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

Abstract

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.