Assessment of wood load condition by Near Infrared (NIR) spectroscopy

The assessment of the mechanical properties of wood using non-destructive evaluation (NDE) tools has been widely developed and refined. These NDE tools mainly rely on vibrational, ultrasonic or stress-wave approaches. Vibrational techniques generally show higher correlations between the estimated modulus of elasticity (MOE), or modulus of rupture (MOR), and the measured MOE, or MOR, than stress-wave techniques. They are, however, relatively difficult to apply in the field due to boundary conditions common in many timber structures. Thus, improved tools for assessing timber structures are still needed. Recently, near infrared (NIR) spectroscopy (500–2400 nm) has shown promise for predicting the MOE and MOR of wood. This work focuses on extending the use of NIR for measuring the load applied to small wood beams. The reflectance NIR spectrum was measured as the applied load was increased. Good correlations (r > 0.96) between the measured load and the predicted load were obtained using spectra taken from both the tension and compression surfaces of the small wood beams.