Caractérisation par microtomographie de la mésostructure des renforts fibreux pour la fabrication de composites
Bibliographic record
Abstract
RESUME Au cours des dernieres annees, les procedes de fabrication par injection comme le moulage par transfert de resine (RTM) ont connu un fort developpement ayant mene a des applications industrielles concretes dans les domaines aeronautique et automobile. Toutefois, ces reussites ne doivent pas faire oublier que plusieurs problemes scientifiques relies aux procedes de fabrication par injection sur renforts restent mal compris. Parmi ces problemes, l’impregnation de renforts textiles reste un point critique car la performance mecanique d’un composite peut etre fortement affectee par les vides generes lors de l’etape d’injection. Cette etape de fabrication est cruciale pour obtenir une impregnation totale et produire des composites de hautes performances. Du fait de la double echelle de porosite des renforts, l’ecoulement de resine est complexe. Une meilleure connaissance de la porosite des renforts fibreux permettrait une meilleure comprehension des modes d’ecoulement de la resine et la mise en place d’ajustements lors de la phase d’injection. La microtomographie aux rayons X est une technique d’imagerie non destructrice des materiaux, qui est utilisee depuis quelques annees pour caracteriser la microstructure des materiaux composites. Ses applications sont vastes, de la detection des defauts dans les pieces fabriquees a la calibration de modeles de compression de renforts tisses. Cette methode est fondee sur l’attenuation des rayons X par la matiere, qui permet d’avoir une image tridimensionnelle de l’echantillon. Le microtomographe XT H 225 de Nikon, disponible a l’Ecole de Technologie Superieure a Montreal a ete utilise pour realiser toutes les observations effectuees dans le cadre de ce projet. La presente etude basee sur cette approche vise a etudier l'influence du niveau compaction sur la morphologie du renfort et la repartition des mesopores. Un premier dispositif in-situ de compaction est developpe pour effectuer des observations microtomographiques preliminaires a differents taux de fibres. Apres avoir montre le potentiel de la microtomographie pour caracteriser la mesoporosite d’un renfort fibreux et les possibles ameliorations a apporter au dispositif, un nouveau dispositif est ensuite concu et fabrique. Deux types de tissus ont ete caracterises avec le nouveau dispositif : un renfort orthogonal tridimensionnel en fibres de verre et un renfort tisse bidimensionnel en fibres de verre.----------ABSTRACT In recent years, injection manufacturing processes such as resin transfer molding (RTM) have experienced strong development leading to concrete industrial applications in the aerospace and automotive fields. However, these successes should not overshadow the fact that many of the scientific issues related to reinforcement injection manufacturing processes remain poorly understood. Among these problems, the impregnation of textile reinforcements remains a critical point because the mechanical performance of a composite can be strongly affected by the voids generated during the injection step. This manufacturing step is crucial to achieve total impregnation and produce high-performance composites. Due to the double porosity scale of the resins, the resin flow is complex. A better knowledge of the porosity of the fibrous reinforcements porosity would allow a better understanding of the resin flow modes and the setting up of adjustments during the injection phase. X-ray microtomography is a non-destructive imaging technique for materials that have been used for some years to characterize the microstructure of composite materials. There are numerous applications, from the detection of defects in manufactured parts to the calibration of compression models of woven reinforcements. This method is based on the attenuation of X-rays by the material, which makes it possible to have a three-dimensional image of the sample. The Nikon XT H 225 microtomography, available at ETS « Ecole de Technologie Superieure » in Montreal, was used to perform all the observations made in this project. The present study based on this approach aims to explore the influence of the compaction level on the morphology of the reinforcement and the distribution of the mesopores. A first in-situ compaction device is developed to perform preliminary microtomographic observations at different fiber levels. Having shown the potential of microtomography to characterize the mesoporosity of a fibrous reinforcement and the possible improvements to be made to the device, a new device is then designed and manufactured. Two types of fabric have been characterized by the new device: three-dimensional orthogonal fiberglass reinforcement and two-dimensional fiberglass reinforcement. Several observations with a fiber content between 45% and 65% are made for both tissues. An image processing procedure was implemented using the FIJI software.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".