Evaluation of maximum strength and modulus of elasticity of Douglas-fir lumber in axial to grain tension by two nondestructive techniques

Resumo

Modulus of elasticity (MOE) of Douglas-fir (Pseudotsuga menziesii) lumber loaded in parallel to grain tension was evaluated by nondestructive techniques (transverse vibration and longitudinal stress wave) and the results were correlated to the actual properties. Nondestructive parameters of specific gravity, wave frequency and attenuation and wave speed were measured. Destructive tests were performed with the use of static tension and bending techniques. Regression analyses were performed to correlate all nondestructive and destructive techniques. Results showed the MOE in static bending can be predicted with good efficiency. The correlation coefficients (R) for this test ranged from 0.818 to 0.941. The maximum tensile strength presented a poor correlation to the nondestructive parameters with the highest R=0.582.