Fatigue response of carbon fiber epoxy laminates with vertically-aligned carbon nanotube interfacial reinforcement
Heather Conway, Daniel Chebot, Christopher Gouldstone, Ryan D. Williams
Presented at SAMPE Baltimore May 2015
ABSTRACT: Quasi isotropic carbon fiber epoxy laminates were fabricated for fatigue testing using a modified ASTM D2344 short beam shear (SBS) strength testing to quantify the effect of vertically-aligned carbon nanotubes (VACNTs) on fatigue life. Parts were globally reinforced with VACNTs grown in-house using a continuous chemical vapor deposition process on metallic ribbon substrate. VACNTs were then transferred onto prepreg and laminated using industry standard practices for composite manufacturing. Short beam shear fatigue testing revealed that globally reinforced laminates using VACNTs survived longer under a given cyclic load than baseline samples, resulting in a fatigue life over two orders of magnitude longer than conventional carbon fiber composite laminates.
Reinforcing Ply Drop Interfaces Using Vertically-Aligned Carbon Nanotube Forests
Christopher Gouldstone, David Degtiarov, Ryan D. Williams
Presented at SAMPE Seattle June 2014
ABSTRACT: Unidirectional symmetric ply-dropped test specimens were fabricated with vertically-aligned carbon nanotube (VACNT) forests (“nano-reinforcement”) located at specific ply interfaces to improve interlaminar mechanical properties of the structure. A second, baseline set of specimens were fabricated without nano-reinforcement for comparison. The nano-reinforced specimens exhibited 5% higher useful strength and failure modes that were distinct from the baseline set, with no change in overall mass, thickness, porosity or stiffness owing to the inclusion of VACNTs. Nano-reinforcement of the interlaminar region local to ply drops prevented crack propagation along those ply interfaces, with failures instead due to intra-ply cracking or fiber breakage, indicating nano-reinforcement mitigates weakness at ply interfaces.
Other Relevant Articles and Papers
Aligned carbon nanotube reinforcement of aerospace carbon fiber composites: substructural strength evaluation for aerostructure applications
de Villoria, R. Guzmán, et al.
Proceedings of the 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. 2012
This paper, prepared by MIT and Saab AB, reports improved mechanical properties of carbon-fiber reinforced polymers with Nanostitch®, including tension bearing (+30% useful strength), open hole compression (+10%) and L-bending (+40% energy-to-break).
Electrothermal Icing protection of Aerosurfaces Using Conductive Polymer Nanocomposites
Buschhorn, Samuel T., et al.
Boston, AIAA (2013): 2013-1729
Metis Development and MIT used a precursor to Surface Layer System™ films as resistive heaters on an aerosurface to demonstrate an aligned CNT-based deicing solution effective down to -5°F and up to 125mph.
Joining prepreg composite interfaces with aligned carbon nanotubes
Garcia, Enrique J., Brian L. Wardle, and A. John Hart
Composites Part A: Applied Science and Manufacturing 39.6 (2008): 1065-1070
This paper reports increased strain energy release rate in Mode I (+150%) and Mode II (+200%) for autoclave composite systems including IM7/977-3 and AS4/8552, when adding Nanostitch®.
High-yield growth of vertically aligned carbon nanotubes on a continuously moving substrate
de Villoria, R. Guzmán, et al.
Nanotechnology 20.40 (2009): 405611
MIT reports early progress towards achieving a continuous growth process, by growing Nanostitch® and Fuzzy Fiber™ on a moving substrate. Today, N12 uses a continuous, roll-to-roll growth process for producing Nanostitch® at increasing scale.
Fabrication and multifunctional properties of a hybrid laminate with aligned carbon nanotubes grown in situ
Garcia, Enrique J., et al.
Composites Science and Technology 68.9 (2008): 2034-2041
MIT reports large increases in interlaminar shear strength (+69%) and conductivity (106-108) using Fuzzy Fiber™ technology i.e., radially-aligned CNTs grown directly on alumina fiber cloth.