Composites are used in a wide range of applications in surface transport. Damage to composite components in vehicles and surface transport applications is not always visible to the naked eye and the extent of damage is best determined for structural components by suitable non-destructive and evaluation (NDT & E) techniques. A detailed NDT and/or health monitoring procedure for proper damage assessment needs to be performed. This involves identification of the nature of the damage, its position and its extent, during different phases of the material and/or structure, i.e. during manufacturing and assembly, as well as during maintenance and repair.
Damage can also be located by simply tapping the composite s surface and listening to the sound (boundary between good and damaged composite can easily be mapped to identify the area for repair). Inspection for composite damage should be included in the regular maintenance schedules for composite structures. Nonetheless, particular attention should be made to areas that are more prone to damage by using continuous health monitoring approaches, as well as prompt and reliable NDT approaches. Transient thermal NDT is a prompt and reliable approach and has the ability to provide quantitative information about hidden defects features in composite materials and/or structures.
Analysing the transient temperature in the time domain typically attains this. Furthermore, since most damage to fibre-reinforced composites is a result of low velocity and sometimes high-velocity impact, 3-D laser micro-topography could also be used for the surface morphology and analysis of the composites. The SMEs and RTOs in this project are proposing to bring their expertise in composites assessment and/or NDT & E and in partnership with the LEs Public Bodies who also have great expertise in the field of composites and/or surface transport and/or NDT.
The aim of the ComPair project is to build a new and novel method for continuous health monitoring and non-destructive testing (NDT) assessment of composite panels and associated repairs on surface transport applications. In addition, guidelines on a certified procedure have been initiated to produce a cost-effective manufacturing and maintenance procedure.
The ComPair project has developed two areas of research: in-situ inspection by means of a scanning a process using transient thermography and Near Infra-Red (NIR) NDT techniques; and a continuous monitoring process through a combined interrogative approach using Acoustic Emission (AE) and Long Range Ultrasonic Guided waves (LRU).
- Developing quantitative non-invasive NDT approaches for prompt assessment of composites during the manufacturing and assembly stages of the composite materials and structures.
- Developing a health monitoring approach for the composite components on full scale structures.
- Developing a robotic scanner that will accommodate the NDT approach for the in-situ testing of the structures during inspection and maintenance.
The ComPair project, comprised of eleven partners from six European countries, was the culmination of three years of research on non-destructive assessment and repair of composite panels on surface transport, namely:
- High and low speed trains
A multi-axis robotic scanner has been manufactured for in-service inspection of composite components using thermography NDT. The robotic scanner has the following features:
- Capability of carrying both thermographic and NIR equipment
- NDT procedures to perform reflection and transmission mode using the same scanner
- Ability to place and orientate the NDT equipment with 6 degrees of freedom
- Ability to inspect curved samples
A monitoring system has been developed featuring a dual-purpose NDT technique - based on AE and LRU - for health monitoring of full-scale composite structures during service. The integration of the two NDT techniques provides a dual-purpose sensor system able to successfully detect defects with good sensitivity.
The research, leading to the development of the ComPair system, provides an opportunity for automotive manufacturers to develop safer composite structures. The ComPair consortium aims to achieve additional market interaction with the automotive industry sector.
2. Innovating for the future: technology and behaviour.