IMPACT PROBABILITY-DISTRIBUTION, SWEET SPOT, AND THE CONCEPT OF AN EFFECTIVE POWER REGION IN TENNIS RACKETS

A two-dimensional impact probability density distribution for tennis r ackets has been established. It was found that the center of this dist ribution, and therefore the most likely candidate for a preferred impa ct center, is the nodal point of the fundamental transverse vibration mode. It is suggested that the node be defined as the sweet spot and t he location of maximum restitution as the power spot. The concept of a n effective power region centered at the sweet spot and accounting for both the decreasing impact probabilities around the sweet spot and th e global restitution function has been introduced. About 78% of all im pacts fair within this region, which is therefore truly representative of the power transfer characteristics of a racket. It has been found that high-quality rackets have an effective power area in excess of 10 0 cm(2).