TY - JOUR T1 - Effect of ageing on the calibration of ballistic gelatin JF - Journal of the Royal Army Medical Corps JO - J R Army Med Corps SP - 277 LP - 280 DO - 10.1136/jramc-2018-000924 VL - 164 IS - 4 AU - Jason Guey AU - S Rodrigues AU - A Pullen AU - B Shaw AU - D C Kieser Y1 - 2018/08/01 UR - http://militaryhealth.bmj.com/content/164/4/277.abstract N2 - Purpose Ballistic gelatin is commonly used as a validated surrogate for soft tissue during terminal ballistic testing. However, the effect of a delay between production and testing of a gelatin mould remains unknown. The aim of this study was to determine any potential effects of ageing on ballistic gelatin.Methods Depth of penetration (DoP) of 4.5 mm spherical fragment simulating projectiles was ascertained using mixtures of 10%, 11.25% and 20% Type A 250 Bloom ballistic gelatin. Testing was performed daily for 5 days using velocities between 75 and 210 m/s. DoP at day 5 was statistically compared with day 1, and net mass change was recorded daily.Results No significant difference was found for DoP observed with time in any of the samples (P>0.05). Spearman correlation was excellent in all moulds. The moulds with known standard calibrations remained in calibration throughout the study period. Mass loss of less than 1% was noted in all samples.Conclusion Mass loss was the only quantifiable measure of changes in the blocks with time, but did not correlate with any changes in DoP. This may provide reassurance when undertaking such testing that an inadvertent delay will not significantly alter the penetration properties of the mould. Future research is recommended to determine any potential effect on the mechanical properties of gelatin at higher velocity impacts and whether the calibration corresponds to an adequate simulation under such conditions. ER -