Overview of DTI-funded programme on 'Standardised procedures for ultrasonic inspection of polymer matrix composites'

The increasing use of composite materials in critical structural components combined with stringent requirements for safety and quality assurance has resulted in considerable investment in the development of non-destructive evaluation (NDE) methods suited to the characterisation of these heterogenous materials. A number of techniques have been developed, of which ultrasonic C-scan inspection is the most widely used. This technique can be used to detect, measure and characterise a wide range of manufacturing and in-service defects in composite materials. At present, there are no universally accepted standards or procedures for ultrasonic C-scan inspection of composites, and as a result of this absence, the reliability and traceability of this method have been limited. The routine use of C-scan techniques, particularly in the aerospace industry, supports the need for standardised procedures and improved reliability. In response to this need, a programme 'Standardised Procedures for Ultrasonic Inspection of Polymer Matrix Composites' was initiated. The project sponsored by the Department of Trade and Industry (United Kingdom) was led by the National Physical Laboratory. The work was supported by the Defence Evaluation and Research Agency. This paper provides an overview of the research objectives and activities of the programme, the contents of the working procedures developed within the programme and the pre-standardisation work undertaken by the two research establishments.