Investigation of head impact kinematics during sepak takraw ball heading / Nik Mohd Haikal Bin Mohamed Hassan

Faculty of Mechanical and Automotive Engineering Technology

Thesis (Master of Science) -- Universiti Malaysia Pahang – 2024

Includes bibliographical references

Sepak Takraw is an acrobatic sport where players use their feet, knees, chests, and heads to keep a rattan ball aloft. Concussions and subconcussions from intentional ball-to-head impacts are a concern in the sport. Compared to soccer balls, the Sepak Takraw ball is claimed to have higher hardness while players must receive high-speed serves. Multiple ball-to-head impacts may increase subconcussion risk. Thus, the objectives of this study are to determine the quasi-static and dynamic properties, to predict the head impact kinematics of the sepak takraw ball heading model using a mass-spring-damper system, and to investigate the head impact kinematics and injury risk of takraw ball heading through an anthropomorphic testing device (ATD) experiment. The study employed a compression test to quantify the quasi-static properties of the ball and a drop ball test to characterize its dynamic properties. The tests were done using two types of tournamentspecific ball: Marathon (MT908) and Gajah Emas (GE908). Building on a mass-springdamper model established for soccer balls in literature, the model was adapted for the Sepak Takraw ball. Subsequently, a ball-heading experiment was conducted using a ball launcher on an ATD. The findings revealed three distinct orientations of the takraw ball, each influencing both quasi-static and dynamic stiffness. Orientation 1 exhibited the highest quasi-static stiffness, while the dynamic stiffness indicated that MT908 was stiffer than GE511. The drop ball test yielded crucial stiffness, k and damping coefficient values, c incorporated into the mathematical model: the proposed sepak takraw ball k and c are 26673.23 N/m and 18.492 Ns/m for GE511, and 30672.20 N/m 20.249 Ns/m for MT908, respectively. The mass-spring-damper model enabled the quantification of peak linear acceleration, aligning with Sepak Takraw literature and corroborating with results from other soccer sports studies. Comparison between the model and the ball-heading experiment demonstrated coherence, validating the accuracy (89.38%) of the model. Importantly, both linear and rotational accelerations recorded during the ball-heading experiment were found to be distinctly below the concussion threshold even at 80 km/h (27.37g for PLA). The assessment of head injury risk, utilizing the Head Injury Criteria (HIC) value (0.008%), indicated an almost negligible Probability of Abbreviated Injury Scale 1 (AIS1) occurrence. In conclusion, the study recommends further exploration into subconcussive impacts during Sepak Takraw ball heading to provide a comprehensive understanding of head injury risks in this dynamic sport.