Ultrasonic Phased Array on Time-of-Flight Diffraction for Non-destructive Testing via Numerical Modelling

摘要

An inspection technique for steel pipes that utilises phased array (PA) probes in time-of-flight diffraction (TOFD) configuration to continuously monitor the defect growth over time is being developed, so that when the defect reaches a critical size the power plant can be shut down and maintenance can take place before failure. The numerical models for PA/TOFD in either symmetric or asymmetric pitch-catch configuration were developed using CIVA simulation platform developed specifically for non-destructive testing applications. The probe characteristics were selected and the beam profile was predicted for different points in the weld and heat affected zone (HAZ). The probes positions and interspacing in emission and reception were also selected in order to achieve max inspection coverage. The PA probes use piezoelectric elements for generation and reception of the ultrasound beam. Single crystal gallium orthophosphate (GaPO_4) was selected for impedance analysis as a candidate for application in the PA probe. Impedance characteristics of GAPO_4 elements were investigated up to 580 °C and then used to derive the material properties of these elements up to the temperature stated above. Finally, the calculated properties were used to evaluate the developed PA/TOFD technique at high temperatures (HT) using COMSOL simulation package.