Further Studies on Elastic Properties of Douglas Fir

Abstract

The objective of this study was to examine the elastic behavior of Douglas fir in the radial‐longitudinal plane. Parallel‐ and perpendicular‐to‐grain tensile test results were used to establish linear elastic behavior. Off‐axis tensile test results were used to determine modulus of elasticity for grain angles of 15°, 30°, 45°, and 60° and the radial‐longitudinal shear modulus. The results of this study indicated that the material behaved in a linear elastic manner shown by symmetry in the compliance matrix. The measured off‐axis modulus of elasticity was found to be similar to that predicted by the transformation laws. It was concluded that the behavior of the material studied could be adequately described by linear orthotropic elastic theory in the radial‐longitudinal plane. Longitudinal and radial modulus of elasticity, and Poisson's ratios, νRL and νRL, were found to be within the same range as those previously reported. However, the radial‐longitudinal shear modulus was found to be from 10 to 30% lower than previously reported values. The difference in shear modulus was primarily due to the different testing methods used.