The reduction in errors associated with ultrasonic non-destructive testing of timber arising from differential pressure on and movement of transducers

Timber is a valuable structural material to construction and other industries. The trees which are its source have also environmental value which make its conservation obligatory. Due to its organic origins control of material quality is primarily retrospective. This makes its structural behaviour difficult to predict. Material status is further diminished where test regimes used to predict structural behaviour are inexact. Such deficiencies have been identified when testing timber with the ultrasonic contact method. A differential pressure applied to and movement of ultrasonic transducers during testing is cited for causing fluctuations in transmission time readings and pulse velocity data calculated from it. Two mechanical units using hydraulic fluid were developed to restrict movement of and exert an equal pressure on a pair of 54 and 200 kHz transducers. Test results show a reduction in transmission time variations of on average 86.7%.