Analytical and Experimental Analysis of Tubular Braided Composites

• Author / Creator

  Melenka, Garrett W.

• Tubular braided composites consist of woven fibers imbedded in a resin matrix. Braided composites are manufactured using a device known as a Maypole braider. Braiding machines can be configured to produce several braiding patterns including: Diamond (1/1), Regular (2/2), Hercules (3/3) and triaxial braids. Presently, most researchers focus on one braiding pattern when evaluating braided composites. A comprehensive comparison of the different braiding patterns has not been performed. The goal of this thesis is to develop a new analytical model that predicts the mechanical properties of each of the available braiding patterns. To achieve this aim a new Volume Averaging methodology was used. In order to support the proposed analytical model experimental analysis of braided composites samples were performed. Braided composite samples were evaluated using micro-computed tomography in order to characterize the three dimensional structure of braided composites. Braided composite samples were also evaluated under tensile and torsional loads in order to determine the longitudinal and shear moduli for tubular braided composites. Braid samples were examined using a three dimensional digital image correlation (3D DIC) method in order to measure the three dimensional strain fields. The 3D DIC method allow for the mechanical properties of braid samples to be evaluated. The effect of braiding pattern and braid angle on the 3D strain field was also investigated. The 3D DIC results demonstrate the periodic strain field that occurs in tubular braided composite braids due to the nature of the braid manufacturing process. The Volume Averaging methodology presented in this thesis was also applied to fiber-reinforced 3D printed structures. The results of this work demonstrate the adaptability of the Volume Averaging methodology to different composite structures in order to predict mechanical properties. The results of this work demonstrate that braids of different geometry can be model using an analytical Volume Averaging method. The presented model results were experimentally validated using a 3D DIC optical measurement technique. The versatility of the Volume Averaging method is also demonstrated since this technique was applied to the modelling of both tubular braided composite braids and fiber-reinforced 3D printed structures.

• Subjects / Keywords

  • Tubular Braided Composite
  • Analytical Model
  • 3D printing
  • 3D DIC
  • Micro-computed tomography

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3J09WF76

• 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.