Elastic tensions in a wood material subjected to thermo-mechanical treatment by pressure drop

Thermo-mechanical treatment by pressure drop consists in heating of the material under high pressure of external gas or vapor up to the temperature close to the saturation value under given pressure, with subsequent abrupt drop of the external pressure. This procedure is accompanied by significant mechanical stress as a result of the pressure gradient action and deformations caused by drying. Here, the elastic tensions inside the matrix material have been calculated taking into account simultaneous action of the both factors. Calculations were performed for various values of the parameters, characterizing material properties and regime parameters, namely the sample size, permeability, initial moisture content, initial pressure and the rate of the external pressure drop. Based on the results of calculations, the conditions for the material mechanical destruction have been determined.