A METHOD FOR ESTIMATING THE MINIMUM RADIUS OF CURVATURE IN SOLID WOOD BENDING

摘要

This study was conducted to devise a method for estimating the minimum radius of curvature (RC) in solid wood bending. The physical (relative density, RD), mechanical (compression and tension parallel to the grain), chemical (holocellulose and lignin contents) and anatomical properties (fiber length < FL >, fiber diameter < FD >, cell wall thickness < CWT > and lumen width < LW >) of gubas (Endospermum peltatum Merr.), mangium (Acacia mangium Wild.) and river red gum (Eucalyptus camaldulensis Dehner) were determined. Correlation and regression analyses on the data resulted in the following regression equation with a coefficient of determination (R~2) equals to 79.0%: RC = -17.68 + 97494.48 (LW)~2 + 106.84 (RD)~2 + 76.44 (FL)~2. This equation correctly predicted only 20% of the bending quality of previously studied species actual bending tests. A second regression equation based on the properties of 42 species previously studied by actual bending tests at FPRDI resulted in the following equation with R~2 value of 40%: RC = 44.12 - 433.00 RD + 19.66 LC. This equation correctly predicted 60.0% of the bending quality of species previously tested by actual bending tests. This study shows the need to investigate the relationship between basic wood properties and minimum bending radii of curvature of more species with a wide range of relative density.