Analysis of multiple reflected ultrasonic waves generated during a drilling process

Abstract. The propagation behavior of ultrasonic waves plays a crucial role in Structural Health Monitoring and non-destructive testing applications. Understanding the reflections and interactions of these waves within a material is essential for accurately diagnosing the integrity of structures, especially when using time-domain and non-stationary features. This study focuses on the analysis of multiple reflected ultrasonic waves generated during thread forming. The measured ultrasonic waves are multiple times reflected at pre-drilled bore holes on the path between their origin and the sensor position. The extracted features derived from signal processing are used to train regression models to predict the propagation distance between bore hole and sensor position. The predictions of the regression models are evaluated and used to investigate the propagation paths based on the prediction accuracy. The findings reveal a relationship between the propagation distance and the derived features from the signal processing of the Acoustic Emission data indicating a change of ultrasonic wave characteristics due to reflections at material boundaries. The results of this study contribute to the development of more accurate and robust Structural Health Monitoring and non-destructive testing techniques. By considering the behavior of reflected ultrasonic waves, the detection and localization of defects can be enhanced.