Effect of Torsional Properties of CFRP Golf Club Shafts on Speed and Directional Stability of Ball

The mechanical properities of golf clubs are represented mainly by the flex(flexural property)and the torque-degree(torsional property). The initial speeds and the fly-out directions of balls hit by golf clubs with different torque-degree shafts were evaluated using a golf shaft swing machine. It was found that golf clubs with low torque-degree shafts can achieve higher initial speeds and are more stable in the fly-out direction than clubs with high torque-degress shafts. The reasons are as follows.1) The degree of torsion of low torque-degree shafts during the time the golf club head hits(touches)the ball is lower than that of high torque-degree shafts.2) A golf club shaft exhibits torsional vibration behavior during the swing even before the impact point. In the case of low torque-degree shafts, the amplitude of vibration is smaller and the face of the club head returns to a proper angle.