Tadashi Uozumi

Energy Absorption Capability of 3D Braided-Textile Composite Tubes with Rectangular Cross Section

Fiber Reinforced Plastics (FRPs) are now under research as crush element because of its contribution in energy absorption. The 3D-textile braiding was introduced in this study as a reinforcement form of fibers. The CFRP square tubes with rectangular cross section were tested in quasi-static experiments. The results show that 3D structure was effective in holding back the propagation of the central crack and the composite tube with a design on the corners could perform better energy absorption capability.

Experimental Investigation on the Crushing Properties of Carbon Fibre Braided Composite Tubes

Braided textile fabric reinforcements are popularly used in manufacturing composite tubes due to the near-net-shape of the final tubular preform. Their Fabrication technique is highly automated offering good balance in architecture and reduced manufacturing costs. In the study presented herein, a highly automated production with a pultrusion machine at the end is used in the fabrication of braided composite tubes. This production method substantially reduces the manufacturing cost, while constantly maintaining the quality of the product and superior surface finish. The achieved efficiency coupled with many inherently advantages such as good general mechanical properties, good off-axis properties and good impact behaviour makes braided composites to be prime candidates for load bearing structures that require high energy absorption capability. Results presented in this study indeed show compressed braided composite tubes to posses this high capability of absorbing large quantity of energy as a function of the fibre orientation angle. The work done thereof is governed by a number of distinct failure mechanisms that are classified through a step-by-step analysis of the failure zone by using micrographs.

Structure and machine braiding procedure of coupled square braids with various cross sections

Braids provide an ideal preform for textile composite materials while the structure of the braids is restricted by the machine braiding procedure. A wide variety of braided structures found in historical Japanese braids, however, implies a possibility for us to obtain a more rational preform. Thus, a systematic approach to translate the braided structures into a machine braiding procedure is required. We determined the bundle path and number of bundles of square braids and derived formulas giving the optimum number of bundles. The arrangement of horn gears and the number of necessary horn docks were studied. It was found feasible to develop a rotary braiding machine capable of manufacturing braids with arbitrary cross sections.

Development of Manufacturing Techniques by Hand for Non-straight Braids

Using a Marudai and hand braiding methodology, with repetitive thread movement patterns and bobbin positioning, different curved (curvature radius) braids were created. While the conventional straight braid was made keeping thread arrangements symmetrically on the Marudai, the non-straight braid was realized by breaking the symmetry principle. By using different braiding patterns, braids that are curved can be created by without applying external force. This represents a study of the relationship between the structure and the curve.

Teaching Method of Technique to Make the Braiding

In the previous study, we assigned one expert and two non-experts to braid strands, and measured the movements of their eyes and evaluated the quality of the finished braids. From the measurement result, we clarified two points of the know-how hidden behind the skilled worker’s technique. The first is the height from marudai, a circular frame stand, used for Japanese style braiding and the strand being moved. The other is the angle between marudai, a circular frame stand, and the strands being moved. In this study, we firstly conducted trainings with focusing on the height from the circular frame stand and the angle between the stand and strands. And then, conducted eye movement measurement and motion analysis to verify how the know-how extracted from these results brought the educational benefits to instruct a non-expert on the braiding technique.