Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150904

150904 - Controlled Deposition of Nanofibers: Towards 3d Printing of Complex Nano-Filamentary Materials 

Carbon fiber composites are lightweight materials with high strength and modulus. Interfacial delamination is a common failure mechanism in these materials, caused by high interlaminar stresses near edges. These interlaminar stresses are due to Poisson’s coefficient mismatch and shear-extension coupling in anisotropic laminates. Over the years, numerous methods, such as ply-layup optimization, edge capping, and stitching, have been developed and implemented to reduce delamination. Many of these methods are difficult and expensive to implement, while some also negatively affect primary composite in-plane properties. In addition, most approaches developed to date resulted in significant weight penalties.

A recent study from our research group demonstrated that continuous nanofiber (NF) interleaves can simultaneously improve Mode I and II interlaminar fracture toughness. Nanofibers also proved capable of effectively suppressing delamination initiation by reducing interlaminar edge stresses. To date, the NF interleaves were produced through conventional electrospinning. Electrospinning is a process where polymer solutions are jetted in high electrical fields. Polymer jets undergo several types of instabilities, creating a broad conical process zone, and are deposited on a substrate in a random mat form. The conventional process is reasonably well suited for depositing random nanofibers over large surfaces. However, precision deposition of patterned aligned nanofiber constructs has not yet been demonstrated. Such precise deposition could significantly increase the effectiveness of nanofibers for edge delamination suppression as well as for general reinforcement of ultrahigh-performance nanocomposites and other applications.

This poster presents a manufacturing method that uses a 3-axis computer numerical control (CNC) system to deposit nanofibers in predetermined locations on substrates. Manipulating the electric field during electrospinning enabled a significant, up to 84%, reduction of the deposition radius of NFs. This, in turn, enabled the writing of complex nano-filamentary patterns on several substrates. The ability to precisely deposit nanofiber reinforcement near straight and curved edges as well as around holes has been demonstrated. Laminates with strategically nano-reinforced interlaminar areas near edges have been cured and tested, demonstrating efficient low-cost delamination suppression with minimal use of nanofibers. Finally, the controlled deposition of aligned nanofibers is demonstrated. Combined with 3-axis CNC, the latter enables the fabrication of intricate 2D and 3D nanofiber assemblies and composites for a wide range of applications. Ultimately, a 6-DoF robotic arm system will be implemented to promote integrating electrospun NF interleaves with industrial composite manufacturing.

 

References

[1]       Y. Dzenis, Spinning Continuous Fibers for Nanotechnology, Science 304 (2004) 1917–1919. https://doi.org/10.1126/science.1099074.

[2]       Y. Dzenis, Structural Nanocomposites, Science 319 (2008) 419–420. https://doi.org/10.1126/science.1151434.

[3]       D. Papkov, Y. Zou, M.N. Andalib, A. Goponenko, S.Z.D. Cheng, Y.A. Dzenis, Simultaneously Strong and Tough Ultrafine Continuous Nanofibers, ACS Nano 7 (2013) 3324–3331. https://doi.org/10.1021/nn400028p.

Presenting Author: Emmanuel Kweku Mensah University of Nebraska Lincoln

Presenting Author Biography: Emmanuel Kweku Mensah is a dedicated Ph.D. candidate in Mechanical Engineering and Applied Mechanics at the University of Nebraska-Lincoln. His research specializes in the precision manufacturing of nanofibers via electrospinning. Applying the fundamentals of electrical, mechanical, and material engineering, Kweku fabricates continuous ultrafine nanofibers that combine exceptional strength and toughness. His work ensures consistent and reproducible outcomes by advancing electrospinning from an art to a science. Kweku’s research promotes interdisciplinary collaboration, leveraging nanofibers to address complex challenges across various fields.

Authors:

Emmanuel Kweku Mensah University of Nebraska Lincoln
Benjamin Bashtovoi University of Nebraska Lincoln
Mikhail Kartoshov University of Nebraska Lincoln
Yuris Dzenis University of Nebraska Lincoln