Method to measure blast overpressure exposure on military personnel using orthogonal sensor orientations

Measuring and recording blast exposure to military personnel from shoulder-fired weaponry or improvised explosive devices to correlate health outcomes like mild traumatic brain injury has been a goal for many years. To ensure overpressure is recorded, sensor manufacturers either recommend multiple sensors on different parts of the body or have integrated multiple sensors into one unit. Despite this, knowing the sensor orientation in relation to the blast source is important to know if it's a head on, side on or oblique pressure recording. This research investigates whether pressures recorded at three independent orientations in the x, y and z planes can be combined to a representative pressure that is independent of orientation. Important metrics such as peak overpressure and impulse were used to provide a full picture of the exposure measurements. Using the root mean square (RMS) formula, the results from peak pressure and impulse were combined and analyzed as a single vector pressure. Results from the RMS calculations for peak pressure show a small range (70.67 kPa to 87.91 kPa). However, the impulse RMS calculations revealed a consistent value throughout the test series, holding steadily around 33.5 ± 1 kPa.ms. Further analysis revealed that by using the exposed surface are of a sensor face, the averaged pressure values could be linearized. Enabling the calculation of a steady RMS pressure value around 71.0 ± 2.5 kPa. Compared to prior range in RMS pressure values (70.67 kPa to 87.91 kPa) the resultant calculation vastly decreased the range of reported pressure values.