Additive Manufacturing of Structural Cores and Washout Tooling for Autoclave Curing of Hybrid Composite Structures
This paper presents a study combining additive manufactured (AM) elements with carbon fiber-reinforced polymers (CFRP) for the autoclave curing of complex-shaped, lightweight structures. Two approaches were developed: First, structural cores were produced with AM, over-laminated with CFRP, and co-cured in the autoclave. Second, a functional hull is produced with AM, filled with a temperature- and pressure-resistant material, and over-laminated with CFRP. After curing, the filler-material is removed to obtain a hollow lightweight structure. The approaches were applied to hat stiffeners, which were modeled, fabricated, and tested in three-point bending. Results show weight savings by up to 5% compared to a foam core reference. Moreover, the AM element contributes to the mechanical performance of the hat stiffener, which is highlighted by an increase in the specific bending stiffness and the first failure load by up to 18% and 310%. Results indicate that the approaches are appropriate for composite structures with complex geometries.
© 2018 by ASME. Paper No: MANU-17-1796. Manuscript received December 20, 2017; final manuscript received May 19, 2018; published online July 9, 2018. Assoc. Editor: Zhijian J. Pei. We thank Professor P. Ermanni of ETH Zurich for providing unlimited access to the laboratory facilities of CMASLab, Professor G. Terrasi and T. Lämmlein of EMPA for assisting in three-point bending testing. We also thank R. Kussmaul of ETH Zurich for providing the optimization algorithms on which the truss design is based and L. Völker for his support on the honeycomb design. Financial support from the Product Development Group Zurich pd|z of ETH Zurich is gratefully acknowledged.
Published - manu_140_10_105001.pdf