Virtual human crash model is no dummy
Safety engineers have come a long way in understanding the biomechanical response of the human body to automobile crash loading. But even the bio-fidelity of today's crash test dummies is still limited. "If you design a car based on dummy response," says WSU Bioengineering Professor King Hay Yang, "you're going to design a car that is good for dummies, but not necessarily for humans."
Computer models developed by Yang and fellow researchers at the WSU Bioengineering Center attempt to predict injuries suffered by occupants in automobile accidents. While crash test dummies are designed for impact assessment in only one direction, the computer model can be used for measuring omni-directional loads and responses, says Yang.
Recently the Wayne State brain model was validated against re-enactments of 'real world' crashes of which the injury outcomes were known. The tests were conducted at the proving ground of General Motors Holden in Australia. Yang says he traveled to Australia because it is one of the few suitable places in the world where the most expert bioengineering research features could be easily assembled - accident collation provided by the Monash University Accident Research Center, side-impact expertise provided by Holden, and the biomechanics provided by Wayne State.
The tests, the first of their kind, were covered in a television documentary aired by the Australian Broadcasting Company late last year entitled "High Speed Impact: Anatomy of a Crash". The documentary covered the work of the Wayne State, GM Holden and MUARC engineers as they forensically pieced together a one-car accident involving an Australian woman who suffered serious brain injuries when her car collided with a tree.
Developing accurate human injury models is a continuing challenge for safety researchers faced with quantifying the intricate properties and responses comprising the human body. The Wayne State brain model utilizes more than 300,000 cubes to represent the human brain. "Different properties can be applied to each individual cube, depending on whether they comprise gray or white matter, or lie in the right or left hemisphere, or in the brain stem," says Yang.
Yang and his research team use data from various sources to identify the mechanism of injuries to the brain. One is from studies by WSU Bioengineering Center researcher Warren Hardy, who uses a high-speed three-dimensional X-ray technique to quantify the relative displacements between the skull and brain when a cadaver head is impacted from different directions. Additionally, data from studies conducted by fellow researcher Liying Zhang on concussions sustained by National Football League players is also used to calibrate the brain models.
For the Australian tests, identical vehicles were equipped with crash test dummies and launched with the same speeds and angles of impacts of the original accidents. The accelerations measured by the crash test dummies were used as input to the Wayne State computer brain model.
"The outcomes predicted by the computer model compared against this case of real-life injuries of the occupants were very close," says Yang. Once all six Australian tests are accurately re-created based on data recorded by police and photos of the cars involved, "We can use patient data collated by MUARC from the hospital to judge if a computer model predicts similar injuries," he adds.