Investigations on the thermo-mechanical behaviour of densified veneer wood for cryogenic applications

ABSTRACT

In this study, the thermo-mechanical behaviour of densified veneer wood (DVW) for cryogenic applications like load-bearing insulation elements for liquid energy sources is investigated. Mechanical tests with compression parallel and transverse to the veneer plane were performed after conditioning the material at five temperature levels: +60°C, +20°C, −40°C, −78°C (dry ice) and −196°C (liquid nitrogen). The investigations showed increasing compression moduli but also increasing brittleness with decreasing temperature. The compressive strength increased with decreasing temperature until about −30°C. Below this temperature, the strength slightly decreased again. The specific heat capacity was determined in the range of −150°C to +60°C and showed a linear dependency on temperature below +20°C. Above +20°C, a non-linear increase is observed due to evaporation of bound water. Finally, a technique is presented to mould DVW boards transverse to the lamination direction with a thermo-hygro-mechanical process in order to reduce waste material associated with commonly used chipping techniques.

KEYWORDS:

• Compressive strength
• cryogenic temperatures
• compressed laminated wood
• moulding technique
• specific heat capacity

Acknowledgements

The authors thank the project partner Deutsche Holzveredelung Schmeing GmbH & Co. KG, Kirchhundem for collaboration.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the German Federal Ministry for Economic Affairs and Climate Action (Bundesministerium für Wirtschaft and Klimaschutz) by the ZIM cooperation projects under grants ZF4453301WZ7 and ZF4453302WZ9.