Secondary bonded pi-joint out of autoclave process
Bibliographic record
Abstract
Composite materials are widely used in the aerospace industry due to their high strength and stiffness properties, as well as the manufacturing possibilities they offer for large components at lower assembly costs.To further lower the manufacturing cost, the use of Out of Autoclave (OOA) process is increasing in popularity.However, mechanically joining parts is a necessary step in the assembly of a large component, driving up the weight of the component and the final assembly cost.A Pi-Joint is one way to offer lower assembly cost through secondary bonding while ensuring the joint's reliability due to the redundancy in the load path.Predicting the failure strength of a bonded joint is essential for the initial stages of aircraft structure design.In this research project, the OOA process is used to manufacture Pi-Joints using pre-impregnated carbon fibre fabric.The Pi-Joint is co-cured with the skin, followed by a secondary bond operation of the web onto the Pi-Joint and skin assembly.To assess the strength of the joint, four different manufacturing techniques are used.In addition, a finite element analysis technique is used to estimate the first mode of failure for the different configurations of the Pi-Joint.The failure strength is correlated with experimental test results to determine the reliability of the manufacturing techniques.Static strength analyses are carried out along with mechanical tests to assess the redundancy of the load path.It is shown in this research that the finite element modelling results are in agreement with the test results.iii Résumé Les matériaux composites sont largement utilisés dans l'industrie aéronautique en raison de leur grande résistance, de leur rigidité, et de leur facilité à être fabriquée en composantes de grandes dimensions à faible coût.Afin de minimiser d'avantage les coûts liés à la fabrication des pièces, le processus de fabrication hors autoclave ou OOA est de plus en plus utilisé.Cependant, l'assemblage mécanique des pièces constitue une étape inévitable de l'assemblage du produit.Ce processus a pour effet d'augmenter le poids et le coût de l'assemblage final.L'utilisation du Joint en Pi qui assemble la structure par un collage secondaire permet de réduire les coûts et d'augmenter la fiabilité du produit final grâce à la multiplicité des chemins de charge qu'il offre.Prédire la défaillance d'un joint collé est essentielle aux phases préliminaires de design des structures primaires d'un avion.Dans ce projet de recherche, le procédé OOA est utilisé afin de fabriquer des joints en composite à base de fibre de carbone.Le Joint en Pi est cocuit avec le revêtement puis une cuisson secondaire permet de joindre l'âme à l'assemblage du Joint en Pi et du revêtement.Afin de déterminer la rigidité du joint, quatre techniques de fabrication sont utilisées.De plus, des analyses par éléments finis sont utilisées afin de prédire le premier mode de défaillance pour diverses configurations du Joint en Pi.La résistance à la défaillance est corrélée avec des résultats de tests expérimentaux afin d'assurer la fiabilité du procédé de fabrication.Des analyses statiques et des tests sont réalisés afin de démontrer la multiplicité du chemin de charge.Dans cette recherche il est montré que les résultats des analyses par élément finis sont en accord avec les résultats des tests.I wish to express my sincere gratitude to my supervisor, Dr. Pascal Hubert, for giving such a great opportunity to be a member of his research group and providing me with the opportunity to work in such dynamic environment.He is an admirable person of great knowledge and experience and I am truly grateful for his immense guidance and support throughout my study.It is paramount to mention the partners in this project: Bombardier Aerospace, Bell Helicopter Textron Canada, Delastek Inc., the Centre for the Development of Composites of Québec (CDCQ), the Consortium for Research and Innovation in Aerospace in Québec (CRIAQ), the National Research Council of Canada (NRC), the Center for Applied Research on Polymers (CREPEC) and NSERC, specifically to Bombardier Aerospace and Bell Helicopter for providing the materials and essentials.I would like to thank Melanie Brillant, Jim Kratz and Timotei Centea
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".