Please see the paper for additional information. The following is posted for your convenience:
SMAC EQUIVALENT DELTA-V:
In the original form of the SMAC computer program, the speed-change for a given acceleration exposure was determined by the integration of the resultant acceleration. For each time increment, a resultant acceleration was determined by the vector sum of the x and y components of the vehicle accelerations:
- Where:
- ac = resultant acceleration, g-units
ax = acceleration in the vehicle x direction, g-units
ay = acceleration in the vehicle y direction, g-units
- ac = resultant acceleration, g-units
- The resultant speed-change was determined by integration of the resultant acceleration from initial contact to separation.
- The initial contact is defined as the first instance where the resultant acceleration goes above 1 g-unit.
- The point of separation is defined as the first time that the acceleration again drops back below 1 g-unit.
- It was assumed that in general handling maneuvers and vehicle spinouts that the resultant acceleration would normally be below 1 g-unit (given that the nominal friction coefficient of roadways is normally less than 1 g-unit).
- The Direction of Principle Force (DOPF) was determined for a given acceleration exposure in the SMAC program as the direction of the acceleration at the instance of peak resultant acceleration by:
- For the reported RICSAC full-scale tests the analysis of the accelerometer data to determine the vehicle speed-change consisted primarily of the integration of the vehicle ax & ay accelerometer traces separately to determine the time histories of velocities in the x & Y directions.
The velocity time-history plots were then analyzed to determine the magnitude of the changes in the individual velocity components:- DeltaVx and DeltaVy .