Elastic Wood Properties from Dynamic Tests and Computer Modeling

Elastic moduli for a specimen of Norway spruce (Picea abies) have been evaluated by dynamic tests and corresponding computer calculations. Modal testing of a wooden beam of structural size resulted in modal properties for 13 different modes of vibration. Corresponding modes of vibration were calculated using a finite element model based on Timoshenko beam elements with constant homogeneous properties. Similarity between experimental and theoretical values for eigenfrequencies for the fundamental axial mode of vibration required a value for Young's modulus E=11,444MPa. Corresponding matching of the fundamental frequency for torsional vibration yielded G=1,074MPa. The calculated eigenfrequencies for higher modes of vibration correspond very well to the experimental values. It should be noted specifically that the eigenfrequencies for edge‐wise bending modes correspond well, although the value for the shear modulus was based on a torsional mode matching.