Page 148 - 3D Fibre Reinforced Polymer Composites

Chapter 6

Braided Composite Materials

6.1 INTRODUCTION

Much of the current knowledge behind the technologies used to manufacture 3D
braided preforms was generated in a period of time between the early 1980’s and the
late 1990’s. Mostly funded through the US Government, research programs, of which
the NASA Advanced Composite Technology (ACT) Program was a major focus,
brought together preform suppliers such as Atlantic Research Corporation and Drexel
University, with research laboratories (University of Delaware, NASA Langley, Drexel
University, etc) and aerospace end-users (Boeing, Douglas and Lockheed). It was
during this period that some of the more significant studies on the mechanical behaviour
of 3D braided composites were performed.
However, in common with the other forms of 3D textile composites described in this
book, the extent of the published literature on the mechanical properties of 3D braided
composites would only constitute a small part of the information necessary to fully
characterise this class of composite material. In Section 2.3 the main techniques of
producing 3D braided preforms were described. Each of these manufacturing processes
would result in preforms whose final consolidated properties would be influenced not
only by the characteristics of the process itself but also by the variations in braid
architecture that can be generated within each manufacturing technique. Figure 6.1
illustrates the highly interlinked nature of a 3D braid and critical factors such as the yarn
size, the angle of the braiding yarns, the percentage content of axial yarns, etc, all have a
major influence upon the resultant composite properties.

Figure 6.1 Photomicrograph of a 3D braided architecture (courtesy of Atlantic
Research Corporation)