JOINT STRESS ANALYSIS TOOL (JOSAT)
Industrial glueing: towards reinforced confidence
Although invisible to the naked eye, adhesives are present in numerous assembled structures (both monolithic and stratified) used in the aeronautics, automotive, railway or even construction sectors.
Compared to its "competing" technique of bolting, adhesives offer several key benefits. Whether you are attaching objects to metal or composite materials, it offers the option of assembling structures without making holes in them, damaging them or weighing them down.
Whereas bolting transfers forces in a discrete manner, glueing does so throughout the glued surface, over a very thin layer compared to those of substrates, which means with less volume, mass and density, but greater effectiveness. Moreover, an ample selection of adhesives are available "off the shelf" and it is always possible to produce a customised adhesive.
Diagnose and predict
However, industrial firms have difficulty understanding whether the glue has taken well, if it is still in place and distributed evenly and if it is serving its purpose flawlessly throughout the life cycle – from production to in-service support. So, how do you conduct non-intrusive inspections and guarantee that the product does not experience a significant deterioration in its performance which, over time, could pose a risk of parts becoming detached?
Since 2008, our physical engineering department has been plugging away at perfecting a calculation tool to predict the mechanical behaviour of adhesive joints, within the framework of the Joint Stress Analysis Tool project. When incorporated into an embedded system, it can be used to monitor the current state of disrepair and subsequently provide the user with a diagnosis and prediction of the state of health of the adhered structures being monitored.
Current CIFRE doctoral thesis projects
The challenge is sizeable: it consists in boosting the level of trust in adhesives amongst industrial firms, in order to associate the benefits of this method with a high level of reliability and safety. A doctoral student at the University of Toulouse III has started thesis research on this topic, alternating between our Blagnac branch and the Clement Ader Institute in Toulouse.
Along with our engineers specialised in embedded systems and structural mechanics, this doctoral student is developing a system prototype applicable to adhesive joints. The study centres on experimental characterisation, modelling and simulation of the mechanical behaviour of adhesive joints as well as on sensors and their implementation, without interfering with embedded system in the aircraft, train or car. We are confident that the innovative role of diagnostics and verification will help industrial firms view the technique of glueing with maximum equanimity.
- Eric ParoissienPhysics Engineering Expert
+33 (0)5 34 36 26 84
Eric ParoissienPhysics Engineering Expert
+33 (0)5 34 36 26 84
<p style="text-align: justify;">Eric Paroissien completed <a href="http://thesesups.ups-tlse.fr/3/">his doctoral thesis</a> at Toulouse University III on the mechanical behaviour of bolted and glued hybrid assemblies in aeronautics.</p> <p style="text-align: justify;">The objective is to model in order to understand better, and to understand in order to model better. Within this framework, a partnership with the "Institut supérieur de l’aéronautique et de l’espace" (ISAE), an aerospace engineering school in Toulouse, was launched to facilitate research on bolting and glueing with professor Frédéric Lachaud.</p> <p style="text-align: justify;">In 2007, he joined Sogeti High Tech in Toulouse, where he had the opportunity, within the framework of research, to continue his thesis work for Airbus. Since 2008, he has been in charge of an internal innovation project, dubbed JoSAT (Joint Stress Analysis Tool), which aims to improve our understanding, by means of modelling, of the mechanical behaviour of multi-material assemblies (metals, composites) and multi-technique assemblies (bolting, glueing) in order to produce an industrialisable analysis and design tool from these relationships.</p>