Experimental Validation of a Phased Array Ultrasonic Testing Probe Model and Sound Field Optimization

Licentiate thesis, 2020

New manufacturing technologies are developed to facilitate flexible product designs and production processes. However, the quality of the final products should not be compromised, especially for safety prioritized industries, e.g. aerospace industry. The assessment of product quality and integrity lies on various nondestructive inspection methods and the ultrasonic testing method, among others, is widely used as an effective approach. The phased array technique in the ultrasonic testing area shows more advantages comparing to conventional ones and is revealing more benefits to industrial applications. To incorporate new technique into practical operations, it needs to be qualified with practical experiments. Due to the extensive costs and considerable challenges with experimental works, the necessity of researching on numerical simulation models arises and several models had therefore been developed. The numerical simulation model implemented in the software, simSUNDT, developed at the Scientific Center of NDT (SCeNDT) at Chalmer University of Technology is one of these models for ultrasonic inspection. However, the validity of the models should be proved before supporting or replacing the experiments, and this validation work should be accomplished by experiments ultimately.

In the current work, the main purpose is to further validate the phased array probe model in simSUNDT by comparing simulation results with corresponding experiments. An experimental platform is built with the intention to fully control the operation conditions and the set of testing results. Well-defined artificial defects in test specimens are considered in both simulations and experiments. Comparisons in the end validate the current phased array probe model and could be treated as an alternative to experiments.

With the aid of this validated probe model, optimization of the generated sound field from a phased array probe is then conducted. The optimization aims at searching for a proper combination of main beam angle and focus distance of the probe at this stage, so that the echo amplitude from a certain defect reaches its potential maximum.