Title: Printed Modular Tooling with Vacuum Integrity for Large-Scale Composite Structures

Authors: Garam Kim, Jordan Kalman, Alexander Carlson, Johnathan Goodsell, R. Byron Pipes, Eduardo Barocio

DOI:

Abstract: Additive manufacturing (AM) of modular tooling using fiber-reinforced thermoplastic composites provides a pathway to overcome manufacturing scale, transportation, and lead-time limitations associated with conventional composite tooling. While large-scale additive manufacturing (LSAM) enables rapid fabrication of tooling segments, successful modular tooling implementation requires joint designs capable of maintaining vacuum integrity under thermo-mechanical loading. This work presented an experimental framework for the evaluation and system-level validation of gasketed joints in modular, additively manufactured composite tooling. Candidate elastomeric gasket materials were screened through plate-level vacuum decay tests and characterized at the material and joint-element levels. Compression and stressrelaxation experiments quantified viscoelastic behavior under sustained clamping loads, shearinduced vacuum integrity tests evaluated tolerance to relative in-plane deformation, and thermal aging experiments assessed long-term sealing stability. Based on these results, a butyl rubber gasket was down-selected for system-level validation. The selected gasket was implemented in a 1/3-scale modular tooling demonstrator consisting of a curved mold surface approximately 1.2 m × 1.0 m, subdivided into two LSAM-fabricated modules joined by bolted flange interfaces with alignment features. System-level vacuum integrity was evaluated using vacuum decay measurements, with pressure loss remaining below 10 mbar over a 30-minute hold. The results demonstrate that properly designed gasketed joints enable reliable vacuum integrity in modular LSAM tooling and provide a foundation for scalable, cost-effective composite tooling design.

References: [1] L.J. Love, V. Kunc, O. Rios, C.E. Duty, A.M. Elliott, B.K. Post, R.J. Smith, C.A. Blue, The importance of carbon fiber to polymer additive manufacturing, J. Mater. Res. 29 (2014) 1893–1898. https://doi.org/10.1557/jmr.2014.212. [2] [3] C.E. Duty, V. Kunc, B. Compton, B. Post, D. Erdman, R. Smith, R. Lind, P. Lloyd, L. Love, Structure and mechanical behavior of Big Area Additive Manufacturing (BAAM) materials, RPJ 23 (2017) 181–189. https://doi.org/10.1108/RPJ-12-2015-0183. H.L. Tekinalp, V. Kunc, G.M. Velez-Garcia, C.E. Duty, L.J. Love, A.K. Naskar, C.A. Blue, S. Ozcan, Highly oriented carbon fiber–polymer composites via additive manufacturing, Composites Science and Technology 105 (2014) 144–150. https://doi.org/10.1016/j.compscitech.2014.10.009. [4] P. Yeole, S. Kim, A.A. Hassen, V. Kumar, V. Kunc, U. Vaidya, Large-scale additive manufacturing tooling for extrusion-compression molds, Additive Manufacturing Letters 1 (2021) 100007. https://doi.org/10.1016/j.addlet.2021.100007. [5] [6] [7] [8] [9] M.D.A. Valentine, A. Radhakrishnan, V.K. Maes, E.C. Pegg, M.D.R. Valero, J. Kratz, V. Dhokia, Additively manufactured cure tools for composites manufacture, Int J Adv Manuf Technol 127 (2023) 4237–4251. https://doi.org/10.1007/s00170-023-11254-y. B.G. Compton, B.K. Post, C.E. Duty, L. Love, V. Kunc, Thermal analysis of additive manufacturing of large-scale thermoplastic polymer composites, Additive Manufacturing 17 (2017) 77–86. https://doi.org/10.1016/j.addma.2017.07.006. P. Liu, R.B. Dinwiddie, J.K. Keum, R.K. Vasudevan, S. Jesse, N.A. Nguyen, J.M. Lindahl, V. Kunc, Rheology, crystal structure, and nanomechanical properties in large-scale additive manufacturing of polyphenylene sulfide/carbon fiber composites, Composites Science and Technology 168 (2018) 263–271. https://doi.org/10.1016/j.compscitech.2018.09.010. G. Kim, E. Barocio, W. Tsutsui, P. Wang, S. Dubikovsky, R.B. Pipes, R. Sterkenburg, Applicability assessment of thermoset coating onto additively manufactured thermoplastic composite molds, Additive Manufacturing 61 (2023) 103289. https://doi.org/10.1016/j.addma.2022.103289. B.N.J. Persson, Theory of rubber friction and contact mechanics, The Journal of Chemical Physics 115 (2001) 3840–3861. https://doi.org/10.1063/1.1388626. [10] A.N. Gent, ed., Engineering with rubber: how to design rubber components, 3rd ed, Hanser Publishers, Munich ; Cincinnati, 2012. [11] R. Flitney, Seals and sealing handbook, Sixth edition, Butterworth-Heinemann, an imprint of Elsevier, Amsterdam, 2014. [12] P. Bortolotti, D. Berry, R. Murray, E. Gaertner, D. Jenne, R. Damiani, G. Barter, K. Dykes, A Detailed Wind Turbine Blade Cost Model, 2019. https://doi.org/10.2172/1529217. [13] P. Brøndsted, H. Lilholt, A. Lystrup, COMPOSITE MATERIALS FOR WIND POWER TURBINE BLADES, Annu. Rev. Mater. Res. 35 (2005) 505–538. https://doi.org/10.1146/annurev.matsci.35.100303.110641. [14] T. Ashwill, Materials and Innovations for Large Blade Structures: Research Opportunities in WInd Energy Technology, in: 50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, American Institute of Aeronautics and Astronautics, Palm Springs, California, 2009. https://doi.org/10.2514/6.2009-2407. [15] Y. Li, Y. Xiao, L. Yu, K. Ji, D. Li, A review on the tooling technologies for composites manufacturing of aerospace structures: materials, structures and processes, Composites Part A: Applied Science and Manufacturing 154 (2022) 106762. https://doi.org/10.1016/j.compositesa.2021.106762.

Conference: SAMPE 2026

Publication Date: 2026/04/27

SKU: 45

Pages: 16

Price: $32.00