Numerical modelling currently cannot accurately reproduce the onshore-offshore transport asymmetry observed on gravel beaches. The role of the impulsive pressure response generated by plunging waves has been hypothesised to aid mobilisation of sediment, and thus may contribute to transport asymmetry. This process is not currently included in models. Laboratory tests were conducted across a range of wave conditions to investigate the role of plunging wave-breaker impacts on the mobilisation of sediment of gravel beaches. Pressure records were obtained at positions close to the plunging impact locations, to monitor the localised pressures that lead to sediment mobilisation. The correction of the recorded pressure to the bed surface, for further analysis, was achieved through a two stage approach. Adoption of a new technique for separating the pressure records into two components, each determined by different processes is presented. Each component is then corrected to the bed surface with the application of a pragmatic prediction of the experienced attenuation. Data covering a wide range of Iribarren values was assessed, and the impact pressure was parameterised against the wave-breaker type. This procedure identified a potential peak in the impact pressure-Iribarren space in the plunging breaker region, consistent with the previous hypothesis. Comparison of cross-shore profile records provides further limited evidence that morphological prediction fails to reproduce specific characteristics associated with profiles generated under plunging breaker action. Finally, a brief discussion is provided on how the role of the additional pressure generated under plunging impacts can be incorporated into future numerical models.

Every year in the United States, an estimated 1.6 to 3.8 million people sustain sports-related traumatic brain injuries (TBIs), with an appreciable number of these injuries coming from the sport of softball. Several studies have analyzed the impact performance of catcher’s masks within the context of baseball; however, virtually no studies have been performed on fielder’s masks within the context of softball. Thus, the main objective of the present work was to evaluate the protective capabilities of softball fielder’s masks. To better understand the injury mechanisms and frequency associated with softball head/facial injuries, epidemiological data from a national database was reviewed first. Results displayed “struck-by-ball” as the most frequent injury mechanism (74.3%) for all head/facial injuries with a large majority occurring to defensive players (83.7%). With further motivation, the present work focused on testing the impact attenuation and facial protection capabilities of fielder’s masks from softball impacts. Testing with an instrumented Hybrid III headform was conducted at two speeds and four impact locations for several protective conditions: six fielder’s masks, one catcher’s mask, and unprotected (no mask). The results showed that most fielder’s masks reduced head accelerations, but not to the standard of catcher’s masks. On average, they reduced peak linear and angular acceleration from 40-mph impacts by 36-49% and 14-45%, respectively, while for 60-mph impacts they were reduced by 25-42% and 13-46%, respectively. Plastic-frame fielder’s masks were observed to allow facial contact when struck at the nose region at high speed. Observed differences in impact attenuation across fielder’s mask designs further suggested influence from specific design features such as foam padding and frame properties. Overall, the results clearly demonstrate that head/facial injuries may be mitigated through the broader use of masks, while further optimization of impact attenuation for fielder’s masks is pursued.

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