Sub-unit Cell Modeling and Manufacturing of Non-Orthogonal Three-Dimensional Braided Structures

• Author / Creator

  Batten, Evan R. J.

• Three-dimensional (3D) braiding is commonly considered an advantageous method for producing near-net composites that provide improved transverse properties relative to two-dimensional (2D) braiding. Modeling of 3D braids is an ever-growing field of research – particularly the use of sub-unit cell models. The production of complex braid shapes and patterns – and the modeling of the same – serves to allow 3D braids to be used more widely, such as various mechanical, infrastructure, or medical applications. This research focused improving the functionality of a purpose-built braiding machine and on the improvement of sub-unit cell models used for predictive modeling through an expansion of modeling capabilities and through validation. In this research, the braiding machine’s maximum capacity was upgraded from 9 to 49 motors, 24 to 161 yarns, and 3 to 50 motor drivers. The control and take-up systems were also dramatically improved by the addition of 112 new I/O connections and the ability to vary or pause the take-up speed respectively. Through these improvements, many new braid shapes were possible – including three braid shapes novel to this work: isosceles triangle, right triangle, and curve approximation. The modeling application was expanded to match the capabilities of the braiding machine. In doing so, predictions of stiffness for various orthogonal braid shapes were made possible and several novel sub-unit cells were identified. The novel sub-unit cells included the isosceles triangle edge, upper corner, and lower corner and the right triangle edge, upper corner, and lower corner. It was predicted that as the isosceles triangle had a larger braid angle than orthogonal shapes (and the right triangle larger again) that the longitudinal stiffness of the triangular shapes would be reduced relative to orthogonal shapes, but that transverse properties would be improved. The interior braid angle and braid pitch predicted by the model were validated using a micro-computed tomography (micro-CT) analysis. The relative errors between the model predictions and micro-CT results for interior braid angle and braid pitch were found to be 13.00% and 6.16% respectively. It was suggested that additional measurements to normalize the model data could further reduce these errors in the future.

• Subjects / Keywords

  • 3D Braid
  • Sub-unit cell
  • Modeling
  • Micro-CT
  • Multi-step braid
  • Machine Emulation

• Graduation date

  Spring 2021

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-7qcc-k098

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.