Similar to a normal wave, a shock wave travels as energy through matter but it causes an abrupt raise of pressure, temperature and density. In this study the influence of shock waves on wood structure were investigated in the light of possible future industrial utilization e.g. timber impregnating treatment. On that account, an autoclave containing a shock wave generating device has been constructed and built by Technische Universität Ilmenau, Germany, and Premetec Automation GmbH, Suhl, Germany, respectively. Thereby shock waves were generated by an electrical pulse breakdown of a spark gap arrangement or by electromagnetic accelerators or actuators within the fluid inside the autoclave. In order to analyze the penetration depths, water stained with Aniline blue was used as putative impregnating liquid. The impact of pressure pulse shock waves on the wood tissue integrity and on cellular structure of the tested fir wood samples was investigated by light microscopy, SEM as well as by micro-computed tomography. Apart from visual assessment, penetration depths were also analyzed by IR spectroscopy.
Once a shock wave has been released by the spark gap or by an electromagnetic actuator, pressure should be instantly identical in the cylinder of the autoclave. But whether the orientation to the shock wave is perpendicular or longitudinal to the grain, the effects depend more on the intensity of the incident shock wave, on the distance to the shock wave generating device, as well as on the orientation of sample arrangement. The tissue structure was either heavily damaged or hardly affected at all.
Keywords: shock wave, pressure pulse, impregnation, microtomography
Authors
Moritz Sanne
Eberswalde University for Sustainable Development, Faculty of Wood Engineering, Eberswalde, Germany
Anja Kampe
Eberswalde University for Sustainable Development, Faculty of Wood Engineering, Eberswalde, Germany
Claudia Lenz
Eberswalde University for Sustainable Development, Faculty of Wood Engineering, Eberswalde, Germany
Stefan Gossel
Technische Universität Ilmenau, Interdepartmental Center for Energy Technologies, Research Unit High-Voltage Technologies, Germany
Sabine Wagner
Dipl.-Ing. Sabine Wagner, PREMETEC Automation GmbH
Astrid Haibel
Beuth University of Applied Sciences Berlin, Department II – Mathematics – Physics – Chemistry, Berlin, Germany
Eckhard Melcher
Thünen Institute of Wood Research, Hamburg, Germany
Carsten Leu
Technische Universität Ilmenau, Interdepartmental Center for Energy Technologies, Research Unit High-Voltage Technologies, Germany
Alexander Pfriem
Eberswalde University for Sustainable Development, Faculty of Wood Engineering, Eberswalde, Germany
Silke Lautner
Eberswalde University for Sustainable Development, Faculty of Wood Engineering, Eberswalde, Germany
Login to download the PDF