The influence of impact vibration modes and frequencies on cricket bat performance

Abstract

The performance or hitting power of a number of cricket bats has been compared by measuring the absorption of impact vibration energy along the length of their blades. The measurements lead to the characterization of the position and size of the nodal sweet spot, i.e. impact area giving high performance, in addition to the identification of areas of poor performance on the blade. For the range of bats tested, the sweet spot position varies from 140 to 170 mm from the blade tip and its length varies from 130 to 160 mm. The results show that the blade profile, i.e. mass distribution, has an influence on the sweet spot characteristics, although small notches or cutouts have limited effect. Heavier bats are also shown to absorb less energy, and hence perform better, than lightweight bats. The development of a simplified discontinuous beam model has shown that the frequencies of vibration of a bat can be controlled by altering the stiffness and/or mass of the blade or handle. In particular, it has been shown that the use of a lightweight, high stiffness handle, possibly manufactured from advanced composites, could raise the third bending mode natural frequency out of the excitation range of a cricket ball-bat impact. Such a bat would show a significant performance improvement over current designs. The energy absorption procedure described in this paper offers designers a quantitative approach for optimizing the design of cricket bats and other sports equipment.