologies, such as lithic or bone tools. Our multianalytical study includes micro-CT scanning, 3-dimensional microscopy, and Fourier transform infrared spectroscopy, supporting a systematic technological and taphonomic analysis, thus setting a new standard for wooden tool analysis. In illustrating the biography of one of Schöningen’s double-pointed sticks, we demonstrate new human behaviours for this time period, including sophisticated woodworking techniques. The hominins selected a spruce branch which they then debarked and shaped into an aerodynamic and ergonomic tool. They likely seasoned the wood to avoid cracking and warping. After a long period of use, it was probably lost while hunting, and was then rapidly buried in mud. Taphonomic alterations include damage from trampling, fungal attack, root damage and compression. Through our detailed analysis we show that Middle Pleistocene humans had a rich awareness of raw material properties, and possessed sophisticated woodworking skills. Alongside new detailed morphometrics of the object, an ethnographic review supports a primary function as a throwing stick for hunting, indicating potential hunting strategies and social contexts including for communal hunts involving children. The Schöningen throwing sticks may have been used to strategically disadvantage larger ungulates, potentially from distances of up to 30 metres. They also demonstrate that the hominins were technologically capable of capturing smaller fast prey and avian fauna, a behaviour evidenced at contemporaneous Middle Pleistocene archaeological sites.
PLOS ONE
1932-6203
10.1371/journal.pone.0287719
urn:nbn:de:kobv:b43-580012
publish
31.07.2023
false
true
Creative Commons - CC BY - Namensnennung 4.0 International
A. Milks
J. Lehmann
D. Leder
M. Sietz
T. Koddenberg
U. Böhner
Volker Wachtendorf
T. Terberger
eng
uncontrolled
FTIR
eng
uncontrolled
Stone Age
eng
uncontrolled
Middle Pleistocene
eng
uncontrolled
Throwing-stick
eng
uncontrolled
Wood
eng
uncontrolled
Micro-CT scanning
eng
uncontrolled
3-dimensional microscopy
Ingenieurwissenschaften und zugeordnete Tätigkeiten
7 Bauwerkssicherheit
7.5 Technische Eigenschaften von Polymerwerkstoffen
Material
Degradation von Werkstoffen
Verlagsliteratur
Datei für die Öffentlichkeit verfügbar ("Open Access")
Wissenschaftliche Artikel der BAM
Bundesanstalt für Materialforschung und -prüfung (BAM)
https://opus4.kobv.de/opus4-bam/files/58001/Wachtendorf_Schoeningen_throwing_stick_PlusOne_2023.pdf