In-Process Monitoring of Automated Carbon Fibre Tape Layup Using Ultrasonic Guided Waves

Abstract

This paper presents an investigation into the inspection of an Automated Tape Placement (ATP) process, which automates the process of laying composite plies on a tool surface. The requirement for monitoring this process is motivated by the need to detect common defects in the process which could compromise the integrity of the structure. An experimental procedure was carried out where the tool surface, where composite is laid during the ATP, was excited with ultrasonic guided waves. Several types of defects were introduced during this process, and a methodology is presented to extract features from the signals acquired, model the process using this data and identify the defects. The main challenge in modelling this process is the cumulative trend throughout the application of the composite plies. A method is presented where wavelet analysis is used to model short-term dynamics while the long term, cumulative trends are eliminated using cointegration. The results show that one can detect various types of defects during an ATP process using the methodology introduced here. The key result is that the trends in the data due to the normal process can be removed using cointegration in order to reveal abnormalities.