Pullen Amy, Kieser D C, Hooper G
University of Otago Christchurch, Christchurch, New Zealand
University of Otago Christchurch, Christchurch, New Zealand.
BMJ Mil Health. 2022 Apr;168(2):124-127. doi: 10.1136/bmjmilitary-2020-001430. Epub 2020 Mar 12.
A review of ballistic gelatin calibration standards has highlighted that data used from studies with different calibrations methods may not be able to be compared. Calibration of ballistic gelatin did not occur until the mid-1980s when Fackler recognised the deficiencies of uncalibrated gelatin. He determined that the calibration standard should be 85±5 mm of ball bearing penetration for a 180 m/s impact velocity. This study looks to improve on and optimise current ballistic gelatin calibration standards METHODS: Nine 0.177 cal (4.5 mm) spheres were fired using a Daisy Powerline air rifle at velocities between 134 m/s and 224 m/s at 25 gelatin blocks (n=225). Velocities were measured using an Model 36 Chronograph with three Model 57 screens. Depth of penetration (DoP) was measured from the entry surface to the back end of the sphere via a Mitutoyo Absolute vernier calliper.
The R-squared regression model showed that all batches had a close fit to the regression line. Using the R-squared regression model, the equation y=0.584x - 20.02 (where x is the velocity) returned a DoP of 84.918 mm for a 180 m/s impact and therefore needed minimal adjustment to align with Fackler's 85 mm DoP. The equation can be adjusted to y=0.584x - 20.12 to return a DoP of 85 mm for 180 m/s.
We propose that the calibration standard of ballistic gelatin with 4.5 mm spheres is DoP=0.584x - 20.12 where DoP is the depth of penetration (mm) and x is the impact velocity (m/s), The measured DoP should be within 5% of the calculated DoP.
对弹道明胶校准标准的回顾凸显出，来自不同校准方法研究的数据可能无法进行比较。直到20世纪80年代中期，法克勒认识到未校准明胶的缺陷后，才开始对弹道明胶进行校准。他确定，对于180米/秒的撞击速度，校准标准应为滚珠穿透深度85±5毫米。本研究旨在改进和优化当前的弹道明胶校准标准。方法：使用黛西动力线气步枪以134米/秒至224米/秒的速度向25个明胶块（n = 225）发射9颗0.177口径（4.5毫米）的球体。使用带有三个型号57屏幕的36型计时仪测量速度。通过三丰绝对游标卡尺从球体的入射表面到后端测量穿透深度（DoP）。
R平方回归模型表明，所有批次的数据点都与回归线拟合紧密。使用R平方回归模型，方程y = 0.584x - 20.02（其中x为速度）得出，对于180米/秒的撞击速度，穿透深度为84.918毫米，因此只需进行最小调整即可与法克勒的85毫米穿透深度标准对齐。该方程可调整为y = 0.584x - 20.12，以便在180米/秒时返回85毫米的穿透深度。
我们建议，对于4.5毫米球体的弹道明胶校准标准为DoP = 0.584x - 20.12，其中DoP为穿透深度（毫米），x为撞击速度（米/秒），测量得到的DoP应在计算得到的DoP的5%以内。
