Title: Performance and Durability Assessment of Shape Memory Polymer Tools for Closed Composite Structures

Authors: Christian Pfledderer, Steven Shewchuk, Craig Neslen, Elizabeth Loiacono, Thomas Margraf, Michael Matlack

DOI: 10.33599/nasampe/s.21.0470

Abstract: Shape memory polymer (SMP) tools that are rigid for lay-up, elastomeric for cure, and reformed into the inside mold line (IML) shape of the composite article between cycles. They have been used to control the inner geometry of composite structures. SMP tools are fabricated using resins formulated to have an elastic modulus that changes depending on the material temperature and the specific material formulation. At room temperature, the SMP tools have a high elastic modulus (i.e. rigid epoxy), in their rigid state, and can be used as lay-up mandrels to apply composite pre-preg, apply dry fiber textiles, or used as a mandrel during an overbraid process. At cure temperatures, SMP tools classified as bladders and cauls transition to a highly elastomeric state (i.e. medium durometer silicone), and when internally pressurized, transfer compaction force into the composite laminate to ensure good material consolidation during the cure process. This paper describes the application of SMP tools to the fabrication of a double I-beam composite design using composite pre-preg material. Part to part geometrical accuracy, part porosity, surface roughness, and a durability evaluation of the SMP tooling was completed after 59 thermal and/or laminate cycles in the double I-beam configuration.

References: 1. Lindner, Donna, AFRL, associates improve processes for fabricating aircraft engine inlet ducts, Wright-Patterson AFB, 30 March 2020, https://www.wpafb.af.mil/News/Article-Display/Article/2129592/afrl-associates-improve-processes-for-fabricating-aircraft-engine-inlet-ducts/ 2. Hood, Patrick J, et al. Method of using a shape memory material as a mandrel for composite part manufacturing. US Patent US7422714B1. Filed 24 January 2002, Issued 9 September 2009. 3. Margraf, Thomas W, et al. Cauls and methods of using cauls to produce composite articles. US Patent 10391684B1. Filed 30 November 2016, Issued 27 August 2019. 4. 3900 Prepreg System. https://www.toraycma.com/files/library/929aa2c254676d99.pdf, rev 5. 18 Jan 2018. 5. https://www.convergent.ca/products/raven-simulation-software

Conference: SAMPE NEXUS 2021

Publication Date: 2021/06/29

SKU: TP21-0000000470

Pages: 15

Price: FREE