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Holmgren, Sven-Erik
Publications (3 of 3) Show all publications
Holmgren, S.-E., Svensson, B. A., Gradin, P. A. & Lundberg, B. (2008). An Encapsulated Split Hopkinson Pressure Bar for Testing of Wood at Elevated Strain Rate, Temperature and Pressure. Experimental techniques (Westport, Conn.), 32(5), 44-50
Open this publication in new window or tab >>An Encapsulated Split Hopkinson Pressure Bar for Testing of Wood at Elevated Strain Rate, Temperature and Pressure
2008 (English)In: Experimental techniques (Westport, Conn.), ISSN 0732-8818, E-ISSN 1747-1567, Vol. 32, no 5, p. 44-50Article in journal (Refereed) Published
Abstract [en]

This paper presents a device, based on a split Hopkinson pressure bar (SHPB) setup, by which it is possible to obtain stress vs. strain for a wood specimen at high deformation rate, high temperature and high steam pressure. The need for determining the mechanical properties of wood not only at high deformation rate but also at high temperature and pressure is motivated by the need to model the wood chip refining process in mechanical pulp-ing. At mechanical chip refining, e.g. in thermomechanical pulping processes, preheated wood chips together with added water are fed into the centre of a refiner which in essence consists of two circular discs. Most often one disc is stationary and the other is rotating. The wood chips are transported radially between the discs due to inertia. On their way, due to impacts from radial bars on the discs, they are eventually broken down to individual fibres and fibre fragments. The device presented here is an SHPB set-up, modified so that the bars and the specimen are encapsulated in a pressure vessel within which the temperature is constant. In this way effects of temperature gradients in the bars are avoided. Pilot tests have been carried out which verify the intended per-formance of the device.

Keywords
dynamic testing
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:miun:diva-1692 (URN)10.1111/j.1747-1567.2008.00318.x (DOI)000259524500006 ()2-s2.0-54749107120 (Scopus ID)5058 (Local ID)5058 (Archive number)5058 (OAI)
Note
VR-Available from: 2008-11-30 Created: 2008-11-17 Last updated: 2017-12-13Bibliographically approved
Svensson, B. A., Holmgren, S.-E., Gradin, P. A. & Höglund, H. (2007). High Strain Rate Compression and Sliding Friction of Wood under Refining Conditions. In: International Mechanical Pulping Conference 2007, TAPPI: . Paper presented at International Mechanical Pulping Conference 2007, TAPPI; Minneapolis, MN; United States; 6 May 2007 through 9 May 2007; Code 73991 (pp. 983-994). , 2
Open this publication in new window or tab >>High Strain Rate Compression and Sliding Friction of Wood under Refining Conditions
2007 (English)In: International Mechanical Pulping Conference 2007, TAPPI, 2007, Vol. 2, p. 983-994Conference paper, Published paper (Other academic)
Abstract [en]

Compression and friction characteristics are needed in order to gain a better grasp of the forces acting during refining. To this end, both stress-strain relations and frictional behavior of wood were investigated under simulated chip refining conditions (hot saturated steam, high strain rate compression, and high sliding speed). Two new, custom-designed, experimental set-ups were used. Both pieces of equipment allow a testing environment of hot saturated steam. The wood-steel friction investigations indicate that when making measurements in the lower temperature region (100C-130C), surface properties such as lubrication have a great influence on the coefficients of friction. Traces of lubricating layers, comprising fatty acids, were found on friction-tested pine surfaces using a staining technique and light microscopy; in the higher-temperature region no traces of lubrication could be detected in this way.

Keywords
Friction, Compression
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-4279 (URN)2-s2.0-55849096900 (Scopus ID)5060 (Local ID)978-160560293-6 (ISBN)5060 (Archive number)5060 (OAI)
Conference
International Mechanical Pulping Conference 2007, TAPPI; Minneapolis, MN; United States; 6 May 2007 through 9 May 2007; Code 73991
Available from: 2008-09-30 Created: 2009-06-08 Last updated: 2016-09-23Bibliographically approved
Svensson, B., Holmgren, S.-E., Höglund, H., Gradin, P. & Lundberg, B.High Strain Rate Compression of Spruce Wood in a Saturated Steam Environment.
Open this publication in new window or tab >>High Strain Rate Compression of Spruce Wood in a Saturated Steam Environment
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-9399 (URN)
Available from: 2009-07-16 Created: 2009-07-16 Last updated: 2011-05-29Bibliographically approved
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