Representative testing of personal protection equipment
thesisposted on 03.06.2014, 15:21 by P.J. Walker
The purpose of the work reported within this thesis was to design and implement a series of tests which better replicate the impact conditions experienced during a game, and allow for quantitative measurements of performance of various items of personal protection equipment (PPE). The sports of cricket and taekwondo were used as case studies. The aim was to improve on existing testing protocols making them more representative of real life, an approach that has not been previously attempted in the literature and so required design of multiple items of novel equipment. A representative cricket impact test was developed utilizing a ball canon firing a cricket ball mass at an equivalent bowling velocity of 31 m/s (70 mph) and a novel, freely suspended force acquisition system with embedded accelerometers from which the transmitted force values could be derived. Throughout the testing secondary variables of coefficient of restitution (COR), deformation and contact time were measured from high speed video footage to give further insight into the impact mechanics of the three tested leg guards. Contact times were in the range of 3 ms - 4 ms, COR between 0.38 - 0.50 and deformation between 45 mm - 52 mm. These results were compared against other benchmark tests to establish how close the representative test was to an actual human related ball-pad impact and to estimate human tolerance levels to impact. A rig to mimic a human on human kicking impact in taekwondo was designed to measure performance of the piece of body protection equipment used in training and competition, commonly referred to as a hogu. Primarily a mechanical simulator was designed to replicate the speed and mass of a human leg impacting during a roundhouse kick. A force acquisition system was manufactured, capable of integrating with the kicking robot functioning, with a human torso sized and shaped anvil, using a similar accelerometer based system of force measurement as that introduced in the cricket testing. This test was then used to measure performance levels of nine off-the-shelf hogus and protective training pads. Using transmitted peak force and time to peak force (TTPF) as indicators of protection, these values were found to range from between 0.5 kN 7.5 kN and 9 ms - 23 ms across the pads indicating a major difference in the protection provided.
ESPRC and partner funded
- Mechanical, Electrical and Manufacturing Engineering