Development of a Virtual Instrument for Immersion Type Ultrasonic Inspection with a Computer Controlled Multi-Axis Motion Controller
The Pulse Echo (PE) technique is a widely used ultrasonic non destructive testing technique to test materials by analyzing ultrasound echoes reflected from flaws and discontinuities. In conventional PE technique, called contact type PE, an ultrasonic transducer is in constant contact with a test piece, transmitting and receiving ultrasonic signals from the test specimen. The inherent shortcomings of PE are the need for; uniform couplant conditions, the ultrasonic transducer to remain in contact with the test object throughout the scan and a limitation to scan regular surfaced objects only. This paper provides for extending a system initially developed for contact type PE, to perform Immersion Testing (IT) which is a contactless pulse-echo inspection method with the probe and test piece separated by a predetermined volume of water of certain thickness. A computer controlled 3-axis transducer position manipulator (motion frame) is constructed for assistance in conducting automated tests. The efficacy of immersion testing relies on the precise control of the motion of transducer. The existing immersion type motion controllers along with dedicated data acquisition and analysis system are quite expensive and are beyond the affordability of smaller ultrasonic labs. Hence the proposed system including the motion frame and Data Acquisition Unit (DAQ) can serve as a competent, low-cost and reliable IT system benefitting several small scale industries and labs.
Towards automated interpretation of ultrasonic NDT data
Expert systems have demonstrated potential for automated interpretation of ultrasonic NDT data, but rules do not provide the best solutions for all interpretation problems. In this work, 3D images are reconstructed from raw A-Scans, using CAD models of test specimen geometry to correct positions and remove geometric echoes. A knowledge model for ultrasonic NDT has been implemented in a working expert system, with uncertainty managed using fuzzy logic. A suite of data processing tools is available both to the expert system, and also through an interactive 3D visualization system, which therefore provides a development environment for automated interpretation, as well as being powerful in its own right.
Can we train a computer to be a skilled inspector
The experience and knowledge of its staff are the backbone of any NDT company. New procedures, particularly those based on neural networks, seek to encapsulate this experience and allow fully automated inspection to be considered. The change from manual inspection at least removes the factors of fatigue, boredom, inattention, variability, and subjectivity from the inspections. At best it provides a system with defined, reproducible quality assured standards. This review asks to what extent the new methods might achieve these aims