Comparison of flexible and rigid body modelling of a tennis racket

In this paper a comparison is made between two difference models for simulating a tennis racket during an impact with a tennis ball. The racket was modelled as either a rigid body or a one-dimensional non-uniform flexible beam. The ball was modelled as a simple spring and damper in parallel with the stringbed was modelled as a spring in series with the ball. The models were compared with experimental data obtained from an impact between a ball and a freely suspended racket, for a range of impact positions. The results showed that, for impacts close to the node of vibration (fundamental fequency) the rigid and flexible body models yield almost identical answers and, more importantly, both models correlate well with the experimental data. For impacts away from the node point, the flexible model matches the experimental results better than the rigid body model. The flexible body model can be used by racket designers to predict the effect of changing the material from which the racket is manufactured, on the ball velocity after impact.