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Integrated Design For Manufacturing of Braided Preforms For Advanced Composites Part II: 3D Braiding Yan Tao Gao & Frank K. Ko & Hong Hu

# Springer Science+Business Media Dordrecht 2013

Abstract This paper presents the integrated design of manufacturing of braided preforms by two types of novel 3D braiding technology: 3D Cartesian braiding and novel hexagonal braiding. The principles for design are first introduced and the ensuing software package development is subsequently discussed. The relationships between fiber volume fraction and braiding angle which are key parameters for fiber reinforcement composites were analyzed and compared. Meanwhile, several samples are carried out to verify the software. The result shows it is consistent between theoretical and experimental results. Combined with the Part I: 2D braiding section, many complex shape performs can be made, which will be usefully for design of advanced composites. Keywords 3D Cartesian braiding . Hexagonal braiding . Software package . Fiber volume fraction . Braiding angle

1 Introduction 3D braided composites have been widely used as they have many advantages over conventional laminate composites, such as through-thickness reinforcement, high damage tolerance and near net-shape [1]. As such, the design and fabrication of 3D braided performs has continued to receive considerable attention. 3D Cartesian braiding is a very popular 3D braiding technology that is capable of manufacturing structures such as rectangular and circular; but it is not suitable for polygonal structures. However, the newly developed Y. T. Gao : H. Hu College of textiles, Donghua University, Shanghai 201620, China F. K. Ko (*) Department of Materials Engineering & AMPEL, University of British Columbia, Vancouver, BC, Canada e-mail: [email protected] H. Hu Institute of Textiles and Clothing, The Hong Kong polytechnic University, Hung Hom, Hong Kong

Appl Compos Mater

hexagonal braiding machine by AFML in UBC has impressive capability of producing complex polygonal constructs. If two groups of braiding technology are used together, more kinds of 3D braided preforms could be provided for advanced composites. Based on the above, a 3D braided software package for 3D Cartesian braiding and hexagonal braiding was developed using fundamental principles proposed by Dr. Ko’s group [2].

2 Analysis 2.1 3D Braiding Model The total number of yarn strands required to make a 3-D fabric with a given fiber volume fraction can be determined as follows:

106  ρ Vf AC cos ftan1 ½ Ny ¼ 5:81 Dy

p 2 ffiffiffiffiffiffiffiffi

1þk2 tanðθÞ k

g

ð1Þ

Ny 0 total number of yarn strands; Vf 0 fiber volume fraction; Ac 0 composites crosssectional area; ρ 0 yarn density (g/cm3); K 0 track/column movement ratio; θ 0 fibre surface angle (degree); Dy 0 yarn linear density (denier) For 3D braided structures, relationships between interior angle and surface angle can be obtained: 0

θ ¼ tan

1

½

p 2 ffiffiffiffiffiffiffiffiffiffiffiffiffi 1 þ k2 tanðθÞ  k

ð2Þ

Where θ 0 fibre surface angle (degree). If the number of yarn strands is too large for pr