scholarly journals Finite-element-based moisture transport model for wood including free water above the fiber saturation point

2020 ◽  
Vol 161 ◽  
pp. 120228 ◽  
Author(s):  
Maximilian Autengruber ◽  
Markus Lukacevic ◽  
Josef Füssl
Keyword(s):  
Finite Element ◽  
Moisture Transport ◽  
Transport Model ◽  
Free Water ◽  
Fiber Saturation Point ◽  
Saturation Point ◽  
Fiber Saturation

Moisture in softwoods: fiber saturation point, hydroxyl site content, and the amount of micropores as determined from NMR relaxation time distributions

Holzforschung ◽  
2013 ◽  
Vol 67 (3) ◽  
pp. 291-300 ◽  
Author(s):  
Ville-Veikko Telkki ◽  
Miikka Yliniemi ◽  
Jukka Jokisaari
Keyword(s):  
Melting Point ◽  
Relaxation Times ◽  
Bound Water ◽  
Nmr Relaxation ◽  
Free Water ◽  
Bulk Water ◽  
Fiber Saturation Point ◽  
Saturation Point ◽  
Fiber Saturation ◽  
Nmr Relaxation Times

Abstract Distributions of nuclear magnetic resonance (NMR) relaxation times provide detailed information about the moisture absorbed in wood. In this work, T2*, T2, and T1 distributions were recorded from fresh sapwood and heartwood samples of pine (Pinus sylvestris) and spruce (Picea abies) at various temperatures. Below the melting point of bulk water, free water is frozen and its signal disappears from the distributions. Then, the low-temperature distributions of the unfrozen bound water contain more information about its components, because the large free water peaks hiding some smaller bound water peaks are absent and the exchange between free and bound water is prevented. Comparison of the total moisture signal integrals above and below the bulk melting point enables the determination of fiber saturation point (FSP), which, in this context, denotes the total water capacity of cell wall. T2*, T2, and T1 distributions offer different kinds of information about moisture components. All the peaks in the distributions were assigned, and it was demonstrated that the accessible hydroxyl site content and the amount of micropores can be estimated based on the peak integrals.

Experimental Data Correction of the Dynamic Elastic Moduli, Velocity and Density of Solid Wood as a Function of Moisture Content above the Fiber Saturation Point

Holzforschung ◽  
2000 ◽  
Vol 54 (3) ◽  
pp. 309-314 ◽  
Author(s):  
Song-Yung Wang ◽  
Shih-Tzu Chuang
Keyword(s):  
Moisture Content ◽  
Wave Velocity ◽  
Stress Wave ◽  
Elastic Moduli ◽  
Free Water ◽  
Fiber Saturation Point ◽  
Saturation Point ◽  
Static Tests ◽  
Simulation Procedure ◽  
Fiber Saturation

Summary Experimentally it was observed that the dynamic modulus of elasticity calculated from the velocity of stress wave or ultrasonic wave and the density of wood in green condition increased with increasing moisture content. This statement disagrees with the physical meaning of data observed with static tests, namely the decreasing of all mechanical properties of wood with increasing moisture content. To elucidate this discrepancy a simulation procedure was developed to study the effect of free water, present in wood above the fiber saturation point on wave velocity. For this purpose the coefficient k, related to the mobility of free water was defined, as a ratio of free water vibrating simultaneously with water present in cellular wall (k = 0.6 for stress wave velocity and k = 0.7 for ultrasonic velocity). The simulation procedure using corrected values of velocity and density showed that the elastic moduli are relatively constant above the FSP, as all the mechanical parameters determined with static tests.

scholarly journals Determination of fiber saturation point of rattan (Calamus simplicifolius) using the LF-NMR and two conventional methods

2020 ◽  
Vol 54 (3) ◽  
pp. 667-682
Author(s):  
Limei Yang ◽  
Genlin Tian ◽  
Shumin Yang ◽  
Lili Shang ◽  
Xing’e Liu ◽  
...  
Keyword(s):  
Fiber Saturation Point ◽  
Saturation Point ◽  
Fiber Saturation ◽  
Conventional Methods ◽  
Calamus Simplicifolius ◽  
Lf Nmr

Modeling of Transient Moisture Diffusion in Wood below the Fiber Saturation Point

2011 ◽  
Vol 312-315 ◽  
pp. 455-459
Author(s):  
Johannes Eitelberger ◽  
Karin Hofstetter
Keyword(s):  
Steady State ◽  
Moisture Diffusion ◽  
Transport Processes ◽  
Fiber Saturation Point ◽  
Saturation Point ◽  
Transient Transport ◽  
Fiber Saturation ◽  
Physical Background ◽  
The Difference ◽  
Near Future

During the last two decades the macroscopic formulation of moisture transport in wood below the fiber saturation point has motivated many research efforts. From experiments the difference in steady-state and transient transport processes is well known, but could not be explained in a fully physically motivated manner. In the following article, first the microstructure of wood is depicted, followed by a description of the physical background of steady-state and transient transport processes in wood, and thereon based mathematical formulations. For a correct macroscopic description of transient transport processes, three coupled differential equations have to be solved in parallel, which is done using the finite element method. The validation of the whole model by comparison of model predictions with experimentally derived values is currently in progress and will be published in near future.

Relationship Between the Degree of Resistance to a Pulsed Electric Current and Wood in Progressive Stages of Discoloration and Decay in Living Trees

1972 ◽  
Vol 2 (3) ◽  
pp. 236-243 ◽  
Author(s):  
Terry A. Tattar ◽  
Alex L. Shigo ◽  
Thomas Chase
Keyword(s):  
Electric Current ◽  
Calcium Ions ◽  
Fiber Saturation Point ◽  
Decayed Wood ◽  
Saturation Point ◽  
Mineral Contents ◽  
Fiber Saturation ◽  
Pulsed Electric Current

The degree of resistance to a pulsed electric current of wood in progressive stages of discoloration and decay in living trees was correlated primarily with the moisture and mineral contents of the wood. Below the fiber saturation point, the degree of resistance was correlated primarily with the amount of moisture while above the fiber saturation point resistance was correlated primarily with the concentration of mobile potassium and calcium ions. The apparatus used to produce the current and to measure the resistance to it was accurate in detecting and in indicating the stage of deterioration of discolored and decayed wood. The apparatus was tested and found to be reliable electrically within the range of resistances encountered in the trees studied.

Sign in / Sign up

Export Citation Format

Share Document