Standards Development

Scope

The proposed deliverable will further refine and validate 5 draft operational procedures for nondestructive inspection of fibre-reinforced plastic composites. The draft procedures were produced as the key deliverables from a European Metrology Research Programme (EMRP) project entitled “Validated Inspection Techniques for Composites in Energy Applications (VITCEA-ENG57)”. The procedures, drafted in ISO format, have undergone initial validation within the VITCEA project, but will require additional refinement and generation of precision data.

Purpose

The use of FRP composites provides several advantages including lighter weight, better mechanical and environmental performance and reduced costs compared to more traditional materials. The potential benefits of increasing FRP composite usage in different industry sectors are highlighted within the 2016 UK Composites Strategy. Most notably, the biggest opportunity for growth is identified as the wind energy sector with FRPs enabling larger, stronger and more durable turbine blades to be built. The wave and tidal sector is also seen as a key growth area as composites will enable the design of innovative, durable and corrosion resistant devices for generation of power from river and coastal resources. In the oil and gas sector, the strategy highlights the benefits of utilising composites to rehabilitate corroded steel structures and develop solutions to discover and access untapped energy reserves off shore and at greater depths. Finally, the benefit of light weight composites in transport (aerospace, automotive, rail and marine) applications is highlighted as a key enabler to reducing fossil fuel consumption and greenhouse gas emissions and increasing transport efficiencies.

Widespread adoption of FRP composites is hindered by the large number and diverse range of defect types and complex multiple failure mechanisms compared to metals. Thus, there is a requirement for a range of validated NDE techniques with contrasting detection capabilities for the identification and sizing of different defects that directly impact component performance and working life. This would also enable integration of novel NDE techniques at an earlier stage of production, allowing improved design, manufacturing and assembly with inspection being facilitated throughout the life cycle, not only in-service. Furthermore, defect detection capability has a major influence on the service intervals for FRP composite assets, affecting markedly the whole life costs of the installation.

Despite many innovations in the development of NDE for the assessment of defects and damage, relatively few methods are commonly used. This is mainly since standardised operational procedures are not available and perceptions that NDE is too unproven, costly or complex. There are currently no ISO NDE standards in existence that are specific to defect detection in composites. Several ASTM composite NDE specific standards are available, but these tend to be focussed on the aerospace sector and do not provide enough detail and validated data addressing issues such as probability of detection (POD), defect size and location sensitivity. Therefore, procedures tend to be developed in-house for specific equipment and applications, but no generic guidance on the use of relatively novel NDE techniques exists that is suitable for a broad range of composite material grades used across different industry sectors. This situation tends to exclude SMEs that do not have large R&D and capital equipment budgets, from adopting these techniques and developing expertise in NDE. Opportunities for NDE are emerging particularly in the renewable energy and transport sectors driven by the need for material and design innovation.

The aim of this project is to standardise operational procedures for 5 NDE techniques (microwave, active thermography, laser shearography and phased array/air-coupled ultrasonics), that have been the subject of a significant European research project, including reference panels and defects; thereby overcoming the issues described above and to encourage the further uptake of fibre-reinforced plastic composites.