Title: Modeling and Simulation of the Co-Cure of Honeycomb Core Sandwich Structures

Authors: Daniel Zebrine, Pavel Simacek, Mark Anders, Navid Niknafs Kermani, Suresh G. Advani, Steven R. Nutt

DOI: 10.33599/nasampe/s.21.0600

Abstract: Co-cure of honeycomb sandwich structures offers efficient manufacturing of parts by simultaneously consolidating composite facesheets and joining them to the core with an adhesive layer. This process reduces manufacturing time but can result in high defect levels. The coupling of phenomena, including formation of the bond-line, consolidation of facesheets, and evolution of core gas pressure causes complex interactions that are not well understood. Further, modeling tools for co-cure are limited. Clarifying the underlying process physics and developing predictive capabilities can guide decisions to increase manufacturing efficiency and process robustness. We present an overview of a multi-year research effort culminating in stand-alone software for simulation of autoclave co-cure. Lab-scale studies, including in situ visualization of the bond-line during cure, were used to identify key parameters influencing defect formation. Experiments were used to build a physics-based modeling framework and simulation software for co-cure. Given user input for material and processing parameters, the software simulates key phenomena (core pressure evolution, fillet formation, and facesheet consolidation) and predicts porosity in the bond-line. Validation studies demonstrated that although accurate quantitative predictions of porosity values were challenging due to the stochastic nature of co-cure, the model captured trends in bond-line quality and will be useful for guiding adjustments to process parameters and protocols.

References: [1] Campbell, F.C. Manufacturing Technology for Aerospace Structural Materials. London:, Elsevier, 2006. [2] Hubert, P. and Poursartip, A. "A Review of Flow and Compaction Modelling Relevant to Thermoset Matrix Laminate Processing". Journal of Reinforced Plastics and Composites 17, 4 (1998), 286–318. [3] Centea, T., Grunenfelder, L.K., and Nutt, S.R. "A review of out-of-autoclave prepregs - Material properties, process phenomena, and manufacturing considerations". Composites Part A: Applied Science and Manufacturing 70, (2015), 132–154. [4] Banea, M.D. and Da Silva, L.F.M. "Adhesively bonded joints in composite materials: An overview". Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 223, 1 (2009), 1–18. [5] Higgins, A. "Adhesive bonding of aircraft structures". International Journal of Adhesion and Adhesives 20, 5 (2000), 367–376. [6] Grimes, G.C. "The Adhesive-Honeycomb Relationship". Applied Polymer Symposia 3, (1965), 154–190. [7] Hou, T.-H., Baughman, J.M., Zimmerman, T.J., Sutter, J.K., and Gardner, J.M. "Evaluation of Sandwich Structure Bonding in Out-Of-Autoclave Processing". Sampe Journal 47, 1 (2011), 32–39. [8] Hayes, B.S., Seferis, J.C., and Chen, J.S. "Development and hot-melt impregnation of a model controlled flow prepreg system". Polymer Composites 17, 5 (1996), 730–742. [9] Pearce, P.J., Arnott, D.R., Camilleri, A., Kindermann, M.R., Mathys, G.I., and Wilson, A.R. "Cause and effect of void formation during vacuum bag curing of epoxy film adhesives". Journal of Adhesion Science and Technology 12, 6 (1998), 567–584. [10] Butukuri, R.R., Bheemreddy, V.P., Chandrashekhara, K., Berkel, T.R., and Rupel, K. "Evaluation of skin-core adhesion bond of out-of-autoclave honeycomb sandwich structures". Journal of Reinforced Plastics and Composites 31, 5 (2012), 331–339. [11] Grove, S.M., Popham, E., and Miles, M.E. "An investigation of the skin/core bond in honeycomb sandwich structures using statistical experimentation techniques". Composites Part A: Applied Science and Manufacturing 37, 5 (2006), 804–812. [12] Bascom, W.D. and Cottington, R.L. "Air Entrapment in the Use of Structural Adhesive Films". The Journal of Adhesion 4, 3 (1972), 193–209. [13] da Silva, L.F.M., Adams, R.D., and Gibbs, M. "Manufacture of adhesive joints and bulk specimens with high-temperature adhesives". International Journal of Adhesion and Adhesives 24, 1 (2004), 69–83. [14] Nagarajan, S., Menta, V.G.K., Chandrashekhara, K., et al. "Out-of-Autoclave Sandwich Structure: Processing Study". Sampe Journal 48, (2012), 24–31. [15] Alteneder, A.W., Renn, D.J., Seferis, J.C., and Curran, R.N. "Processing and Characterization Studies of Honeycomb Composite Structures". Proceedings of the 38th International SAMPE Symposium, (1993), 1034–1047. [16] Tavares, S.S., Caillet-Bois, N., Michaud, V., and Månson, J.A.E. "Non-autoclave processing of honeycomb sandwich structures: Skin through thickness air permeability during cure". Composites Part A: Applied Science and Manufacturing 41, 5 (2010), 646–652. [17] Tavares, S.S., Michaud, V., and Månson, J.A.E. "Assessment of semi-impregnated fabrics in honeycomb sandwich structures". Composites Part A: Applied Science and Manufacturing 41, 1 (2010), 8–15. [18] Tavares, S.S., Michaud, V., and Månson, J.-A.E. "Through thickness air permeability of prepregs during cure". Composites Part A: Applied Science and Manufacturing 40, 10 (2009), 1587–1596. [19] Tavares, S.S., Roulin, Y., Michaud, V., and Månson, J.A.E. "Hybrid processing of thick skins for honeycomb sandwich structures". Composites Science and Technology 71, 2 (2011), 183–189. [20] Tavares, S.S., Caillet-Bois, N., Michaud, V., and Månson, J.-A.E. "Vacuum-bag processing of sandwich structures: Role of honeycomb pressure level on skin–core adhesion and skin quality". Composites Science and Technology 70, 5 (2010), 797–803. [21] Kratz, J. and Hubert, P. "Vacuum bag only co-bonding prepreg skins to aramid honeycomb core. Part I. Model and material properties for core pressure during processing". Composites Part A: Applied Science and Manufacturing 72, (2015), 228–238. [22] Kratz, J. and Hubert, P. "Vacuum-bag-only co-bonding prepreg skins to aramid honeycomb core. Part II. In-situ core pressure response using embedded sensors". Composites Part A: Applied Science and Manufacturing 72, (2015), 219–227. [23] Kratz, J. and Hubert, P. "Anisotropic air permeability in out-of-autoclave prepregs: Effect on honeycomb panel evacuation prior to cure". Composites Part A: Applied Science and Manufacturing 49, (2013), 179–191. [24] Kratz, J. and Hubert, P. "Processing out-of-autoclave honeycomb structures: Internal core pressure measurements". Composites Part A: Applied Science and Manufacturing 42, 8 (2011), 1060–1065. [25] Rion, J., Leterrier, Y., and Månson, J.-A.E. "Prediction of the adhesive fillet size for skin to honeycomb core bonding in ultra-light sandwich structures". Composites Part A: Applied Science and Manufacturing 39, 9 (2008), 1547–1555. [26] Chen, C., Li, Y., Gu, Y., Li, M., and Zhang, Z. "Prediction of the resin fillet size in honeycomb sandwich composites with self-adhesive prepreg skin". Journal of Reinforced Plastics and Composites 35, 21 (2016), 1566–1575. [27] Kratz, J., Genest, M., Preau, M., and Hubert, P. "Vacuum-Bag-Only Prepreg Processing of Honeycomb Structures : From Lab-Scale Experiments To an Aircraft Demonstrator". SAMPE 2014 Proceedings, (2014). [28] Centea, T., Zebrine, D., Anders, M., Elkin, C., and Nutt, S.R. "Manufacturing of Honeycomb Core Sandwich Structures: Film Adhesive Behavior Versus Cure Pressure and Temperature". Proceedings of the Composites and Advanced Materials Expo, (2016). [29] Anders, M., Zebrine, D., Centea, T., and Nutt, S. "In Situ Observations and Pressure Measurements for Autoclave Co-Cure of Honeycomb Core Sandwich Structures". Journal of Manufacturing Science and Engineering 139, 11 (2017), 111012. [30] Anders, M., Zebrine, D., Centea, T., and Nutt, S.R. "Process diagnostics for co-cure of sandwich structures using in situ visualization". Composites Part A: Applied Science and Manufacturing 116, October 2018 (2019), 24–35. [31] Centea, T., Zebrine, D., Anders, M., and Nutt, S.R. "Facesheet Consolidation During Autoclave Co-cure of Honeycomb Core Sandwich Structures". Proceedings of the SAMPE 2017 Technical Conferences, Society for the Advancement of Material and Process Engineering (2017). [32] Zebrine, D., Anders, M., Centea, T., and Nutt, S.R. "Adhesive Bond-line Formation During Co-cure of Honeycomb Sandwich Structures". Proceedings of the SAMPE 2018 Technical Conference (Student Competition), Society for the Advancement of Material and Process Engineering (2018). [33] Centea, T., Anders, M., Zebrine, D., and Nutt, S. "The Co-Cure of Honeycomb Sandwich Structures: Process Physics and Manufacturing Strategies". Proceedings of the 18th European Conference on Composite Materials, European Society for Composite Materials (2018), 24–28. [34] Zebrine, D., Centea, T., Anders, M., and Nutt, S.R. "Process Mapping for Defect Control in the Adhesive Bond-line of Co-cured Honeycomb Core Sandwich Structures". Proceedings of CAMX 2019, Society for the Advancement of Material and Process Engineering (2019). [35] Anders, M., Centea, T., Zebrine, D., et al. "Through-thickness gas permeability of prepreg composite facesheets during co-cure of honeycomb core sandwich structures". Proceedings of the SAMPE 2018 Technical Conference, Society for the Advancement of Material and Process Engineering (2018). [36] Palit, T., Centea, T., Anders, M., Zebrine, D., and Nutt, S.R. "Permeability of Cured Composite Skins Produced using Co-cure over Honeycomb Core". Proceedings of CAMX 2018 (Student Competition), Society for the Advancement of Material and Process Engineering (2018). [37] Lo, J. and Nutt, S. "Method for In Situ Analysis of Volatiles Generated during Cure of Composites". Composites Part A: Applied Science and Manufacturing, May (2019). [38] Niknafs Kermani, N., Simacek, P., Erdal, M., and Advani, S.G. "A Numerical Model to Simulate Void Dynamics during Processing of Honeycomb Core Sandwich Structures with Prepreg Face-Sheets". Proceedings of the 33rd Technical Conferences of the American Society for Composites, American Society for Composites (2018). [39] Niknafs Kermani, N., Simacek, P., and Advani, S.G. "A simple analysis tool to simulate the co-cure of honeycomb core composite sandwich structures". Proceedings of the SAMPE 2019 Technical Conference, Society for the Advancement of Material and Process Engineering (2019). [40] Niknafs Kermani, N., Simacek, P., and Advani, S.G. "A Model for the Equilibrated Co-Cure of Honeycomb Core Sandwich Structures in Autoclave Processing". Proceedings of the 33rd Technical Conferences of the American Society for Composites, American Society for Composites (2019).

Conference: SAMPE NEXUS 2021

Publication Date: 2021/06/29

SKU: TP21-0000000600

Pages: 15

Price: FREE