Evaluation of selected timber properties using dielectric constant by low frequency techniques / Rohana Hassan

Currently, nondestructive studies have been carried out in various fields in timber engineering. However, fewer of the research focus on non-destructive evaluation by means of electromagnetic field in low frequencies. This research is focuses on the application and development of Capacitor Probe and Parallel Plate Electrode System in low frequency range of 1 kHz to 100 kHz. A Capacitor Probe and Parallel Plate Electrode System developed at Universiti Teknologi MARA were used to measure the electromagnetic property that is the dielectric constant of wood. For this study, 61 selected small-size specimens from seven strength groups of timber were taken for observation. Another 120 selected full-size specimens from Strength Group 5, 6 and 7 specified in MS 544:2001 were taken for static bending test. The experimental results proved that 100 kHz is the most suitable frequency for timber application. The dielectric constant with respect to timber grade, strength group, moisture content, density, timber defects and modulus of elasticity were discussed. The results indicated that dielectric constant has strong significance relations to the moisture content and density. Moderate relation was found between MOE and the dielectric constant. However, it shows potential for prediction of timber grade, strength group and defects detection in timber. Nonetheless, the use of the measured dielectric constant shows the ability of the approach systems in the evaluation of the properties of timber.