Brain injury is one of the major health concerns in sport. Studying brain injury needs insight into the mechanical response of the brain to traumatic loadings. Impact tests on anthropomorphic test devices and finite element human models are used to gain insight into the mechanism of brain injury. In this research, the predicted head kinematics and brain responses of different anthropomorphic test devices and biofidelic human models in various head impacts were studied and compared to understand the mechanism of brain injury for evaluation and improvement of new bicycle helmets.
The effect of brain material models, the geometry of the head, brain-skull connection, and loading condition was investigated for a mild deceleration of the head by comparing the strain response of brain models with the strains measured using magnetic resonance imaging. The simulated strain responses from all the models agreed with the experimental peak strain locations but were lower in magnitude. The neck contributed measurably to the rotational acceleration of the head and, in turn, the brain strain.
Assessment of two methods of head impact reconstruction was performed by simulating the unhelmeted and helmeted head impacts using an anthropomorphic test device and a human model. Favorable agreement (Less than 20% difference) in the brain injury measures of the two methods was observed in all impacts while higher difference (up to 50%) in head accelerations was observed for some impacts.
The effect of the head surrogate on the performance of bicycle helmets was investigated by comparing the kinematic response and brain injury measures of two headforms at three oblique impact orientations with three helmet models. The results showed that differences in the headforms` center of gravity led to differences in headforms` rotational accelerations (up to 60%) which caused noticeable differences (an average 61%) in their brain injury measures.
A finite element model of an aluminum honeycomb helmet liner was developed and applied to oblique headform drop tests. The importance of the honeycomb liner shear strength on the performance of the helmet in mitigating head rotational acceleration was shown where a 30% decrease in the liner shear strength mitigated the head rotational acceleration by 35%.
|Advisor:||Smith, Lloyd V.|
|Commitee:||Cofer, William F., Vasavada, Anita|
|School:||Washington State University|
|School Location:||United States -- Washington|
|Source:||DAI-B 81/9(E), Dissertation Abstracts International|
|Subjects:||Mechanical engineering, Biomechanics|
|Keywords:||Anthropomorphic test devices, Brain injury, Finite element, Head impact, Head kinematics, Helmet|
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