Cricket neck guards: An investigation into testing methods

2018-08-06T09:37:59Z (GMT) by Chris Peploe Ben W. Stone Andy Harland
This report documents an investigation into potential testing methods for cricket neck guards, and an initial assessment of existing neck guard performance when subjected to the recommended tests. Three primary tests were conducted; 1) Impact from a drop tower 2) High-speed ball impacts against a rigid plate 3) High speed ball impacts against a freely suspended compliant head model. Results and observations allowed direct comparison between tests, and informed recommendations to be made. Impacts made using the drop tower were considered to be poor representations of those to which the neck guards would be subjected in play and therefore an inappropriate test to determine their efficacy. Both projected ball tests were considered to represent more appropriate methodologies, although each had notable advantages and disadvantages meaning neither should be considered ideal. It is therefore concluded that, of the options considered, ball impacts against a rigid plate offer the best testing solution, since they allow the neck guard specimens to be subjected to impacts from balls of suitable mass travelling at match realistic speeds and permit measurements such as time resolved reaction force and total contact time to be taken. Whilst the geometry and compliance of the plate do not represent the human neck as closely as the head model, the ability to measure reaction force and contact time – which has been shown to relate well to contact times measured from impacts with the head form – make it the preferred option. However, the construction of one particular neck guard, made it difficult to be tested against a flat plate. Given its much improved performance when assessed using the head model, it is likely that the flat plate test does not fairly assess its true protection performance. Given this situation, two possible considerations should be made when determining whether a flat plate test is appropriate; firstly that the manufacturer concerned may feel unfairly prejudiced against and may seek to recover any development costs should their product be deemed unsuitable for testing, and secondly, that such a test method would restrict the range of designs that manufacturers might consider in future. The measures taken during flat plate impacts allow each neck guard product to be assessed. Assuming that a lower peak force and longer contact duration were preferable characteristics of an effective neck guard (consistent with literature and other test standards), two neck guards appear to outperform the others. Consideration should be made as to which ball is used in testing, since when tested using a new cricket ball (as opposed to a polyurethane BOLA training ball), the difference between the more effective neck guards and the others was amplified. Despite of the results allowing relative comparison between neck guards to be made, an absolute measure of effective protection is not currently available, making it impossible to propose a clear passfail criteria. However, to assist with any determination of acceptable performance, results for NO protection, and protection of 5mm polyurethane and 15mm ethylene-vinyl acetate are included, together with 15mm of Confor foam (the material used to line cockpits of formula 1 cars). Further research is ongoing, considering alternative test methods that allow better assessment of neck injury mechanisms and the associated protective equipment and looking mores specifically at key injuries (e.g. the case of Phillip Hughes) to consider how well specifically known high risk blows might be mitigated by guards tested in a more generalised manner.