Vibration Response of Golf Clubs With Steel and Composite Shafts

In a previous paper (Barpanda and Mantena, 1998), the dynamic response of three commercially available hockey sticks with wooden, aluminum and graphite shafts was characterized using a combined modal analysis and vibration response approach. The extension of this technique to golf clubs with steel and graphite shafts is reported here. Using an instrumented impact hammer, a complete modal survey is initially conducted on the golf clubs to study their dynamic behavior. A comparative study of the modal parameters (natural frequency, damping and mode shapes) of the golf clubs provides valuable information for design optimization. The contour and associated vector plots of the mode shapes are very useful for generating node (zero displacement) lines on the club-head surface. A two-accelerometer technique was then used to perform vibration response tests on the impact surface. Linear and angular vibration level maps were plotted for identifying ‘sweet spot regions’ on the impact surface. These tests yield quasi-quantitative information regarding the level of vibrations felt by a player due to simultaneous linear and angular motion of the shaft and club-head. The mapping also serves as an effective tool for determining the relative merits of steel and graphite shafted club heads based on their vibration performance. Results of modal analysis and vibration response tests indicate that the golf club with a graphite shaft had a larger sweet spot zone enclosing the area of maximum node line density compared to the club with a steel shaft. The combined strategy of using both modal analysis and vibration response measurements provides a better understanding of the dynamic response of golf clubs made with different materials.