Spotlight 2002 Abstracts
Wood Products EngineeringDEVELOPMENT OF ENHANCED DIGITAL IMAGE CORRELATION (EDIC) TECHNIQUE
Ohkyung Kwon, Ph. D Candidate of CM WPE, 303 Walters, SUNY College of Environmental Science and Forestry, Syracuse, NY 13210
A measurement of local displacement, an influence of structural and morphological variation to material properties, and a continuous or sequential measurement and analysis are required in many researches. Digital image correlation (hereafter, DIC) is the most proper technique for the requirements because it is a non-contact and non-destructive method which makes a successive measurement possible. Since DIC technique assumes that intensity pattern of material surface does not change with deformation of material, direction and intensity of illumination sources should be stable for accurate results. If a material surface shows too smooth or uniform to apply DIC technique, the surface of material is treated by a method creating random pattern.
In this project, Enhanced Digital Image Correlation (hereafter, EDIC) is developed to improve a method revealing random pattern of material surface and to be more tolerant to illumination condition. Edge detection using phase congruency algorithm and image characterization using wavelet techniques are newly adopted to increase tolerance over illumination condition. The edge detection technique provides a way to reveal details of a surface which cannot be detected by naked eyes. A pretreatment procedure to make random pattern on the surface of material can be removed because of this edge detection technique. Wavelet analysis is a very useful technique to characterize 2 dimensional image as a minimal set of coefficients.
Graphical user interface (GUI), batch file processing, matched image validation, and displacement presentation are also developed for efficient processing and analysis. An export function of geometric coordinates is expected to integrate EDIC with finite element analysis (FEA).
Patrick Rappold and Dr. William Smith, Faculty of Construction Management and Wood Products Engineering, 175 Baker Laboratory, SUNY College of Environmental Science and Forestry, Syracuse, NY 13210.
The preferred color of kiln dried hard maple is bright white. There are many variables in the steps leading up to and during the kiln drying process which can affect color. In this study the relationships between harvest season, log age and kiln drying schedule on coloration in hard maple lumber was examined.
Trees were harvested in the winter, spring, and summer. For each harvest season one-inch boards were sawn from freshly felled trees, logs stored four weeks, and logs stored eight weeks. Logs not freshly sawn were end coated with a commercial wax emulsion. Drying schedules that produce “normal” orange-yellow (T8-C3) and “white” (T3-C5) colored hard maple were used to dry the boards. Comparison of lumber color between harvest season, log age, and drying schedule was done with a spectrophotometer. Results showed that drying schedule is a much more important variable in determining lumber color than harvest season or log age. Color differences due specifically to felling season and log age were insignificant. Recommendations include to end coat all logs that will not be immediately sawn, and to use a drying schedule that starts with an initial dry bulb temperature of 110ºF or less and a wet bulb depression of 10ºF to produce white hard maple from green lumber (>50% MC).