The aging population is expected to increase substantially in the future. The fatal crash rates (per mile traveled) involving older
drivers (65+) are considerably higher than those of younger drivers. This research involved conducting computational experiments involving
dummy models to investigate the biomechanics of older drivers in vehicular crashes. Before conducting these experiments, the concepts of
biological changes in older populations needed to be addressed. This allowed us to first find out what makes the older drivers different from
younger drivers. It was found that driving posture is one of the two key differences between the two age groups. The Hybrid III computational
dummy model was used to investigate the effect of driving posture. The other key finding shows that older drivers are affected by aging
factors such as material properties decrease and thickness decrease of bones. The Total Human Model for Safety (THUMS) was used because it
can be modified to represent an aged driver to be used in the crash simulations. For the posture investigation, the idea is that driving
posture for older drivers tend to be closer to the steering wheel whereas younger drivers are more laid back was incorporated. All
computational work was completed in LS-DYNA; a finite element code used for non-linear impact analysis. The Finite Element (FE) simulation
was validated by comparing the FE results with physical crash test results. These results were found in the Federal Motor Vehicle Safety
Standards and Regulations (FMVSS) Report 208 for Frontal Crash Test. For subsequent simulations, posture changes based on the idea of aging
according to literature review were implemented. For the Head Injury Criteria, the extended shoulders of an older driver yielded percent
differences as high as 16%. The arms acted like braces to restrain the torso while the head continued forward. The extended knees also
yielded a 16% increase in head injury. As for the chest acceleration, the extended hip and torso joints showed increased values. It was
concluded that sitting closer was beneficial for the Head Injury Criteria but the opposite was true for the chest acceleration. The posture
changes did not affect the pelvis acceleration. This investigation gave us a better understanding of what occurs in automobile accidents
specific to older occupants. This knowledge can be useful in designing engineering approaches to mitigate injuries. Using the aged model, the
material properties decrease yielded the highest chest deflection of 13.3%. For the bone thickness decrease, the chest acceleration showed
the highest increase of 12.5%. The head acceleration and chest deflection showed noticeable increases. Overall with all three aging factors
in place, the head and chest accelerations yielded high increases. Whereas for the deflection, it remains the same. The thoracic rotation
increased the head resultant acceleration. The rotation decreased the deflection of the thorax because the ribs were more in line with the
force imposed by the crash. It can withstand more force when the ribs are more parallel with the force. As for the chest acceleration, no
significant change was present. It can be concluded that the older drivers in rear impacts experienced higher (Neck Injury Criterion) NICmax
than younger drivers as much as 6.9% percent for the material property decrease and bone thickness decrease. The thorax rotation yielded a
4.7% decrease in NICmax. It is possible that this aging factor caused the thorax to conform more into the seatback thus reducing the injury.
The bone thickness decreased affected the NICmax greatly whereas the material property decreased did show signs of minimal positive
influence. The material property decreased yielded 0.8% increase while the thickness decreased yielded a 3.0% increase. / A Dissertation submitted to the Department of Civil and Environmental Engineering in partial fulfillment of
the requirements for the degree of Doctor of Philosophy. / Fall Semester 2017. / November 8, 2017. / Includes bibliographical references. / Sungmoon Jung, Professor Directing Dissertation; Changchun Zeng, University Representative; John
Sobanjo, Committee Member; Kamal Tawfiq, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_604965 |
| Contributors | Fung, Kakit (author), Jung, Sungmoon (professor directing dissertation), Zeng, Changchun (Chad) (university representative), Sobanjo, John Olusegun, 1958- (committee member), Tawfiq, Kamal Sulaiman (committee member), Florida State University (degree granting institution), FAMU-FSU College of Engineering (degree granting college), Department of Civil and Environmental Engineering (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, doctoral thesis |
| Format | 1 online resource (104 pages), computer, application/pdf |
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