Summary of Guardian Protective Cover Impact Testing April 5, 2011

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1 Summary of Protective Cover Impact Testing April 5, 11 Attached is the graphical data and analysis of representative impacts that occurred during testing from our tri-axial accelerometer. We used the DTS Data Acquisition Sensors for measuring the impact on the human head. This is the same device used by all major helmet companies for measuring Severity Index and Head Injury Criteria from sudden impacts on athletic and military helmets. From the graphical data it shows that the decreases the sudden G force and attenuation on the brain. The measured and calculated data makes it apparent that adding the to the outer surface of the helmet improves the Head Injury Criteria significantly. We are not suggesting that the will prevent concussions, but it appears to reduce the impact that the brain may see on multiple hits. The blue line represents the helmet tested out any additional padding. This would represent the baseline performance out the. The red lines represent the previous prototype, the halo logo, and the yellow line represents the current design the wing logo. My readings show that there were momentary spikes lower when the is attached, and overall less duration. This is shown in the graph as a brief spike at the peak of the curve. This series of testing demonstrates that the reduces the calculated Head Injury Criteria that results in brain injury. This is a brief summary of the testing. Please don t hesitate to call if you have any further questions, request further details, or would like more testing. Justin Greeley Instrumentation Engineer Oregon Ballistic Laboratories, LLC Front Side Back Max Acceleration (G s) Head Injury Criteria (HIC) Percent Improvement 31% 33% 25% is recommended that all products be field-tested. Page 1

2 The Science Behind Measuring Head Injury Criterion Acceleration Based Head Injury Criterion (HIC(g)) Although the mechanism for brain axonal injury is internal shear and tensile forces, often produced by high angular or rotational accelerations, such accelerations would be very difficult to measure and interpret. However skull fractures are usually only produced by translational accelerations, therefore translational accelerations have been proposed for the basis of an injury criterion. The severity or level of brain injury or skull fracture is a combination of both the acceleration level and the duration of that acceleration. High accelerations can be tolerated for very short durations (g for 2 msec) while lower accelerations for longer durations (8g for msec) cannot. Results from biomechanical tests have produced tolerance curves where the onset of brain injury / skull fracture is defined by acceleration plotted against loading duration. The equation best fitting the tolerance curve is acceleration to the power 2.5 multiplied by the time. In order to predict the onset of brain damage from the complex acceleration curve for the head, the Head Injury Criterion was produced, requiring computer analysis for calculation. Head Injury Criterion Equation With Abbreviations Where t1 and t2 are the initial and final times (expressed in seconds) of the interval during which the HIC attains a maximum value and a(t) is the resultant acceleration (expressed in G) measured at the head CG. The time duration (t1-t2) used in the calculation should be taken as the contact time for the impact, however, this is often very difficult to ascertain in physical evaluations using crash test dummies or headform simulators. In using HIC for assessing the potential of concussion then a maximum time duration of 15 msec should be used, which was the maximum time duration for which the original tolerance curve was developed. Longer contact time durations can be used to predict skull fracture. The highest acceleration, independent of location or direction, should be used in the Head Injury Criterion, which will therefore be the resultant acceleration measured at the heads centre of gravity. Application The Head Injury Criterion (HIC) should be used for all impacts to the head, independent of impact type or location as it is the best predictor of brain concussion. Due to difficulties in assessing exactly the location and acceleration direction, it is proposed to use the same tolerance levels for any direction of impact. is recommended that all products be field-tested. Page 2

3 8 Front Impact Old Gaurdian New is recommended that all products be field-tested. Page 3

4 Side Impact Old Gaurdian New is recommended that all products be field-tested. Page 4

5 Rear Impact Old Gaurdian New is recommended that all products be field-tested. Page 5