Predicted Performance of an Optimized Energy-Absorbing Crashworthy Seat During Idealized and Actual Crash Pulses

Advanced computer simulation was utilized to optimize a generic vertical-load-limiting seat's energy absorber (EA) load-stroke profile to achieve acceptable lumbar axial compressive loads for a 50th percentile anthropomorphic test device (ATD) when exposed to standard military triangular test pulses. The optimized EA profiles included a constant-load type, a progressive-ramp-load type, and a progressive-step-load type. Measured accelerations from three full-scale rotorcraft crash tests were then input to the computer simulation to evaluate the three optimized EA profiles. The modeling showed that both the ramp and step load profile EA's can produce significantly shorter seat stroking distances than a fixed-load EA type without significantly increasing the peak measured ATD lumbar axial compressive loads. The modeling also showed that the lumbar axial compressive load is sensitive to the crash pulse orientation, and that optimizing an EA to pulses with combined forward and vertical loading based solely on the peak ATD axial lumbar load may lead to excessive vertical acceleration levels. Other common injury criteria, including acceleration-duration exposure and Dynamic Response Index (DRI), are also presented for all modeling cases.