Modelling of oblique tennis ball impacts on tennis surfaces

A model has been developed which incorporates features of vicsoelastic, impulsive and Newtonian models for use with oblique tennis ball impacts. The model simulates forces at the front and rear of the ball due to mass in the shell coming to rest. It was found that the impulsive force was larger at the front of the ball than the rear due partly to the topspin gained during impact. Finally, friction was allowed to reverse direction if the ball began to overspin. The model was compared to experimental data from two similar impacts at 34 m.s-1 and 23° to the horizontal on a smooth and rough surface with coefficients of friction of 0.51 and 0.62 respectively. The model predicted the vertical displacements well but under-predicted the horizontal displacements of the ball's centre of mass by 5%. It was suggested that this was due to horizontal deformation of the ball not accounted for in the model.