Session: K20-05: APPLICATIONS OF COMPUTATIONAL HEAT TRANSFER III

Paper Number: 142758

142758 - Determination of the Safe Kiln Drying Rate of Lumber 

Abstract: 

The aim of this paper is to present the mathematical modeling and computer implementation for the kiln drying of lumber without causing cracks.  Wood is heterogeneous, i.e., nonuniform in composition, and orthotropic in which its mechanical or thermal properties are independent in three mutually perpendicular directions. Strength in the longitudinal direction (parallel to the grains) is generally higher than the strengths in the radial and tangential directions. As a part of the growing process, wood in a growing tree contains a considerable amount of water and the amount of water in a wood is expressed as a percent of its dry weight and is called the "Moisture Content." As a result of heating, thermal expansion occurs and because expansion along the grain is small compare to other directions, the problem can be reduced to a two-dimensional heat conduction and moisture diffusion problem. In addition, the stress-strain behavior in a two-dimensional orthotropic disk (a cross-sectional slice) will be investigated.  Stresses that cause cracking are used to identify a safe rate of drying by adjusting the temp and airflow that give the required drying curve. Due to its orthotropic behavior any moisture content change induces different stresses that can cause splitting and warp by different amounts of strains in the materials directions.  The resulting stresses are compared to the stress level that causes cracking. The failure characteristics can be described by the Distortion Energy Criterion in order to identify a safe rate of drying in the kiln. The overall mathematical models are solved numerically and MATLAB is used to expedite computations.
 

Presenting Author: Enayat Mahajerin Saginaw Valley State Univ

Presenting Author Biography: Enayat Mahajerin is a professor of Mechanical Engineering at Saginaw Valley State University (SVSU). His research interests are Applied Mathematics, Computational Mechanics, Solid Mechanics, Structural Failure Analysis, Dynamic and Control system. He received his Ph.D. in Engineering Mechanics from Michigan State University (MSU) in 1981. He is a Fellow of the American Society of Mechanical Engineers (ASME).

Authors:

Enayat Mahajerin Saginaw Valley State Univ