Effects of string tension and impact location on tennis playing

Finite element impact simulations were performed to observe the vibration of a tennis racket and its strings, as well as the effects of string tension and impact location on a player's hand and his chances of getting an injury. Studies using the finite element method [FEM] revealed that decreasing the string tension lowers the coefficient of restitution. The ratio of speed to angle change increases with a decrease in string tension. Moreover, the resultant force on the player's hand is stronger if the tennis ball hits the dead spot than if it hits the sweet spot. For instance, as a tennis ball hits the dead spot with a speed of 10.05m/s, an angle of 15°, and a string tension of 222N, the player's hand feels a maximum resultant force of almost 424N, which is 1.61 times higher than if the ball hits the sweet spot, at t=0.081 and t=0.0149. Moreover, the force exerted on the player's hand if the ball hits either the best-bounce spot or the off-center spot is 1.4 times higher than if the ball hits the sweet spot.