Simulating the Hygromechanical Response of Wood

ISBN-13: 9783838334608 / Angielski / Miękka / 2010 / 140 str.

Henrik Lund Frandsen

Opis

This PhD thesis treats modeling of the hygromechanical response of wood. To do so it is crucial to have accurate models for the moisture transport. Moisture transport in the cellular structure of wood consists of a combination of water vapor transport and bound water transport. In present work these are modeled as two diffusion equations, which are coupled through sorption. Such a model is able to describe so-called non-Fickian effects. Sorption is known to be hysteretic, which must be taken into account in order to describe changes of the moisture content in relation to water vapor pressure accurately. In present work a new sorption hysteresis model suitable for implementation into a numerical method is developed. The sorption hysteresis model is combined with the multi-Fickian model allowing simultaneous simulation of non-Fickian effects and hysteresis. Furthermore temperature dependencies of the model are considered. The latter part of this work deals with the transverse couplings in creep of wood based on experimental observations. A new orthotropic creep model, which provides directionally independent creep rates, is proposed.

O autorze

Dr. Henrik Lund Frandsen did his M.Sc. in civil engineering with specialty in active control of vibrations in wind turbine blades. His Ph.D. was on moisture transport and its influence on creep of wood. His most recent work is on fracture mechanics, creep and plasticity, and failure statistics for different fuel cell stack components.