title: Effects of Initial Seated Position on Whiplash in Low Speed Rear-End Impacts Comparison and Study Using the TNO Rear Impact Dummy (TRID) Model	
Creators: name: Venkataramana, Manjunath P.
Publisher: name: Old Dominion University
publisherIdentifier: https://ror.org/04zjtrb98
publisherIdentifierScheme: ROR
Year: 2004

description: Despite numerous investigations devoted to its scrutiny, injury causing mechanism associated with rear-end impact collision producing injury such as Whiplash Associated Disorder (WAD) has remained a mystery. Several criteria have been proposed to predict the injury causing mechanism, but none have been universally accepted. The challenge lies in determining a set of testing procedures representative of real-world collisions, wherein the results obtained are not only the same as human testing, but remain consistent with various subjects and impact conditions. It is hypothesized that one of the most important considerations is the effect of initial seated position (ISP).

This thesis can be divided in two parts that evaluates the effects of ISP during rear end impact. The first part involves the comparison of head acceleration results of computer simulation using Hybrid III TNO rear impact dummy (TRID) to physical impact testing (PIT) of humans. The second part involves the analysis of whiplash injury parameters using computer simulation studies.

In PIT, a total of 17 rear-impact tests were conducted with a nominal 8-km/hour change in velocity to 5 subjects in four different seated positions comprising of a normal position (NP) and three out of positions (OOP). The first position was a NP, defined as torso against the seat back, looking straight ahead, hands on the steering wheel and feet on the floor. The second position was a head flex position (HFP), defined as the normal position with head flexed forward approximately 20 degrees. The third position was a torso lean position (TLP), defined as the normal position with torso leaned forward approximately 10 degrees away from the seat back. Lastly, a torso lean head flex position (TLHFP), defined as the normal position with the head flexed forward approximately 20 degrees and torso leaned forward approximately 10 degrees.

The PIT resultant head acceleration plots reveal that for the third and fourth positions (TLP and TLHFP) when the subject torso leaned forward, the peak head acceleration for the subject decreased and there was also a delay in reaching the peak. The Hybrid ill-TRID anthropomorphic test dummy (ATD) was used in the same four ISP using computer simulation software Mathematical Dynamic model (MADYMO 6.0) and the head acceleration results were compared to PIT. The comparison demonstrates that the Hybrid ill-TRID ATD with MADYMO can be a reliable testing procedure during low-speed rear end impact for the four ISPs considered since the head acceleration plots deviated within the range of PIT head acceleration plots for different human subjects. With this as basis, the second part therefore had an analysis of the neck injury parameters such as Neck Injury Criterion (NIC), Neck Injury Predictor (ND), neck forces and moments using the simulation study. It was also seen that MADYMO simulation results have greater errors when compared to PIT with more OOP conditions applied to the TRID (TLHFP). All these observations would help in providing a tool to understand the injury mechanisms better and provide an accurate testing procedure for rear end impact.