On 26th january 2018, Léonard Serrano has defended his thesis. Awarded by University of Toulouse III – Paul Sabatier, his work was supervised by both Institut Clément Ader laboratory (CNRS/UT3 Paul Sabatier), the MEGEP doctoral school, and IRT Saint Exupéry.
The high quality and the relevance of Léonard’s thesis contributed to get significant results as a part of COMPINNOV TD project.
“Epoxy Systems – Out of Autoclave and Low Temperature Curing”
About his thesis
The main issues concerning composite part manufacturing (cost, manufacturing time, mechanical performances, etc.) are closely linked to the means of curing, mainly autoclaves; which do not only generate very high installation and maintenance costs, but also limit production rates because of the length of the cycles. In order to reduce this dependence, non-autoclave manufacturing processes have been envisaged (Quickstep, Roctool, VARTM, VBO …) therefore leading to modifications in the design of the materials intended for these processes (including kinetics, rheology, and fiber impregnation methods). In order to limit the changes in terms of manufacturing process, raw materials, environment products and implementation conditions, this study is based on the Vacuum Bag Only process. Several semi-product developments in recent years have made it possible to increase the robustness of this manufacturing process, thereby overcoming the lack of external pressure during an oven cure. However, the viability of these products in relation to their implementation still needs to be demonstrated, this is why three out-of-Autoclave prepreg materials were considered for this study, each one possessing different curing temperatures, although all three have been designed for out-of-autoclave composite part manufacturing (primary and/or secondary structures). Novel curing mechanisms were considered to simulate the curing reaction of prepregs, and a cure cycle optimization was conducted by considering the evolution of the prepreg’s rigidity instead of viscosity. Also, we managed to understand the air removal phenomenon by the mean of X-ray CT-scanning. We demonstrated that this extraction can be directly linked to the prepreg structure and thermal behavior. Hence we were able to decrease the porosity rate of oven manufactured composite parts. Finally, we measured the achievable mechanical properties of composite parts manufactured by vacuum bag only process and compared the latter with their autoclave counterpart.
Defining multifunctional thermo setting compounds for the aerospace world.
- M. Philippe OLIVIER – ICA/UT3 – PhD Advisor
- M. Jacques CINQUIN – Airbus/IRT – Co-Supervisor
- M. Michel BOUQUET – IRT Saint Exupéry – Co-Supervisor
- Mme Nadia BAHLOULI – iCube/Strasbourg University – Examiner
- Mme Ivana PARTRIDGE – ACCIS/Bristol University – Examiner
- M. Frédéric JACQUEMIN – GeM/Nantes University – Rapporter
- M. Eric LACOSTE – I2M/Bordeaux University – Rapporter
- M. Eric DANTRAS – CIRIMAT/University Paul Sabatier – Examiner
- M. Gérard BERNHART – IRT Saint Exupéry – Examiner
L. Serrano, P. Olivier, J. Cinquin : “Compaction Behavior Of Out-of-Autoclave Prepreg Materials”, Apr 2017, Dublin, Ireland. AIP Publisher Logo Conference Proceedings, pp. 1-7, 2017
L. Serrano; P. Olivier, J. Cinquin : “Model of cure kinetics for Out-of-Autoclave prepreg materials” Ecole des Ponts ParisTech, 28th june, 2018
“The main challenges with composite parts manufacturing are related to the curing means, mainly autoclaves, the length of their cycles and their operating costs. In order to decrease this dependency, out of autoclave materials have been considered as a solution for high production rate parts such as spars, flaps, etc… However, most out-of-autoclave process do not possess the same maturity as their counterpart, especially concerning part quality .
Three out-of-Autoclave prepreg materials were considered for this study, each one possessing different curing temperatures: A (180°C), B (125°C) and C (132°C). Those materials have also different chemical compositions, although all three have been designed for out-of-autoclave composite part manufacturing (primary and secondary structures).
The interest of our study is to understand and compare polymerization mechanisms of each matrix, by defining each time a predictive model close to experimental values of the curing of those epoxy/amine systems .”