Proceedings of 7 th ISEA CONFERENCE 2008 Biarritz, June 2-6, 2008 An Examination of Cricket Bat Performance Lloyd Smith 1 , Harsimranjeet Singh 2 School of Mechanical and Materials Engineering Washington State University 201 Sloan, Spokane Street Pullman, WA 99164-2920 USA 509 335 3221(tel)/6442(fax) 1 lvsmith@wsu.edu; 2 harsimran52@yahoo.com ABSTRACT: The aims of this study were to experimentally measure and numerically describe the performance of cricket bats and balls. A dynamic finite element model was employed to simulate the bat-ball impact. The ball was modeled as a linear viscoelastic material which provided the mechanism of energy loss during impact. An experimental test apparatus was developed to measure the performance of cricket bats and balls under dynamic impact conditions representative of play. Experiments were conducted to measure the elasticity and hardness of the cricket balls as a function of incoming speed. A bat- performance measure was derived in terms of an ideal batted-ball speed based on play conditions. The model found good agreement with experimental data for a number of impact conditions. A composite skin, applied to the back of some bats, was observed to increase performance experimentally and in the numerical model. While different treatments and designs typical of cricket bats had a measurable effect on performance, they were much smaller than the 10% difference observed between some solid-wood and hollow baseball and softball bats. Keywords: Cricket bat, Cricket ball, COR, Dynamic stiffness, BBS, Composite skin 1-Introduction Although, the sport of Cricket is 500 years old [B1] there has been little research studying the bat or the ball. Since the 17 th century, the cricket bat has been changed various times, but remains of solid wood [T1]. The aim of the bat is to maximize batted-ball speed, and minimize vibration to the batsman’s hands. The blade is made of willow which is strong, lightweight and has good shock resistance. The handle is made of cane which has good shock absorbing properties. The length of the bat cannot exceed 38 inches (96.5 cm), and the width of the blade must be less than 4.25 inches (10.8 cm) [T1]. The performance of cricket bats has been compared using their coefficient of restitution (COR); defined as the ratio of relative speed of the objects after and before the collision. One study found that the COR of the bat decreased as the bat stiffness increased [F1]. Recent advances in technology and materials have motivated a number of changes in cricket bat design. While some studies suggest these advances have not affected performance, more work is needed to quantify their contribution [S4]. Cricket balls are made from a cork nucleus with layers of wound wool and cork and a leather cover. The leather exterior is usually constructed from four sewn pieces. A cricket ball weighs between 5.5 to 5.75 ounces (155.9 to 163 g) and can be no more than 9 in. (22.9 cm) in circumference [T1]. Cricket balls are made in a number of different ways, with varying core design. Some have shown that greater deformation was found for impacts landing on the seam, compared to those landing perpendicular to the seam [C1]. There is little information on the effect of cricket ball properties on bat performance.