Original title: Analysis of mini-jack technique for in situ measurement of strength
Authors: Kloiber, Michal ; Tippner, J. ; Kunecký, Jiří ; Sebera, V. ; Milch, J. ; Hrivnák, Jaroslav
Document type: Papers
Conference/Event: International Conference on Timber Bridges, ICTB 2017 /3./, Skelleftea (SE), 20170626
Year: 2017
Language: eng
Abstract: The paper presents a recently developed diagnostic technique for in situ determination of modulus of deformability (MODL) and conventional strength (CSL) parallel to the grain using the mini-jack inserted in bored hole. The mini-jack compression technique simulates the standard compression test, it is compared to that to examine its prediction strength (correlation coefficients). The paper shows an influence of moisture content of wood on experimental measurements using this technique. The measurement was carried out at spruce samples at three moisture contents of 12, 18 and 24%. The results of the tests prove a very good correlation of the strength determined by the proposed technique and wood density and strength determined at universal testing machine in compression parallel to the grain. The effect of the moisture content on the measurement by the mini-jack technique was proved to be significant. Beside that, the newly-developed instrument was also studied using digital image correlation (DIC) technique to analyze induced strains around the bored hole. This was studied on halved spruce samples. The DIC revealed symmetric character of the loading and significant differences between strains induced in tangential and longitudinal directions.
Keywords: compression strength; in-situ testing; mini-jack technique; non-destructive testing; wood
Project no.: DG16P02M026 (CEP)
Host item entry: Conference proceedings, ICTB 2017, 3rd International Conference on Timber Bridges, ISSN 0284-5172

Institution: Institute of Theoretical and Applied Mechanics AS ČR (web)
Document availability information: Fulltext is available at the institute of the Academy of Sciences.
Original record: http://hdl.handle.net/11104/0273570

Permalink: http://www.nusl.cz/ntk/nusl-373463

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Research > Institutes ASCR > Institute of Theoretical and Applied Mechanics
Conference materials > Papers
 Record created 2018-03-09, last modified 2018-03-09

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