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The goal of the DECID2 project is to build a demonstrator made of smart composite materials, with a double structural health diagnostics capability using embedded optic fibres and ultrasonic sensors. This project was initiated by the EMC2 and PGCO competitive clusters (France).
(Published on July-August 2008 – JEC Magazine #43)
MONSSEF DRISSI-HABTI, DIRECTOR OF RESEARCHES LABORATOIRE CENTRAL DES PONTS & CHAUSSÉES
Standard civil-engineering reinforcements are made of steel. But steel has a major drawback: it is vulnerable to corrosion.
In structural applications, this drawback inevitably conjures up the question of how well metal structures resist the combined action of corrosion and mechanical stresses. Another important issue is the necessary use of nondestructive testing (NDT) to prevent premature failure of key structural components. Theoretically, NDT serves to detect damage before failure occurs, but this is not an easy task. Some NDT methods in the wide range thus far in use are debatable, as they do not provide all the answers needed by managers of civil engineering projects.
With this as a given, one solution in the way of a corrosionresistant material that could monitor its own structural integrity would be to build structures out of smart materials: specifically, composites embedded with sensors providing continuous structural health diagnostics. The use of extrinsic NDT methods to monitor the structural integrity of composite structures with no embedded instruments requires some form of regular maintenance, whereas data for structures with embedded sensors are provided continuously and extremely reliably without need for maintenance, at least over the medium term.
The three-year DECID2 project proposes to build a smart civil engineering structure at the EMC2 Technocampus (France) to serve as a demonstrator. The 20 m x 7 m footbridge will be made of pultruded composites (glass fibre/vinylester and carbon/epoxy) provided with a structural health diagnostic system in the form of optical fibres and micrometric ultrasonic sensors embedded in the composite materials.
Smart composite structure DECID2 can be statically loaded at several locations to provide ease of comparison between results of test loadings and those out of numerical simulations
This demonstrator project is sponsored by the Pays de La Loire Regional Council, which would like to turn the Technocampus into a technocentre for all composite-material projects. It is being organized principally with the help of partners in the Pays de La Loire region, including ETPO, LCPC, Cetim, Souriau, Ecole Centrale Nantes, the University of Nantes, and Synervia. The other partners are : LARMAUR Laboratory (University of Rennes), iX Fiber and IDIL (Région Bretagne) and DFC Région Picardie).
DECID2 has been accepted for financing through the French Industry Ministry’s business management office, by funds from its interministerial fund FUI. The total budget is €3.3 M, with €1.9 M from the FUI and the Pays de La Loire region. The successful completion of the project at the EMC2 Technocampus (which is probably the largest European composite R&D platform) will constitute a worldclass advance.
DECID2 and the EMC2 and PGCO competitive clusters
DECID2 is a cross-disciplinary collaborative project between the EMC2 and PGCO competitive clusters. Its purpose, as mentioned above, is to build a large, fully instrumented composite structure to demonstrate the potential of this type of smart structure and the technological possibility of extending the concept to a wider range of industries, including automotive, aviation, marine, railway, and chemicals.
For these industries, it is crucial that innovative R&D projects integrating both structural and specific functional aspects of composite materials be implemented and the technological progress validated at the national, European and international level. Because it is a civil engineering structure, the DECID2 demonstrator “bridges” the gap, so to speak, between the EMC2 and PGCO competitive clusters. It also is a demonstration of strategic complementarity, which is a primary concern shared by the two clusters.
On the international front, DECID2 is cooperating with the National Research Council Canada’s Industrial Materials Institute (IMI-CNRC), which will be supplying the micrometric ultrasonic sensors to be used in the demonstrator.
The technology transfer centre is allowing a budget of Can$500,000, financed by Canadian sources. The IMI has many years’ experience in these ultrasonic sensors, which are used in the aviation industry and can operate at temperatures up to 600°C.
In the civil engineering field, the use of pultruded composite materials is widespread in the United States, but has not developed much yet in France. At under €1/kg, glass fibre as reinforcement for pultruded composites could revolutionize this industrial sector, all the more so as there is a need for structural materials with damage detection capability in many applications, including engineering works like dams and motorway bridges. The use of glass fibre in the DECID2 project in France enters into this particular technological context.
Another aspect is human safety, which would be furthered by such “double” monitoring of structural integrity using optical and ultrasonic sensors.
Training and research
With the different technologies that will be developed in this project, the DECID2 demonstrator will constitute an effective R&D tool for the students and scientists who work directly or indirectly with composite materials, as it could serve throughout its service life to model structural performance and explore evaluation/prediction methods for all similar composite projects in future.
The DECID2 project team is planning to carry out R&D activities on an industrial-scale prototype. This should spark the interest of the region’s academics and also of French scientists and manufacturers in the field of composites, given the possibilities for comparing test results on real structures with the different performance models.