Dynamics of the Golf Club-Grip Interaction

Abstract

A two degree of freedom hand-grip model was developed and simulated with a golfer downswing model, which contained an experimentally validated flexible shaft model. Experimental modal analysis was performed on a golf club to derive frequency response functions for both fixedfree and hands-free boundary conditions. Simulated frequency response functions were generated with the developed grip model to impose a hands-free boundary condition. Direct collocation using GPOPS-II was utilized to optimize the swing model with and without the grip model. An increase in clubhead velocity and decrease in shaft deflection was observed with the grip model implemented. In addition, the direct collocation approach resulted in similar joint angle trajectories, shaft deflection patterns, and joint torque profiles to those reported in the literature.

Critique of USGA Reco mmendations for A Method of Putting Green Construction

“…Ksat is the proportionality factor equating flux (volume of water through a cross-section over a time) to hydraulic gradient (head drop per unit distance) [8]. Water movement through the soil profile under saturated conditions may be described by Ksat; however, our research into Ksat of a sectioned USGA style green indicates infiltration rate is most limited by the presence of thatch [9]. Knowing how quickly a rootzone mixture can conduct water is an important consideration in drainage, but proper maintenance of turfgrass to minimize thatch build up is a more important factor to consider.…”

“…In many sand mixtures we have analyzed, it has been rare to find a sand that meets both the air-filled and capillary requirements. We conducted research using sand narrowly outside the USGA reco mmendations due to a fine sand content greater than 20%, which should be capable of holding more water at higher tensions than coarser sands [9]. However, based on Figure 2, water content was 0.08 cm 3 cm -3 at 30 cm tension, Agricultural Research & Technology: Open Access Journal therefore, outside the acceptable range.…”