RELATIONSHIP BETWEEN STRUCTURE AND MECHANICAL PROPERTIES OF BRAIDING GOLF SHAFTS AND KANSEI (P1)
Golf playing skill depends on not only personal’s skill but also golf club performance and golf ball efficiency. The golf club is consisted of grip, shaft and head among three many different requirements required on the shaft rather than the grip and the head. Particularly, high level golf player’s demand for the shaft is severe and these are quite personal issue. Therefore, “Custom-made” shaft requirements naturally are arisen, which is fit the personal skill and feeling.
The golf shafts have been made by using carbon fiber reinforced plastics called Black shaft. Normally, reinforcement configuration is unidirectional aligned fibers. It is difficult that the fiber orientation angle is changed partially. Also, the diameter of the shaft near the grip is larger than that near the head. In the case of fabricating custom made golf shaft,
change of bending rigidity along the longitudinal direction should be suitable for that person, so that we need more fabrication flexibility of fiber orientation angle. From this view point, unidirectional prepreg sheet does not posses fabrication flexibility on the other hand braiding technique has much freedom in fiber orientation state. The fiber orientation state, braiding angle in braided fabric can be determined by the velocity ratio between spindle movement on the circle and picking up movement to the vertical direction. Therefore desired fiber orientation angle can be decided and it is easy to change the angle.
Our purpose of this study is to develop a new braided golf shaft which can be regarded as “Custom made” shaft. In this report, the effects of braiding angle on bending properties of braided composites at the first section. Next, actual golf swing was performed by the expert golf player, and the electromyogram (EMG) activity was measured. At the end of this report, “Kansei” and feeling of the player was evaluated by questionnaire. The characteristics of braided golf shaft would be clear.
2. Braided tubular composite
The schematic drawing of braided fabric is shown in Figure 1. One of the important features is continuity of the fiber bundle in the braided fabric. The all fiber bundles are continuously oriented, so that the seamless composite tube can be fabricated with tubular braiding technique. Moreover, the excellent mechanical properties were expected because of the continuity of fiber bundle. Other characteristic is capability of changing the braiding angle. Using woven fabric or unidirectional prepreg sheet for fabricating the composite tube, the fiber orientation angle is fixed uniformly in a layer.
On the other hand, in braided fabric, all fiber bundles are diagonally oriented in longitudinal direction, and the angle of the fiber bundle to the longitudinal direction can be adjusted freely. Therefore, the mechanical properties can be variously designed according to the requirement.
Figure 2 show the braided fabric with 30, 45, and 60 degrees fabricated using same filament and bundle number of carbon fibers.